WO2023053113A1

WO2023053113A1 - Rotatable submersible filtration systems

Info

Publication number: WO2023053113A1
Application number: PCT/IL2022/051024
Authority: WO
Inventors: Ofer TALMI; Yoel BAHAHLUL; Oded Elish
Original assignee: Yamit Filtration And Water Treatment Ltd.
Priority date: 2021-09-30
Filing date: 2022-09-28
Publication date: 2023-04-06
Also published as: IL286881A

Abstract

The present invention relates to rotatable filtration systems that include partially or fully submersible rotatable filtering assemblies defining filtration apertures small enough to prevent passage of small particulates therethrough.

Description

ROTATABLE SUBMERSIBLE FILTRATION SYSTEMS

FIELD

[001] The present invention relates to rotatable filtrations systems that include partially or fully submersible rotatable filtering assemblies defining filtration apertures small enough to prevent passage of small particulates therethrough.

BACKGROUND

[002] Water pump systems can be used to draw water from a natural water supply source for various uses. The water supply source can be a river, a lake, the sea, a pond, and the like. Various impurities and debris residing within such a natural water supply source can pass through standard water pumps during pumping, resulting in clogging, slow water flow and can eventually damage the pumps. Additionally, undesired impurities entering the water pump systems may harm other components of these systems, thereby damaging the filter system incorporated therein. These impurities may include particles and debris (such as wood, plants, rocks, algae, and the like) and small microorganisms (such as small fish).

[003] One typical method of protecting conventional water pump systems is the utilization of submerged pre-filter systems placed in line ahead of the pump to prevent large quantities of undesired particles and/or small organisms from entering the pump’s intake pipe. These prefilter systems usually include a filter mesh barrier (such as a porous structure or a net for size filtering) surrounding the pump intake pipe, adapted to prevent large particles and/or organisms from entering the pump intake pipe. An example of such a standard system is a pre-pump strainer.

[004] Various pre-filter and filter systems have been previously disclosed. For example, US Pat. No. 8800496 discloses a water circulation pump pre-filter unit (PFU), which is submerged and comprises at least two cleaning mechanisms, wherein the PFU can include mesh screens that act as filtering surfaces. US Pat. No. 7513993 discloses a fluid filter apparatus that uses particulate to filter water in a pool or spa, the fluid filter apparatus comprising at least one porous body. US App. No. 2021/0129053 discloses a pre-filter system that can include a filter portion comprising pipes having apertures, elbows, and tees, wherein the apertures of at least some of the pipes can be covered with a mesh netting.

[005] Pre-filtering is usually performed for prevention of relatively large particle or small organisms from entering into the system, while separate additional filters are further required down the line prior to utilization of the pumped water. Filtration of the water to a desired final quality at the water source itself will require very fine mesh densities which tend to get clogged quickly in such natural environments, and will therefore require frequent maintenance to clean or replace the clogged meshes or other filtering mediums, making this process impractical and costly for ongoing utilization.

[006] Self-cleaning filters are also known in the art for reduction of maintenance costs, but most of the conventional self-cleaning mechanisms are utilized within filters residing in pressure chambers, for example by applying backwash mechanisms to remove accumulated particles from the surface or volume of the filtering medium. Pressurized filter assemblies are usually utilized on-shore and not within natural water sources, as the pressure chamber encompasses the filtering medium and blocks any passage of the surrounding water into the filter medium.

[007] US Pat. No. 7670482 discloses a rotatable drum filter which can be partially submerged in a shallow water source such as a river, such that water can flow into the drum through a portion of the screen submerged in the water, and debris accumulated on the screen can be washed away by a plurality of internal spray nozzles, spraying cleaning water at the portion of the mesh which is above the water level to dislodge such debris. US Pat. No. 8652324 discloses a similar drum filter in which more than half of the screen is submerged.

[008] Such solutions are mainly disclosed for filtering irrigation water, as the screen mesh density and aperture size are still limited and cannot be fine enough without clogging the screen too frequently. The drums are rotated at angular speeds high enough to improve rate of water intake. However, the higher the angular speed of rotation, the more clogged the screen is going to be, such that even the spray nozzles may not provide a sufficient solution and may still require additional frequent maintenance.

[009] Some of the previously disclosed drum-type filters are rotated by means of external jets of water impinging against outwardly extending ribs formed around the drum. Such solution may be sufficient to facilitate rotational movement of the drum, in implementations in which fine control of the angular speed of rotation is of limited importance, as the external jets hit against circumferentially spaced ribs, while the portions of the drum between adjacent ribs is not as affected by these jets, which in turn can cause the drum to rotate at varying angular speeds due to the difference between impinged and non-impinged portions of the drum. Moreover, in such implementations that include outwardly extending radial ribs, the ribs may forcibly hit the water surface in a manner that disturbs the water in the vicinity of the mesh filter, wherein such disturbances of the water may increase filtride accumulation over the filter medium, necessitating increased efforts for ongoing or periodical filtride removal. Finally, some implementations for such suggested devices include reliance on the surrounding water flow to rotate the drum, instead of a motor. While such solutions may occasionally obviate the use of an additional motor, the angular speed of rotation is not controlled and may again result in a high rate of debris accumulation that limits the mesh density and size of apertures.

[010] There is a need in the industry for improved filtering systems that can provide submillimeter filtration quality at the source of the natural water source, employing self-cleaning mechanism and modes of operation that will significantly reduce maintenance costs.

SUMMARY

[Oil] The present disclosure is directed toward filtration systems that include a rotatable filtering assembly that can be partially or fully submerged within a water source, wherein the filtering assembly includes a filter medium having apertures with sub-millimeter size for very fine filtering at the source of the water.

[012] In one representative embodiment, there is provided a filtration system comprising at least one rotatable filtering assembly. The at least one rotatable filtering assembly comprises at least one rotatable support wall configured to rotate around a main axis, and a filter medium coupled to the at least one rotatable support wall. The filter medium comprises a plurality of medium apertures that comprise a plurality of filtration apertures.

[013] The filtration system further comprises an intake pipe defining a minimal intake pipe cross-sectional area. The intake pipe comprises at least one pipe inflow opening in fluid communication with the filter medium. [014] The filtration system further comprises a watertight drive motor in mechanical communication with the at least one rotatable filtering assembly, and a watertight controller for controlling the watertight drive motor to rotate the at least one rotatable filtering assembly around the main axis, the angular speed of rotation not exceeding 6 degrees per second at any moment when the watertight controller is in a filtering mode.

[015] In another representative embodiment, there is provided a filtration system comprising at least one rotatable filtering assembly, an intake pipe and a spray assembly. The at least one rotatable filtering assembly comprises two rotatable support walls configured to rotate around a main axis, and a screen mesh extending between and coupled to the two rotatable support walls. The screen mesh comprises a plurality of medium apertures.

[016] The intake pipe comprises at least one pipe inflow opening in fluid communication with the screen mesh. The screen mesh defines an internal space between an inner surface thereof and the intake pipe. The spray assembly comprises a spray conduit, one or more flexible portions extending from the spray conduit and in fluid communication therewith, and at least one nozzle residing in the internal space. Each nozzle is attached to an end of a corresponding one of the one or more flexible portions.

[017] In another representative embodiment, there is provided a filtration system comprising at least one rotatable filtering assembly, an intake pipe, a spray assembly, a cleaning fluid line, and an air or gas release mechanism. The at least one rotatable filtering assembly comprises two rotatable support walls configured to rotate around a main axis, and a screen mesh extending between and coupled to the two rotatable support walls. The screen mesh comprises a plurality of medium apertures.

[018] The intake pipe comprises at least one pipe inflow opening in fluid communication with the screen mesh. The screen mesh defines an internal space between an inner surface thereof and the intake pipe. The spray assembly comprises a spray conduit, and at least one nozzle attached to the spray conduit and in fluid communication therewith. The at least one nozzle resides in the internal space.

[019] The cleaning feed line is fluidly connected to the spray conduit, and is configured to deliver compressed air or gas to the spray conduit. The air or gas release mechanism comprises a baffle residing within the screen mesh and a release tube. The baffle extends from a circumference of the screen mesh to an opening of the release tube. The release tube extends from the baffle and beyond at least one of the rotatable support walls.

[020] In another representative embodiment, there is provided a rotatable filtering assembly, an intake chamber, an intake pipe, a watertight drive motor and a watertight controller. The rotatable filtering assembly comprises a rotatable support wall configured to rotate around a main axis, and a plurality of filtering sub-assemblies attached to the rotatable support wall. The filtering sub-assemblies are revolvable around the main axis. Each revolvable sub-assembly comprises a filter medium that comprises a plurality of medium apertures.

[021] The intake chamber is defined between the rotatable support wall and a stationary wall portion. The intake pipe comprises at least one pipe inflow opening in fluid communication with the intake chamber. The watertight motor is in mechanical communication with the rotatable support wall. The watertight controller is for controlling the watertight drive motor to rotate the rotatable support wall around the main axis.

[022] In another representative embodiment, there is provided a filtration system comprising a frame comprising at least one frame transverse wall, at least one rotatable filtering assembly attached to the frame, and an intake pipe. The at least one frame transverse wall comprises at least one wall window. The at least one rotatable filtering assembly comprises at least one rotatable support wall configured to rotate around a main axis, and a filter medium coupled to the at least one rotatable support wall. The filter medium comprises a plurality of medium apertures. The intake pipe comprises at least one pipe inflow opening in fluid communication with the filter medium. The at least one window is at least partially facing the filter medium.

[023] In another representative embodiment, there is provided a filtration system comprising at least one rotatable filtering assembly, an intake pipe, and at least one adjustable float. The at least one rotatable filtering assembly comprises at least one rotatable support wall configured to rotate around a main axis, and a filter medium coupled to the at least one rotatable support wall. The filter medium comprises a plurality of medium apertures.

[024] The intake pipe comprises at least one pipe inflow opening in fluid communication with the filter medium. The at least one adjustable float is configured to control the buoyancy of the rotatable filtering assembly, relative to a water level of a water source, when the rotatable filtering assembly is at least partially submersed within the water source. [025] In another representative embodiment, there is provided a filtration system comprising a vertical column, at least one frame movable along the vertical column, at least one rotatable filtering assembly coupled to the at least one frame, an intake pipe, and a height adjustment assembly. The at least one rotatable filtering assembly comprises at least one rotatable support wall configured to rotate around a main axis, and a filter medium coupled to the at least one rotatable support wall. The filter medium comprises a plurality of medium apertures. The intake pipe comprises at least one pipe inflow opening in fluid communication with the filter medium. The height adjustment assembly is configured to elevate or lower one or more of the at least one rotatable filtering assemblies along the vertical column.

[026] In another representative embodiment, there is provided a filtration system comprising a frame, a plurality of filtering sub-assemblies attached to the frame, an intake pipe, and at least one drive motor. Each rotatable filtering assembly comprises two rotatable support walls configured to rotate around a main axis of the corresponding filtering sub-assembly, and a screen mesh extending between and coupled to the two rotatable support walls. The screen mesh comprises a plurality of medium apertures. The intake pipe comprises at least one pipe inflow opening in fluid communication with the filter medium. The at least one drive motor is in mechanical communication with at least one of the plurality of filtering sub-assemblies.

[027] In another representative embodiment, there is provided a filtration system comprising at least one rotatable filtering assembly an intake pipe, a drive motor, a controller, and a camera. The at least one rotatable filtering assembly comprises at least one rotatable support wall configured to rotate around a main axis, and a filter medium coupled to the at least one rotatable support wall. The filter medium comprises a plurality of medium apertures.

[028] The intake pipe comprises at least one pipe inflow opening in fluid communication with the filter medium. The drive motor in mechanical communication with the at least one rotatable filtering assembly. The controller is for controlling the drive motor to rotate the at least one rotatable filtering assembly around the main axis. The configured to acquire images of at least a portion of the filter medium.

[029] The various innovations of this disclosure can be used in combination or separately. This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. The foregoing and other objects, features, and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE FIGURES

[030] Some embodiments of the invention are described herein with reference to the accompanying figures. The description, together with the figures, makes apparent to a person having ordinary skill in the art how some embodiments may be practiced. The figures are for the purpose of illustrative description and no attempt is made to show structural details of an embodiment in more detail than is necessary for a fundamental understanding of the invention. For the sake of clarity, some objects depicted in the figures are not to scale.

In the Figures:

[031] Fig. 1A shows a view in perspectives of one example of a drum-type filtration system.

[032] Fig IB. shows an enlarged view of zone IB indicated in Fig. 1A.

[033] Fig. 2 shows a view in perspective of an exemplary filtration system with a pump.

[034] Fig. 3 shows a partial sectional view of an exemplary drum-type filtration system.

[035] Fig. 4 shows a partial view in perspective of a portion of an exemplary drum-type filtration system.

[036] Fig. 5 shows a partial view in perspective of an exemplary drum-type filtration system with adjustable floats.

[037] Fig. 6 shows a partial view in perspective of an exemplary drum-type filtration assembly with partially exposed wall windows.

[038] Fig. 7 shows a partial view in perspective of an exemplary drum-type filtration system exposing components of an optional gear train of a transmission assembly.

[039] Fig. 8 shows an exemplary drum-type filtration system with an immersion depth marking. [040] Fig. 9 A shows a view in perspective of an exemplary filtration system with an anchoring structure.

[041] Fig. 9B shows a view in perspective of an exemplary filtration system having its rotatable filtering assembly immersed in a water source, and ground to the shore via anchoring structure.

[042] Fig. 10 shows an example of a filtration system with two rotatable filtering assembly mounted on a single frame movable along an elevation assembly.

[043] Fig. 11 shows a partial enlarged view of the filtration system of Fig. 10.

[044] Figs. 12A-B show an exemplary filtration system with two rotatable filtering assemblies independently movable along an elevation assembly, shown immersed within a water source and above the water source level.

[045] Fig. 13 shows an example of a filtration system with a rotatable filtering assembly coupled to, and optionally movable with respect to, an offshore platform.

[046] Fig. 14 shows an example of a drum-type filtration system with a plurality of drumtype rotatable filtering assemblies arranged in a matrix configuration.

[047] Fig. 15 shows an example of a drum-type filtration system with a plurality of drumtype rotatable filtering assemblies arranged side-by-side.

[048] Fig. 16 shows an example of a drum-type filtration system with an expansion chamber.

[049] Figs. 17A-B show a view in perspective and a partial sectional view of exemplary filtration systems with vertically oriented rotatable filtering assemblies.

[050] Fig. 18A shows a view in perspectives of an example of several discs tightly pressed against each other.

[051] Fig. 18B shows the discs of Fig. 18A spaced from each other.

[052] Fig. 19 shows a partial enlarged view of two discs pressed against each other.

[053] Fig. 20 shows one example of a disc-type filtration system. [054] Fig. 21 shows a zoomed in view on a portion of the disc-type filtration system of Fig.

20, with the discs removed from one filtering sub-assembly to exposed its inner structure.

[055] Fig. 22 shows a view in perspective of an example of a disc-type filtration system, with an intake chamber shown with partial transparency.

[056] Figs. 23-25 show various views of an exemplary disc-type filtration system with some of the filtering sub-assemblies in a cleaning mode.

[057] Fig. 26 shows a partial sectional view of an exemplary disc-type filtration system.

[058] Fig .27 shows an example of a disc-type filtration system with a spray assembly.

[059] Fig. 28 shows an example of a disc-type filtration system with floats positioned above the rotatable filtering assembly.

[060] Fig. 29A shows a view in perspective of an example of a coiled thread unit.

[061] Fig. 29B shows the support blank of the coiled thread unit of Fig. 29A.

[062] Fig. 29C shows a partial view in perspective of a coiled thread unit, with a single layer of threads.

[063] Fig. 29D shows another view in perspective of an example of a coiled thread unit.

[064] Fig. 30A shows a view in perspective of a coiled thread-type filtering sub-assembly.

[065] Fig. 30B shows a sectional view of the coiled thread-type filtering sub-assembly of Fig. 30A.

[066] Fig. 31 shows one example of a coiled thread-type filtration system.

[067] Figs. 32-33 show sectional views across different cutting planes of an exemplary coiled thread-type filtering sub-assembly.

[068] Fig. 34A shows a view in perspective an example of a sheaf-like unit.

[069] Fig. 34B shows a sectional view in perspective of the sheaf-like unit of Fig. 34A.

[070] Fig. 35A shows a view in perspective of a sheaf-type filtering sub-assembly. [071] Fig. 35B shows a sectional view of sheaf-type filtering sub-assembly of Fig. 35A.

[072] Figs. 36-37 show views in perspective of one example of a sheaf-type filtration system.

[073] Fig. 38 shows a sectional view in perspective of an exemplary sheaf-type filtering subassembly.

[074] Fig. 39A-C show views in perspective of an exemplary drum-type filtration system with funneling extensions circumscribing wall windows, and with a camera mounted on a camera mount.

[075] Fig. 40 shows an example of a spray conduit with a plurality of flexible conduits extending sideways therefrom.

[076] Fig. 41 shows a view in perspective of an exemplary disc-type filtration system with a planetary transmission mechanism.

[077] Fig. 42 shows a view in perspective of an exemplary disc-type filtration system with independently rotatable filtering sub-assemblies.

[078] Fig. 43 shows a zoomed-in view in perspective of one independently rotatable filtering sub-assembly.

[079] Figs. 44A-C show an exemplary drum-type filtration system with movable floats at various positions.

[080] Figs. 45A-B show zoomed-in views of the float transmission assembly of the filtration system of Figs. 44A-C.

[081] Fig. 46 shows an example of a drum-type filtration system with a plurality of drumtype rotatable filtering assemblies vertically arranged above each other.

[082] Figs. 47A-B show an example of a drum-type filtration system with a bubble generator.

[083] Fig. 48 shows a zoomed-in sectional view of a bubble generator positioned below a drum- type rotatable filtering assembly.

[084] Figs. 49A-B show an example of a drum-type filtration system with a rectangularly- shaped guiding chamber extending upwards from a bubble generator. [085] Fig. 50 show an example of a drum-type filtration system with a frustoconical guiding chamber extending upwards from a bubble generator.

[086] Fig. 51 shows an example of a drum-type filtration system with a bubble generator comprising a plurality of hollow enclosures in fluid communication with each other.

[087] Figs. 52A-C show another example of a drum-type filtration system.

DETAILED DESCRIPTION

[088] For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The disclosed methods, apparatus, and systems should not be construed as being limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The methods, apparatus, and systems are not limited to any specific aspect or feature or combination thereof, nor do the disclosed embodiments require that any one or more specific advantages be present, or problems be solved. The technologies from any example can be combined with the technologies described in any one or more of the other examples.

[089] In view of the many possible embodiments to which the principles of the disclosed technology may be applied, it should be recognized that the illustrated embodiments are only preferred examples and should not be taken as limiting the scope of the disclosed technology. Furthermore, well-known features may be omitted or simplified in order not to obscure the disclosure. In order to avoid undue clutter from having too many reference numbers and lead lines on a particular drawing, some components will be introduced via one or more drawings and not explicitly identified in every subsequent drawing that contains that component.

[090] Although the operations of some of the disclosed embodiments are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth below. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed methods can be used in conjunction with other methods. Additionally, the description sometimes uses terms like “provide” or “achieve” to describe the disclosed methods. These terms are high-level abstractions of the actual operations that are performed. The actual operations that correspond to these terms may vary depending on the particular implementation and are readily discernible by one of ordinary skill in the art.

[091] As used herein, the terms “integrally formed” and “unitary construction” refer to a construction that does not include any welds, fasteners, or other means for securing separately formed pieces of material to each other.

[092] As used herein, operations that occur “simultaneously” or “concurrently” occur generally at the same time as one another, although delays in the occurrence of operation relative to the other due to, for example, spacing between components, are expressly within the scope of the above terms, absent specific contrary language.

[093] As used in this application and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the terms “have” or “includes” means “comprises.” As used herein, “and/or” means “and” or “or,” as well as “and” and “or”. Further, the terms “coupled” and “connected” generally mean electrically, electromagnetically, and/or physically (e.g., mechanically or chemically) coupled or linked and does not exclude the presence of intermediate elements between the coupled or associated items absent specific contrary language. As used herein, “and/or” means “and” or “or,” as well as “and” and “or”.

[094] Directions and other relative references may be used to facilitate discussion of the drawings and principles herein, but are not intended to be limiting. For example, certain terms may be used such as “inner,” “outer,” “upper,” “lower,” “inside,” “outside,”, “top,” “bottom,” “interior,” “exterior,” “left,” right,” and the like. Such terms are used, where applicable, to provide some clarity of description when dealing with relative relationships, particularly with respect to the illustrated embodiments. Such terms are not, however, intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an “upper” part can become a “lower” part simply by turning the object over. Nevertheless, it is still the same part and the object remains the same.

[095] Filtering systems disclosed herein include at least one rotatable filtering assembly which is rotatable defining a main axis Ym, and a watertight drive motor in mechanical communications with the rotatable filtering assembly, configured to rotate it around the main axis Ym. The filtration system can include, in some examples, a frame for supporting various components thereof, such as the filtering assembly and/or the drive motor.

[096] The rotatable filtering assembly comprises a filter medium, such as a screen, a stack of discs, coiled threads, sheaf-like arrangements of elongated threads, and the like, wherein the filter medium defines a medium outer surface and includes a plurality of medium apertures.

[097] The term "plurality", as used herein", means more than one.

[098] The filtering system further includes an intake pipe that defines at least one pipe inflow opening which is in fluid communication with the filter medium, and through which suction or pumping force can facilitate suction of raw water which are in direct contact with the medium outer surface, through the medium apertures, into the intake pipe through the at least one pipe inflow opening. The intake pipe can be attached to a suction line terminating at its opposite end in a suction line outlet, which can be either connected to a pump (e.g., a centrifugal pump) or alternatively, open ended if positioned at a level relatively lower with respect to the at least one pipe inflow opening, such that gravitational force can serve to apply the necessary negative pressure difference to apply suction force at the pipe inflow opening instead of a pump.

[099] The suction force, applied either by a pump or gravitational force, facilitates flow of raw water, through the filter medium, into the intake pipe, and optionally therefrom along the suction line, at an intake flow rate Q. The flow velocity V can vary at various regions of this flow path, for example depending on the cross-sectional area through which the fluid passes at each position along the flow path. The intake pipe can have a uniform or non-uniform crosssection area along its length. For example, some types of intake pipes can have a pipe expanded portion, also termed an expansion chamber, that can have a cross-section area which is significantly larger than the cross-sectional area at the region adjacent pipe inflow opening. A minimal intake pipe cross-sectional area is denoted Ap, through which a maximal pipe velocity Vp can be defined, for a given flow rate Q.

[0100] In some cases, the intake pipe can be integrally formed with the suction line. In other cases, the intake pipe can be separate component terminating at a pipe outflow opening, which can be attached in a sealed manner to a suction line, for example at a suction line inlet, by any suitable pipe coupler known in the art. Furthermore, the intake pipe can be formed from several components fluidly coupled to each other, and can also include a manifold branched into a plurality of pipe branches, each one including at least one pipe inflow opening. [0101] In some cases, the filtration system can include more than one rotatable filtering assembly, each defining its own main axis Ym around which is may rotate, wherein all filtering assemblies can be coupled to a common intake pipe, optionally branched into different pipe branches, each branch coupled to a different rotatable filtering assembly and defining at least one pipe inflow opening which is in fluid communication with the filter medium of the respective rotatable filtering assembly. Alternatively, one intake pipe can be attached, for example by passing through, a plurality of rotatable filtering assemblies, and include a plurality of pipe inflow openings, such that at least one pipe inflow opening is in fluid communication with the filter medium of the respective rotatable filtering assembly.

[0102] A single drive motor can be utilized, in some implementations, to rotate a plurality of filtration assemblies, each around its corresponding main axis Ym. Alternatively, more than one drive motor can be used to drive one or more of a plurality of filtration assemblies.

[0103] In some cases, the rotatable filtering assembly comprises at least one, and optionally more than one, revolvable filtering sub-assembly defining a sub-assembly axis Ys parallel to the main axis Ym (each filtering sub-assembly defining a separate sub-assembly axis Ys), wherein the filtering sub-assembly is configured to revolve around the main axis Ym. In the case of a plurality of filtering sub-assemblies, disposed about a circumference of the filtering assembly, all of the filtering sub-assemblies are configured to revolve around the main axis Ym. Each filtering sub-assembly comprises a filter medium, such that the filter medium of the entire rotatable filtering assembly, in such cases, refers to the combination of the filter mediums of all filtering sub-assemblies comprised therein.

[0104] Each medium aperture can define an aperture open area Aa, for example at the crosssection defined by its outermost edge or edges. The medium apertures can have any of a variety of shapes, such as circular, oval or elliptic, rectangular, and the like. Moreover, depending on the type of medium, various medium apertures can be in the form of small-sized puncture-like opening, elongated channel-like or otherwise formed opening, can define straight, curved or tortuous paths, and so on. Each medium aperture has an aperture size D defined as the narrowest distance between two ends thereof across any cross-section thereof. For example, in the case of a circular filtration aperture, the aperture size D can be its diameter. In the case of an oval or elliptic aperture, the aperture size D is defined as its smallest diameter. In the case of an elongated (e.g., slot-like) aperture, the aperture size D is defined as the distance between its elongated edges (i.e., in a direction perpendicular to the elongated dimensions of the aperture). Thus, while a circularly-shaped aperture and an elongated aperture can have an identical aperture size D, such an elongated aperture will still have a significantly larger aperture open area Aa.

[0105] The filter medium includes a plurality of medium apertures, each having an aperture open area Aa, such that the total area of medium apertures At is defined as the sum of the aperture open areas Aa of all of the medium apertures. The medium apertures comprise filtration apertures, defined as the apertures through which raw water flow from the medium outer surface toward the at least one pipe inflow opening when suction force is applied thereto. In some cases, all of the medium apertures are filtration apertures. In other cases, only a subset of the medium apertures are filtration apertures, while the remainder of the medium apertures are termed non-filtration apertures, as will be described hereinbelow.

[0106] In some implementations, the at least one filtration assembly can be partially submerged in an open water source, preferably a natural water source, such as a sea, lake, pond, river and the like. In such implementations, raw water will pass only through the portion of the filter medium submerged in the water, which will flow therefrom toward the one or more pipe inflow openings. In such cases, a subset of the medium apertures is defined as filtration apertures, which is the portion of medium apertures submerged in the water, while the remaining subset includes non-filtration apertures, through which raw water do not pass. The non-filtration apertures can be exposed, for example, to the atmosphere above the water level. Thus, an effective area of filtration Ae is defined as the sum of aperture open areas Aa of solely the filtration apertures, without the non-filtration apertures. In implementations of a filtration system including a plurality of rotatable filtration assemblies, the effective area of filtration Ae is the sum of aperture open areas Aa of the filtration apertures of all of rotatable filtration assemblies.

[0107] In some implementations, the rotatable filtering assembly is completely submerged within the water source. In some examples applied to these implementations, all medium apertures are filtration apertures, such that the effective area of filtration is equal to the total area of medium apertures, that is to say Ae = At. In other examples, the rotatable filtering assembly comprises a plurality of filtering sub-assemblies, wherein, at a given time, one or more of the filtering sub-assemblies is operating in a filtering mode, while another one or more filtering sub-assembly is operating in a cleaning mode. A filtering mode includes applying suction force through the intake pipe, operable to facilitate flow of raw water through the respective filtering medium, toward and into the intake pipe. In contrast, such suction force is ceased during a cleaning mode, during which any one of a variety of self-cleaning mechanisms, as will be described in greater detail below, serves to clean the filter medium.

[0108] In such cases, the medium apertures of a rotatable filtering assembly, that include all of the medium apertures of all of the filtering sub-assemblies, will include filtration apertures defined as the total number of medium apertures of all filtering sub-assemblies operating in a filtering mode, while the apertures of all filtering sub-assemblies operating in a cleaning mode define the subset of non-filtration apertures. The effective area of filtration Ae, in such cases, will be the sum of apertures open areas Aa of the filtration apertures, belonging solely to the filtering sub-assemblies operating in a filtering mode at any given time.

[0109] While the terms "filtering mode" and "cleaning mode" refer to mutually exclusive states that can occur, for a specific rotatable filtering assembly or a specific filtering sub-assembly, at different periods of time that do not overlap, any rotatable filtering assembly or a specific filtering sub-assembly can also have a filtering region and cleaning region, which are different regions thereof, that allow simultaneous filtering and cleaning operations to co-exists, each taking place along a different region. For example, a partially immersed rotatable filtering assembly, such as a drum-type rotatable filtering assembly, can include a filtering region defined as a portion of the filter medium submerged in the water, through which water flows toward the intake pipe, while the portion of the filter medium exposed to the atmosphere above the water level can be, at the same time, defined as the cleaning region, along which nozzles as or other self-cleaning mechanism may be employed to dislodge accumulated filtride therefrom. The term "water level", as used herein, is defined as the level of the surface of the water source when no waves are present.

[0110] Any rotatable filtering assembly or filtering sub-assembly that includes both a filtering region and a cleaning region, is termed to be in a filtering mode as long as water pass through filtration apertures of the filtering region toward the intake pipe.

[0111] A rotatable assembly can include a plurality of filtering sub-assemblies, wherein at least one of the filtering sub-assemblies is in a filtering mode and at least one other filtering subassembly is in a cleaning mode. In such cases, even if at least one of the filtering sub-assemblies is in a cleaning mode, the whole rotational filtering assembly is termed to be in a filtering mode as long as it also includes at least one filtering sub-assembly which is in a filtering mode. [0112] As mentioned above, the flow rate through the subset of filtration apertures is denoted Q, and is equal throughout the system - along any point of the flow path passing toward and through the intake pipe, for example, and is dictated by the suction force that can be facilitated by a pump of gravitation force, as described hereinabove. Since the flow rate Q is equal at any point, the flow velocity V is dictated by the area through which the water flow at any point along the path from the filter medium and up to the suction line outlet. For example, the flow velocity V will be fastest at the narrowest cross-sectional area of the intake pipe and/or the suction line. Similarly, for any specific flow rate Q, the flow velocity V will be slower as the area through which water flow at the respective region is increased. Thus, for any specific flow rate Q, the larger the effective area of filtration Ae is, the slower is the flow velocity V through the subset of filtration apertures.

[0113] Flow velocity through the filtration apertures can significantly influence the tendency of various particles, debris and particulates to cling or adhere to the medium outer surface. In fact, any disturbance to the water surrounding the filtration assembly may increase adherence of particulates to the surface of the filtration medium. It is an object of the disclosed filtration systems to minimize flow disturbance around and across the filter medium, and more specifically, around and through the filtration apertures, so as to minimize particulate adherence in the first place, instead of allowing such particulates to adhere and cleaning them from the filter medium afterwards.

[0114] While conventional filters may rely on specific self-cleaning mechanisms, such as drums equipped with nozzles configured to spray cleaning liquid that impinges against the surface of the portion of the screen exposed above the level of the water source to dislodge filtride adhered thereto, such solutions may result in suboptimal cleaning for drums that accumulate too much filtride adhered to the surface during filtering modes, especially when reducing the aperture size D to a size that is not greater than 350 microns (including being optionally not greater than 300 microns, not greater than 200 microns, not greater than 100 microns, not greater than 40 microns, not greater than 10 microns, not greater than 5 microns, and/or not greater than 1 micron). This in turn limits aperture size D of conventional filters immersed in natural water sources, which will otherwise require frequent maintenance that will render such solutions impractical. Moreover, even for apertures having aperture size greater than 350 microns, such as aperture size D in the range of 350 microns to 2 millimeters, inclusive, conventional self-cleaning mechanisms, as described above, may still result in reduced operational efficiency of the overall filtration system due to the need to constantly remove relatively significant amount of filtride accumulated over the filter medium. Thus, the unique configurations of the various examples of filtration systems disclosed herein (including systems 200, 300, 400 and/or 500 as will be described in greater detail herein below), while particularly efficient for delicate filtration sizes, can significantly improve overall operational efficiency for any size of filtration apertures.

[0115] Prevention or minimization of filtride adherence to the filter medium may obviate the need for adding self-cleaning mechanisms, or may allow for a significant reduction of the aperture size D such that even if some particulates do adhere to the filter medium, specific selfcleaning mechanisms, as will be further described hereinbelow, may be sufficient to adequately dislodge them and clean the filter medium without requiring frequent additional maintenance.

[0116] In some implementations that include a self-cleaning mechanism, the filtering assembly can transition between a filtering mode and a cleaning mode. For example, the filtering mode can last for a predefined duration of time during which raw water from the water source are filtered through filter medium, and more precisely, raw water flow through the filter medium, and the resulting filtrate flows therefrom into the intake pipe and the suction line. The cleaning mode can last for a predefined duration of time during which water is not sucked toward and into the intake pipe, for example, by actuating a valve that blocks water flow through the intake pipe or suction line, or by stopping the pump when relevant, and cleaning of the filter medium is performed by executing or actuating the self-cleaning mechanism. In such implementations, especially those that do not include separate filtering and cleaning regions, the self-cleaning mechanism is not actuated during the filtering mode, and water suction and filtration are not performed during the cleaning mode, since the forces acting in each mode may counter each other.

[0117] In alternative implementations, both filtering and cleaning can be performed simultaneously, if each is directed, for example, to act on a different region of the filter media. Specifically, some implementations of partially submerged filtering assemblies, such as partially submerged drum-type filtering assemblies, can perform filtration and cleaning at the same time, wherein filtration is performed at the filtering region, through the submerged portion of the filter medium, while spray nozzles may be utilized to spray cleaning fluid at a portion of the filter medium exposed above the level of the water source, serving as the cleaning region. [0118] One way by which the desired goal is achieved is by increasing the effective area of filtration Ae, with respect to the flow rate Q, to be large enough so as to reduce the flow velocity Ve through the filtration apertures to a value that will not disturb the surrounding water and prevent particulates from adhering to the filter medium, or at least significantly reduce their tendency to adhere.

[0119] Since the flow velocity Ve depends on the flow rate Q and the area Ae, for a maximal flow rate Qm, a minimal effective area of filtration Ae is defined such that for any area equal to or greater than Ae, and as long as the flow Q does not exceed the maximal value Qm, the resulting flow velocity Ve through the filtration apertures is low enough to significantly reduce the tendency of particulates around the filter medium to cling or adhere thereto. Thus, a minimal effective area of filtration Ae is designed for a maximal flow rate Qm, in a manner that will result in the flow velocity through the filtration apertures not exceeding maximal flow velocity threshold Ve.

[0120] Preferably, the upper flow velocity threshold Ve is selected to result in laminar flow across the filter medium, and more precisely, across the filtration apertures. In some cases, the upper flow velocity threshold Ve is designed to limit the Reynolds number in the vicinity of the submerged portion of the filter medium below a threshold level.

[0121] Since the maximal flow rate Qm is proportional to the maximal pipe velocity Vp at the minimal intake pipe cross-sectional area Ap, a minimal area ratio Ra can be defined as the ratio between the effective area of filtration Ae and the minimal intake pipe cross-sectional area Ap (i.e., Ra=Ae/Ap), applicable to achieve the same goal in the same manner described above to result in a maximal flow velocity Ve through the filtration apertures. Thus, for any given design of any filtration system disclosed herein (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification), including an intake pipe defining a minimal intake pipe cross-sectional area Ap, the effective area of filtration Ae is designed to result in a predefined minimal area ratio Ra.

[0122] As mentioned, the effective area of filtration Ae is the sum of aperture open area Aa multiplied by the total number of filtration apertures. Thus, the same Ae can be achieved either by multiplying a given number of filtration apertures, each having a relatively large Aa, or by multiplying a greater number of filtration apertures, each having a proportionally smaller Aa. It is an object of the filtration system, described in any of the examples of the current disclosure, to provide a very fine mesh density, meaning that very narrow aperture sizes are desired. Thus, it is to be understood that a minimal area ratio Ra for filtration mediums equipped with filtration apertures having a size which is greater than the maximal desired aperture size D as disclosed herein, is beyond the scope of the current disclosure.

[0123] In some examples, there is provided a filtration system defining a minimal area ratio Ra and having a maximal aperture size D. In some examples, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) comprises a filtration medium defining a plurality of medium apertures (that comprise filtration apertures), wherein the aperture size D is not greater than 350 microns, and wherein the minimal filtration ratio Ra defined by the filtration system is greater than 4, including examples in which Ra is greater than 5, greater than 7, greater than 8, and greater than 10.

[0124] In some examples, there is provided a filtration system defining a minimal area ratio Ra and having a maximal aperture size D. In some examples, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) comprises a filtration medium defining a plurality of medium apertures (that comprise filtration apertures), wherein the aperture size D is not greater than 350 microns, and wherein the minimal filtration ratio Ra defined by the filtration system is greater than 4, including examples in which Ra is greater than 5, greater than 7, greater than 8, and greater than 10.

[0125] In some examples, there is provided a filtration system defining a minimal area ratio Ra and having a maximal aperture size D. In some examples, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) comprises a filtration medium defining a plurality of medium apertures (that comprise filtration apertures), wherein the aperture size D is not greater than 300 microns, and wherein the minimal filtration ratio Ra defined by the filtration system is greater than 4, including examples in which Ra is greater than 5, greater than 7, greater than 8, and greater than 10.

[0126] In some examples, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) comprises a filtration medium defining a plurality of medium apertures (that comprise filtration apertures), wherein the aperture size D is not greater than 200 microns, and wherein the minimal filtration ratio Ra defined by the filtration system is greater than 4, including examples in which Ra is greater than 5, greater than 7, greater than 8, and greater than 10.

[0127] In some examples, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) comprises a filtration medium defining a plurality of medium apertures (that comprise filtration apertures), wherein the aperture size D is not greater than 100 microns, and wherein the minimal filtration ratio Ra defined by the filtration system is greater than 4, including examples in which Ra is greater than 5, greater than 7, greater than 8, and greater than 10.

[0128] In some examples, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) comprises a filtration medium defining a plurality of medium apertures (that comprise filtration apertures), wherein the aperture size D is not greater than 40 microns, and wherein the minimal filtration ratio Ra defined by the filtration system is greater than 4, including examples in which Ra is greater than 5, greater than 7, greater than 8, and greater than 10.

[0129] In some examples, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) comprises a filtration medium defining a plurality of medium apertures (that comprise filtration apertures), wherein the aperture size D is not greater than 10 microns, and wherein the minimal filtration ratio Ra defined by the filtration system is greater than 4, including examples in which Ra is greater than 5, greater than 7, greater than 8, and greater than 10.

[0130] In some examples, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) comprises a filtration medium defining a plurality of medium apertures (that comprise filtration apertures), wherein the aperture size D is not greater than 5 microns, and wherein the minimal filtration ratio Ra defined by the filtration system is greater than 4, including examples in which Ra is greater than 5, greater than 7, greater than 8, and greater than 10.

[0131] In some examples, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) comprises a filtration medium defining a plurality of medium apertures (that comprise filtration apertures), wherein the aperture size D is not greater than 1 micron, and wherein the minimal filtration ratio Ra defined by the filtration system is greater than 4, including examples in which Ra is greater than 5, greater than 7, greater than 8, and greater than 10.

[0132] In one example, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) can include a plurality of medium apertures having an aperture size of 300 microns and an intake pipe defining a minimal intake pipe cross-sectional area Ap of 0.03113 m², wherein the total area of medium apertures At is 0.2940 m², and the effective area of filtration Ae is at least 0.2756 m², for a minimal area ratio of 8.7. Assuming that the maximal flow rate Qm is 0.09435 m³/s, these value will result in a flow velocity Ve through the filtration apertures, that does not exceed 0.34 m/s.

[0133] In another example, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) can include a plurality of medium apertures having an aperture size of 200 microns and an intake pipe defining a minimal intake pipe cross-sectional area Ap of 0.03113 m², wherein the effective area of filtration Ae is at least 0.2205 m², for a minimal area ratio of 7. Assuming that the maximal flow rate Qm is 0.09435 m³/s, these value will result in a flow velocity Ve through the filtration apertures, that does not exceed 0.42 m/s.

[0134] In yet another example, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) can include a plurality of medium apertures having an aperture size of 100 microns and an intake pipe defining a minimal intake pipe cross-sectional area Ap of 0.03113 m², wherein the effective area of filtration Ae is at least 0.1378 m², for a minimal area ratio of 4.3. Assuming that the maximal flow rate Qm is 0.09435 m³/s, these value will result in a flow velocity Ve through the filtration apertures, that does not exceed 0.68 m/s.

[0135] In one more example, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) can include a plurality of medium apertures having an aperture size of 100 microns and an intake pipe defining a minimal intake pipe cross-sectional area Ap of 0.03113 m², wherein the total area of medium apertures At is 0.2940 m², and the effective area of filtration Ae is at least 0.2756 m², for a minimal area ratio of 8.7. Assuming that the maximal flow rate Qm is 0.09435 m³/s, these value will result in a flow velocity Ve through the filtration apertures, that does not exceed 0.34 m/s. [0136] In some examples, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) comprises a filtration medium defining a plurality of medium apertures (that comprise filtration apertures), wherein the aperture size D is not greater than 350 microns, and wherein the maximal effective area of filtration Ae is designed to result in a flow velocity Ve through the filtration apertures, that does not exceed 0.7 m/s, including examples in which Ve does not exceed 0.5 m/s, does not exceed 0.4, and does not exceed 0.3 m/s.

[0137] In some examples, a filtration system (such as any example of filtration system 200, 300, 400 and 500 disclosed in greater detail throughout this specification) comprises a filtration medium defining a plurality of medium apertures that include a minimal portion thereof that constitute filtration apertures, including examples in which at least 50% of the medium apertures are filtration apertures, at least 65% of the medium apertures are filtration apertures, at least 70% of the medium apertures are filtration apertures, at least 85% of the medium apertures are filtration apertures, and examples in which all of the medium apertures are filtration apertures (i.e., Ae=At).

[0138] A rotatable filtration assembly according to any of the examples disclosed herein, comprises at least one rotatable support wall, to which the filter medium is coupled, directly or indirectly. Some examples of rotatable filtering assemblies include a filter medium, such as a screen of mesh of a drum-type rotatable filtering assembly, which can be circumferentially disposed around main axis Ym. Other examples of rotatable filtering assemblies include one or more filtering sub-assemblies attached to the rotatable support wall, each of which includes its own filter medium defined around sub-assembly axis Ys which is offset radially away from main axis Ym, such that rotation of the rotatable support wall about main axis Ym, causes the one or more filtering sub-assemblies to revolve around the same main axis Ym.

[0139] In the case of rotatable filtration assemblies, the angular speed W of the rotatable filtration assembly is also of utter importance, as high angular speeds of rotation will also disturb the raw water surrounding the submerged portion of the filter medium, thereby increasing adherence of particulates to the filter medium. Thus, another factor of importance of the disclosed filtration systems relies on limiting the maximal angular speed of rotation W to a value that will minimize flow disturbance around and across the filter medium. It has been found by the inventors of this specification that a maximal angular speed of rotation W of 6 degrees per second can achieve this goal. [0140] A rotatable filtering assembly according to various examples of the current disclosure may rotate during a filtering mode and/or during a cleaning mode. The limitation of maximal angular speed of rotation is mainly relevant during the filtration mode, and may exceed, in some implementation, the threshold of 6 degrees per second, during the cleaning mode. As mentioned above, any rotatable filtering assembly that includes a plurality of filtering subassemblies, is termed to be, as a whole, in a filtering mode, even if any of the filtering subassemblies is in a cleaning mode. Thus, as long as at least one of the filtering sub-assemblies is in a filtering mode, the angular speed W of the rotational filtering assembly itself, should not exceed 6 degrees per second.

[0141] Filtering assemblies according to various examples disclosed herein can rotate continuously or periodically. For example, a rotatable filtering assembly can be programmed, by a controller operable to control the drive motor, to rotate continuously at a maximal angular speed of rotation of 360 degrees per minute, meaning that it will not complete a full revolution in less than 1 minute. In another example, a rotational filtering assembly can be programmed to rotate in an intermittent or otherwise periodical manner, such as rotating less than 360 degrees, ceasing rotation for a specific period of time, and them commencing rotational movement again, optionally also spanning less than 360 degrees, wherein this pattern can be repeated for any number of cycles. Such periodical rotational movement can be desired, for example, to change the angular orientation of various regions along the circumference of the filter medium with respect to main axis Ym, or to change the position of one or more filtering sub-assemblies relative to main axis Ym.

[0142] It is to be understood that in the case of periodical rotation of the filtering assembly, an upper limit of angular speed of rotation W refers solely to the period of time during which is rotates, and not to an average between rotation and non-rotation time periods. Moreover, even for implementations in which angular speed of rotation may vary, the upper threshold W refers to a limit of the maximal angular speed at any given time, and not to an average thereof. Thus, in the case rotation of the rotational filtering assembly is not continuous but rather periodical, W should not exceed an angular speed of 6 degrees per second during rotation of the rotatable filter assembly, as long as it is in a filtering mode during the rotational movement.

[0143] The filtration system can include a controller configured to control the rotational movement of the rotational filtering assembly, preferably programmed to limit the filtering assembly to a maximal angular speed of rotation W of 6 degrees per second, when the filtration assembly is in a filtering mode. Otherwise states, a filtration system can include a controller for limiting angular speed of rotation thereof to 6 degrees per second, preferably during a filtering mode. It is to be understood that the controller is also utilized to control optional transition of the filtering assembly, or any sub-assembly thereof, between filtering and cleaning modes, Thus, any reference to the filtering assembly being in a filtering mode and/or in a cleaning mode throughout the specification and the claims, similarly refers to the controller being in the filtering mode and/or in the cleaning mode, respectively.

[0144] In some examples, the filtration system includes a controller for limiting the angular speed of rotation of the rotatable filtering assembly to a maximal value of 1 revolution per minute when the filtering assembly is in a filtering mode (meaning that the controller is also termed to be in the filtering mode). In some examples, the filtration system includes a controller for limiting the angular speed of rotation of the rotatable filtering assembly to a maximal value of 6 degrees per second when the filtering assembly (and when the controller itself) is in a filtering mode. In some examples, the filtration system includes a controller for limiting the angular speed of rotation of the rotatable filtering assembly to a maximal value of 4 degrees per second when the filtering assembly is in a filtering mode. In some examples, the filtration system includes a controller for limiting the angular speed of rotation of the rotatable filtering assembly to a maximal value of 2 degrees per second when the filtering assembly is in a filtering mode. In some examples, the filtration system includes a controller for limiting the angular speed of rotation of the rotatable filtering assembly to a maximal value of 1 degrees per second when the filtering assembly is in a filtering mode.

[0145] In some examples, the controller further limits the rate of acceleration and deceleration of the rotatable filtering assembly. For example, a filtration system may include cycles of rotation and non-rotation, or cycles of lower and higher angular speeds of rotation, wherein the transition from a non-rotation or lower angular speed of rotation, to a higher angular speed of rotation, will be gradual and not abrupt. Similarly, the transition from a higher angular speed of rotation to a lower speed of rotation, or to a total halt, can be gradual and not abrupt.

[0146] It is contemplated by the inventors that the combination of a minimal effective area of filtration Ae to result in a predefined ratio Ra, combined with the control of the movement of a rotational filtration assembly not to exceed a maximal angular speed of rotation as described above, results in favorable water stability in the vicinity of the submerged portion of the filter medium during filtering mode, sufficient to minimize adherence of particulates to the surface of the filter medium, which in turn will reduce maintenance requirements and allow for reduction of the aperture size D a value that is not greater than 350 microns, not greater than 300 microns, not greater than 200 microns, not greater than 100 microns, not greater than 40 microns, not greater than 10 microns, not greater than 5 microns, and/or not greater than 1 micron.

[0147] Examples of any filtration system disclosed in the current specification can include a rotatable filtering assembly which is either partially immersed of fully immersed within the natural water source. When partially immersed, raw water pass into the intake pipe through filtration apertures at the filtering region, while the non-filtration apertures of the cleaning region positioned at any moment above the water level can undergo self-cleaning procedures, by implementation of various self-cleaning mechanisms as will be further elaborated below.

[0148] When fully immersed, raw water pass into the inlet pipe through all of the medium apertures, for example during a filtering mode, while various self-cleaning mechanisms, as will be elaborated below, can be implemented to clean filtride accumulated on or in the filter medium during a cleaning more.

[0149] The term "raw water", as used herein, refers to unfiltered water that can be present in a natural water source. The term "filtrate", as used herein, refers to water that passed through the filter medium toward the intake pipe. For example, water from which a substantial portion of debris or particulates have been filtered is filtrate. The term "filtride", as used herein, refers to the residue (e.g., microalgae, debris, or other particulates) that has been separated from the filtrate by the filter medium.

[0150] While various filtration systems are known in the art for utilization inland, i.e. - in a relatively dry environment, the filtration systems of the current disclosure are meant for partial or full immersion within an open water source, differentiating their structure, designed for such environments. For example, various known filtration systems adapted for inland utilization, such as disc-type, sheaf-type, or coiled-thread type filters, are placed within pressure vessels that are sealed from the surrounding environment, except for a dedicate inlet for unfiltered liquid entering the enclosed housing that defined the pressure vessel. This liquid flows through an intermediary passageway defined between the walls of the vessel's housing and the filter medium, through the filter medium, and toward a dedicated outlet of the resulting filtrate. Such vessels can further include dedicated inlets and outlets for wash liquid. In contrast, all of the filtration systems disclosed herein are devoid of such a pressure vessels. Specifically, the filter medium is configured to be directly exposed to the environment such that raw liquid of the environment is in direct contact with the medium outer side, without passing through an intermediary passageway.

[0151] In some implementations, either partially or fully-immersed rotatable filtering assemblies can transition between filtering and cleaning modes, wherein suction of raw water through all or a portion of the medium apertures may be stopped for the duration of the cleaning phase. In other implementations, either partially or fully-immersed rotatable filtering assemblies do not necessarily need to transition between filtering and cleaning modes, but rather cleaning via specific self-cleaning mechanisms, as will be elaborated below, can be performed at a cleaning region while raw water continuously pass through some or all of the medium apertures and toward the one or more pipe inflow openings.

[0152] For simplicity, any reference throughout the specification to "pipe inflow openings" will refer to either a single pipe inflow opening or to a plurality of pipe inflow openings, unless stated otherwise.

[0153] In yet further implementations, either partially or fully-immersed rotatable filtering assemblies can be continuously operable for filtering water that pass through some or all of the medium apertures and toward the pipe inflow opening(s), without the need for any selfcleaning mechanisms, if the minimal effective filtration surface open area Ae resulting in minimal Rq or Ra for a maximal aperture size D, and/or control of the movement of a rotational filtration assembly is set to limit the angular speed of rotation W not to exceed an upper threshold during filtering mode, result in almost no accumulation of filtride on or in the filter medium(s), to a degree that does not require use of any type of an additional self-cleaning mechanism.

[0154] While some filtration systems known in the art can include a rotatable filtering assembly that can be rotated by means of a turbine or impeller coupled to the filtering assembly, such as a drum, such solutions provide only limited control over the angular speed of rotation W of the filtering assembly. Some conventional types of immersible filtering assemblies can include a driving motor positioned in a dry environment on the shore, which again, will require the rotational movement to be translated to the offshore position of the filtering assembly, which will reduce the accuracy and degree of control of angular speed of rotation W. Since the angular speed of rotation W of the currently disclosed rotatable filtering assemblies during filtering mode is of utmost importance, it is desirable to position the driving motor in close proximity to the rotatable filtering assembly, wherein the motor is optionally attached to the frame, for example. This will result in a compact transmission assembly that will efficiently transmit rotational movement from the drive motor to the filtering assembly, with minimal variability and improved control over the angular speed W of the filtering assembly.

[0155] Placement of the drive motor in close proximity to the filtering assembly means that it is positioned offshore, optionally partially or fully immersed within the water of the surrounding natural water source, or at the very least, may be subjected to frequent splashes of water. Thus, it is important for such a drive motor to be watertight for adequate operability thereof in this environment. Consequently, the drive motor utilized for rotating any filtering assembly disclosed herein is a watertight drive motor.

[0156] The term "watertight", as used herein, refers to a seal which is capable of preventing water from the surrounding environment, and specifically, from raw water of the natural water source, passing the seal for extended periods of time when immersed in the water source. The term "watertight drive motor", as used herein, refers either to a drive motor which is constructed to be watertight, or a conventional, not necessarily watertight, drive motor, which is encapsulated in a watertight motor housing.

[0157] A watertight drive motor can refer to an electric motor, which must be watertight to prevent contact between any electric component thereof and the surrounding water, or a water motor, which is powered by a water feedline and is advantageously provided as a watertight motor with an integrally formed watertight casing, as it similarly needs to prevent any dripping or trickling of the water fed thereinto for normal operation thereof. It is to be understood that dedicated inflow and outflow lines extending into or out of a water motor can still deliver water, as the term "watertight" refers to sealing from raw water surrounding the immersed water, for example, but optionally allowing water (or other liquid) required for operating or powering this type of motor, pass into and out of the motor through dedicated, sealed, pipes or feed lines.

[0158] As mentioned above, the system also includes a controller, which can include at least one control sub-unit for controlling the operation of the motor, such as for setting up and controlling the desired rotational movement of the drive motor, thereby controlling the angular speed of rotation W of the filtering assembly. The controller can also include a receiver and/or transmitter for wireless communication with an onshore component. If the controller is placed in close vicinity to the drive motor or any portion of the filtering assembly, that is to say, in an offshore position, it may be similarly partially of fully immersed in the water or be subjected to water splashes, and thus also needs to be watertight. In some implementations, the controller can be provided as a watertight component, or can be optionally placed within a watertight housing, wherein the same watertight motor housing can serve to protect both the drive motor and the controller or control sub-unit.

[0159] Thus, any motor comprised in any filtration system disclosed herein, including filtration systems 200, 300, 400 or 500 described further below, is a watertight motor, unless stated otherwise. Similarly, any controller comprised in any filtration system disclosed herein, including filtration systems 200, 300, 400 or 500 described further below, is a watertight controller, unless stated otherwise.

[0160] In some examples, the filtration system (such as system 200, 300, 400 and/or 500 disclosed herein below) further includes at least one sensor, which can be chosen from, but not limited to, angular speed of rotation sensor, flow sensor, pressure sensor, and the like. The filtration system (200, 300, 400, 500) can include a plurality of sensors, including combination of various types of sensors. In such examples, the one or more sensors are operatively coupled to the controller (including any specific control sub-unit thereof, as desired), such that the sensor may transmit sensed signals to the controller, which in turn can transmit such signals, either as raw data or after manipulating such data, to a receiver that can be, for example, on shore or otherwise remote from the filtration system. In such examples, the controller can include a wireless transmitter, receiver, and/or transceiver. A transmitter and/or transceiver can be utilized to transmit signals, for examples based on sensed signals by one or more sensors, to a remote receiver, while a receiver and/or transceiver can be utilized to receive signals from a remote transmitter, for example in the form of commands, including requests for updated sensed signals and/or operation instructions that may be based on transmitted sensed signals.

[0161] For example, the controller may be configured to transmit actual speed of rotation of the filtering assembly, sensed by a corresponding angular speed of rotation sensor. In another example, the controller may be configured to transmit flow velocity sensed by one or more sensors at different regions of or near the filtration system, such as the flow velocity within the intake pipe, across the filter medium, or the flow of water in the vicinity of the filtration system (e.g., indicative of currents, waves and the like within the water source). In yet another example, the controller may be configured to transmit pressure readings from pressure sensors placed on various portions of the filtration system. Pressure sensors can measure the environmental pressure in the vicinity of the filtration system, which may be indicative of the depth of immersion within the water source. Two or more pressure sensors can also provide the pressure drops along or across various regions of the filtration system, from which flow velocities may be derived.

[0162] The controller can be configured to receive operational instructions from a remote location, which can include commands for controlling the angular speed of rotation of the one or more filtering assembly, the duration of rotation, acceleration and/or deceleration rates thereof, direction of rotation, as well as commands for changing the immersion depth of the one or more filtering assemblies according to various mechanisms that will be described further below, such as controlling adjustable floats, controlling height adjustment assemblies, and/or controlling offshore platform connection assemblies. The controller can receive commands for controlling additional components associated with self-cleaning mechanisms as will be elaborated in greater detail below, including controlling the operation of a vibration motor, ultrasonic transducers, spray assemblies, and/or flush tube valve actuators.

[0163] One possible implementation of a filtration system, referred to as drum- type filtration system 200, provided with a drum-type rotatable filtering assembly 202, will now be described in detail with reference to Figs. 1A-17B and 39A-40 of the accompanying drawings. Fig. 1A shows a view in perspectives of one example of a drum-type filtration system 200. Fig. IB shows an enlarged view of zone IB of a filter medium 244 indicated in Fig. 1A. Fig. 2 shows a view in perspective of an exemplary filtration system 200 with a pump 66. Fig. 3 shows a partial sectional view of an exemplary drum-type filtration system 200. Fig. 4 shows a partial view in perspective of a portion of an exemplary drum-type filtration system 200, exposing some component of a drum-type rotatable filtering assembly 202 thereof. Fig. 5 shows a partial view in perspective of an exemplary drum-type filtration system 200 with adjustable floats 50. Fig. 6 shows a partial view in perspective of an exemplary drum-type filtration assembly 200 with partially exposed wall windows 42. Fig. 7 shows a partial view in perspective of an exemplary drum- type filtration system 200 exposing components of an optional gear train of a transmission assembly 80. Fig. 8 shows an exemplary drum-type filtration system 200 with an immersion depth marking 46. [0164] Fig. 9A shows a view in perspective of an exemplary filtration system 200 with an anchoring structure 120. Fig. 9B shows a view in perspective of an exemplary filtration system 200 having its rotatable filtering assembly 202 immersed in a water source 20, and ground to the shore 26 via anchoring structure 120. Fig. 10 shows an example of a filtration system 200 with two rotatable filtering assembly 202 mounted on a single frame 30 movable along an elevation assembly 130. Fig. 11 shows a partial enlarged view of the filtration system 200 of Fig. 10. Figs. 12A-12B show an exemplary filtration system 200 with two rotatable filtering assemblies 202 independently movable along an elevation assembly 130, shown immersed within a water source 20 and above the water source level 22, respectively. Fig. 13 shows an example of a filtration system 200 with a rotatable filtering assembly 202 coupled to, and optionally movable with respect to, an offshore platform 150.

[0165] Fig. 14 shows an example of a drum-type filtration system 200 with a plurality of drumtype rotatable filtering assemblies 202 arranged in a matrix configuration. Fig. 15 shows an example of a drum- type filtration system 200 with a plurality of drum- type rotatable filtering assemblies 202 arranged side-by-side. Fig. 16 shows an example of a drum-type filtration system 200 with an expansion chamber 264. Figs. 17A and 17B show a view in perspective and a partial sectional view of exemplary filtration systems 200 with vertically oriented rotatable filtering assemblies 202. Figs. 39A-C show a partial view in perspective of exemplary drum-type filtration systems 200 with funneling extensions 48 circumscribing wall windows 42, and with a camera 56 facing filter medium 244. Fig. 40 shows an example of a spray conduit 282 with a plurality of flexible conduits 283 extending sideways therefrom.

[0166] Figs. 44A-C show a drum-type filtration system 200 with movable floats 50 at various positions. Figs. 45A-B show zoomed-in view of the float transmission assembly 102 of the filtration system 200 of Figs. 44A-C. Fig. 46 shows an example of a drum-type filtration system 200 with a plurality of drum-type rotatable filtering assemblies 202 vertically arranged above each other. Figs. 47A-B show an example of a drum-type filtration system 200 with a bubble generator 140. Fig. 48 shows a zoomed-in sectional view of a bubble generator 140 positioned below a drum-type rotatable filtering assembly 202. Figs. 49A-B show one example of a guiding chamber 190 extending from a bubble generator 140. Fig. 50 shows another example of a guiding chamber 190 extending from a bubble generator 140. Fig. 51 shows an example of a drum-type filtration system 200 with a bubble generator 140 that includes a plurality of hollow enclosures 142 in fluid communication via an interconnecting pipe 143. Fig 52A shows another example of a drum-type filtration system 200. Fig. 52B shows the drum-type filtration system 200 of Fig. 52A with partial transparency of some components, such as one of the frame transverse walls 32, to expose other components of the system. Fig. 52C shows the drum-type filtration system 200 with some components removed from view, such as one of the frame transverse walls, to expose other components of the system. Figs. 1A-17B, 39A-40, and 44A- 52C, are described herein together.

[0167] As shown throughout Figs. 1A-17B, a drum-type filtration system 200 includes at least one drum-type rotatable filtering assembly 202, at least one watertight drive motor 72 and at least one controller 76. Each drum-type rotatable filtering assembly 202 defines a main axis Ym (indicated for example in Fig. 3) around which it is configured to rotate by the corresponding watertight drive motor 72. For simplicity, any reference to a component of filtration system 200 (such as filtering assembly 202, drive motor 72, controller 76, and so on) in a single form throughout the current specification, will similarly refer to "one or more" of said components for implementations that include a plurality of said components, unless otherwise stated.

[0168] The terms "drum-type filtration system 200" and "filtration system 200" are interchangeable, and the terms "drum-type filtering assembly 202" and "filtering assembly 202" are also interchangeable, for system and assembly numerals 200 and 202 throughout the specification, and particularly with respect to Figs. 1A-17B, unless otherwise stated.

[0169] In some examples, the filtration system 200 further comprises a frame 30. Both the rotatable filtering assembly 202 and the watertight drive motor 72 can be coupled to the frame 30, wherein the rotatable filtering assembly 202 is movably coupled to the frame 30 (i.e., can rotate around main axis Ym while being supported, directly or indirectly, by frame 30). It is to be understood that reference to components coupled to each other throughout this specification may refer either to direct coupling, or indirect coupling via intermediate components.

[0170] The rotatable filtering assembly 202 can include a drum support structure 204, over which a filter medium 244 is disposed (and attached thereto), in the form of a screen mesh for a drum-type filtration system 200. The filter medium defines a medium outer surface, which is a screen outer surface 246 in the illustrated examples, and a medium inner surface, which is a screen inner surface 248 in the illustrated examples. Any type of medium outer surface of any example of a filtration system disclosed herein, including screen outer surface 246 in the case of a drum-type filtration system 200, is facing the surrounding water it is immersed in, at least along the immersed portion thereof. Specifically for the example of filter medium 244 comprising a screen mesh, the screen outer surface 246 is facing away from main axis Ym. The opposite screen inner surface 248 is facing main axis Ym. Medium apertures 252 comprise filtration apertures 254, and in some cases, for example when partially immersed, can further include non-filtration apertures 256.

[0171] Filter medium 244 includes a plurality medium apertures 252 (an example of which is shown in Fig. IB). Each medium aperture 252 has an aperture size D and an aperture open area Aa. In some implementations, the medium aperture 252 has a circular shape, such that the aperture size D is the diameter of the medium aperture 252, and the aperture open area Aa can be calculated as 7t-D². However, it is to be understood, as described above, that the medium aperture 252 can take the form of any other geometrical shape. For example, in some implementations the medium aperture 252 is square-shaped, such that the aperture size D is the length of its edge, and the aperture open area Aa can be calculated as D². In the example illustrated in Fig. IB, the screen mesh 244 is shown to be formed of weft and warp wires defining medium aperture 252 that can extend over a not necessarily planar screen outer surface 246 (as evident in the zoomed-in view). The aperture size D in the example illustrated in Fig. IB can be defined by the distance between adjacent weft wires, which is shown in this specific example to be narrower than the distance between adjacent warp wires.

[0172] While screen mesh 244 is illustrated in Fig. IB as composed of intersecting weft and warp wires, it is to be understood that this is shown by way of illustration and not limitation, and that a screen mesh 244 can be provided in any other form known in the art, including meshes being formed of single-layered material sheets, in which the medium apertures 252 can be formed by laser cutting, punching, or other manufacturing methods known in the art.

[0173] For a filtration system 200 that includes a drum-type rotatable filtering assembly 202, the terms "filter medium 244" and "screen mesh 244" are interchangeable, and refer to a filter medium which is implemented as a drum-shaped screen mesh.

[0174] A rotatable filtering assembly according to any example disclosed herein, includes at least one rotatable support wall. As shown in greater detail in Fig. 4, the drum-type rotatable filtering assembly 202 includes two rotatable support walls 206a, 206b, which are comprised in its drum support structure 204. The rotatable support walls 206a, 206b are implemented as two coaxial transverse walls, spaced apart from each other along main axis Ym, wherein each rotatable support wall 206 extends along a plane substantially orthogonal to the main axis Ym. The filter medium 244 (Fig. 1A) extends between the rotatable support walls 206a and 206b, cylindrically shaped around main axis Ym.

[0175] The drum support structure 204 can include, in some examples, one or more concentric circular hoops 212 disposed around central axis Ym, and support strips 214 parallel to central axis Ym and extending between corresponding hoops 212, as shown in the exemplary illustration in Fig. 4. The filter medium 244 can be formed as a unitary screen mesh cylindrically disposed around the drum support structure 204 between both rotatable support walls 206a, 206b, or include a plurality of mesh sections together defining the complete filter medium 244. For example, the filter medium 244 can include a plurality of panels, which can be independently replaceable panels, supported between adjacent hoops 212 and support strips 214.

[0176] The hoops 212 and support strips 214 provide the necessary structural integrity to the filter medium 244, and optionally serve as support elements to which corresponding panels can be mounted, for example by bolts or any other suitable mechanical fasteners.

[0177] The filtration system 200 is further shown to comprises an intake pipe 260, which can be optionally disposed at least partially within the rotatable filtering assembly 202, such as within the space enclosed by the cylindrically shaped filter medium 244 and/or within the drum support structure 204. The intake pipe 260 includes at least one pipe inflow opening 262 which is in fluid communication with the medium apertures 252. In some examples, the pipe inflow openings 262 are offset from the main axis Ym, facing a portion of the filter medium 244, optionally facing downward toward a bottom portion of the filter medium 244, which constitutes part of the filtering region in some implementations. While two pipe inflow openings 262 are illustrated in the example shown in Fig. 3, it is to be understood that any other number, such as a single pipe inflow opening or more than two pipe inflow openings, is contemplated. Any reference to "pipe inflow openings 262" throughout this specification, unless otherwise stated, refers also to implementation of a single pipe inflow opening 262.

[0178] The intake pipe 260 can be an independent component of a suction line 60, attached thereto and in fluid communication therewith, or can be formed as an integral part or extension of the suction line 60. Intake pipe 260 is coupled to at least one rotatable support wall 206, and in the specific examples illustrated throughout Figs. 1A-17B, to both support wall 206a, 206b, in a manner that allows the at least one support wall 206 to rotate around intake pipe 260, while intake pipe 260 remains stationary in position, that is to say that intake pipe 260 is a non- rotatable component of the filtration system 200. Intake pipe 260 can extend, for example along main axis Ym, away from the at least one rotational support wall, and terminate with a pipe outflow opening 266 that can be coupled, for example by a pipe coupler 68, to a suction line inlet 62. The intake pipe 260 and suction line 60 together define a fluid-communication line between the pipe inflow openings 262 and a suction line outlet 64 (see for example Fig. 1A) which can be placed onshore. This fluid-communication line is intended to direct filtrate from the rotatable filtering assembly 202 to a target location, which can be onshore, for example by applying suction force at the pipe inflow openings 262. This may be accomplished by creating a negative pressure difference between the pipe inflow openings 262 and the suction line outlet 64.

[0179] In some implementations, such a negative pressure difference can be created by an absolute height difference between the pipe inflow openings 262 and the suction line outlet 64, wherein the suction line outlet 64 can be an open-ended outlet positioned remotely at a height which is lower than that of the pipe inflow openings 262, allowing for gravitational flow through the intake pipe 260 and suction line 60 (schematically exemplified in Fig. 1A). Alternatively, the suction line 60 can be connected to a pump 66 (such as a centrifugal pump, or any other appropriate pump type) at the suction line outlet 64, wherein the pump 66 (Fig. 2) is utilized to create the necessary negative pressure to facilitate flow from the water source 20, through the submerged portion (e.g., filtering region) of the filter medium 244, toward the pipe inflow openings 262 and into the intake pipe 260.

[0180] In some implementations, as shown for example in Fig. 3, the intake pipe 260 is coaxial with main axis Ym. In other implementations (not illustrated), at least a portion of the intake pipe 260 extends along an axis which is parallel to main axis Ym. Such implementations can be applicable, for example, for approximating the pipe inflow openings 262 closer to the filter medium 244 while still remaining within the water, when the rotatable filtering assembly 202 is only partially submerged in the water source 20.

[0181] The medium apertures 252 generally extend radially between the screen outer surface 246 and screen inner surface 248, and an internal space 250 is defined between the screen inner surface 248 and the intake pipe 260. During filtration mode, raw water 10 which is in direct contact with the screen outer surface 246, at least along a submerged portion thereof, flow through the filtration apertures 254 into the internal space 250, becoming filtrate 12 that flows therefrom, through the pipe inflow openings 262, into intake pipe 260.

[0182] The at least one rotatable support wall 206 can include a central sealed opening 208, coaxial with main axis Ym, along which the intake pipe 260 is coupled to the rotatable support wall 206, optionally extending through the sealed opening 208 toward internal space 250.

[0183] The frame 30 can include at least one frame transverse wall 32, such as the two frame transverse walls 32a and 32b in the illustrated examples (see for example Figs. 4 or 6), shown to be spaced apart from each other along main axis Ym, wherein each frame transverse wall 32 can extend along a plane substantially orthogonal to the main axis Ym. The rotatable filtering assembly 202, including both rotatable support walls 206, is disposed between both frame transverse walls 32, for example such that rotatable support wall 206a is disposed adjacent to (and optionally spaced from) frame transverse wall 32a, and rotatable support wall 206b is disposed adjacent to (and optionally spaced from) frame transverse wall 32b (see for example Fig. 3).

[0184] As mentioned, at least one rotatable support wall 206 includes a central sealed opening 208, through which the intake pipe 260 can optionally extend into the filtering assembly 202. If the intake pipe 260 extends all the way from side to side of the filtering assembly 202, both of the rotatable support walls 206 can include corresponding coaxial central sealed openings 208 through which the intake pipe 260 extends (see for example Fig. 3). In some implementations, as in the illustrated example, one or both of the frame transverse walls 32 include similar pipe through opening 34, which are coaxial with, and preferably similarly dimensioned to, the corresponding central sealed opening 208, allowing the intake pipe 260 to extends through both the frame transverse walls 32 and the rotatable support walls 206.

[0185] The intake pipe 260 can extend from the pipe outflow opening 266, through the pipe through opening 34 of a frame transverse walls 32a and a corresponding central sealed opening 208 of a rotatable support wall 206a, into the filtering assembly 202. The intake pipe 260 can terminate within the filtering assembly 202 before reaching the opposite rotatable support wall 206b, or it can further extend through a central sealed opening 208 of the opposite rotatable support wall 206b, out of the filtering assembly 202, and further through the corresponding pipe through opening 34 of the opposite frame transverse wall 32b. [0186] As mentioned above, the filtration system 200 optionally comprises, in some examples, a motor, which can be optionally a watertight drive motor 72 (see Fig. 1A, for example), configured to rotate the filtering assembly 202 around main axis Ym. As shown, the drive motor, which can be a watertight drive motor 72, can be secured to the frame 30, such as to one of the frame transverse walls 32 (though securement to other parts of the frame is similarly possible). When the intake pipe 260 extends through both frame transverse walls 32, the drive motor 72 can be offset from the main axis Ym, so as not to interfere with the intake pipe 260. Thus, since the axis of rotation of the watertight drive motor 72 is offset from the main axis Ym in such a case, the filtration system 200 can include a transmission assembly 80, configured to transmit the torque produced by the drive motor 72 to the corresponding rotatable support wall 206, thereby rotating the entire drum support structure 204 there-along.

[0187] The transmission assembly 80 can include a gear train with one or more gears. For example, the transmission assembly 80 illustrated in the example illustrated in Figs. 4 and 7 includes a driving gear 84 attached to a shaft 82 driven directly by the watertight drive motor 72, and a driven gear 86 attached to the surface of the corresponding rotatable support wall 206 and meshed with the driving gear 84, wherein the size of the gears dictates the transmission ratio between the angular speed of rotation of the motor and the resulting angular speed of rotation W of the filtering assembly 202, such that the transmission assembly 80 can also serve as a motor speed reduction mechanism.

[0188] While two gears are illustrated in Figs. 4 and 7, it is to be understood that any other number of gears can be chosen, for example - including intermediary idler gears (see for example Fig. 52C) and the like. Moreover, while a gear train is illustrated, it is to be understood that any other type of transmission assembly known in the art can be implemented, such as a transmission assembly that includes one or more chains, endless belts and pulleys, and the like.

[0189] Any of the rotatable support walls 206 can also include a plurality of rollers 70 rotatable around axes that are parallel to the main axis Ym, each configured to contact and roll over the outer surface of the intake pipe 260 at the portion extending out of the respective central sealed opening 208 (for example, between the rotatable support wall 206 and the respective frame transverse wall 32). If the intake pipe 260 extends from both sides of the filtering assembly 202, each of the rotatable support walls 206 can include a plurality of rollers 70. While the illustrated example shows three rollers 70 attached to each of the rotatable support walls 206a, 206b, it is to be understood that any other number of rollers is contemplated. [0190] The watertight drive motor 72 can be either an electric motor or a water motor. A water motor refers to any type of water motor or water engine that is operable to rotate a shaft 82 thereof in response to an inflow of water (supplied through a motor feedline 92), and can include a set of pistons movable by the inflow of such water. Advantageously, a water motor 72 is readily constructed as a watertight motor, without the need for further modifications to seal it, since such watertight sealing is required for proper operation thereof, preventing any leak of the water contained therein. Thus, attachment of a water motor 72 to a frame 30 of a filtration system 200 allows placement thereof in close proximity to an immersible rotatable filtering assembly 202, wherein the motor 72 itself can be safely immersed, or otherwise placed in an environment in which it can be contacted by water of the water source 20 (as shown for example in Figs. 9B or 12A), without the risk of malfunctioning as described above.

[0191] Utilization of a water motor as the watertight drive motor 72, requires adaptation of the filtration system 200 to include at least one motor line 92 (see for example Figs. 5-6) fluidly coupled to the motor 72, configured to provide water (or other suitable liquid) to operate the water motor 72. In some implementations, the motor line 92 can extend from a source of water onshore, all the way to the water motor 72 positioned offshore, coupled to the frame 30. This is an unconventional adaptation that can be implemented for utilization of an immersible water drive motor 72 for facilitating rotation of the filtering assembly 202, as most conventional water motors do not include feed lines extending over a length of several meters from a source that can be onshore, to a motor that can be placed offshore. In other implementations, the motor line 92 can be adapted to pump water from the surrounding water source 20 and into the water motor 72. However, such a solution may be less ideal since unfiltered water from a surrounding natural water source 20 may include debris and impurities that will harm the motor or degrade it over time.

[0192] In some examples, the at least one motor line 92 includes two lines, one motor inflow line 92a configured to direct feed water into the water motor 72, and the other motor outflow line 92b configured to direct water out of the water motor 72 (see Fig. 7). Both lines 92a, 92b are sealed to allow water inlet and outlet only therethrough, while preserving the watertight sealing of the motor from the surrounding raw water 10 in which the motor is immersed.

[0193] In contrast to water motors, a conventional electric motor that may be used for rotating onshore rotatable filtering assemblies, is not necessarily watertight as it is usually placed in a dry environment. Thus, when the drive motor 72 is an electric motor, it needs to be sealed from the environment in a watertight manner to prevent any damage to its operation when immersed within, or otherwise being contacted by, water from the water source 20. An electric drive motor 72 can be, for example, a DC servo motor, a pneumatic actuator, a step motor, and the like. In some implementations, the electric drive motor 72 is a brushless DC (BLDC) motor. The electric drive motor 72 may further be a slotted or slotless BLDC motor. An electric drive motor 72 can become a watertight drive motor 72 by being encased within a watertight housing 74 (see for example Fig. 5-6), which can be similarly attached to the frame 30, such as to a frame transverse wall 32, as in the illustrated example. When implemented as an electric motor, a motor line 92 can be utilized for transmitting power to the motor, such as cables for transmitting energy.

[0194] As mentioned above, the filtration system 200 further includes at least one controller 76 (see for example Fig. 1A), which can include at least one motor control sub-unit, configured to control functionality of the drive motor 72. In some implementations, the filtration system 200 also includes a speed sensor, such as an encoder (not shown) that may be attached to the drive motor's shaft. This can be implemented as an absolute encoder, configured to generate a signal commensurate with the angular speed of rotation and angular displacement of the motor's shaft 82. The controller 76 can receive signals from the absolute encoder, and can include software for interpreting sensed signals and readjusting the motor's functioning accordingly.

[0195] The controller 76 can include a dedicated processor and/or other component of a control circuitry, including a wireless receiver or transmitter, which, for the same reasons described above of an electric drive motor, should be also watertight to prevent any damage to such components when immersed or otherwise contacted by water from the water source 20. Thus, the controller 76 should be also a watertight controller 76. This can be achieved, for example, by placing the controller 76 in its own watertight controller housing 78 (see for example Fig. 4). Alternatively, when the drive motor 72 is placed within a watertight housing 74, the controller, or at least a motor control sub-unit thereof, can be placed next to the motor 72, within the same housing 74, such that housing 74 it utilized to provide watertight sealing both the drive motor 72 and the controller 76 at the same time (not shown).

[0196] While Figs. 2-7 illustrate an exemplary filtration system 200 in which the motor 72 and the transmission assembly 80 are positioned at the frame transverse wall 32a that is opposite to the transverse wall 32b, configured to rotate a support wall 206a that is opposite to the support wall 206b through which the intake pipe 260 extends toward and/or into internal space 250, in other examples, the motor 72 and the transmission assembly 80 can be disposed on and/or coupled to the same side of the frame transverse wall 32b and/or support wall 206b through which the intake pipe 260 extends, as illustrated in Figs. 52A-C.

[0197] While Figs. 2-7 illustrate an exemplary filtration system 200 in which the transmission assembly 80 includes a driving gear 84 configured to rotate a driven gear 86 which is attached to support wall 206a, in other examples, the rotatable support wall 206 is provided with external teeth that allow it to serve as the driven gear 86. For example, Fig. 52C shows an example of a transmission system 80 that includes a driving gear 84 rotatable over a shaft 82 extending from the motor 72, as described above. The driving gear 82 can be meshed with a larger first intermediate gear 87, attached to the same shaft 81 as a second, optionally smaller, intermediate gear 89, wherein the second intermediate gear 89 can be meshed directly with teeth of the rotatable support wall 206b, which also serves as the driven gear 86 in such a case. It is to be understood that first and second intermediate gears 87 and 89 are shown by way of example, and that alternatively, the driving gear 84 can be meshed directly with rotatable support wall 206b, or via any other number of intermediate gears.

[0198] In some implementations, the frame 30 can include legs 38 terminating below the rotatable filtering assembly 202, for supporting the frame 30 and the rotatable filtering assembly 202 over the water source bed 24, for example when placed in a shallow natural water source 20 or when lowered enough to completely immerse the rotatable filtering assembly 202 within the water source 20. Water source bed 24 (see for example Fig. 12A), which can be, for instance, the sea bed or the ground of a lake or river, can include a variety of rocks, small stones, mud, algae and the like, which, absent of any protective means, can contact the filter medium 244 and damage it, or clog the medium apertures 252, when the rotatable filtering assembly 202 is immersed deep enough to rest over the or in close proximity to the water source bed 24. Thus, in some implementations, the frame 30 further includes a bottom plate 40 (Fig. 2), which can be in the form of a horizontal plate positioned below the rotatable filtering assembly 202, but preferably somewhat above the lower ends of legs 38. The bottom plate 40 preferably extends over an area which is larger than the horizontal projection of filter medium 244, to protect it entirely from its bottom side.

[0199] In some implementations, filtration system 200 also includes a spray assembly 280, configured to spray liquid or gas toward a portion of filter medium 244 to dislodge filtride that may be clung thereto. Spray assembly 280 can include a spray conduit 282 with one or more nozzles 284 attached thereto, optionally directed toward a target region of the filter medium 244. The spray conduit 282 can be attached to, or otherwise fluidly connected to, a cleaning feed line 94 which can provide cleaning liquid or gas, including cleaning water, through the spray conduit 282, toward one or more nozzles 284.

[0200] As illustrated in Figs. 3-4, one example of a spray assembly 280 can include a spray conduit 282 extending into the rotatable filtering assembly 202, with a plurality of nozzles 284 residing within the internal space 250, configured to spray water toward the filter medium 244 from the inside. The cleaning feed line 94 can extend from outside of the frame 30 into the intake pipe 260, and at a specific point within the rotatable filtering assembly 202, it may define a spray conduit 282 by continuously extending radially outward out of the intake pipe 260 (for example, through a corresponding sealed opening formed at the wall of the intake pipe 260), and then assume a longitudinal orientation (e.g., parallel to main axis Ym) with a plurality of nozzles 284 directed toward the filter medium 244, and more particularly, toward screen inner surface 248.

[0201] In some implementations, as in the illustrated example, the nozzles 284 can be directed toward an upper portion of the filter medium 244. This can allow the nozzles 284 to spray the cleaning water at the upper portion of the filter medium 244 without interfering with the flow path of filtrate entering into the pipe inflow openings 262, which are directed oppositely toward the lower portion of the filter medium 244.

[0202] While rotatable filtering assembly 202, including its filter medium 244, is configured to rotate about main axis Ym during normal use, the intake pipe 260 extending through its center remain stationary, such that the pipe inflow openings 262 are always oriented at the same direction (e.g., directed downward as in the illustrated examples). Thus, raw water from the water source 20 continuously pass through different regions of the filter medium 244 toward pipe inflow openings 262, depending on the rotational movement of the filtering assembly 202.

[0203] In contrast to self-cleaning mechanisms, which are designed to remove filtride that has accumulated on the filter medium, it is to be understood that some examples of filtration systems disclosed herein (e.g., systems 200, 300, 400 and/or 500 described throughout the specification) can optionally include mechanisms and/or features designed to minimize the amount of filtride accumulated on or in their filter mediums to begin with. As described, reduced filtride accumulation may be achieved by (a) limiting the angular velocity of rotation W of the rotatable filtering assembly, when the controller (and hence, the rotatable filtering assembly itself) is in a filtering mode; (b) by designing the filtration system with filtration apertures sized to preserve a minimal area ratio Ra that will, in turn, result in a maximal desired flow velocity Ve through the filtration apertures during filtering mode, and (c) any combination of (a) and (b).

[0204] While designed to minimize filtride accumulation over the filter medium 244, filtration system 200 may still include self-cleaning mechanisms, such as spray assembly 280, which can be utilized as safety measure, or as additional measures that can be utilized in implementations in which the aperture size D is not greater than 350 microns (including being optionally not greater than 300 microns, not greater than 200 microns, not greater than 100 microns, not greater than 40 microns, not greater than 10 microns, not greater than 5 microns, and/or not greater than 1 micron), which can still require certain self-cleaning measured to be employed for such fine mesh densities.

[0205] While described throughout the specification with respect to aperture sizes D not greater than 350 microns, inclusive, it is to be understood that any of the filtration systems disclosed herein (e.g., systems 200, 300, 400 and/or 500 described throughout the specification), implementing a mechanism or feature designed to minimize filtride accumulation over the filter medium, can be similarly utilized, either without or with selfcleaning mechanisms disclosed herein, for aperture sizes than can be greater than 350 microns, such as apertures sizes up to 2 millimeters, inclusive, In such implementations, the reduced filtride accumulation will still result in improved overall efficiency of the filtration system.

[0206] The spray assembly 280 can also be a non-rotatable, stationary assembly, similar to the stationary nature of intake pipe 260, such that during rotation of the drum (i.e., rotation of filter medium 244), the nozzles 284 spray water impinging against different portions of the filter medium 244 (each time exposing a different subset of medium apertures 252 to the jets sprayed from the nozzles).

[0207] As noted, a filtration system 200 can include a rotatable filtering assembly 202 that can be partially or fully immersed within the water source 20. When partially immersed, the pipe inflow openings 262 are also immersed, optionally facing the immersed portion of the filter medium 244, while the nozzles 284 can be designed to reside in a portion of the rotatable filtering assembly 202 exposed to the atmosphere above water level 22.

[0208] While the nozzles 284 in the illustrated examples are shown to be oriented toward an opposite portion of the filter medium 244 than that of the pipe inflow openings 262, in alternative configurations the nozzles and the pipe inflow openings can face the same portion of the filter medium 244. For example, the nozzles can be directed downward (not shown), same as the pipe inflow openings. Such implementations will require alteration between filtering and cleaning modes of the rotatable filtering assembly 202. For example, the nozzles can be inactive while suction is applied through the pipe inflow openings 262 during a filtering mode, and may be activated to spray water or air while suction is deactivated during the cleaning mode.

[0209] While nozzles 284 and spray conduit 282 are shown throughout Figs. 3-7 to constitute a relatively rigid structure, which maintains fixed orientation of the nozzles at all times, in other implementations the spray assembly 280 can include one or more flexible conduits, each leading to a nozzle at its end. Fig. 40 shows one such example of a spray conduit 282, which can be in the form of a relatively rigid conduit, equipped with a plurality of side openings from which flexible conduits 283 extend, terminating with nozzles at their opposite ends. When high-pressure water (or air) are directed toward the nozzle(s) 284 in such implementations, the relatively loose flexible conduit(s) 283 can randomly "dance", resulting in the nozzle(s) frequently changing orientations to spray at various regions of the filter medium 244. Such an implementation can advantageously cover a larger zone of the filter medium 244 impinged by the water or air spray from the nozzle.

[0210] The flexible conduit(s) 283 can be in the form of a hose, a flexible tube, and the like. While a relatively rigid spray conduit 282 is illustrated in Fig. 40, with separate flexible conduits 283 extending from side openings formed along its circumference, it is to be understood that this example is not meant to be limiting, and that in other examples, the spray conduit itself can be in the form of a flexible conduit, for example forming a fully flexible hoselike conduit along the entire length thereof, residing within the internal space 250. It is to be understood that any reference to a spray assembly throughout the specification, including in combination with any of the filtration systems 200, 300, 400, 500, may include examples in which the spray assembly include one or more flexible conduits, as described above. [0211] While spray conduit 282 and nozzles 284 are shown in the illustrated example to reside within the internal space 250 defined by the rotatable filtering medium 202, in alternative implementations, the spray conduit, with one or more nozzles, and according to any of the implementations described herein, can extend out of the rotatable filtering assembly 202, configured to spray water or air toward a portion of the screen outer surface 246.

[0212] In some implementations, the cleaning feed line 94 can extend from a source of water or compressed air onshore. In other implementations, the cleaning feed line 94 can be adapted to pump water from the surrounding water source 20 and into the spray conduit 282 and nozzles 284.

[0213] In some implementations, the same water (or other liquid) can be used for the spray assembly 280 and for operating a water motor 72. In such implementations, a unified feed line, or a feed line manifold 90 (one example of which is shown in Fig. 14) can be branched into a one or more motor lines 92 and a cleaning feed line 94, optionally with appropriate controllable valves for controlling adequate flow through each as necessary.

[0214] In some implementations, the frame 30 can include one or more wall windows 42 that can be optionally closed or opened by one or more corresponding window covers 44. For example, the frame 30 illustrated in Figs. 5-6 includes two wall windows 42 formed in each frame transverse wall 32, wherein the windows 42 of each frame transverse wall 32 are aligned with each other, and are formed along portion of the frame transverse walls 32 that are at least partially facing a portion of the filter medium 244. The wall windows 42 can be covered, in some examples, by window covers 44 that can transition between closed and open positions. Fig. 5 shows all window covers 44 in a closed position, fully covering the wall windows 42. Fig. 6 shows the window covers 44 in an open position, or a partially open position, exposing at least a portion of the wall windows 42.

[0215] The wall windows 42 and window covers 44 may serve as an additional or alternative self-cleaning mechanism, that can be used, for example, with a partially immersible rotatable filtering assembly 202. The wall windows 42 are designed to be at a height of the water level 22 when the rotatable filtering assembly 202 is partially immersed. For example, the wall windows 42 can be positioned above the main axis Ym, designed to face an upper portion of the filter medium 244. When placed in a natural water source 20 that includes moving water, such as sea waves or running water of a river, opening the window covers 44 will expose the windows 42 to such waves or moving river water, which will flow therethrough from side to side, along the filter medium 244, dislodging any accumulated filtride and cleaning the filter medium along with the flow.

[0216] The window covers 44 can be hinged to pivot about their hinged connection between the closed and open states as in the illustrated example, though any other mechanism for moving such covers between open and closed position, as known in the art, is contemplated. Moving the window covers 44 between closed and open positions can be performed either manually, or by implementation of electrically controlled (including remote-controlled) mechanisms.

[0217] For rotatable filtering assemblies 202 that can transition between filtering and cleaning modes, the window covers 44 may be opened to expose the wall windows 42 to a surrounding water flow during a cleaning mode, and may be closed to prevent such flow from interfering with the filtering mode.

[0218] While described for use with partially immersible rotatable filtering assemblies 202, it is to be understood that wall windows 42 with window covers 44 can be also utilized as a cleaning mechanism for fully immersible rotatable filtering assemblies 202. For example, a rotatable filtering assembly 202 can be fully immersed during a filtering mode, while the window covers 44 are in the closed position. When transitioning to the cleaning mode, the rotatable filtering assemblies 202 can be raised upward to be partially immersible, for example placing the wall windows 42 at the height of the water level 22, at which point the window covers 44 may be opened. When cleaning is no longer required, the window covers 44 can be closed again, and the rotatable filtering assembly 202 can be lowered downward back to the fully immersible position, to transition back to the filtering mode.

[0219] Furthermore, wall windows 42 can be exposed to the surrounding water and utilized in a cleaning mode also when the rotatable filtering assembly 202 is fully immersed, taking advantage of water streams occurring not only at the water level 22, but also below water level 22. For example, river water may stream at high velocities at any depth of the river, and sea waves may be accompanied by high water velocities up to 10 meters below the sea level, in some occasions.

[0220] Wall windows 42 can be provided in various shapes and sizes, such as a trapezoid shape shown throughout Figs. 2-8, an hourglass shape shown in Figs. 39A-C, or any other suitable shape. The hourglass-shaped wall windows 42 shown in Figs. 39A-C are designed to increase the open area through which water may flow through the window openings, toward filter medium 244, with the side edges of the windows 42 curved around the regions of the floats 50 and the intake pipe 260. In some examples, particularly for wall windows 42 provided with irregular shapes such as the hourglass-shape in Figs. 39A-C, the frame 30 can be devoid of window covers, leaving the wall windows 42 exposed to the surrounding environment at all times.

[0221] In some examples, frame 30 further comprises funneling extensions 48, each funneling extension 48 circumscribing a corresponding wall window 42, thus generally shaped in the same shape defined by the borders of the wall window 42, and extending from the frame transverse wall 32 in a direction opposite to the filter medium 244. Each funneling extension 48 can include a tapering inner surface 49 that forms a funnel-like guide for streaming the water toward the opening of wall window 42. Each wall window 42 can define a window axis Yw passing through its center, parallel to main axis Ym, such that the tapering inner surface 49 is angled relative to the window axis Yw, defining a minimal area at the wall window 42 itself. When placed in a water source 20 with moving water, such as sea waves or streaming river, the funneling extensions 48 can serve to funnel the streaming water toward and through the wall windows 42, wherein the tapering inner surfaces can increase the flow speed of the streaming water toward filter medium 244, thus improving the surrounding water's capability of effectively washing away filtride that may have accumulated over filter medium 244. The length of the funneling extensions 48 and angle of their tapering inner surfaces 49 relative to window axes Yw may vary to provide desired flow speed increase of the streaming water.

[0222] While trapezoid- shaped wall windows 42 are shown throughout Figs. 2-8 with window covers 44 but without funneling extensions 48, and hourglass-shaped wall windows 42 are shown in Fig. 39A with funneling extensions 48 but without window covers 44, it is to be understood that these examples are shown by way of illustration and not limitation, and that wall windows 42 of any size and shape can be provided with any combination of window covers 44 and/or funneling extensions 48. For example, while not illustrated separately, it is to be understood that wall windows 42, such as trapezoid-shaped wall windows 42 illustrated throughout Fig. 2-8, can be provided both with window covers 44 and with funneling extensions 48, that can be similarly trapezoid-shaped funneling extensions 48 circumscribing the borders of the corresponding wall windows 42. Moreover, while not illustrated as such, it is to be understood that in some examples, when frame 30 includes both windows covers 44 and funneling extensions 48, the window covers can be hinged to the funneling extensions 48, so as to block or allow water flow through the wall windows 42 by blocking or exposing the space defined by the funneling extensions 48.

[0223] In some implementations, the filtration system 200 also includes at least one float 50 attached to the frame 30, such as the couple of floats 50 shown in Fig. 1A to extend through float opening 36 formed in both frame transverse walls 32 on both sides of the rotatable filtering assembly 202. Floats 50 can be utilized to keep the rotatable filtering assembly 202 partially submersible at a desired height relative to the water level 22. While two floats 50^a and 50^b are illustrated in Fig. 1A, it is to be understood that any other number, such as a single float (as shown, for example, in Fig. 14) or more than two, are contemplated, and that the plural use of the term "floats 50" is not limiting, and may similarly refer to a single float.

[0224] In some implementations, the floats are adjustable floats 50, meaning that the weight of the floats 50 can be adjusted to control their buoyancy. In some implementations, the adjustable floats 50 may be provided in the form of ballast tanks, with at least one port for controlling the level of ballast water. In some implementations, each adjustable float comprises a float water port or liquid port 52 through which water (or other suitable liquid), such as ballast water, can be poured to fill the internal volume of the float 50, thereby increasing its weight, and an air port or gas port 54, through which air (or other suitable gas) may flow into the float 50 while water may exit through the water port 52.

[0225] Adjustable floats 50 can be utilized, by increasing and decreasing the weight of the floats 50, to control the buoyancy of the rotatable filtering assembly 202 and its height, relative to the water level 22. Such implementations can be used in combination with cleaning mechanisms that rely on opening and closing window covers 44 of wall windows 42 and/or funneling water through wall windows 42 provided with funneling extensions 48 as described above, for example by being filled with water (or other suitable liquid) to increase their weight and allow the rotatable filtering assembly 202 to be fully submerged during the filtration phase, and filling air (or other suitable gas) to raise the rotatable filtering assembly 202 and the wall windows 42 to the water source level 22 during the cleaning mode.

[0226] In some implementations, the floats are movable floats 50, meaning that the position of one or more float(s) can change relative to the main axis Ym, for example. Movable floats 50 can be either adjustable or non-adjustable floats. Any reference to movable floats 50, without further reference to the type of the floats, can refer to either movable adjustable floats or movable non-adjustable floats. Figs. 44A-C show an example of a drum-type filtration system 200 equipped with two movable adjustable floats 50^a and 50^b. The filtration system 200 can include float displacement motor 101 and a float transmission assembly 102, configured to controllably move the position of one or more movable floats 50 relative to the main axis Ym of the rotatable filtering assembly. The float displacement motor 101 can be a watertight motor, an electric motor, can be placed in a watertight motor housing, similar to housing 74, and can be generally implemented according to any example described herein for drive motor 72, mutatis mutandis.

[0227] In some examples, one or more movable floats 50 are pivotably attached to frame 30. The filtration system 200 can include float arms 112, each attached at an engagement end 112 thereof to the frame, such as to a frame transverse wall 32, at a corresponding float arm pivot 116, wherein the support end 115 of each arm, opposite to the engagement end 113, is attached to a corresponding movable float 50. In the illustrated example, each movable float 50 is attached to the support ends 115 of two float arms 112, one float arm 112 attached to one frame transverse wall 32a, and the other attached to another frame transverse wall 32a. While in the illustrated example, each movable float 50 is attached to a float arm 112a which is coupled to frame transverse wall 32a, and to a float arm 112b which is coupled to frame transverse wall 32b, it is to be understood that in other implementations, any movable float (50) can be attached to a single float arm (112) that can be, in turn, attached to any portion of the frame 30, or to more than two float arms (112).

[0228] Figs. 45A-B show a zoomed in view of the float transmission assembly 102, with the intake pipe removed from view for clarity. In the illustrated example, the float transmission assembly 102 includes a float driving gear 101 that can be attached and rotated by the float displacement motor 102, for example by being attached to a shaft extending from the motor 102, and to transfer gears 104, 108 configured to rotate in opposite directions, one of which is directly meshed with the float driving gear 103 and rotatable thereby. Specifically, a first transfer gear 104 and a second transfer gear 108 are coaxially aligned and are meshed via an internal planetary transmission.

[0229] The first transfer gear 104 is equipped with first gear outer teeth 106 around its outermost perimeter, which are meshed with the teeth of the float driving gear 103. The first transfer gear 104, shown in Fig. 45B with partial transparency thereof, further includes a first gear extension 105, formed around an opening that can be defined to accommodate the intake pipe. The first gear extension 105 extends along main axis Ym toward the second transfer gear 108 and includes outer extension teeth 107, which are axially offset from the first gear outer teeth 106, as shown in Fig. 45B.

[0230] The second transfer gear 108 includes second gear outer teeth 110 which are aligned with the first gear outer teeth 106, and second gear inner teeth 109 (exposed in Fig. 45B) oriented radially inward. One or more internal planetary gears 111 are disposed between both transfer gears 104, 108, meshed on one side with the extension teeth 107, and on the other side with the second gear inner teeth 109. While three planetary gears 111 are illustrated in Fig. 45B, it is to be understood that any other number is contemplated.

[0231] Each float arm 112 can include a series of engagement teeth 114 disposed along a round edge formed by the engagement end 113, wherein the engagement teeth 114 of each float arm 112 are meshed with the teeth of a different float transfer gear. For example, engagement teeth 114^b of float arm 112^b can be meshed with the first gear outer teeth 106, while engagement teeth 114^a of float arm 112^a can be meshed with the second gear outer teeth 110.

[0232] Both transfer gears 104, 108 can be disposed around intake pipe 260, such that both gears 104, 108 can be rotatable, in opposite directions, about main axis Ym. As shown in Fig. 44A, the engagement ends 113^ab and 113^bb of both float arms 112 are positioned on opposite lateral sides of the float transfer gears 104, 108, such that the engagement teeth 114^a and 114^b are meshed with outer teeth 106, 108, respectively, at opposite lateral sides thereof. Float arm pivots 116 define pivot axes extending therethrough, parallel to main axis Ym. Both float arm pivots 116^a, 116^b are laterally aligned with each other, and can be laterally aligned with, or otherwise parallel to, main axis Ym. The term "laterally" refers to a direction parallel to water level 22.

[0233] When the float displacement motor 102 rotates float driving gear 103, the first float transfer gear 106 rotates in an opposite direction, at a speed of rotation that can be dictated by the transmission ratio between both gears. The planetary transmission causes the second transfer gear 108 to rotate in a direction opposite to that of the first transfer gear 104. Since the engagement teeth 114 of each float arm 112 are meshed with the outer teeth of a different transfer gear, both of the float arms 112 pivot about their respective float arm pivots 116 in opposite directions. This in turn causes the movable floats 50 to pivot along with the corresponding arms 112. Assuming that the floats 50 are filled with sufficient air (or other gas) to remain at the same water level throughout this displacement procedure, this forces the frame 30 and the filtering assembly 202 attached thereto to move toward or away from the water level 22, depending on the relative position of the movable floats 50 relative to main axis Ym.

[0234] Fig. 44A shows one position in which the filter medium 244 is completely immersed within water source 20, below water level 22. Rotational movement of first and second transfer gears 104, 108 in specific opposite rotational directions causes the float arm 112^a with movable float 50^a attached thereto, to rotate about float arm pivot 116^a in a first rotational direction 16, and the float arm 112^b with movable float 50^a attached thereto, to rotate about float arm pivot 116^b in a second rotational direction 18, opposite to direction 16, for example until the main axis Ym is at the water level 22, as shown in Fig. 44B, meaning that about half of the medium apertures 252 are immersed in the water source, optionally serving as filtration apertures (254), while the other half is exposed to the atmosphere, optionally serving as non-filtration apertures (256). Further rotational movements in the same directions can further elevate the filter medium 244 above the water level 22, wherein the main axis Ym is above water level 22 as shown in Fig. 44C, such that a larger portion of the medium apertures 252 are exposed to the atmosphere in such a position. Reversing the directions of rotation will similarly serve to move the filter medium 244 toward and below water level 22.

[0235] The float displacement motor 101 and float transmission assembly 102 are shown in the example adjacent to frame transverse wall 30b, opposite to frame transverse wall 30a. It is to be understood that this is shown by way of illustration and not limitation, and that float displacement motor 101 and float transmission assembly 102 can be positioned on either side of the rotatable filtering assembly 202. The arms 103^aa and 103^ba, which are attached to frame transverse wall 30a, can be pivotably coupled to the wall 30b at corresponding pivots (116) without having engagement teeth 114 around the edges of their engagement ends 113, since these arms 112 mainly serve to provide additional support to the floats (50) and are not necessarily meshed with any other gears.

[0236] While engagement teeth 114 are shown to be integrally formed on the edges of the corresponding engagement ends 113 of float arms 112, other implementations can be similarly applied, including attachment of separate gears to the engagement ends 112 (embodiments not shown). Furthermore, it is to be understood that the number of gears can vary and is not limited to the gears shown in Figs. 44A-45B. Moreover, while a gear train is illustrated, it is to be understood that any other type of transmission assembly known in the art can be implemented, such as a transmission assembly that includes one or more chains, endless belts and pulleys, and the like.

[0237] Movable floats 50 can be utilized, by increasing and decreasing the position of the floats 50 relative to main axis Ym, to raise or lower the rotatable filtering assembly 202 relative to the water level 22. Controller 76, including any control sub unit 76, can be utilized to control the float displacement motor 101 so as to raise or lower rotatable filtering assembly 202 as desired.

[0238] In some implementations, the filtration system can include a shore anchoring structure 120, also termed an "anchoring structure 120" for simplicity, attached to the frame 30, as shown for example in Fig. 9A. The anchoring structure 120 can include any number of anchoring arms 122 attached to the frame 30 at arms coupling ends 126, and extending to opposite arm grounding ends 124. As shown in the example illustrated in Fig. 9B, the arm grounding ends 124 can be grounded on shore 26, while the arms 122 extend therefrom to a sufficient length allowing the frame 30 and rotatable filtering assembly 202 to be partially or fully submerged in the water source 20. An anchoring structure 120 can be utilized to prevent undesirable movement of the rotatable filtering assembly 202 away from the shore 26, for example due to intrinsic currents of the natural water source 20.

[0239] While anchoring arms 122 are shown in the illustrated examples in the form of relatively rigid elongated components (such as rods, pipes and the like), it is to be understood that this is shown by way of illustration and not limitation, and that anchoring arms 122 can be also implemented as elongated flexible members, which can include chains, cables, ropes, and the like.

[0240] In some implementations, filtration system 200 comprises an elevation assembly 130 to which at least one frame 30 and rotatable filtering assembly 202 are movably mounted, wherein the elevation assembly 130 is configured to control the height of the rotatable filtering assembly 202, for example relative to water level 22. The elevation assembly 130 includes a vertical column 132 that can extend from a column lower end 136 at the water source bed 24, to a column upper end 134 that can be at or above the water level 22, and one or more height adjustment assembly 138 configured to elevate or lower one or more rotatable filtering assembly 202.

[0241] Figs. 10-11 show an example of a filtration system 200 that includes two rotatable filtering assemblies 202a and 202b, both of which are mounted on a single frame 30 movably coupled to the vertical column 132. The height adjustment assembly 138 can be powered by any mechanism known in the art for elevating and lowering structures, such as hydraulic or pneumatic pistons, rack and pinion mechanisms, electric actuators, pulley assemblies and the like. The height adjustment assembly 138 can be operated to elevate or lower the frame 30 along vertical column 132, thereby simultaneously controlling the height of both rotatable filtering assemblies 202a and 202b.

[0242] In some implementations, the intake pipe 260 can include a manifold split into more than one pipe branches 268. For example, an intake pipe 260 is shown in Fig. 10 to split into pipe branches 268a and 268b, extending into rotatable filtering assemblies 202a and 202b, respectively.

[0243] Elevation assembly 130 can be utilized to control the height of one or more rotatable filtering assembly 202, relative to the water level 22. Such implementations can be used in combination with cleaning mechanisms that rely on opening and closing window covers 44 of wall windows 42 and/or funneling water through wall windows 42 provided with funneling extensions 48 as described above, for example by utilizing the height adjustment assembly 138 to lower the rotatable filtering assembly 202 until it is fully submerged during the filtering mode, and elevating the rotatable filtering assembly 202 and the wall windows 42 to the water level 22 during the cleaning mode.

[0244] Figs. 12A-B show two states of a filtration system 200 that includes two rotatable filtering assemblies 202a and 202, each of which is mounted on a respective frame 30, such that both frames 30a, 30b with the respective rotatable filtering assemblies 202a, 202b are independently movable along vertical column 132. Specifically, the elevation assembly 130 can include more than one height adjustment assembly 138, such as height adjustment assembly 138a operable to elevate or lower frame 30a with rotatable filtering assembly 202a, and height adjustment assembly 138b operable to elevate or lower frame 30b with rotatable filtering assembly 202b. [0245] Independent maneuverability of a plurality of rotatable filtering assemblies 202 provides improved control and flexibility during utilization of filtration system 200. For example, when utilized to transition frames 30 with wall windows 42 that can include window covers 44 and/or funneling extensions 48 to elevated or submerged positions, as described above, independently controllable frames 30 with rotatable filtering assemblies 202 can be utilized in a more efficient manner, such that while one or more of a plurality of rotatable filtering assemblies 202 is in a filtering mode (i.e., submerged in a lower height), another one or more of the plurality of rotatable filtering assemblies 202 can be in a cleaning mode (i.e., at an elevated height).

[0246] In some implementations, filtration system 200 comprises an offshore platform connection assembly 154 for coupling the frame 30 to an offshore platform 150, as shown for example in Fig. 13. The offshore platform connection assembly 154 can include elongated flexible members 156, such as chains, cables, ropes, and the like, coupled to the frame 30 on one end, for example to eyelets formed in frame 30, and to a winch 158 positioned on the offshore platform topside 152, configured to control the length of the elongated flexible members 156. The filtration system 200 can also include one or more weights 160, attached for example to the frame 30 as shown in the illustrated example, such that when the elongated flexible members 156 are released (i.e., elongated), the weights 160 pull the frame 30 and rotatable filtration assembly 202 downward (for example, deeper into the water source 20). In alternative implementations, additional weights are not required if the frame 30 is designed to be heavy enough to strive to tension the elongated flexible members 156.

[0247] Offshore platform connection assembly 154 can be utilized to control the height of rotatable filtering assembly 202, relative to the water level 22. Such implementations can be used in combination with cleaning mechanisms that rely on opening and closing window covers 44 of wall windows 42 and/or funneling water through wall windows 42 provided with funneling extensions 48 as described above, for example by releasing a greater length of elongated flexible members 156 to lower the rotatable filtering assembly 202 until it is fully submerged during the filtering mode, and shortening the elongated flexible members 156 (for example, by winding them around winch 158) to pull the rotatable filtering assembly 202 and the wall windows 42 upwards, to the water level 22, during the cleaning mode.

[0248] Another self-cleaning mechanism that can be implemented for filtration system 200 relies on changing the height of the rotatable filtering assembly 202 relative to the water level 22, at a speed high enough during which the impact of the filter medium 244 against the surface of the water at the water level 22 will dislodge filtride from the filter medium 244. For example, the rotatable filtering assembly 202 can be positioned such that at least a portion of the filter medium 244, and in some implementations, the whole of the filter medium 244, is above the water level 22. Then, lowering the rotatable filtering assembly 202 into the water at a high- enough speed, will cause the filter medium 244 to impact the water surface at the water level 22 at a force which is sufficient to dislodge filtride therefrom.

[0249] Any of the above-mentioned height-control mechanisms, including movable and/or adjustable floats 50, elevation assembly 130, and/or offshore platform connection assembly 154, can be utilized to elevate and lower the height of the rotatable filtering assembly 202 to forcibly impact the filter medium 244 against the surface of the water at the water level 22. In some implementations, alteration of the height of the rotatable filtering assembly 202 to impact the filter medium 244 against the surface of the water at the water level 22 is performed during a cleaning mode, while no suction is applied through the pipe inflow opening 262. In some implementations, more than one cycle of raising and lowering the rotatable filtering assembly 202 can be sequentially performed, wherein each subsequent cycle can serve to further dislodge filtride that remained stuck against the filter medium 244.

[0250] Another self-cleaning mechanism that can be implemented for filtration system 200 relies on accelerating the angular speed of rotation of rotatable filtering assembly 202 while being partially submerged in the water source 20. While filtration is performed at a very low angular speed of rotation W during filtering mode, to minimize accumulation of particles over the filter medium 112, the rotatable filtering assembly 202 can be accelerated for a limited time period to a significantly higher angular speed of rotation, such as an angular speed of rotation higher than 60 degrees per second (i.e., more than 10 revolutions per minute), causing the portion of the filter medium 244 that hits against the water at the water level 22, to hit at an impact force high enough so as to dislodge filtride from this portion of the filter medium 244. In some implementations, the direction of rotation can be also altered between subsequent cycles.

[0251] The controller 76 can be configured to transition the drive motor's 72 angular speed of rotation between low speeds during a filtering mode, and high speeds during a cleaning mode, as well as optional alteration of the direction of rotation during the cleaning mode. [0252] In some implementations, the filter medium 244 comprises copper, for example by being completely made of copper or coated by a copper layer. Copper is known to repel algae and other microorganisms that are present in many natural water sources. Embedding copper into the filter medium 244, or forming it from copper, can significantly reduce the likelihood of algae and other microorganisms from clinging to the filter medium and clogging its apertures 252 when immersed in a natural water source 20.

[0253] As mentioned, the minimal ratio Ra and/or maximal flow velocity across the filtration apertures Ve depend on the effective area of filtration Ae, such that for a given maximal flow rate Qm, a minimal effective area of filtration Ae is required to result in the minimal desired Ra and/or maximal desire Ve. Furthermore, as also mentioned above, the filtration apertures 254, which in some cases can constitute only a subset of the medium apertures 252, contribute to the effective area of filtration Ae. Thus, while for rotatable filtering assemblies 202 that are completely submerged, the total area of medium apertures At is equal to the effective area of filtration Ae, this is not the case for partially submerged rotatable filtering assemblies 202, in which case the depth of submergence and the size of the drum-shaped filter medium 244 directly influence the effective area of filtration Ae.

[0254] For example, a drum-shaped filer medium 244 can be submerged to a depth substantially equal to the radius of the drum-form of the filter-medium 244 (or the hoops 212), such that the main axis Ym is substantially at the water level 22. In such a case, the sum of aperture open areas Aa of about half of the medium apertures 252, constituting the submerged filtration apertures 254, will contribute to the effective area of filtration Ae.

[0255] In some examples, a distinction between filtration apertures 254 and non-filtration apertures 256 can be easily recognized by a visible marking indicating the level of submersion. In some examples, the filtration system comprises an immersion depth marking that indicates the level of immersion, such that all medium apertures above the immersion depth marking are non-filtration apertures, and all medium apertures below the immersion depth marking are filtration apertures. In some examples, the frame 30 comprises such an immersion depth marking 46. Fig. 8 shows one example in which at least one, or both of, the frame transverse walls 32, include an immersion depth marking 46. In use, the rotatable filtering assembly 202 is immersed such that the immersion depth marking 46 is substantially aligned with the water level 22, so that all medium apertures 252 above the immersion depth marking 46 are non- filtration apertures 256, and all medium apertures 252 below the immersion depth marking 46 are filtration apertures 254.

[0256] The immersion depth marking 46 can take any form which is visually identifiable, such as, but not limited to, printed marking, a slot, a groove, or any combination thereof. Fig. 8 shows an example of an immersion depth marking formed both as a slot 46a extending from a float opening 36 to a free edge of the frame transverse wall 32, and a groove 46b extending between two float openings 36.

[0257] In some cases, the level to which the rotatable filtering assemblies 202 may be submerged is limited, for example in the case of a shallow water source 20, which may result in a smaller portion of filtration apertures 254 contributing to the effective area of filtration Ae. Low depth submergence (e.g., to a depth which is smaller than the radius of the drum-form of the filter-medium 244) can be also desired in some implementations to reduce resistance applied by the water against the rotation of the filtering assembly 202.

[0258] One manner by which the effective area of filtration Ae may be increased even in low- depth submergence, is by increasing the diameter of the drum-shaped filer medium 244. However, such a solution will result in a very large rotatable filtering assembly 202, only a small portion of which is submerged and actually utilized for filtration, rendering such solutions ineffective and almost impractical for meeting the minimal ratio Ra or maximal velocity Ve requirements, without which it may not be possible to form very small apertures having an aperture size D that is not greater than 350 microns (including being optionally not greater than 300 microns, not greater than 200 microns, not greater than 100 microns, not greater than 40 microns, not greater than 10 microns, not greater than 5 microns, and/or not greater than 1 micron).

[0259] One possible solution by which the effective area of filtration Ae can be significantly increased to meet the minimal ratio Ra and/or maximal flow velocity across the filtration apertures Ve requirements, without significantly increasing the diameter of the drum-shaped filer medium 244, is by providing a filtration system 200 that includes a plurality of smaller, partially submergible, rotatable filtering assemblies 202. One example of such a filtration system 200 is illustrated in Fig. 14. While the illustrated example of Fig. 14 is shown to include four rotatable filtering assemblies 202a, 202b, 202c, 202d, it is to be understood that any other number, such as two, three, or more than four rotatable filtering assemblies 202 are also contemplated.

[0260] It is to be understood that for any implementation of a filtration system 200 that includes a plurality of rotatable filtering assemblies 202, the total area of medium apertures At is the sum of the aperture open areas Aa of all medium apertures 252 of all of the plurality of filtering assemblies 202, and the effective area of filtration Ae is the sum of aperture open areas Aa of all submerged filtration apertures 254 of all of the plurality of filtering assemblies 202. For example, the effective area of filtration Ae of the filtration system 200 illustrated in Fig. 14 will include the aperture open areas Aa of all submerged filtration apertures 254 of filter mediums 244a, 244b, 244c and 244d, combined.

[0261] Compared to a single rotatable filtering assembly 202 partially submerged to a low- depth below the water source level 20, a plurality of rotatable filtering assembly 202 can be submerged to the same depth, wherein each of the rotatable filtering assemblies 202 can have a significantly smaller diameter of its drum-shaped filer medium 244, to result in an equivalent effective area of filtration Ae. As a matter of fact, smaller rotatable filtering assembly 202 can be added to such a system 200 to further increase the effective area of filtration Ae, even in low-depth submergence implementations, thus significantly improving performance and efficiency of the filtration system 200, compared with an alternative based on one large rotatable filtering assembly as described above.

[0262] In some implementations, the intake pipe 260 can include a manifold or be otherwise split into several pipe branches 268, each pipe branch 268 coupled to, being in fluid communication with, and optionally extending through, a different rotatable filtering assembly 202. For example, the filtration system 200 illustrated in Fig. 14 shows an intake pipe 260 split into pipe branches 268a, 268b, 268c and 268d, extending through rotatable filtering assemblies 202a, 202b, 202c and 202d, respectively.

[0263] In some implementations, a filtration system 200 with a plurality of rotatable filtering assemblies 202 can include a corresponding plurality of watertight drive motors 72, such as drive motors 72a, 72b, 72c and 72d coupled to rotatable filtering assemblies 202a, 202b, 202c and 202d in the example illustrated in Fig. 14. However, in alternative implementations, a single drive motor can be utilized to drive more than one rotatable filtering assembly 202, and optionally all of the plurality of rotatable filtering assemblies 202, for example by adding appropriate transmission assemblies 80 configured to transmit the rotational movement of the drive motor 72 to the corresponding rotatable filtering assembly 202, each of which optionally implementing a different transmission ratio, depending on the distance and position of each rotatable filtering assembly 202 with respect to the mutual drive motor 72. Similarly, a plurality of controllers 76 can be provided, each for controlling a corresponding drive motor 72, or a single motor controller 76 can be implemented to control a plurality of drive motors 72.

[0264] A filtration system 200 with a plurality of rotatable filtering assemblies 202 can include a plurality of frames 30, wherein one or more of the plurality of rotatable filtering assemblies 202 are mounted to each of the frames 30. For example, the filtration system 200 illustrated in Fig. 14 shows two frames 30a, 30b connected to each other via the intake pipe 260 and pipe branches 268 extending therethrough, such that two rotatable filtering assemblies 202a and 202b are mounted to one frame 30a, and the other rotatable filtering assemblies 202c and 202d are mounted to the other frame 30b. It is to be understood that this implementation is shown by way of illustration and not limitation. For example, filtration system 200 can include four frames 30, such that each rotatable filtering assemblies 202 is mounted on a separate frame, or it can include a single frame 30 supporting all four rotatable filtering assemblies 202. In some implementations, a feed line manifold 90, as exemplified in Fig. 14, can be split into a plurality of cleaning feed lines 94 and/or a plurality of motor lines 92.

[0265] In some implementations, a single float 50, which can be optionally implemented as an adjustable float 50, can be shaped to extend around the circumference of one or more frames 30. For example, the filtration system 200 illustrated in Fig. 14 shows a single adjustable float 50 circumscribing all frames 30, and more specifically, extending around all four rotatable filtering assemblies 202.

[0266] Fig. 15 shows another example of a filtration system 200 that includes a plurality of rotatable filtering assemblies 202 which are serially arranged side-by-side, optionally mounted on a single frame 30 (though several frames can be also utilized), wherein the intake pipe 260 is split into a plurality of pipe branches 268 corresponding in number to the number of rotatable filtering assemblies 202.

[0267] In some examples, as shown in Fig. 15, one watertight drive motor 72 can be utilized for rotating several, and optionally all of, the rotatable filtering assemblies 202. For example, each of a plurality of rotatable filtering assemblies 202 can include a transfer gear 83, with a roller chain 85 disposed over all transfer gears 83 and meshed therewith. Fig. 15 shows an examples of a single watertight drive motor 72 configured to apply rotational movement to a first filtering assembly 202a of a plurality of filtering assemblies 202a, 202b, 202c and 202d, for example via transmission assembly 80 that includes the gear train described above, with a driving gear 84 mounted on a shaft 82 of the motor, and meshed with a driven gear 86 attached to one rotatable support wall 206a of the first filtering assembly 202a. A first transfer gear 83a can be attached to the first filtering assembly 202a, such as to an opposite rotatable support wall 206b thereof. Similar transfer gears 83 can be provided for the rest of the filtering assemblies 202b, 202c and 202d, with a roller chain 85 (that can be also a toothed belt instead of a chain) disposed over and meshed with all transfer gears 83, such that as the first filtering assembly 202a is rotated, the rotational movement is transferred to the remaining filtering assemblies 202b, 202c and 202d.

[0268] While a plurality of rotatable filtering assemblies 202 are shown to be arranged in a two-by-two matrix in Fig. 14, and side-by-side in Fig. 15, these arrangements are not meant to be limiting, and other arrangements are similarly contemplated. For example, a plurality of rotatable filtering assemblies 202 can be serially arranged one after the other, all rotatable around a single main axis Ym.

[0269] Fig. 46 shows another example of a filtration system 200 that includes a plurality of rotatable filtering assemblies 202 which are vertically arranged on top of each other, each filtering assembly 202 optionally mounted on a separate frame 30 (though no frame, or a single mutual frame over which all filtering assemblies are mounted, are also contemplated), wherein as also shown in other examples in Figs. 47A-B, the intake pipe 260 can be split into a plurality of pipe branches 268 corresponding in number to the number of rotatable filtering assemblies 202. While three

[0270] While three rotatable filtering assemblies 202a, 202b and 202c, are illustrated throughout Figs. 46-47B (and Figs. 49A-51), it is to be understood that any other number is contemplated. In some examples, the plurality of filtering assemblies 202 can be coupled to each other via flexible connectors 96, which can be in the form of chains, ropes, cables and the like. Flexible connectors 96 can allow relative movement between adjacent rotatable filtering assemblies 202, for example along a horizontal plane (which can be a plane substantially parallel to the plane of the water level or water source bed). [0271] In some examples, the lowermost filtering assembly can be coupled to tethers 98 that can anchor it to the water source bed, as illustrated for example for filtering assembly 202c in Fig. 47A. In some examples, the uppermost filtering assembly can be coupled to float(s) 50, as illustrated for example for filtering assembly 202a in Fig. 47A, which can raise or lower its height relative to the water level 22, as well as raise or lower the height of some or all of the filtering assemblies 202. In some examples, the pipe branches 268 are made of a flexible material, for example by being provided in the form of flexible hoses, so as to allow the filtering assemblies 202 coupled thereto, to move within water source 20. Utilization of flexible connectors 97 and flexible pipe branches 268 can allow the plurality of filtering assemblies 202, which are disposed between the water source bed 24 and the water level 22, to move relative to each other and/or relative to the water level 22, for example in response to water current within water source 20 and/or in response to height adjustment of float(s) 50 or other height adjustment assemblies disclosed herein.

[0272] On top of the ability to significantly reduce the size of each rotatable filtering assembly 202 while meeting the minimal ratio Ra and/or maximal flow velocity across the filtration apertures Ve requirements, a further advantage of a filtration system 200 with a plurality of rotatable filtering assemblies 202 is that each of the filtering assemblies 202 can be separately controlled, such that while one or more of the rotatable filtering assemblies 202 is in a filtering mode, the remainder one or more of the rotatable filtering assemblies 202 can be switched to the cleaning mode. This can ensure continuous filtration functionality of the filtration system 200 such that even when one or more of the rotatable filtering assemblies 202 are cleaned, water filtration does not need to be completely stopped but may rather continue through the rest of the rotatable filtering assemblies 202.

[0273] In some examples, the intake pipe 260 further comprises an expansion chamber 264, as shown for example in Fig. 16. An expansion chamber 264 is disposed upstream from the rotatable filtering assembly 202, and is formed as a portion of the intake pipe which expands to an expansion chamber diameter De which is at least twice as great as the minimal pipe diameter Dp, and in some examples, at least three times as great as the minimal pipe diameter Dp. The minimal pipe diameter Dp is the diameter of intake pipe 260 at its minimal intake pipe cross-sectional area Ap, which can be measured at a portion of the intake pipe 260 extending into the rotatable filtering assembly 202, or at least extending through or disposed at the level of, a rotatable support wall 206. [0274] The expansion chamber 264 can be either integrally formed with the remainder of intake pipe 260, or provided as a separate component attached in a sealed manner to the remainder of intake pipe 260. The expansion chamber 264 can include a gradually tapering inflow portion, expanding gradually radially outward from minimal pipe diameter Dp to expansion chamber De, a main expanded portion having a uniform diameter De along a length Lc, and a gradually tapering outflow portion, narrowing gradually radially inward from expansion chamber diameter De back to minimal pipe diameter Dp, after which the pipe may further extend along a certain length and terminate with pipe outflow opening 266. In some examples, the length of expanded main portion Lc is at least twice as great as the expansion chamber diameter De.

[0275] While shown in some of the drawings in a horizontal orientation, such that main axis Ym is substantially parallel to a plane of the water level 22, it is to be understood that this is merely for illustrative purpose, and that any filtration system (200, 300, 400, 500) disclosed herein, and more specifically, a rotatable filtering assembly (202, 302, 402, 502) thereof, can assume a vertical orientation, such that main axis Ym is substantially orthogonal to a plane of the water level 22.

[0276] Fig. 17A shows an example of a filtration system 200 oriented in a vertical orientation, such that its main axis Ym is substantially orthogonal to a plane of the water level 22. In examples of filtration systems that include one or more floats 50, including any of the movable and/or adjustable floats disclosed herein, the orientation of the float(s) 50 is adjusted to allow for vertical orientation of the rotatable filtering assembly 202. In some examples, the float(s) 50 extends along a plane which is substantially orthogonal to the main axis Ym. For example, float(s) 50 illustrated in Fig. 5 extend longitudinally along an axis which is substantially parallel to the main axis Ym, which will result in a horizontal orientation of the rotatable filtering assembly 202. Likewise, a float 50 illustrated in Fig. 14 defines a plane which is substantially parallel to any of the main axes Ym of any one of the plurality of rotatable filtering assemblies 202, also resulting in a horizontal orientation of the plurality of rotatable filtering assemblies 202. In contrast, a float 50 illustrated in Fig. 17A defines a plane which is substantially orthogonal to main axis Ym, resulting in a vertical orientation of the rotatable filtering assembly 202.

[0277] In some examples, the intake pipe 260 extend from the rotatable filtering assembly 202 downward, toward water source bed 24, such that the pipe outflow opening 266 is positioned lower than the rotatable filtering assembly 202. Fig. 17A shows an example of an intake pipe 260 oriented downward toward water source bed 24, and then extending to some length parallel to water source bed 24, wherein pipe outflow opening 266 is closer to water source bed 24, compared to the rotatable filtering assembly 202.

[0278] In some examples, the filtration system (200, 300, 400, 500) further comprises at least one weight 160. Fig. 17A shows an example of a filtration system 200 equipped with a weight 160 opposite to float 50. Any of the float 50 and/or weight(s) 160 can be coupled to the frame 30 and/or to the filtering assembly 202, preferably on opposite sides, via one or more coupling means such as cables, chains, and the like. For example, float 50 is shown in Fig. 17A to be coupled to frame transverse wall 32a via several chains circumferentially disposed therearound, and weight 160 is shown to be to coupled to frame transverse wall 32b via several chains circumferentially disposed therearound. The combination of float(s) 50, and in some examples, movable and/or adjustable float(s) 50, with weight(s) 160, can serve to control the height of rotatable filtering assembly 202 within the water source 20 (i.e., relative to water level 22), for example by adjusting the degree of floatation of float(s) 50, while weight(s) 160 pull the rotatable filtering assembly 202 gravitationally downward. Moreover, the combination of float(s) 50 from above, and weight(s) 160 from below the rotatable filtering assembly 202, can together stabilize the rotatable filtering assembly 202 in a vertical orientation, substantially orthogonal to the plane defined by water level 22.

[0279] In some implementations, the filtration system 200 can further include an additional vibration motor 73, that can be coupled to the rotatable filtering assembly 202 and configured to vibrate, and more specifically, apply vibrational movement to the filter medium 244, which will serve to dislodge filtride accumulated thereon. The vibration motor 73 is a watertight motor, for the same reasons described above with respect to watertight sealing of the drive motor, and can be optionally sealed by being encompassed by a watertight sealed housing, similar to housing 74. Fig. 17A shows an example of a filtration system 200 equipped with both a watertight drive motor 72 and a watertight vibration motor 73, both of which can be attached to the same component of a frame 30, such as both being coupled to frame transverse wall 32a as illustrated, or to different components of the frame 30 or other components of the filtration system 200. Operation of the vibration motor 73 can be controlled by a separate control sub-unit of the controller 76, or the same control sub-unit of the drive motor 72. [0280] The controller 76 can be adapted to control the operation of the drive motor 72 and the vibration motor 73, such that the drive motor 72 is activated to rotate the rotatable filtering assembly 202 during the filtering mode, while the vibration motor 73 is inactive, and the vibration motor 73 is activated, while the drive motor 72 is stopped, during the cleaning mode. The vibration motor 73 can be implemented, in some examples, as an eccentric rotating mass vibration motor. While shown as two separate motors in Fig. 18 A, in some implementations, the same motor 72 can be used to apply both rotational movement for rotating filtering assembly 202, and vibrational movement to facilitate vibration of the filter medium 244. The controller 76 can control the operation of such a multi-purpose motor 72, to transition between rotational movement during the filtering mode and vibrational movement during the cleaning mode.

[0281] In some examples, filtration system 200 can include one or more ultrasonic transducer(s) 96, positioned to apply ultrasonic energy directed at the filter medium 244. Fig. 17A shows an example of a filtration system 200 comprising an array of several ultrasonic transducers 96 facing the filter medium 244. The ultrasonic transducer(s) 96 can apply ultrasonic energy that can disintegrate and/or create ultrasonic waves that will impact against the filter medium 244 in a manner that will dislodge filtride therefrom. Advantageously, the desire ultrasonic waves, directed at the filter medium, do not require high energy, enabling utilization of the ultrasonic transducer as low-energy long-term self-cleaning mechanism.

[0282] In some examples, the filtration system 200 further comprises one or more tethers 98, that can be coupled to a component of the filtration system 200 such as to frame 30 or to the intake pipe 160, as illustrated in Fig. 17A. The tethers 98 are intended to secure the filtration system 200 to the water source bed 24 by anchor elements or heavy structures, and can be in the form of cables, chains, ropes, moorings and the like.

[0283] In some implementations, the filtration system 200 includes a fully immersible rotatable filtering assembly 202, such that the entire filter medium 244, as well as nozzles 284, reside within the water source 20, as shown in Figs. 17A-B for example. While a high-velocity jet sprayed from nozzles 284 may still be employed, in other implementations, nozzles 284 can be adapted to spray air (or other suitable gas) instead of water, which can be more suitable for fully-submersible implementations. [0284] Utilization of air instead of water sprayed from nozzles 284 may require additional adaptation for improved efficiency, such as approximation of the nozzles to the filter medium 244, and optionally orienting the nozzles 284 at a preferred angled relative to the filter medium 244. Fig. 17B shows a filtration system 200 equipped with a spray assembly 280 adapted to spray jets of compressed air (or other suitable gas) instead of water. In such cases, cleaning feed line 94 is not shared with a motor feed line (92), since a water motor may require a feed line for supplying water, while cleaning feed line 94 may be utilized to deliver compressed air. As shown, feed line 94 can extend, for example through a sealed opening formed at rotatable support wall 206a, into internal space 250, and offset to approximate spray conduit 282 and nozzles 284 closer to filter medium 244.

[0285] Unlike water, air tends to move upward toward the water level 22 upon exiting the nozzle outlet. The trajectory of the sprayed air may depend on the speed at which it is sprayed from the nozzle 284. Thus, depending on various factors such as the depth of water within which the rotatable filtering assembly 202 is immersed, the jet speed, and the like, the orientation and relative position of the nozzles 284, preferably in closer proximity to the filter medium 244 (at least compared to water spraying nozzles of partially submersible filtering assemblies), can be selected, as illustrated in Fig. 17B.

[0286] One possible risk associated with utilization of air nozzles instead of water nozzles, is that air bubble may be trapped within internal space 250, for example flowing upward until such air is stuck against an upper rotatable support wall 206a. This may pose a risk of air eventually being sucked into intake pipe 260 along with the filtrate. In some examples, filtration system 200 further comprises an air or gas release mechanism 285 (termed "air release mechanism" for short from now on, but intended for utilization for gas release as well), as shown in Fig. 17B, to overcome such issues. Air release mechanism 285 can include baffle 286, which can be an upper inclined baffle 286, residing within screen mesh 244, extending from the circumference of the of the screen mesh 244, such as an upper edge of the screen mesh 244 in the illustrated example, optionally in a tapering manner, to a narrower opening leading to a release tube 287. The release tube 287 can extend upward, for example through an upper rotatable support wall 206a and optionally through an upper frame transverse wall 32a, having its upper end, through which air may be released, positioned above the water level 22. The release tube 287 can extend along main axis Ym or any axis parallel to main axis Ym. [0287] The cleaning feed line 94, utilized for feeding compressed air or gas to spray assembly 280, can penetrate into release tube 287 at an outer portion thereof, extend through the release tube into the filtering assembly 102, at which point it can extend sideways toward screen inner surface 248, to approximate the spray conduit 282 and air nozzles 284 closed to the screen inner surface 248, as illustrated in Fig. 17B.

[0288] The baffle 286 can be made of a rigid or flexible material, such as a membrane, and is used to direct air bubbles along its inclined surface, through the release tube 287, to the atmosphere. For example, when air is sprayed from nozzle 284 toward screen inner surface 248, some air bubbles that remain within internal space 250 will float upward, toward baffle 286. The inclined angle of the baffle 286 will direct such air bubbles into release tube 287, allowing them to be released therefrom to the atmosphere at its upper end. In order to allow trapped air to be released to the atmosphere, yet prevent particles that may be occasionally present in the surrounding atmosphere from falling into internal space 250 through the same release tube 287, the release tube can be further equipped with a unidirectional valve 288 at its upper end, such as a ball valve 288 illustrated in Fig. 17B, or any other type of unidirectional valve.

[0289] While in some examples, as shown in Fig. 3, pipe inflow openings 162 are offset from main axis Ym, for example by being formed along a sidewall of the intake pipe 260, in other examples, a pipe inflow opening 162 can be formed as an open end of intake pipe 260, defined over a plane substantially orthogonal to main axis Ym. Fig. 17B shows an example of an intake pipe 260 terminating with an open end defining pipe inflow opening 162 disposed within internal space 250, and in fluid communication with filter medium 244 and internal space 250. The intake pipe 260 extends along a relatively short length into internal space 250, or in other examples, intake pipe 260 can terminate substantially at the level of rotatable support wall, such as rotatable support wall 206b in the illustrated example, resulting in the pipe inflow opening 162 being substantially flush with a surface of the rotatable support wall 206.

[0290] In some examples, the filtration system 200 further comprises an inner flange 209 formed around the edge of the pipe inflow opening 262, for example along an inner surface of a rotatable support wall 206b, adjacent central sealed opening 208. The flange 209 can define a tapering inner edge 210, extending radially inward to a narrower diameter of the pipe inflow opening 262, as shown in Fig. 17B, for improved hemodynamic behavior. [0291] In some examples, as shown in Figs. 39A-C, the filtration system 200 further comprises at least one camera 56 configured to acquire images of at least a portion of filter medium 244. The camera 56 can be mounted on a camera mount 58 connected to and/or, extending from, the frame 30. The camera 56, which can be a CCD camera or any other suitable type of camera, may face an upper portion, or any other portion, of filter medium 244, configured to take images of the filter medium at a resolution sufficient to detect the amount of filtride accumulated on the imaged portion of the filter medium 244.

[0292] In some examples, the camera mount 58 is an adjustable arm, allowing the position of the camera 56 to be changed with respect to the filter medium 244. Adjustment of camera mount 58 can include any combination of angular and axial movement of at least one link member Ln of the camera mount 58, wherein the arm 58 can include any number of links Ln that can be movable relative to each other and/or relative to the connection of the camera mount 58 with frame 30. For example, one or more links of the mount 58 can pivot relative to each other or relative to frame 30 about joints Jn, and one or more links of the mount 58 can be telescopically movable to change the overall length of the mount 58.

[0293] Fig. 39A shows one example of a non-adjustable camera mount 58 that includes a stationary support member 59. In the illustrated example, the stationary support member 59 is shown to extend from one of the frame transverse walls 32, wherein the stationary support member 59 is immovable with respect to other immovable portions of the frame 30, such as frame transverse walls 32. The stationary support member 59 can be integrally formed with the frame transverse wall 32, formed as an extension thereof, or otherwise affixed thereto, such as by welding, bolting, and the like.

[0294] Fig. 39B shows another example of an adjustable camera mount 58 that includes link members Ln configured to pivot about respective joints Jn. For example, a first link member Lnl can be movably coupled to one of the frame transverse walls 32 at a rotatable joint Jnl, allowing it to rotate about an axis extending along the length of the link Lnl. A second link member Ln2 can be coupled to the first link member Lnl at pivot joint Jn2, allowing it to pivot relative to the first link member Lnl. A third link member Ln3, to which the camera 56 can be attached, may be coupled to the second link member Ln2 at pivot joint Jn3, allowing it to pivot relative to the second link member Ln2. [0295] Fig. 39C shows another example of an adjustable camera mount 58 that includes a stationary support member 59 and link members Ln configured to pivot about respective joints Jn. The stationary support member 59 can be implemented in a similar manner to that described above with respect to Fig. 39 A, and the link members Ln can be implemented in a similar manner to that described above with respect to Fig. 39B, with the exception that the first link member Lnl is movable coupled at joint Jnl to the stationary support member 59. The stationary support member 59 added in the example illustrated in Fig. 39C can offset the camera 56 further away from the filter medium 244, while allowing for the same degree of position adjustment as that shown in Fig. 39B.

[0296] While shown throughout Figs. 39A-C to be attached to, or extend from, frame transverse wall 32b, it is to be understood that the camera mount 58 can be similarly attached to, or extend from, other portions of the frame 30. While three link members are illustrated in Figs. 39B-C, it is to be understood that any other number of link members, such as one, two, or more than three, is contemplated, and that a camera mount 58 can be provided with or without a stationary support member, and with or without movable links. While pivotable links are illustrated in Figs. 39B-C, it is to be understood that other types of movable link members, such as telescopically movable or otherwise axially movable link members, are similarly contemplated.

[0297] Camera mount 58 can be, in some examples, manually adjustable, allowing an operator to manually adjust the position of camera 56 and lock it in a selected position. Camera mount 58 can be, in some examples, electronically adjustable, and may include any combination of hydraulic, pneumatic, or electric components, such as linear or angular actuators. A controller 76e, which can be a control sub-unit 76e of controller 76, can control the operation of camera 56 and/or camera mount 58. Any of the camera 56 and/or camera mount 58 can be, in some examples, remotely controlled, for example by an operator remotely located on shore or any other remote location relative to filtration system 200. Control sub-unit 76e can include a receiver, a transmitter, and/or a transceiver, configured either to transmit images acquired by camera 56, and/or receive operation commands for controlling the camera 56 and/or the adjustable camera mount 58. For example, camera 56 can acquire one or more images that can be transmitted to a remote location, allowing an operator to readjust the position of the camera, by remotely controlling camera mount 58, to a desired position relative to filter medium 244. [0298] One or more images of the filter medium 244, acquired by the camera 56, can be analyzed, to indicate the amount of filtride over the imaged portion of filter medium 244, such that any of the self-cleaning mechanisms described above can be utilized in response. In one example, control sub-unit 76e includes image processing algorithms configured to analyze the images acquired by camera 56, and activate any of the self-cleaning mechanisms described above if cleaning is required. For example, if the amount of filtride, according to the analysis, exceeds a threshold value or is otherwise decided, by the analysis, to require cleaning of the filter medium 244, the control sub-unit 76e can further control the transition between filtering mode and cleaning mode, control the angular speed of rotation of the rotatable filtering assembly 202, control the degree of immersion of filtration system (for example, by controlling elevation assembly 130, offshore platform connection assembly 154, movable and/or adjustable float(s) (50), control operation of ultrasound transducer(s), control flow of cleaning fluid through spray assembly 280, and the like.

[0299] Imaging of the filter medium 244 can be performed in a continued manner, for example throughout the duration of cleaning mode operation, or after a selected amount of time, to reexamine and update filtride accumulation status, to decide in a similar manner if and when such operations related to cleaning mode should be halted or readjusted. For example, the angular speed of rotation can be continuously adjusted in response to the degree of accumulated filtride over the imaged portion of filter medium 244.

[0300] In some examples, images acquired by camera 56 are transmitted to a remote location, for example via a transmitter and/or transceiver of control sub-unit 76e. A remote device can include image-processing algorithms similar to those described above with respect to control sub-unit 76e. Alternatively or additionally, such images can be manually inspected by an operator situated at the remote location. Operational commands to control any of the selfcleaning mechanisms in a similar manner to that described above, can be received by the control sub-unit 76e, for example via a receiver and/or transceiver of control sub-unit 76e.

[0301] In some examples, the position of camera 56 can be continually or occasionally readjusted, for example by adjustable camera mount 58, to direct the camera toward different regions of filter medium 244, to analyze filtride accumulation at more than one region of filter medium 244. In some examples, filtration system 200 includes a plurality of cameras 56, each optionally mounted on a corresponding camera mount 58. An array of camera 56 can be utilized to simultaneously acquire images of more than one region of the filter medium 244. [0302] In some implementations, a rotatable filtering assembly 200 is immersed such that the filter medium's 244 upper end is in close proximity to the water level 22, such as being within a range of 10 cm below or above water level 22, within a range of 5 cm below or above water level 22, within a range of 2 cm below or above water level 22, and/or at the level of the water level 22. Such implementation may be advantageous in that the close proximity of the drum or screen mesh 244 to the water level 22 may cause the surrounding water, during the rotation movement of the screen mesh 244, to form a boundary layer over or in close proximity to the upper portion of the screen mesh 244, which serves as a self-cleaning mechanisms that removes filtride from this upper portion. This may further increase the overall efficiency of system 200, since a relatively large portion of the medium apertures 252 serve as filtration apertures 254, contributing to an increased ratio Ra, while only the portion of the apertures 254 at the region which is closed to the water level 22, which can be preferably less than 10% of the total number of medium apertures 252, serve as non-filtration apertures 256.

[0303] In some examples, a filtration system can be equipped with a bubble generator 140, which can be positioned below the filter medium of at least one filtering assembly, when immersed within a water source 20. Figs. 47A-47B show an example of a filtration system 200 that includes a plurality of vertically arranged drum-type rotatable filtering assemblies 202, with a bubble generator 140 positioned below the lowermost filtering assembly 202c. While Figs. 47A-B show a bubble generator 140 used in combination with a plurality of vertically arranged drum-type filtering assemblies 202, which can be similar to the plurality of filtering assemblies 202 described with respect to Fig. 46, it is to be understood that this is not meant to be limiting, and that a bubble generator 140 can be used also with a single filtering assembly by being placed below the single filtering assembly when immersed in a water source, and that the bubble generator can be used in combination with any other type of one or more filtering assemblies, such as one or more disc-type filtering assembly 302, one or more coiled-thread type filtering assembly 402, or one or more sheaf-type filtering assembly 502.

[0304] The bubble generator 140 includes a hollow enclosure 142 defining an internal lumen 141, and a plurality of bubble apertures 144 facing upward, toward the at least one filter medium. Fig. 48 shows an enlarged sectional view of one example of a bubble generator 140, wherein the hollow enclosure 142 can be provided in the form of a plurality of interconnected tubes sharing a joined lumen 141. It is to be understood that any other type of hollow enclosure can be similarly used, including a hollow housing having any shape and enclosing an internal lumen 141 with a plurality of bubble apertures 144 formed along an upper surface thereof, the bubble apertures 144 being in fluid communication with the lumen 141, and facing upward, for example toward water level 22 and opposite to water source bed 24.

[0305] The bubble generator further includes an air/gas hose 146 attached to the hollow enclosure, 142 which can be in the form of a pipe, hose, tube and the like, and can be either rigid or flexible. The air/gas hose 146 is in fluid communication with the lumen 141, and is configured to deliver air (including compressed air) or any other gas intro the lumen 141 of the hollow enclosure 142, which is then released through the bubble apertures 144 in the form of bubbles 28 floating upward, toward the one or more filter medium(s).

[0306] In some examples, the bubble generator 140 further includes one or more tethers 98 that can be attached to the hollow enclosure 142, so as to anchor it to the water source bed 24. While the bubble generator 140 is illustrated in Figs. 47A-B with tethers 98, it is to be understood that this is not meant to be limiting, and that in other implementations, bubble generator can be devoid of tethers 98.

[0307] A bubble generator 140 can serve as a self-cleaning mechanism that can be the sole cleaning-mechanism of any filtration system disclosed herein, or utilized in combination with one or more other self-cleaning mechanism(s) disclosed herein. During a cleaning mode, air or other gas can be delivered, through the hose 146, into lumen 141, and through the bubble apertures 144, to form air or gas bubbles 28 that float upward, toward the one or more filter medium(s). The bubbles 28 impinge against the filter medium in a manner that can dislodge filtride accumulated thereon. During filtering mode, bubble formation may be ceased by discontinuing air or gas flow through the hose 146.

[0308] In the illustrated examples, the hollow enclosure 142 is shaped to generate bubbles that surround the entire horizontal planar projection of the filter medium 244. However, it is to be understood that in other implementations, the hollow enclosure can be shaped to generate bubble 28 that are aligned only with a fractional portion of the filter medium's planar projection. For example, the hollow enclosure can be, in some variations, have the shape of a single tube or hose positioned below a portion of the nearest filter medium (variation not shown).

[0309] In some examples, the bubble generator 140 can be coupled to the nearest (e.g., lowermost) filtering assembly, such as to a frame 30 thereof, via one or more flexible connectors 97. While a single bubble generator 140 is shown in Figs. 47A-B below a lowermost filtering assembly 202c when a plurality of filtering assemblies 202 are provided, it is to be understood that in other examples, a separate bubble generator 140 can be provided below any one of a plurality of filtering assemblies.

[0310] In some examples, the filtration system further includes a guiding chamber 190 extending upward from the bubble generator 140 and around the one or more filtering assemblies 202, as shown in Figs. 49A-50. The guiding chamber 190 includes a chamber wall 194 extending from a chamber lower end 193 to a chamber upper end 192, wherein the one or more filtering assemblies can be disposed within the guiding chamber 190, substantially enclosed by the chamber wall 194. The chamber lower end 193 can be below the filtering assembly 202, and in the case of a plurality of filtering assemblies, below the lowermost filtering assembly, such as filtering assembly 202c in the illustrated examples. In some implementations, the chamber lower end 193 can be at the level of the bubble generator 140, such as the level of the hollow enclosure 142. In some implementations, the chamber lower end 193 can be below or at the level of the bubble apertures 144.

[0311] The chamber lower end 193 can be attached to the bubble generator 140, such as to the hollow enclosure 142, optionally via a plurality of support extensions 195 extending between the bubble generator 140 and the chamber lower end 193. The chamber lower end 193 can be optionally an open end. The chamber upper end 192 is open ended, and can be positioned slightly below the water level 22 as shown in Fig. 49A. Alternatively, the chamber upper end 192 can be positioned at the level of the water level 22, or even terminate above the water level 22. The chamber wall 194 is dimensioned to enclose the one or more filtering assemblies 202. In some examples, the chamber wall 194 is designed to circumscribe the entire perimeter of any of the filtering assemblies 202. In some examples, the chamber wall 194 is designed to circumscribe only a portion of the perimeter of any one of the filtering assemblies 202, such as at least 50% of the perimeter, at least 70% of the perimeter, or at least 90% of the perimeter. The chamber wall 194 can include openings through which pipes or hoses of the filtration system 200 can extend into the guiding chamber 190, such as any one of intake pipes 260a, 206b, 206c, air hose 146, and the like.

[0312] Guiding chamber 190 is designed to direct bubbles 28 generated by the bubble generator 140 through the filter mediums 244 of the one or more filtering assemblies 202 as the bubbles 28 float upward, toward the water level 22. Specifically, guiding chamber 190 is designed to prevent dispersion of bubble 28 farther away from the one or more filter medium 244. As such, the shape and dimensions of the chamber wall 194 are designed to closely match the horizontal projections of the filtering assemblies 202 and/or of the hollow enclosure 142, since placing the chamber wall 194 too far away from any of the filter mediums 244 might allow bubble dispersion sideways, contrary to the desired path for bubbles 28.

[0313] Fig. 49B shows one optional design of the guiding chamber 190, in which the chamber wall 194 is provided with a uniform rectangular cross-sectional shape, defining four walls that can be offset from the frames 30, such as being offset laterally from edges of corresponding bottom plates 40. Fig. 50 shows another optional design of a guiding chamber 190, in which the chamber wall 194 is provided with a circular non-uniform cross-sectional area between the chamber lower end 193 and the chamber upper end 194, that can follow a frustoconical profile, extending from a wider cross-sectional area at the chamber lower end 193 to a narrower cross- sectional area at the chamber upper end 192, so as to direct the bubbles 28 closer to the filter mediums 244 as the bubble 28 float further upwards. It is to be understood that while two cross- sectional shapes are illustrated, any other cross-sectional shape of the chamber wall is contemplated, such as triangular, trapezoidal, star-shaped, elliptic, and the like.

[0314] While a bubble generator 140 is shown in Figs. 47A-50 to be positioned below a filtering assembly 202, and optionally below all filtering assemblies 202, in other examples, one or more bubble generator can be positioned sideways from filter medium 244 of a corresponding filtering assembly 202. Fig. 51 shows another example of a filtration system 200 that includes a plurality of filtering assembly 202, wherein the bubble generator 140 can include a corresponding plurality of hollow enclosures 142, such as corresponding hollow enclosures 142a, 142b and 142c, positioned sideways from filter mediums 244a, 244b and 244c, respectively. In such cases, the bubble generator can be configured to release bubble 28 in a lateral or horizontal direction, directed toward a portion of a corresponding screen mesh 244 (such as a lower side of the corresponding screen mesh), allowing the bubble to jet toward the screen mesh and float upward through the medium apertures.

[0315] In the example illustrated in Fig. 51, each hollow enclosure 142 can include bubble apertures 144 through which bubbles 148 can be jettisoned toward the corresponding filter medium 244, wherein all hollow enclosures 142 can be in fluid communication with the air hose 146 via a suitable hose or interconnecting pipe 143 extending therebetween. While a single bubble generator 140 comprising a plurality of hollow enclosures 142 in fluid communication with each other and with a common air hose 146 is illustrated in Fig. 51, in other examples, separate bubble generators 140 can be provided, each having its own hollow enclosure and corresponding air hose, wherein the separate hollow enclosures are not necessarily in fluid communication with each other.

[0316] Figs. 52A-C show another example of a filtration system 200 that can be designed for improved assembly and disassembly of components thereof. In some examples, a frame 30 can include one or more spacing elements, such as spacer tubes 162, disposed between two opposing frame transverse walls 32a, 32b. the spacer tubes 162 can be made of a rigid material, disposed over corresponding central threaded rods 161, by which the spacer tubes 162 can be coupled to the frame transverse walls 32a, 32b. The spacer tubes 162 can advantageously retain structural integrity of the frame 30, keeping both frame transverse walls 32a, 32b spaced away from each other, during removal or attachment of other components of the filtration system 200 to the frame 300, such as removal or insertion of the float(s) 50 through the corresponding float openings 36.

[0317] The rotatable filtering assembly 202 can include one or more seals disposed around various openings of the support walls 206, such as around central sealed opening 208. In some examples, a spring 164 can be utilized to bias the support walls 206 against the seals. Fig. 52A shows one example of a spring 164 disposed over a spring support shaft 154, between one of the support walls 206a and a corresponding frame transverse wall 32a, or between one of the support walls 206a and an opposing flange-like spring base 163. The spring can serve to apply pressure in a manner that improves engagement of seal 167 (see Fig. 52A) with support wall 206a, and seal 168 (see Fig. 52B) with support wall 206b, which may be required at least during initial operational cycle (e.g., of a filtering mode) of the rotatable filtering assembly 202.

[0318] While two spacer tubes 162 are illustrated in Fig. 52A-C, any other number of spacer tubes or other spacer elements can be utilized, such as a single spacer tube, or more than two. While the filtration system 200 is shown in Figs. 52A-C to include spacer tubes 162, spring 164, and seals 168, it is to be understood that these components are not necessarily meant to be combined together in the same filtration system, and that any example of a filtrations system disclosed herein can include any of spacer tubes, springs and/or seals, alone or in combination. Moreover, while the filtration system 200 of Figs. 52A-C is shown to include a transmission assembly 80 in which the rotatable support wall 206 also serves as the driven gear, and while the system 200 shown in these drawings illustrates the motor 72 and/or transmission assembly 80 attached to the same frame transverse wall 32 and/or support wall 206 through which the intake pipe 260 extends, it is to be understood that the example of Figs. 52A-C can be adapted to include any other configuration disclosed herein for such features, and that such features are not limited to the example illustrated in Figs. 52A-C but can be adapted for any other example of a filtration system disclosed herein, mutatis mutandis.

[0319] As mentioned, a filtration system 200 according to the current specification may be provided, in some implementations, without the need for any self-cleaning mechanisms. However, it is to be understood that for implementations that do include a self-cleaning mechanism, the filtration system 200 is not limited to a single type of mechanism, but may rather include any combination of the above-mentioned self-cleaning mechanisms. For example, the same filtration system can include a combination of any of: a spray assembly 280, wall windows 42, optionally with movable window covers 44 and/or funneling extensions 48, movable and/or adjustable floats 50, a height adjustment assembly 138 of elevation assembly 130 or an offshore platform connection assembly 154, a vibration motor 73, a bubble generator 140, a guiding chamber 190, a controller configured to accelerate and decelerate angular speed of rotation and/or change direction of rotation, a filter medium 244 that comprises copper, and/or ultrasonic transducer(s) 96, and can optionally include at least one camera 56 configured to acquire images of filter medium 244.

[0320] While various water conduits such as suction lines 60, intake pipes 260, feed line manifolds 90, cleaning feed lines 94, and motor lines 92, are illustrated throughout the figures as relatively rigid pipes, it is to be understood that this is shown by way of illustration and not limitation, and that any of such conduits can be flexible, such as being implemented in the form of hoses and the like.

[0321] While a filtration system is described above, for example with respect to Figs. 1A-17A, 39A-C, 44A-52C, to include a drum-type rotatable filtering assembly 202 (or a plurality of such assemblies), it is to be understood that filtration systems of the current specification are not limited to drum-type filtering assemblies, as will be further elaborated for other types of implementations hereinbelow.

[0322] While certain features are shown in the drawings in combination with each other, it is to be understood that a combination of features throughout the drawings is not meant to be limiting, and that optional features described throughout the current specification can be used in isolation for certain implementations of filtration systems described herein. For example, while filtrations system 200, 300, 400, and/or 500, are illustrated throughout the drawings in combination with a frame (30), it is to be understood that any of these filtration systems can be optionally provided without a frame. While the filtration systems are illustrated in some of the drawings in combination with one or more floats (50), the filtration systems can be similarly provided without any float(s). While the frame (30) of the filtration systems is illustrated to include wall windows (42) throughout the drawings, the filtration systems, when provided with a frame, can be devoid of wall windows. While the frame (30) of the filtration systems is illustrated to include a bottom plate (40) throughout the drawings, the filtration systems, when provided with a frame, can be devoid of a bottom plate, as shown for example in Figs. 52A-C. While some of the filtration systems (e.g., system 200) are illustrated in some of the drawings in combination with a spray assembly (280), the filtration systems can be similarly provided without a spray assembly.

[0323] Moreover, while the filtration systems are illustrated throughout the drawings with a watertight drive motor (72) and at least one watertight controller (76), in some implementations of the filtration systems, the motor is not necessarily a watertight motor and is not necessarily positioned in close proximity to a filtering assembly, and a controller can be similarly be placed elsewhere or not present at all. For example, a motor can be positioned closer or at the shore, with an appropriate transmission assembly designed to transfer its driving force to rotational movement of one or more filtering assembly. Likewise, some implementations of the filtration systems disclosed herein can be rotatable by other mechanisms that do not include any motor, such as being rotatable by turbines or other mechanisms known in the art.

[0324] Similarly, a vibration motor (73) can be either a watertight motor if designed for full or partial immersion in the water source, or a regular (i.e., not necessarily watertight) vibration motor, for example in implementation in which it can be positioned out of the water (such as above the water level 22). Moreover, while shown as a supplementary motor, combined with a drive motor (72), such as in Fig. 17A, a vibration motor (73) can be provided in isolation, without a drive motor, in some implementations of the filtration systems. Likewise, while ultrasonic transducers (96) are illustrated, for example in Fig. 17A, in combination with a frame (30), a drive motor (72), float (50), vibration motor (73), tethers (98), weight (160) and the like, it is to be understood that one or more ultrasonic transducer can be provided in some implementations of the filtration systems in isolation (or combined with any combination of such other components). For example, at least one ultrasonic transducer can be coupled to a components of a filtering assembly, such as a rotatable support wall or any other component, instead of to the frame.

[0325] While some of the filtration systems (e.g., system 200) are illustrated in some of the drawings (e.g., Figs. 17A-B) in combination with tethers (98), the filtration systems can be similarly provided without any tether(s), and tether(s) can be included in any of the filtration systems described herein, in isolation and without any other components illustrated in Figs. 17A-B, such as any of a frame (30), a drive motor (72), float (50), vibration motor (73), ultrasonic transducers (96), weight (160) and the like, or with any combination of only some of such components.

[0326] While some of the filtration systems (e.g., system 200) are illustrated in some of the drawings (e.g., Figs. 13 and 17A-B) in combination with a weights (160), the filtration systems can be similarly provided without any weight(s), and weight(s) can be included in any of the filtration systems described herein, in isolation and without any other components illustrated in Figs. 17A-B, such as any of a frame (30), a drive motor (72), float (50), vibration motor (73), ultrasonic transducers (96), tethers (98), offshore platform connection assembly (154) and the like, or with any combination of only some of such components.

[0327] It is to be understood that any reference to the term "filtration systems", without a numeral indicator specified next to the term, throughout the current specification, refers to any of the filtration systems 200, 300, 400 and/or 500 disclosed herein.

[0328] While some components disclosed herein may be illustrated only in combination with one type of a filtration system, it is to be understood that they may be similarly utilized in combination with other filtration systems disclosed herein. For example, while any of an anchoring structure (120), elevation assembly (130), offshore platform (150) and offshore platform connection assembly (154), immersion depth marking (46), funneling extensions (48), ultrasonic transducers (96), tethers (98), weights (160), spray assembly (280), flexible conduits (283), air release mechanism (285), expansion chamber (264), camera (56), camera mount (58) and the like, are illustrated primarily in combination with a drum-type filtration system 200, and some are illustrated in combination with a disc-type filtration system 300, any of these components (in isolation or in any combination thereof) can be similarly utilized with any of the filtration systems disclosed herein, as will be further elaborated below, even without an accompanying illustration of any such optional combination. [0329] Another possible implementation of a filtration system, referred to as disc-type filtration system 300, provided with a disc-type rotatable filtering assembly 302, will now be described in detail with reference to Figs. 18A-28 and 41-42 of the accompanying drawings. Fig. 18A shows a view in perspectives of an example of several discs 332 tightly pressed against each other. Fig. 18B shows the discs 332 of Fig. 18A spaced from each other. Fig. 19 shows a partial enlarged view of two discs 332 pressed against each other. Fig. 20 shows one example of a disc-type filtration system 300. Fig. 21 shows a zoomed in view on a portion of the disc-type filtration system 300 of Fig. 20, with the discs removed from one filtering subassembly 320 to expose its inner structure. Fig. 22 shows a view in perspective of an example of a disc-type filtration system 300, with an intake chamber 370 shown with partial transparency. Figs. 23-25 show various views of an exemplary disc-type filtration system 300 with some of the filtering sub-assemblies 320 in a cleaning mode. Fig. 26 shows a partial sectional view of an exemplary disc-type filtration system 300. Fig .27 shows an example of a disc-type filtration system 300 with a spray assembly 280. Fig. 28 shows an example of a disctype filtration system 300 with floats 50 positioned above the rotatable filtering assembly 302. Figs. Fig. 41 shows an example of a disc-type filtration system 300 in which a plurality of filtering sub-assemblies 320 are revolvable around a main axis of the filtering assembly 302, and are simultaneously rotatable around their own respective axes. Fig. 42 shows an example of a disc-type filtration system 300 in which a plurality of filtering sub-assemblies 320 are revolvable around a main axis of the filtering assembly 302, and are independently rotatable around their own respective axes. Fig .43 shows a zoomed-in view of one of the independently rotatable filtering sub-assemblies 320. Figs. 18A-28 and 41-43 are described herein together.

[0330] A disc-type filtration system 300 comprises a disc-type rotatable filtering assembly 302, that includes at least one, and preferably a plurality of, revolvable filtering sub-assemblies 320. Each filtering sub-assembly 320 includes a filter medium 344, implemented as a stack of discs 332 which are normally pressed against each other, for example during a filtering mode, and can be optionally spaced from each other during a cleaning mode.

[0331] Fig. 18A shows three such discs 332, according to one example, shown to be normally pressed against each other. Fig. 18B shows the discs 332 of Fig. 18A spaced away from each other. Fig. 19 shows a zoomed in view of an example of two discs 332 pressed against each other. Each disc 332 defines a disc first side 338a, illustrated as an upper surface in Fig. 18B, and a disc second side 338b, illustrated as a lower surface in Fig. 18B. When the discs 332 are stacked together, disc first sides 338a and disc second side 338b of adjacent discs 332 are facing each other. Each disc 332 further defines a disc outer surface 334, which is its outermost surface, and a disc inner surface 336, such that the disc sides 338 radially extend between the disc outer surface 334 and the disc inner surface 336.

[0332] Each disc further comprises a plurality of grooves 340 extending along at least one disc side 338, and optionally along both disc sides 338a, 338b, from the disc outer surface 334 to the disc inner surface 336. When the discs 332 are tightly pressed against each other, the grooves 340 and disc sides 338 facing each other define a plurality of medium apertures 352, implemented as channels 352 as shown for example in Fig. 19.

[0333] The geometry of the grooves 340 illustrated throughout Figs. 18A-19 is shown by way of illustration and not limitation, and it is to be understood that the grooves 340 may take any of various geometrical configurations. In some examples, the grooves are formed only on one disc side 338, while the opposite side remains relatively flat, such that when the discs are pressed against each other, channels 352 are formed between grooves 340 of one disc 332 and a flat disc surface of the side 338 of the adjacent disc. In some examples, as shown in Figs. 18A-19, both disc sides 338 define grooves 340, such that channels 352 are defined between the grooves 340 of two adjacent discs 332 pressed against each other.

[0334] In some examples, grooves 340 can have a uniform cross-sectional shape and size across their length, as shown in Fig. 18A-19. In alternative examples, grooves 340 can have a non-uniform profile, for example tapering configuration from the disc outer surface 334 to the disc inner surface 336. The groove 340 can have any cross-sectional shape, such as being rectangularly shapes (as shown in Fig. 18A-19), V-shaped, elliptical or otherwise circularly shaped, any other regular polygonal shape, or irregularly shaped - including irregular polygonal shapes. In some examples, grooves 340 can extend along a linear path, which can be either radial or diagonal. In other examples, as show in Fig. 18A-19, the grooves 340 can be curved.

[0335] In some examples, the grooves 340 on each disc side 338 are shaped in different patterns. For example, the discs 332 of Fig. 19 include grooves 340 curved in opposite direction on both sides 338 of each disc 332, such that the resulting channels 352 are shaped in a zigzagged pattern. [0336] Each channel 352 defines the aperture size D, which can be the narrowest dimension of any cross-section of the channel 352. The groove 340 can have a height and width, which can be uniform or non-uniform along its length, and dictate the aperture size D. For example, the aperture size D can be the smallest between any width and any total height (which can be the sum of two heights when two grooves of two adjacent discs define the channel) along the length of the channel 352. The aperture open area Aa is defined as the cross-sectional area of the groove 340 at the disc outer surfaces 334.

[0337] Channels 352 are adapted to allow through the flow of raw water from the disc outer surface 334 to the disc inner surface 336, and are further adapted to trap particles contaminating the water during the flow through the channels. The channels 352 are further adapted to restrict entry of relatively larger particles (i.e., larger than aperture open area Aa) into the channels 352.

[0338] As shown throughout Figs. 20-28, a disc-type filtration system 300 includes a disc-type rotatable filtering assembly 302, at least one watertight drive motor 72 and at least one controller 76. The disc-type rotatable filtering assembly 302 defines a main axis Ym (indicated for example in Fig. 25) around which it is configured to rotate by the corresponding watertight drive motor 72. Disc-type rotatable filtering assembly 302 further comprises at least one rotatable support wall 306, and at least one, and preferably a plurality of, disc-type revolvable filtering sub-assemblies 320, attached to the at least one rotatable support wall 306. Each revolvable sub-assembly 320 defines a sub-assembly axis Ys which is parallel to, and offset from, main axis Ym (see, for example, Fig. 25). For simplicity, any reference to a component of filtration system 300 (such as filtering sub-assembly 320, rotatable support wall 306, controller 76, and so on) in a single form throughout the current specification, will similarly refer to "one or more" of said components for implementations that include a plurality of said components, unless otherwise stated.

[0339] The terms "disc-type filtration system 300" and "filtration system 300" are interchangeable, the terms "disc-type rotatable filtering assembly 302" and "filtering assembly 302" are interchangeable, and the terms "disc-type filtering sub-assembly 320" and "filtering sub-assembly 320" are also interchangeable, for system, assembly, and sub-assembly numerals 300, 302 and 320 throughout the specification, and particularly with respect to Figs. 20-28, unless otherwise stated. [0340] For a filtration system 300 that includes a disc-type rotatable filtering assembly 302 equipped with disc-type filtering sub-assemblies 320, the terms "filter medium 344" and "stack of discs 344" are interchangeable, and refer to a filter medium which is implemented as a stack of discs 332 compresses against each other.

[0341] In the illustrated examples, the filtration system 300 comprises a single rotatable support wall 306 extending along a plane substantially orthogonal to the main axis Ym. However, this is not meant to be limiting, and in alternative examples, two rotatable support walls can be provided, wherein each filtering sub-assemblies can be optionally disposed between both walls.

[0342] Each filtering sub-assembly 320 comprises a spine 322 (see, for example, in Fig. 21) disposed along corresponding sub-assembly axis Ys, and a plurality of discs 332 disposed along the length of the spine 322. The discs 332 are in a naturally compressed stacked formation, wherein the stack of discs, when compressed against each other, defines the filter medium 344. The filter medium 344 has a medium outer surface 346, which can be also referred to as a stack outer surface 346, defined by the combined outer surfaces 334 of the discs 332 in the stack 344. The filter medium 344 also has an opposite medium inner surface 348, which can be also referred to as a stack inner surface 348, defined by the combined inner surfaces 336 of the discs 332 in the stack 344.

[0343] In some examples, each filtering sub-assembly 320 includes a compression mechanism, configured to retain the plurality of discs 332 in a normally compressed configuration. In some examples, as shown in Fig. 21, each filtering sub-assembly 320 comprises a compression plate 324, mounted on the spine 322 opposite to the rotatable support wall 306, such that the discs 332 are stacked between the rotatable support wall 306 and the compression plate 324. The filtering sub-assembly 320 can further include one or more stems 326 extending from the compression plate 324 in a direction opposite to the discs 332, each stem 326 having a flanged head portion 328 at an end thereof, opposite to the compression plate 324. The filtering subassembly 320 can further include one or more springs 330 extending around the stems 326, each spring 330 disposed between the compression plate 324 and the flanged head portion 328 of the corresponding stem 326. [0344] The springs 330 serve to bias the compression plate 324 away from head portion 328, toward rotatable support wall 306, thereby compressing the discs 332 against each other between the compression plate 324 and the rotatable support wall 306.

[0345] In some examples, the filtering sub-assembly 320 further includes a support base 325, opposite to the compression plate 324, as shown for example for sub-assembly 320a in Fig. 41. In such examples, the discs 332 are stacked between the support base 325 and the compression plate 324, such that the disc 332 which is farthest from the compression plate 324 may abut support base 325 instead of directly contacting the rotatable support wall 306.

[0346] The filtration system 300 is further shown to comprises an intake pipe 360, which is coupled to the rotatable filtering assembly 302 and optionally extends therethrough, such as through a central sealed opening 308. The intake pipe 360 includes at least one pipe inflow opening 362 which is in fluid communication with the medium apertures 352.

[0347] In some examples, the filtration system 300 further comprises a sealed intake chamber 370, which is sealed from the outer environment (e.g., raw water of the water sources 20), and is in fluid communication with the intake pipe 360 (for example, via pipe inflow opening 362) and with at least some of the filtering sub-assemblies 320.

[0348] The intake chamber 370 can be defined between the rotatable support wall 306 and a stationary wall portion 372 that includes a stationary transverse wall 374, such that the rotatable support wall is rotatable around main axis Ym, while stationary wall portion 372 is a non- rotatable component of the filtration system 300. In some examples, the filtration system can further include a circumferential wall portion 376 defining the external perimeter of the intake chamber 370. In some examples, as in the illustrated examples, the circumferential wall portion 376 is affixed or integrally formed with the stationary transverse wall 374, such that the circumferential wall portion 376 and the stationary transverse wall 374 together define the stationary wall portion 372. The rotatable support wall 306 can then be movably coupled, in a sealed manner, to the edges of the circumferential wall portion 376. In other examples, the circumferential wall portion can be affixed to or integrally formed with the rotatable support wall, configured to rotate therewith while stationary transverse wall 374 remains immovable. In such examples, the circumferential wall portion 376 can be movably coupled, in a sealed manner, to the edges of the stationary transverse wall 374. [0349] In some examples, the intake pipe 360 extends into the intake chamber 370. In some examples, the one or more pipe inflow openings 362 are disposed within the intake chamber 370. In some examples, the pipe inflow openings 362 are disposed around the circumference of the portion of the intake pipe 360 which is disposed in the intake chamber 370, and are offset from the main axis Ym, facing the circumferential wall portion 376. While four pipe inflow openings 362 are illustrated in the example shown in Fig. 26, it is to be understood that any other number, such as a single pipe inflow opening, two, three, or more than four pipe inflow openings, is contemplated. Any reference to "pipe inflow openings 362" throughout this specification, unless otherwise stated, refers also to implementation of a single pipe inflow opening 362.

[0350] The intake pipe 360 can be an independent component of a suction line 60, attached thereto and in fluid communication therewith, or can be formed as an integral part or extension of the suction line 60. Intake pipe 360 is coupled to rotatable support wall 306 in a manner that allows it to rotate around intake pipe 360, while intake pipe 360 remain stationary in position, that is to say that intake pipe 360 is a non-rotatable component of the filtration system 300. Intake pipe 360 can extend, for example along main axis Ym, away from the rotational support wall, and terminate with a pipe outflow opening 366 that can be coupled, for example by a pipe coupler 68, to a suction line inlet 62 as described above with respect to filtration systems 200.

[0351] In some examples, the stationary transverse wall 374 is affixed to the intake pipe 360. For example, the stationary transverse wall 374 can include a stationary wall sealed opening 378 that can be aligned with the central sealed opening 308 of the rotatable support wall 306, such that the intake pipe 360 can extend, in a sealed manner, through both openings 308 and 378.

[0352] In some examples, the filtration system 300 further comprises a frame 30. Both the rotatable filtering assembly 302 and the watertight drive motor 72 can be coupled to the frame 30, wherein the rotatable filtering assembly 302 is movably coupled to the frame 30 (i.e., can rotate around main axis Ym while being supported, directly or indirectly, by frame 30). In some implementations, as in the illustrated example, one or both of the frame transverse walls 32 include pipe through openings 34, which are coaxial with, and preferably similarly dimensioned to, the corresponding central sealed opening 308, allowing the intake pipe 360 to extends through the frame transverse walls 32 and the rotatable support wall 306. Thus, in the illustrated examples, the rotatable filtering assembly 302 is indirectly coupled to the frame 30 by intake pipe 360 coupled to, and extending both through, the rotatable support wall 306 and the frame transverse walls 32b.

[0353] While shown, for example in the illustration of Fig. 26, to extend through both the central sealed opening 308 of the rotatable support wall 306 and the sealed opening 378 of the stationary transverse wall 374, and optionally further on through a pipe through opening 34 of the corresponding frame transverse wall 32 (wall 32a in the illustrated example), other configurations are available for keeping fluid communication between the intake pipe 360 and the intake chamber 370. For example, the intake pipe 360 can terminate at any point within the intake chamber 370, without further extending through the stationary transverse wall 374, while at least one pipe inflow opening is still exposed to the intake chamber 370. The stationary transverse wall can be affixed to a different component of the filtration system other than the intake pipe, such as a frame transverse wall 32. In other examples, an end portion of the intake pipe 360 can terminate at the stationary transverse wall 374, affixed thereto, without necessarily further extending therethrough.

[0354] In yet other alternative examples, the intake pipe can include a single pipe inflow opening 362 coaxial with main axis Ym, defined by an open end of the intake pipe 360, which can either partially extend into the intake chamber 370, or alternatively terminate at the level of the rotatable support wall 306, having its edges attached to the edges of the central sealed opening 308 in a manner that retain fluid communication of the intake pipe 360 with the intake chamber 370 via central sealed opening 308.

[0355] The rotatable support wall 306 can include, in some examples, at least one offset opening 310, each offset opening 310 is aligned with a corresponding filtering sub-assembly 320 and its sub-assembly axis Ys, offset from main axis Ym. Each offset opening 310 is in fluid communication with the internal space defined between the stack inner surface 348 and the spine 322, in a manner which is sealed from the surrounding environment (e.g., sealed from the raw water of the water source 20), at least during a filtering mode of the respective filtering sub-assembly 320.

[0356] The intake pipe 360 and suction line 60 together define a fluid-communication line between the pipe inflow openings 362 and a suction line outlet 64 (same outlet 64 described hereinabove and shown, for example, in Fig. 1A) which can be placed onshore. This fluidcommunication line is intended to direct filtrate from the rotatable filtering assembly 302 to a target location, which can be onshore, for example by applying suction force at the pipe inflow openings 362. This may be accomplished by creating a negative pressure difference between the pipe inflow openings 362 and the suction line outlet. The negative pressure difference can be created by gravitational forces, or a pump (e.g., pump 66) in the same manner described above with respect to filtration systems 200. This pressure difference facilitates flow from the water source 20, through the filter medium 344, into the intake chamber 370, toward the pipe inflow openings 362 and into the intake pipe 360.

[0357] In some examples, the rotatable filtering assembly 302 is partially submerged, such that only some of the filtering sub-assemblies 320 are immersed in the water source 20. In such examples, any filtering sub-assembly 320 which is not immersed in the water source 20 cannot be in a filtering mode, such that all of its non-submerged medium apertures 352 are nonfiltration apertures 356. Any filtering sub-assembly 320 which is immersed within the water source 20, can optionally transition between filtering and cleaning modes, as will be elaborated below. In some examples, the rotatable filtering assembly 302 is fully submerged, such that all of the filtering sub-assemblies 320 are immersed in the water source 20. In such examples, similar to the partially immersed configurations, any filtering sub-assembly 320 can optionally transition between filtering and cleaning modes, as will be elaborated below.

[0358] As mentioned above, the channels 352 generally extend between the stack outer surface 346 and stack inner surface 348, and an internal space 350 (see Fig. 26) is defined between the stack inner surface 348 and the spine 322. This space is in fluid communication with the corresponding offset opening 310 at the region of attachment of the filtering sub-assembly 320 to the rotatable support wall 306. During filtering mode, raw water 10 which is in direct contact with the stack outer surface 346, flow through the channels 354 into the internal space 350, becoming filtrate that flows therefrom, through the offset opening 310, into the intake chamber 370, and therefrom, through the pipe inflow openings 362, into intake pipe 360.

[0359] Similar to filtration system 200, the filtration system 300 comprises a watertight drive motor 72 (see Fig. 25, for example) configured to rotate the filtering assembly 202 around main axis Ym. As shown, the watertight drive motor 72 can be secured to the frame 30, such as to one of the frame transverse walls 32. When the intake pipe 360 extends through one or both frame transverse walls 32, the drive motor 72 can be offset from the main axis Ym, so as not to interfere with the intake pipe 360. Thus, since the axis of rotation of the watertight drive motor 72 is offset from the main axis Ym in such a case, the filtration system 300 can include a transmission assembly 80, configured to transmit the torque produced by the drive motor 72 to the corresponding rotatable support wall 306, thereby rotating the entire filtering assembly 302 there-along.

[0360] The transmission assembly 80 can include a gear train with one or more gears. For example, the transmission assembly 80 illustrated in the example illustrated in Fig. 25 includes a driving gear 84 attached to a shaft 82 driven directly by the watertight drive motor 72, and a driven gear 86 attached to the surface of the rotatable support wall 306 and meshed with the driving gear 84, wherein the size of the gears dictates the transmission ratio between the angular speed of rotation of the motor and the resulting angular speed W of the filtering assembly 302, such that the transmission assembly 80 can also serve as a motor speed reduction mechanism.

[0361] In some examples, at least a portion of the transmission assembly 80, such as gears 84, 86, and optionally shaft 82, is disposed within the intake chamber 370, as in the illustrated example. In other examples, part or all of the transmission assembly 80 can be sealed from the filtrate flowing in the intake chamber 370, for example by the addition of a housing or other type of enclosure around components of the transmission assembly 80.

[0362] While two gears are illustrated in Fig. 25, it is to be understood that any other number of gears can be chosen, for example - including intermediary idler gears (not shown) and the like. Moreover, while a gear train is illustrated, it is to be understood that any other type of transmission assembly known in the art can be implemented, such as a transmission assembly that includes one or more chains, endless belts and pulleys, and the like.

[0363] The rotatable support walls 306 can also include a plurality of rollers 70 rotatable around axes that are parallel to the main axis Ym, each configured to contact and roll over the outer surface of the intake pipe 360, for example at the portion extending out of the respective central sealed opening 308 away from the intake chamber 370 (though in other configurations, the rollers 70 can be also situation within the intake chamber). While the illustrated example shows three rollers 70 attached to the rotatable support wall 306, it is to be understood that any other number of rollers is contemplated.

[0364] The watertight drive motor 72 can be either an electric motor or a water motor. Utilization of a water motor as the watertight drive motor 72, requires adaptation of the filtration system 300 to include at least one motor line 92 (see for example Figs. 25) fluidly coupled to the motor 72, configured to provide water (or other suitable liquid) to operate the water motor 72. In some implementations, the motor line 92 can extend from a source of water onshore, all the way to the water motor 72 positioned offshore, coupled to the frame 30. This is an unconventional adaptation that can be implemented for utilization of an immersible water drive motor 72 for facilitating rotation of the filtering assembly 202, as most conventional water motors do not include feed lines extending over a length of several meters from a source that can be onshore, to a motor that can be placed offshore. In other implementations, the motor line 92 can be adapted to pump water from the surrounding water source 20 and into the water motor 72. In some examples, the at least one motor line 92 includes two lines, one motor inflow line 92a configured to direct feed water into the water motor 72, and the other motor outflow line 92b configured to direct water out of the water motor 72.

[0365] In contrast to water motors, a conventional electric motor that may be used for rotating onshore rotatable filtering assemblies, is not necessarily watertight as it is usually placed in a dry environment. Thus, when the drive motor 72 is an electric motor, it needs to be watertight to prevent any damage to its operation when immersed within, or otherwise being contacted by, water from the water source 20. An electric drive motor 72 can be, for example, a DC servo motor, a pneumatic actuator, a step motor, and the like. In some implementations, the electric drive motor 72 is a brushless DC (BLDC) motor. The electric drive motor 72 may further be a slotted or slotless BLDC motor. An electric drive motor 72 can become a watertight drive motor 72 by being encased within a watertight motor housing 74, which can be similarly attached to the frame 30, such as to a frame transverse wall 32, as in the illustrated example. When implemented as an electric motor, a motor line 92 can be utilized for transmitting power to the motor, such as cables for transmitting energy.

[0366] As mentioned above, the filtration system 300 further includes at least one controller 76 (see for example Fig. 26), which can be also referred to as a motor controller, configured to control functionality of the drive motor 72. In some implementations, the filtration system 300 also includes a speed sensor, such as an encoder (not shown) that may be attached to the drive motor's shaft. This can be implemented as an absolute encoder, configured to generate a signal commensurate with the angular speed of rotation and angular displacement of the motor's shaft 82. The controller 76 can receive signals from the absolute encoder, and can include software for interpreting sensed signals and readjusting the motor's functioning accordingly.

[0367] The controller 76 can include a dedicated processor and/or other component of a control circuitry, including a wireless receiver or transmitter, which, for the same reasons described above of an electric drive motor, may be also preferably sealed in a watertight manner to prevent any damage to such components when immersed or otherwise contacted by water from the water source 20. Thus, the controller 76 can be also a watertight controller 76. This can be achieved, for example, by placing the controller 76 in its own watertight controller housing 78. Alternatively, when the drive motor 72 is placed within a watertight motor housing 74, the controller can be placed next to the motor 72, within the same housing 74, such that housing 74 it utilized to provide watertight sealing both the drive motor 72 and the controller 76 at the same time.

[0368] In some examples, each filtering sub-assembly is not only revolvable around the main axis Ym, but is also rotatable around its sub-assembly axis Ys. Examples can include subassembly which are simultaneously revolvable around main axis Ym and rotatable around their respective axes Ys. For example, Fig. 41 shows an implementation of a disc-type filtration system 300 in which a plurality of filtering sub-assemblies 320 are revolvable around main axis Ym, and each filtering sub-assembly 320 is also rotatable around its own axis Ys. The transmission assembly 80 illustrated in Fig. 41 includes a planetary transmission mechanism, configured to allow simultaneous rotation of the rotatable support wall 306 around main axis Ym, as well as rotation of the filtering sub-assemblies 320 - each around its own sub-assembly axis Ys.

[0369] In the illustrated example, the driven gear 86, which is configured to be driven by the driving gear 84 as described above, is shown to include two portion: a first gear portion 86' which is meshed with the driving gear 84, and a second gear portion 86" which is meshed with planetary gears 88 of the filtering sub-assemblies. The first gear portion 86' can reside within the intake chamber 370 on one side of the rotatable support wall 306, and the other gear portion 86" can be positioned on the opposite side of the rotatable support wall 306, out of the intake chamber. Both the first gear portion 86' and the second gear portion 86" can be formed as a unitary component, coupled to each other in a manner that rotates both portions simultaneously.

[0370] Each filtering sub-assembly 320 can include a planetary gear 88 that can be attached to another component thereof, such as the spine 322 and/or the support base 325, such that rotation of the planetary gear 88 results in rotation of the corresponding filtering sub-assembly 320 therewith. In the illustrated example of Fig. 41, when the driving gear 84 rotates, the driven gear 86 is rotated as well due to the meshed interaction of the driving gear with the first gear portion 86', which in turn rotates both the rotatable support wall 306 to which it is attached, and the planetary gears 88 which are meshed with the second gear portion 86", such that the plurality of filtering sub-assemblies 320 revolve around the main axis Ym and rotate around the respective axes Ys at the same time.

[0371] In some implementations, cleaning mode can include rotation of the filtration system 300, and more specifically its rotatable support wall, at a high angular speed of rotation, for example exceeding 6 degrees per second, during a cleaning mode. In some implementations, additional rotational movement of the filtering sub-assemblies 320 can be advantageous to improve the efficiency of the cleaning, by allowing each fub-assembly 320 to rotate around its axis Ys in a manner that can dislodge filtride from the medium apertures 352.

[0372] In some examples, the disc-type filtration system 300 is configured to rotate during the filtering mode, at angular speeds of rotations that can be lower than, equal to, or greater than 6 degrees per second. The angular speed of rotation can be chosen so as to create water movement around the circumference of the filter medium 344 so as to reduce likelihood of particles, micro-organisms and the like, from clinging to the medium outer surface 346 or the medium apertures 352.

[0373] While Fig. 41 shows all of the plurality of the filtering sub-assemblies 320 including planetary gears 88, it is to be understood that this is not meant to be limiting, and that in other examples, a filtration system 300 can include a plurality of filtering sub-assemblies 320, all of which are revolvable around the main axis Ym, but only some of which include planetary gears, meaning that only some (including only one) of the filtering sub-assemblies are rotatable around their respective axes Ys, while the remainder of the sub-assemblies (one or more) are not necessarily rotatable around their axes.

[0374] While shown to be divided into two gear portions 86' and 86", it is to be understood that this is not meant to be limiting, and that in alternative implementations, a single driven gear (86) can be provided, meshed both with the driving gear 84 and the planetary gears 88. For example, a single driven gear (86) can be attached to the rotatable support wall 306 outside of the intake chamber 370, for example at the position illustrated for gear 86" in Fig. 41, and the driving gear can be also position out of the intake chamber, for example by extending the shaft 82 from the drive motor 72 through the intake chamber and the rotatable support wall, or by placing the motor 72 in another position, such as next to the stationary wall portion or any other suitable position. [0375] While all planetary gears 88 are shown to be directly meshed with the driven gear 86, it is to be understood that this is not meant to be limiting, and that the transmission assembly 80 can include additional intermediary gears, such as idler gears between the driven gear 86 and the planetary gears 88.

[0376] In some examples, each filtering sub-assembly is independently rotatable around its own sub-assembly axis Ys, irrespective of its resolvability around main axis Ym or rotatability of any other filtering sub-assemblies of the filtration system. For example, Figs. 42 and 43 show an implementation of a disc-type filtration system 300 in which a plurality of filtering sub-assemblies 320 are revolvable around main axis Ym, and each filtering sub-assembly 320 is also rotatable around its own axis Ys, wherein the resolvability of all filtering sub-assembly 320 is independent of the rotatability of any single filtering sub-assembly 320, and the rotatability of any single filtering sub-assembly 320 is independent of the rotatability of any other filtering sub-assembly of the filtration system 300.

[0377] While the filtration system 300 illustrated in Fig. 41 includes a main drive motor 72 and a transmission assembly 80 configured to rotate the rotatable support wall 306, and the plurality of filtering sub-assemblies 320 attached thereto, around main axis Ym, in the same manner described hereinabove with respect to Fig. 25, for example, a plurality of sub-assembly drive motors 180 and sub-assembly transmissions 184 are also included in this example, each sub-assembly drive motor 180 and sub-assembly transmission 184 are associated with a separate, corresponding filtering sub-assembly 320. Fig. 42 shows a zoomed in view of one sub-assembly drive motor 180 and its vicinity, wherein the filter medium 344 (i.e., stack of discs) is shown with partial transparency to expose internal components of the sub-assembly 320.

[0378] Each sub-assembly drive motor 180 is configured to rotate, via sub-assembly transmission 184, the corresponding filtering sub-assembly 320, for example during a cleaning mode of the sub-assembly 320. The sub-assembly drive motor 180 can be a watertight motor, for example by being retained in a watertight housing (such as housing 74), and may be implemented as an electric motor or as a water motor, in the same manner described above for any implementation and example of main drive motor 72. The motor can be controlled by controller 76, including implementations in which, as illustrated, a plurality of control subunits 76s are provided to separately control each sub-assembly drive motor 180. [0379] The sub-assembly drive motor 180 is operable to rotate the corresponding filtering subassembly 320 via a corresponding sub-assembly transmission 184, which can be implemented in the same manner described above for any example of main transmission assembly 80. In the illustrated example, the sub-assembly transmission 184 is implemented as a gear train that includes a sub-assembly drive gear 186 directly rotatable by drive motor 180, and a subassembly main gear 188 meshed therewith, and attached to the corresponding filtering subassembly 320. The sub-assembly drive gear 186 may be rotated by the sub-assembly drive motor 180, for example via a shaft extending from the motor 180. Rotational movement of the sub-assembly drive gear 186 results in rotation of the sub-assembly main gear 188, according to a desired transmission ratio dictated by the size and number of teeth of both gears, for example. Any other number of gears can be similarly utilized, for example by adding idler gears to the sub-assembly transmission.

[0380] The sub-assembly main gear 188 is attached to a component of the filtering subassembly 320, in a manner that preferably causes the entire sub-assembly, and particularly its filter medium, to rotate around its axis Ys. For example, the sub-assembly main gear 188 can be attached to the spine 322, to the support base 325, or other components of the sub-assembly 320.

[0381] Each filtering sub-assembly can further include, in some examples, an internal pressure sensor 182 disposed within its internal space, configured to measure the pressure within the internal space. Sn internal pressure sensor 182 is shown in Fig. 43 attached to the spine 322, though other configuration may be similarly implemented, for example by attaching the sensor 182 to the medium inner surface 348 or other components of the sub-assembly 320. Measurement signals may be delivered from the internal pressure sensor 182 to the controller 72, including being delivered to the corresponding control sub-unit 72s. While a single internal pressure sensor 182 is illustrated within a sub-assembly 320, each sub-assembly 320 can also include more than one internal pressure sensor. For example, a series of pressure sensors can be disposed along the length of the sub-assembly 320, and/or at different angular positions around its axis Ys.

[0382] In some examples, an additional external pressure sensor 183 can be also provided next to each filtering sub-assembly, configured to measure the pressure around and in the vicinity of the stack outer surface. An external pressure sensor 183 is shown to be attached to the rotatable support wall 306 in the example illustrated in Figs. 42-43, though other attachment positions are similarly contemplated. Measurement signals may be delivered from the internal pressure sensor 182 to the controller 72, including being delivered to the corresponding control sub-unit 72s.

[0383] The internal pressure sensor 182 can be utilized to measure, either continuously or periodically, the pressure (e.g., water pressure) within internal space 350 of the corresponding sub-assembly 320. In some implementations, the internal pressure measured by internal pressure sensor 182 is compared to the external pressure measured by external pressure sensor 183. Water pressure can be slightly different at different depths, such that measuring the water pressure by a local outer pressure sensor 183 disposed next to, and in close vicinity of, each filtering sub-assembly 320, can be advantageous to accurately compare the internal pressure to the external pressure of the specific sub-assembly 320 at the relevant depth, which can be of significance for a plurality of filtering sub-assembly 320 that may be disposed at different positions (and different depths) around main axis Ym, and may change their position during their evolvement around main axis Ym. Nevertheless, in other implementations, for example when the changes in outer water pressure between the highest and lowest positions are negligible, a single external pressure sensor (183) can be utilized, wherein any of the internal pressure sensor 182 of any of the sub-assemblies 320 can be compared with this mutual outer pressure sensor.

[0384] Filtride may accumulate over the medium outer surface (346) and/or within medium apertures (for example, within channel 352), in a manner that blocks water passage through a portion of the filtration apertures 354. The pressure measured within internal space 350, including pressure difference between the inner and outer sides of the filter medium 344, can be compared, for example by control sub-unit 76s, to pre-defined threshold value(s), wherein a rise in pressure (or pressure difference) during filtration mode may be indicative of a larger portion of the filtration apertures (354) being blocked. Thus, when the pressure (or pressure difference) exceeds a pre-defined threshold value(s), the control unit 76 (or control sub-unit 76s) may transition the corresponding filtering sub-assembly 320 from a filtering mode to a cleaning mode, during which the corresponding sub-assembly drive motor 180 is actuated to rotate the filtering sub-assembly 320.

[0385] In some examples, the filtering sub-assembly 320 is rotated by sub-assembly drive motor 180 and flushed via flush tube 390 simultaneously during its cleaning mode. In other example, filtering sub-assembly 320 is only rotated during the cleaning mode, without being flushed. For example, a filtration sub-assembly 300 can be devoid of a flush tube (390), or include a flush tube 390 as well as sub-assembly drive motors 180, wherein the control unit 72 (and/or control sub-units 72s) can operate both simultaneously, or any of the flushing via flush tube 390 or rotation of the sub-assembly 320 via sub-assembly drive motor 180, during the cleaning mode, separately. Rotation of the filtering sub-assembly 320 around its axis Ys is performed at a speed that is high enough to dislodge filtride from the filter medium (344). This speed of rotation can be higher than 1 RPM, higher than 5 RPM, higher than 10 RPM, higher than 100 RPM, or higher than 300 RPM.

[0386] Independent rotation of each of the plurality of filtering sub-assembly 320 can be therefore advantageous in that any one or more of the sub-assemblies 320 can transition to a cleaning mode, in which it is rotated around its axis Ys to dislodge filtride accumulated thereon, while the remainder of the sub-assemblies (320) can continue to operate in filtration mode. It is to be understood that an outer pressure sensor (183) is not mandatory, and that in some implementation, the absolute value of the pressure within internal space 350 can be compared to previous values and/or threshold values, to detect a relative rise in pressure overtime.

[0387] The sub-assembly drive motors 180 are immovable relative to the filtering subassemblies 320 they are configured to rotate, meaning that motors 180, as well as sub-assembly transmissions 184, should be revolvable around main axis Ym to move along with filtering sub-assemblies 320. In some examples, the sub-assembly drive motors 180 can be attached to the rotatable support wall 306, to rotate therewith. In implementation in which the circumferential wall portion 376 is rotatable as well, for example by being affixed to or integrally formed with the rotatable support wall, instead of the stationary transverse wall (374), the sub-assembly drive motors 180 can be attached to the circumferential wall portion 376, to rotate therewith.

[0388] In some implementations, the frame 30 can include legs 38 terminating below the rotatable filtering assembly 302, for supporting the frame 30 and the rotatable filtering assembly 302 over the water source bed 24, for example when placed in a shallow natural water source 20 or when lowered enough to completely immerse the rotatable filtering assembly 302 within the water source 20. Water source bed 24, as described above in conjunction with Fig. 12A for example, can include a variety of rocks, small stones, mud, algae and the like, which, absent of any protective means, can contact the discs 332 and damage them, or clog the channels 352, when the rotatable filtering assembly 302 is immersed deep enough to rest over the or in close proximity to the water source bed 24. Thus, in some implementations, the frame 30 further includes a bottom plate 40 (Fig. 23), which can be in the form of a horizontal plate positioned below the rotatable filtering assembly 302, but preferably somewhat above the lower ends of legs 38. The bottom plate 40 preferably extends over an area which is larger than the horizontal projection of the stacks of discs 344, to protect them entirely from their bottom side.

[0389] In some implementations, the filtration system 300 comprises a backwash self-cleaning mechanism. Backwash is a process typically comprising flushing a cleaning fluid (e.g., cleaning water) in the opposite direction to that of the flow during the filtering mode, and is utilized in order to remove accumulated filtride from the filter medium 344.

[0390] Disc-type filters, including such that implement backwash self-cleaning mechanisms, are conventionally known to be adapted for inland utilization, wherein a stack of discs is placed within a pressure vessel that is sealed from the surrounding environment, except for a dedicate inlet for unfiltered liquid entering the enclosed housing that defined the pressure vessel. This liquid flows through an intermediary passageway defined between the walls of the vessel's housing and the stack of discs, toward and through the channels, into the space defined by the internal lumen of the discs, and toward a dedicated outlet of the resulting filtrate. Such vessels can further include dedicated inlets and outlets for backwash. In contrast, the disc-type filtration system 300 disclosed herein includes filtering sub-assemblies 320 which are devoid of such a pressure vessel. Specifically, the stacks of discs 344 are configured to be directly exposed to the environment such that raw water 10 of the environment is in direct contact with the stack outer surface 346, without passing through an intermediary passageway. Thus, the disclosed disc-type filtration system 300 implements utilization of filter mediums in the form of stacks of discs 344, with optional backwash-type self-cleaning mechanisms, in an unconventional manner which is devoid of pressure vessels enclosed around the stack outer surfaces 346.

[0391] In some examples, the filtration system 300 includes a backwash mechanism that includes at least one flush tube 390, optionally at least one flush tube flange 394, and optionally at least one flush tube valve actuator 392, as illustrated in Figs. 22 and 25. Each flush tube 390 is branched from, or continuously extends from, and is in fluid communication with, the cleaning feed line 94. Each flush tube 390 is generally aligned with a sub-assembly axis Ys of a corresponding filtering sub-assembly 320. Each sealing flange 394 is disposed over a respective flush tube 390, aligned with a corresponding offset opening 310, movable between a closed position and an open position. [0392] In the closed position, the sealing flange 394 pressed against the offset opening 310 in a manner that seals the offset opening 310, and therefore the internal space 350 of the filtering sub-assembly 320, from the intake chamber 370, allowing for fluid communication of the internal space 350 only with the flush tube 390. In the open position, the sealing flange 394 is spaced away from the offset opening 310, exposing it to the intake chamber 370.

[0393] Each flush tube valve actuator 392 can be operable to move the corresponding sealing flange 394 toward or away from the corresponding offset opening 310, to transition between the closed and open positions.

[0394] In order to transition a filtering sub-assembly 320 from a filtering mode to a cleaning mode, and apply backwash procedure thereto, the flush tube valve actuator 392 can be actuated to advance the sealing flange 394 toward the offset opening, to the closed position, at which point washing fluid such as water (or any other liquid or gas), supplied by the cleaning feed line 94, flows from the flush tube 390 into the internal space 350. The washing fluid is introduced at a relatively high pressure, flowing in a "reverse" direction from the internal space 350 toward the stack outer surface 348, substantially displacing any particles trapped within the channels 352. If the cleaning flow pressure is high enough, it impinges against the compression plate 324, compressing the springs 330 in a manner that allows the discs 332 to be "decompressed", similar to the spaced-apart configuration shown in Fig. 18B, which allows the fluid to flow over the sides 338 of the discs and their grooves 340 to better dislodge any filtrate that may have accumulated therein. Once backwash is no longer required, cleaning fluid flow terminates and the flush tube valve actuator 392 can be actuated to retract the sealing flange 394 away from the offset opening, to the open position, at which point the springs 330 serve to recompress the discs 332 against each other.

[0395] In the examples illustrated in Figs. 22 and 25, two flush tubes 390 are shown to be branched from the cleaning feed line 94, such that two filtering sub-assemblies 320, shown as sub-assemblies 320c and 320f, may transition to a cleaning mode. However, it is to be understood that this is merely shown by way of illustration and not limitation, and that a single flush tube 390 (with a single valve actuator 392 and sealing flange 394) can be similarly implemented, as well as more than two flush tubes 390, for example to enable more than two filtering sub-assemblies 320 to be simultaneously backwashed. [0396] Six filtering sub-assemblies 320 are shown in the illustrated example, with filtering subassemblies 320a, 320b, 320d, and 320e, positioned against corresponding offset openings 310 which are fully exposed to the intake chamber 370, meaning that all of these filtering subassemblies 320 can be in a filtering mode in this position. Two filtering sub-assemblies 320f and 320c are aligned with flush tubes 390a and 390b. As long as the sealing flanges 394 are in the open position, these two sub-assemblies can also be in a filtering mode. However, when the sealing flanges 394 transition to the closed position, filtering sub-assemblies 320f and 320c are in a cleaning mode.

[0397] When cleaning of filtering sub-assemblies 320f and 320c is no longer required, the sealing flanges 394 can transition back to the open position. The rotatable support wall 306 can then rotate, by the drive motor 72 and transmission assemble 80, around main axis Ym, such that two other filtering sub-assemblies 320 are positioned in front of the flush tubes 390a and 390b, at which point rotation is terminated, and the sealing flanges 394 can transition to the sealed mode, allowing these two filtering sub-assemblies 320 to be cleaned in a similar manner.

[0398] This procedure can be repeated as required, advantageously allowing the filtering procedure to be continuous such that at least some of the filtering sub-assemblies 320 (one or more) remain in a filtering mode, while others (one or more) are in a cleaning mode.

[0399] In some examples, one or more controllers 76 are utilized to control the tube valve actuators, such as controllers 76a and 76b that can be used for controlling the transition between the closed and open positions of the sealing flanges 394a and 394b, and a separate controller 76c can be used for controlling motor 72 as described above. Each controller 76a, 76b, 76c can be a watertight controller. In such implementations, all of the separate controllers are referred to as a controller 76 of the filtration system (e.g., systems 200, 300, 400 and/or 500), which can include separate control sub-units, such as control sub-units 76a and 76b for controlling the sealing flanges 394a and 394b, and control sub-unit 76c for controlling the drive motor. In other examples, instead of providing separate controllers, a single controller (for example, the controller or control sub-unit designated 76c) can be used to control both the drive motor 72 and any of the flush tube valve actuators 392.

[0400] In the illustrated examples, while the filtering sub-assemblies 320f and 320c are in the cleaning mode, their channels or medium apertures 352 are non-filtration apertures 356, and as long as all other four filtering sub-assemblies 320a, 320b, 320d, and 320e, are fully immersed and are in a filtering mode, all of their medium apertures 352 are filtration apertures 354, the total sum of their aperture open areas Aa constituting the effective area of filtration Ae. When the filtering sub-assemblies 320f and 320c are aligned with flush tubes 390, but the valve flanges 394 are in the open position and both filtering sub-assemblies 320f and 320c are in a filtering mode, their medium apertures 352 are also filtration apertures 354, such that in such situations, the effective area of filtration Ae can be equal to the total area of medium apertures At.

[0401] Rotational movement of the rotatable filtering assembly 302 can be periodical, such that it rotates only when repositioning of other filtering sub-assemblies 320 is required, as described above. In alternative implementations, rotational movement of the rotatable filtering assembly 302 can be continuous, wherein the angular speed of rotation W is slow enough to allow adequate backflow self-cleaning of each of the filtering sub-assemblies 320 as it passes along a corresponding flush tube 390.

[0402] In the illustrated configuration, the flush tubes 390 are preferably positioned to align with the left-most and right-most filtering sub-assemblies 320. These positions are advantageous in that the sub-assemblies, such as filtering sub-assemblies 320f and 320c shown in the illustrated example, are not positioned above any portion of any other filtering subassembly, such that when they are backwashed, any filtride disposed and washed away therefrom, will tend to sink downward without interacting with any of the other filtering subassemblies 320. If, alternatively, flush tubes 390 would have been positioned elsewhere, such as the positions of filtering sub-assemblies 320a and 320b in the illustrated examples, particles dislodged from these filtering sub-assemblies 320 could sink downward and land on medium outer surfaces 346 of other filtering sub-assemblies 320.

[0403] While six filtering sub-assemblies 320 are illustrated throughout Figs. 20-28, it is to be understood that a rotatable filtering assembly 302 can include any other number of filtering sub-assemblies 320, such as more or less than six filtering sub-assemblies 320, and in some implementations, even a single filtering sub-assembly 320.

[0404] In some implementations, filtration system 300 also includes a spray assembly 380, configured to spray liquid or gas toward a portion of filter medium 344 to dislodge filtride that may be clung thereto. Spray assembly 380 can include a spray conduit 382 with one or more nozzles 384 attached thereto, optionally directed toward a target region of the filter medium 344. The spray conduit 382 can be attached to, or otherwise fluidly connected to, a cleaning feed line 94 which can provide cleaning liquid or gas, including cleaning water, through the spray conduit 382, toward one or more nozzles 384.

[0405] As illustrated in Fig. 27, one example of a spray assembly 380 can include a spray conduit 382 extending into the rotatable filtering assembly 302, with a plurality of nozzles 384 facing the stack outer surface 347 of any one of the filtering sub-assemblies 320 aligned against it, the nozzles 384 configured to spray water toward the filter medium 344 from the outside. The cleaning feed line 94 can extend from outside of the frame 30 into the intake pipe 360, and at a specific point, it may define a spray conduit 382 by continuously extending radially outward out of the intake pipe 360 (for example, through a corresponding sealed opening formed at the wall of the intake pipe 360), and then assume a longitudinal orientation (e.g., parallel to main axis Ym) with a plurality of nozzles 384 (only one is illustrated for simplicity) directed toward the filter medium 344, and more particularly, toward stack outer surface 346.

[0406] Filtration system 300 can be partially immersed, such that the nozzles 384 are positioned above the water level 22, designed to spray against a filtering sub-assembly 320 which is also positioned above the water level 22. Alternatively, filtration system 300 can be fully immersed, with the nozzles 384 positioned within the water source 20, designed to spray high-pressure liquid jets, or alternatively, spray air or other suitable gas, while being immersed within the water source.

[0407] The spray assembly 380 can also be a non-rotatable, stationary assembly, similar to the stationary nature of intake pipe 360, such that due to rotation of the support wall 306, the nozzles 384 spray water (or other liquid or gas) impinging against different filtering subassemblies 320. The rotatable filtering assembly 302 may rotate such that it aligns each time a different filtering sub-assembly 320 against the nozzles 384. Rotational movement of the rotatable support wall 306 can be periodical or continuous. For example, periodical rotational movement can be employed when it is desired to align a specific filtering sub-assembly 320 against the nozzles 384, at which point rotation is halted to allow the jets sprayed from the nozzles 384 to clean the corresponding filter medium 344. Alternatively, rotation can be continuous, such that each filtering sub-assembly 320 may be cleaned by the jets sprayed from the nozzles 384 as it passes them during such continuous rotational movement. [0408] When any filtering sub-assembly 320 is sprayed by nozzles 384, it is in a cleaning mode, meaning that no internal pressure is applied thereto to apply suction toward and into intake pipe 360. It is to be understood that backwash, as disclosed above, can be combined with a spray-assembly 380, such that any filtering sub-assembly 320 can be backwashed by pressurized fluid flowing into its internal space 350, and be simultaneously sprays by nozzles 384 from the outside, thereby applying self-cleaning mechanisms directing cleaning fluid both from the stack inner surface 348 outward, and from the stack outer surface 346 inward.

[0409] In the exemplary configuration illustrated in Fig. 27, the filtering sub-assembly 320 being cleaned by spray assembly 380 is shown to be in a relatively upper position, above other filtering sub-assembly 320, posing a risk that filtride particles dislodged therefrom may find their way to the outer surfaces 346 of other filtering sub-assemblies 320, or otherwise fall back into the water of the water source 20 and contaminate the raw water in the immediate vicinity of the other filtering sub-assemblies 320. In some examples, a tray (not shown) may be added below the position of the nozzles 384 and/or the position at which a filtering sub-assembly 320 is being cleaned, so that any filtrate particles dislodged therefrom can fall into the tray, which can be periodically cleaned.

[0410] While designed to minimize filtride accumulation over or in the filter mediums 344, filtration system 300 may still include self-cleaning mechanisms, such as flush tubes 390 or spray assembly 380, which can be utilized as safety measures, or as additional measures that can be utilized in implementations in which the aperture size D is not greater than 350 microns (including being optionally not greater than 300 microns, not greater than 200 microns, not greater than 100 microns, not greater than 40 microns, not greater than 10 microns, not greater than 5 microns, and/or not greater than 1 micron), which can still require certain self-cleaning measured to be employed for such fine filtering densities.

[0411] In some implementations, the cleaning feed line 94 can extend from a source of water or compressed air onshore. In other implementations, the cleaning feed line 94 can be adapted to pump water from the surrounding water source 20 and into the spray conduit 382 and nozzles 384, and/or into the flush tubes 390.

[0412] In some implementations, the same water (or other liquid) can be used for the spray assembly 380 and/or the flush tubes 390, and for operating a water motor 72. In such implementations, a unified feed line, or a feed line manifold, can be branched into a one or more motor lines 92 and a cleaning feed line 94, optionally with appropriate controllable valves for controlling adequate flow through each as necessary.

[0413] In some implementations, the frame 30 can include one or more wall windows 42 that can be closed or opened by one or more corresponding window covers 44 (see Fig. 22 for example). For example, the frame 30 can includes two wall windows 42 formed in each frame transverse wall 32, wherein the windows 42 of each frame transverse wall 32 are aligned with each other, and are formed along portion of the frame transverse walls 32 that are at least partially facing a portion of the filter medium 344 of one or more filtering sub-assemblies 320. The wall windows 42 can be covered, in some examples, by window covers 44 that can transition between closed and open positions. Fig. 22 shows all window covers 44 in a closed position, fully covering the wall windows 42. The open position of the window covers 44 is similar to that shown in Fig. 6.

[0414] The wall windows 42 and window covers 44 may serve as an additional or alternative self-cleaning mechanism, that can be used, for example, with a partially immersible rotatable filtering assembly 302. The wall windows 42 are designed to be at a height of the water level 22 when the rotatable filtering assembly 302 is partially immersed. When placed in a natural water source 20 that includes moving water, such as sea waves or running water of a river, opening the window covers 44 will expose the windows 42 to such waves or moving river water, which will flow therethrough from side to side, along the filter mediums 344 of filtering sub-assemblies 320 aligned therewith, dislodging any accumulated filtride and cleaning the filter mediums along with the flow.

[0415] The windows covers 44 can be hinged to pivot about their hinged connection between the closed and open states as in the illustrated example, though any other mechanism for moving such covers between open and closed position, as known in the art, is contemplated. Moving the window covers 44 between closed and open positions can be performed either manually, or by implementation of electrically controlled (including remote-controlled) mechanisms. The window covers 44 may be opened to expose the wall windows 42 to a surrounding water flow during a cleaning mode of the filtering sub-assemblies 320 aligned therewith, and may be closed to prevent such flow from interfering during filtering mode.

[0416] While described for use with a partially immersible rotatable filtering assembly 302, it is to be understood that wall windows 42 with window covers 44 can be also utilized as a cleaning mechanism for a fully immersible rotatable filtering assembly 302. For example, a rotatable filtering assembly 302 can be fully immersed during a filtering mode, while the window covers 44 are in the closed position. When at least some of the filtering sub-assemblies 320, aligned with windows 42, transition to the cleaning mode, the rotatable filtering assemblies 302 can be raised upward to be partially immersible, for example placing the wall windows 42 at the height of the water level 22, at which point the window covers 44 may be opened. When cleaning is no longer required, the window covers 44 can be closed again, and the rotatable filtering assembly 302 can be lowered downward back to the fully immersible position, as the same filtering sub-assemblies 320 transition back to the filtering mode. Furthermore, wall windows 42 can be exposed to the surrounding water and utilized in a cleaning mode also when the rotatable filtering assembly 302 is fully immersed, taking advantage of water streams occurring not only at the water level 22, but also below water level 22.

[0417] Wall windows 42 can be provided in various shapes and sizes, such as a trapezoid shape shown in Figs. 22-23, an hourglass shape similar to that shown in Figs. 39A-C, or any other suitable shape. In some examples, particularly for wall windows 42 provided with irregular shapes such as the hourglass -shape in Figs. 39A-C, the frame 30 can be devoid of window covers, leaving the wall windows 42 exposed to the surrounding environment at all times.

[0418] In some examples, frame 30 further comprises funneling extensions 48, each funneling extension 48 circumscribing a corresponding wall window 42, thus generally shaped in the same shape defined by the borders of the wall window 42, and extending from the frame transverse wall 32 in a direction opposite to the filter medium 344. Each funneling extension 48 can include a tapering inner surface 49 that forms a funnel-like guide for streaming the water toward the opening of wall window 42. When placed in a water source 20 with moving water, such as sea waves or streaming river, the funneling extensions 48 can serve to funnel the streaming water toward and through the wall windows 42, wherein the tapering inner surfaces can increase the flow speed of the streaming water toward filter medium 344, thus improving the surrounding water's capability of effectively washing away filtride that may have accumulated over filter medium 344. While not illustrated as such, it is to be understood that in some examples, wall windows 42 of any size and shape can be provided with any combination of window covers 44 and/or funneling extensions 48. [0419] In some implementations, the filtration system 300 also includes at least one float 50 attached to the frame 30, such as the couple of floats 50 shown in Figs. 20 and 27 to extend through float opening 36 formed in both frame transverse walls 32. Floats 50 can be utilized to keep the rotatable filtering assembly 302 fully or partially submersible at a desired height relative to the water level 22. While two floats 50^a, 50^b are illustrated in Figs. 20 and 27, it is to be understood that any other number, such as a single float or more than two, are contemplated, and that the plural use of the term "floats 50" is not limiting, and may similarly refer to a single float.

[0420] In some implementations, the floats are adjustable floats 50, meaning that the weight of the floats 50 can be adjusted to control their buoyancy. In some implementations, the adjustable floats 50 may be provided in the form of ballast tanks, with at least one port for controlling the level of ballast water. In some implementations, each adjustable float comprises a float water port or liquid port 52 through which water (or other suitable liquid), such as ballast water, can be poured to fill the internal volume of the float 50, thereby increasing its weight, and an air port or gas port 54, through which air (or other suitable gas) may flow into the float 50 while water may exit through the water port 52.

[0421] Adjustable floats 50 can be utilized, by increasing and decreasing the weight of the floats 50, to control the buoyancy of the rotatable filtering assembly 302 and its height, relative to the water level 22. Such implementations can be used in combination with cleaning mechanisms that rely on opening and closing window covers 44 of wall windows 42 and/or funneling water through wall windows 42 provided with funneling extensions 48 as described above, for example by being filled with water (or other suitable liquid) to increase their weight and allow the rotatable filtering assembly 302 to be fully submerged during the filtration phase, and filling air (or other suitable gas) to raise the rotatable filtering assembly 302 and the wall windows 42 to the water source level 22 during the cleaning mode.

[0422] The exemplary filtration system 300 illustrated in Figs. 20 and 27 shows the floats 50 positioned such that, when inflated, their bottom edges are below the level of the upper edges of the top-side filtering sub-assemblies 320 (e.g., sub-assemblies 320a, 320b), such that if these floats 50 are retained at the water level 22 of the water source 20 when inflated, at least some portions of at least some filtering sub-assemblies 320 are not immersed in the water source 20, but are rather exposed to the atmosphere. [0423] In some examples, as shown in Fig. 28, the floats 50 are positioned above all filtering sub-assemblies 320, such that the upper edges of any of the filtering sub-assemblies 320 are below the lower edges of any of the floats 50. In such implementations, when the floats are inflated and retained at the water level 22 of the water source 20, all of the filtering subassemblies 320 can remain fully immersed, below the water level 22.

[0424] In some examples, filtration system 300 comprises one or more movable floats (50), that can be either adjustable or non-adjustable floats, configured to raise or lower the rotatable filtering assembly 302 relative to water level 22. The movable floats (50) can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 44A-45B. The same examples of movable floats (50) can be adapted for use with filtration system 300, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0425] In some implementations, the filtration system 300 can include an anchoring structure 120 attached to the frame 30, which can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 9A-9B. The same examples of anchoring structure 120 can be adapted for use with filtration system 300, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0426] In some implementations, filtration system 300 comprises an elevation assembly 130 to which at least one frame 30 and rotatable filtering assembly 302 are movably mounted, wherein the elevation assembly 130 is configured to control the height of the rotatable filtering assembly 302, for example relative to water level 22. The elevation assembly 130 can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 10-12B. The same examples of elevation assembly 130 can be adapted for use with filtration system 300, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0427] In some implementations, filtration system 300 comprises an offshore platform connection assembly 154 for coupling the frame 30 to an offshore platform 150 according to any of the examples described above in combination with filtration system 200 with respect to Fig. 13. The same examples of offshore platform connection assembly 154 can be adapted for use with filtration system 300, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0428] Another self-cleaning mechanism that can be implemented for filtration system 300 relies on changing the height of the rotatable filtering assembly 302 relative to the water level 22, at a speed high enough during which the impact of a filter medium 344 of at least one of the filtering sub-assemblies 320 against the surface of the water at the water level 22 will dislodge filtride from the respective filter medium 344. For example, the rotatable filtering assembly 302 can be positioned such that a filter medium 344 of at least one filtering subassembly 320, and in some implementations, the filter mediums 344 of all filtering subassemblies 320, are above the water level 22. Then, lowering the rotatable filtering assembly 302 into the water at a high-enough speed, will cause the filter medium 344 to impact the water surface at the water level 22 at a force which is sufficient to dislodge filtride therefrom.

[0429] Any of the above-mentioned height-control mechanisms, including movable and/or adjustable floats 50, elevation assembly 130, and/or offshore platform connection assembly 154, can be utilized to elevate and lower the height of the rotatable filtering assembly 302 to forcibly impact the filter medium 344 of at least one of the filtering sub-assemblies 320 against the surface of the water at the water level 22. In some implementations, alteration of the height of the rotatable filtering assembly 302 to impact the filter mediums 344 against the surface of the water at the water level 22 is performed during a cleaning mode of the filtering subassemblies 320 to be impacted. In some implementations, more than one cycle of raising and lowering the rotatable filtering assembly 302 can be sequentially performed, wherein each subsequent cycle can serve to further dislodge filtride that remained stuck against the corresponding filter mediums 344. In some implementations, rotatable support wall 306 can be rotated so as to position, each time, different filtering sub-assemblies 320 (one or more) above the water level 22, to be impacted.

[0430] Another self-cleaning mechanism that can be implemented for filtration system 300 relies on accelerating the angular speed of rotatable filtering assembly 302 while being partially submerged in the water source 20. While filtration is performed at a very low angular speed of rotation W during filtering mode, to minimize accumulation of particles over the filter medium 344, the rotatable filtering assembly 302 can be accelerated for a limited time period to a significantly higher angular speed of rotation, such as an angular speed higher than 60 degrees per second (i.e., more than 10 revolutions per minute), causing filter medium 344 (of at least one filtering sub-assembly 320) that hits against the water at the water level 22, to hit at an impact force high enough so as to dislodge filtride therefrom. All filtering sub-assemblies 320, including those that may be still immersed prior to angular speed acceleration, are preferably switched to the cleaning mode (i.e., terminating suction into intake pipe 360 from all) prior to angular speed acceleration, as even filtration sub-assemblies that do not necessarily hit against water level 22, will still experience the elevated angular speed of rotation that can disturb the water in their vicinity. In some implementations, the direction of rotation can be also altered between subsequent cycles.

[0431] The controller 76 (e.g., motor control sub-unit 76c) can be configured to transition the drive motor's 72 angular speed of rotation between low speeds during a filtering mode, and high speeds during a cleaning mode, as well as optional alteration of the direction of rotation during the cleaning mode. The controller 76 can be configured to control the acceleration and deceleration rates during the transition between higher and lower angular speeds of rotation.

[0432] In some implementations, the filtration system 300 can further include an additional vibration motor 73, that can be coupled to the rotatable filtering assembly 302 and configured to vibrate, and more specifically, apply vibrational movement to the filter medium 344, which will serve to dislodge filtride accumulated thereon. The vibration motor 73 is a watertight motor, and can be optionally sealed by being encompassed by a watertight housing, similar to housing 74. A filtration system 300 can be equipped with both a watertight drive motor 72 and a watertight vibration motor 73, similar to the example described above for filtration system 200 with respect to Fig. 17A, wherein both motors can be attached to the same component of a frame 30, such as both being coupled to frame transverse wall 32a as illustrated, or to different components of the frame 30 or other components of the filtration system 300. Operation of the vibration motor 73 can be controlled by a separate controller, or the same controller 76 of the drive motor 72.

[0433] The controller 76 can be adapted to control the operation of the drive motor 72 and the vibration motor 73, such that the drive motor 72 is activated to rotate the rotatable filtering assembly 302 during the filtering mode (either periodically or continuously), while the vibration motor 73 is inactive, and the vibration motor 73 is activated, while the drive motor 72 is non-active, during a cleaning mode. The vibration motor 73 can be implemented, in some examples, as an eccentric rotating mass vibration motor. In some implementations, the same motor 72 can be used to apply both rotational movement for rotating filtering assembly 302, and vibrational movement to facilitate vibration of the filter mediums 344. The controller 76 can control the operation of such a multi-purpose motor 72, to transition between rotational movement during the filtering mode and vibrational movement during the cleaning mode.

[0434] In some examples, filtration system 300 can include one or more ultrasonic transducer(s) 96, positioned to apply ultrasonic energy directed at the filter medium 344, similar to the manner described above for filtration system 200 with respect to Fig. 17A. The ultrasonic transducer(s) 96 can apply ultrasonic energy that can disintegrate and/or create ultrasonic waves that will impact against the filter medium 344 in a manner that will dislodge filtride therefrom. Advantageously, the desire ultrasonic waves, directed at the filter medium, do not require high energy, enabling utilization of the ultrasonic transducer as low-energy longterm self-cleaning mechanism.

[0435] In some examples, the intake pipe 360 further comprises an expansion chamber 364 (not illustrated separately for filtration system 300), similar to the manner described above for filtration system 200 with respect to Fig. 16. An expansion chamber 364 is disposed upstream from the rotatable filtering assembly 302, and is formed as a portion of the intake pipe which expands to an expansion chamber diameter De which is at least twice as great as the minimal pipe diameter Dp, and in some example, at least three times as great as the minimal pipe diameter Dp. The minimal pipe diameter Dp is the diameter of intake pipe 360 at its minimal intake pipe cross-sectional area Ap, which can be measured at a portion of the intake pipe 360 extending into the rotatable filtering assembly 302, or at least extending through or disposed at the level of, a rotatable support wall 306.

[0436] The expansion chamber 364 can be either integrally formed with the remainder of intake pipe 360, or provided as a separate component attached in a sealed manner to the remainder of intake pipe 360. The expansion chamber 364 can include a gradually tapering inflow portion, expanding gradually radially outward from minimal pipe diameter Dp to expansion chamber De, a main expanded portion having a uniform diameter De along a length Lc, and a gradually tapering outflow portion, narrowing gradually radially inward from expansion chamber diameter De back to minimal pipe diameter Dp, after which the pipe may further extend along a certain length and terminate with pipe outflow opening 366. In some examples, the length of expanded main portion Lc is at least twice as great as the expansion chamber diameter De. [0437] In some examples, a filtration system 300 can be oriented in a vertical orientation, such that its main axis Ym is substantially orthogonal to a plane of the water level 22. In examples of filtration systems that include one or more floats 50, including any of the movable and/or adjustable floats disclosed herein, the orientation of the float(s) 50 is adjusted to allow for vertical orientation of the rotatable filtering assembly 302. In some examples, the float(s) 50 extends along a plane which is substantially orthogonal to the main axis Ym. For example, float(s) 50 illustrated in Fig. 20 extend longitudinally along an axis which is substantially parallel to the main axis Ym, which will result in a horizontal orientation of the rotatable filtering assembly 202. In contrast, a float 50 can be implemented in a similar manner to that described above for filtration system 200 with respect to Fig. 16, defining a plane which is substantially orthogonal to main axis Ym, resulting in a vertical orientation of the rotatable filtering assembly 302.

[0438] In some examples, the intake pipe 360 extends from the rotatable filtering assembly 302 downward, toward water source bed 24, such that the pipe outflow opening 366 is positioned lower than the rotatable filtering assembly 302.

[0439] In some examples, the filtration system 300 is equipped with a weight 160 opposite to float 50. Any of the float 50 and/or weight(s) 160 can be coupled to the frame 30 and/or to the filtering assembly 302, preferably on opposite sides, via one or more coupling means such as cables, chains, and the like, in a manner similar to that described above for filtration system 200 with respect to Fig. 17A. The combination of float(s) 50, and in some examples, movable and/or adjustable float(s) 50, with weight(s) 160, can serve to control the height of rotatable filtering assembly 302 within the water source 20 (i.e., relative to water level 22), for example by adjusting the degree of floatation of float(s) 50, while weight(s) 160 pull the rotatable filtering assembly 302 gravitationally downward. Moreover, the combination of float(s) 50 from above, and weight(s) 160 from below the rotatable filtering assembly 302, can together stabilize the rotatable filtering assembly 302 in a vertical orientation, substantially orthogonal to the plane defined by water level 22.

[0440] In some implementations, the discs 332 comprise copper, for example by being completely made of copper or coated by a copper layer. Embedding copper into the discs 332, or forming them from copper, can significantly reduce the likelihood of algae and other microorganisms from clinging to the discs 332 and clogging channels 352 when immersed in a natural water source 20. [0441] As mentioned, the minimal ratio Ra and/or maximal flow velocity across the filtration apertures Ve depend on the effective area of filtration Ae, such that for a given maximal flow rate Qm, a minimal effective area of filtration Ae is required to result in the minimal desired Ra and/or maximal desire Ve. Furthermore, as also mentioned above, the filtration apertures 354, which in some cases can constitute only a subset of the channels 352 of some of the filtering sub-assemblies 320, contribute to the effective area of filtration Ae. A filtration system 300 configured to have at least one of its filtering sub-assemblies 320 in a filtering mode, while at least one other filtering sub-assembly 320 is in a cleaning mode, can be designed such that the minimal number of filtering sub-assemblies 320 that continue to operate in a filtering mode at all times, including when one or more filtering sub-assemblies 320 are in a cleaning mode, provides a sufficient minimal effective area of filtration Ae.

[0442] In the example illustrated in Figs. 23-25, two flush tubes 390 are provided to allow backwash of two corresponding filtering sub-assemblies 320, such that even during this cleaning mode, at least four other filtering sub-assemblies 320 continue to operate in a filtering mode. Thus, while in some instances, all six filtering sub-assemblies 320 can operate in a filtering mode, the minimal number of filtration apertures 354 includes all medium apertures 352 of at least four filtering sub-assemblies 320. The minimal effective area of filtration Ae, based on the filtration apertures of four filtering sub-assemblies 320 in such an example, can be designed to result in the minimally desired Rq and/or Ra.

[0443] In examples of a partially immersible filtration system 300, the medium apertures or channels 352 of any filtering sub-assemblies 320 that can be at any instant of time above the water level 22 are non-filtration apertures, such that only the minimal number of filtering subassemblies 320 which always remain submerged in the water source 20 at any given time, will contribute to the effective area of filtration Ae. In such cases, the filtration system 300 can include an immersion depth marking 46 that can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Fig. 7. The same examples of immersion depth markings 46 can be adapted for use with filtration system 300, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0444] In some examples, filtration system 300 can include at least one camera 56 configured to take images of at least a portion of filter medium(s) 344, optionally mounted on a camera mount 58 that can be an adjustable arm, wherein each of the camera 56 and/or mount 58 can be controlled by control sub-unit 76e. Any of the at least one camera 56 and camera mount 58, as well as control sub-unit 76e, can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 39A-C. The same examples of camera(s) 56, camera mount(s) 58, and/or controller sub-unit 76e, can be adapted for use with filtration system 300, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0445] In some examples, filtration system 300 comprises a bubble generator (140) that includes a hollow enclosure 142 with bubble apertures 144 facing at least one stack of discs 344 of at least one rotatable filtering sub-assembly 320, configured to generate bubble (28) that can float toward the corresponding one or more stack of discs 344 during a cleaning mode. The filtration system 300 can further comprise a guiding chamber (190) extending upward from the bubble generator (140). The bubble generator (140), with or without a guiding chamber (190), can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 47A-51. The same examples of bubble generator (140), with or without a guiding chamber (190), can be adapted for use with filtration system 300, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0446] Another possible implementation of a filtration system, referred to as coiled thread-type filtration system 400, provided with a coiled thread-type rotatable filtering assembly 402, will now be described in detail with reference to Figs. 29A-33 of the accompanying drawings. Figs. 29A and 29D show views in perspectives of an example of a coiled thread unit 432. Fig. 29B shows the support blank 434 of the coiled thread unit 432 of Fig. 29A. Fig. 29C shows a partial view in perspective of the coiled thread unit 432 of Fig. 29D, with a single layer of threads 445. Fig. 30A shows a view in perspective of a coiled thread-type filtering sub-assembly 420. Fig. 30B shows a sectional view of the coiled thread-type filtering sub-assembly 420 of Fig. 30A. Fig. 31 shows one example of a coiled thread-type filtration system 400. Figs. 32 and 33 show sectional views across different cutting planes of an exemplary coiled thread-type filtering subassembly 420. Figs. 29A-33 are described herein together.

[0447] A coiled thread-type filtration system 400 comprises a coiled thread-type rotatable filter assembly 402, that includes at least one, and preferably a plurality of, revolvable filtering subassemblies 420. Each filtering sub-assembly 420 includes a filter medium 444, implemented as threads 445 coiled or wound around support blanks 434. [0448] Figs. 29A-D show various views of a coiled thread-unit 432, that includes threads 445 coiled around a support blank 434. An example of a support blank 434 is shown in isolation in Fig. 29B, comprising a blank first end 436 with a blank outlet 438, a blank second end 440 which is a closed end opposite to the blank first end 436, and one or more blank arms 442 extending between the blank first end 436 and blank second end 440, around which one or more threads 445 are wound, as shown in Figs. 29A and 29D, such that an internal space 450 (see Fig. 30B, for example) is formed between the resulting coiled threads 445, the blank arms 442, and both blank ends 436, 440. In some examples, the thread(s) 445 are wound around the blank arms 442 in a manner that forms several threaded layers, together forming the filter medium 444. Fig. 29C shows a view of a single thread 445 looped around the blank arms 442, and Fig. 29D shows a final configuration of a multi-layered filter-medium 444 with several layers of threads 445 looped or coiled around support blank 434.

[0449] As shown, the support blank 434 may have an overall trapezoid shape, with blank second end 440 being generally wider than blank first end 436, such that blank arms 442, such as the two arms illustrated in the example of Fig. 29B, extend diagonally on both sides from the shorter blank first end 436 to the wider second end 440, defining a trapezoidal internal space 450 there-between. The filter medium 444, defined by the plurality of coiled threads 445, has a medium outer surface 446, also termed the coiled threads outer surface 446, and a medium inner surface 448 (hidden from view), also termed the coiled threads outer surface 446.

[0450] The term "threads 445" can relate to any kind of strings, yarns, fabric stripes, etc., and may be made of any suitable rigid or flexible material, such as metal, plastic, fabric and the like. The threads 445 are tightly wound around the blanks 434, wherein the support blank 434 retains an internal space defined between both opposing sides of the looped threads. The spacing between adjacent portions of coiled threads, for example along one full circumferential loop of the threads 445, is defined as the medium aperture 452, further defining the aperture size D. The aperture size D can be controlled as a function of a combination between: the number of wound layers, the winding tension, and the properties of the thread material, such as thread size and thread surface properties. The aperture open area Aa is defined as the cross- sectional area across one full loop between outermost adjacent coiled thread 445, defined at the coiled threads outer surface 446.

[0451] During a filtering mode, raw water pass from the coiled threads outer surface 446, through the spacings between the threads 445 along various layers thereof and into internal space 450. The spacings between adjacent threads are adapted to trap particles contaminating the water during flow there-through, as well as restrict entry of relatively larger particles (i.e., larger than aperture open area Aa) into these spacings to begin with. Since the blank second end 440 is a closed end, the only available flow path for the filtrate, after passing through the filter medium 444 into the internal space 450, is toward and through the blank outlet 438.

[0452] Figs. 30A-B show an example of a coiled thread-type filtering sub assembly 420, which includes a plurality of coiled-thread units 432 mounted on a hollow hub 422. Hollow hub 422 can be a tubular structure that includes an open ended hub outlet end 424, and an opposite hub closed end 426, and defining a hub lumen 430, with a plurality of hub openings 428 disposed around its circumference, corresponding to in number to the number of coiled-thread units 432 of the filtering sub assembly 420. Each blank outlet 438 is coupled in a sealed manner to a corresponding hub opening 428, so as to maintain fluid communication between the internal space 450 of the corresponding coiled-thread unit 432 and the hub lumen 430.

[0453] In the illustrated example, a ring-like arrangement is shown with several coiled-thread units 432 disposed around the circumference of the hollow hub 422 at each specific distance from the hub outlet end 424, in a manner that forms a ring-like arrangement at this specific position, with a plurality of ring-like arrangements disposed along the length of the hollow hub 422. It is to be understood that other arrangements may be provided for the coiled-thread units 432 along a hollow hub 422.

[0454] As shown throughout Figs. 31-33, a coiled thread-type filtration system 400 includes a coiled thread-type rotatable filtering assembly 402, at least one watertight drive motor 72 and at least one controller 76. The coiled thread-type rotatable filtering assembly 402 defines a main axis Ym (indicated for example in Fig. 33) around which it is configured to rotate by the corresponding watertight drive motor 72. Coiled thread-type rotatable filtering assembly 402 further comprises at least one rotatable support wall 406, and at least one, and preferably a plurality of, coiled thread-type revolvable filtering sub-assemblies 420, attached to the at least one rotatable support wall 406. Each revolvable sub-assembly 420 defines a sub-assembly axis Ys which is parallel to, and offset from, main axis Ym (see, for example, Fig. 33). For simplicity, any reference to a component of filtration system 400 (such as filtering subassembly 420, rotatable support wall 406, controller 76, and so on) in a single form throughout the current specification, will similarly refer to "one or more" of said components for implementations that include a plurality of said components, unless otherwise stated. [0455] The terms "coiled thread-type filtration system 400" and "filtration system 400" are interchangeable, the terms "coiled thread-type rotatable filtering assembly 402" and "filtering assembly 402" are interchangeable, and the terms "coiled thread-type filtering sub-assembly 420" and "filtering sub-assembly 420" are also interchangeable, for system, assembly, and subassembly numerals 400, 402 and 420 throughout the specification, and particularly with respect to Figs. 3OA-33, unless otherwise stated.

[0456] For a filtration system 400 that includes a coiled thread-type rotatable filtering assembly 402 equipped with coiled thread-type filtering sub-assemblies 420, the terms "filter medium 444" and "coiled threads 444" are interchangeable, and refer to a filter medium which is implemented as threads 445 coiled around a plurality of support blanks 434.

[0457] In the illustrated examples, the filtration system 400 comprises a single rotatable support wall 406 extending along a plane substantially orthogonal to the main axis Ym. However, this is not meant to be limiting, and in alternative examples, two rotatable support walls can be provided, wherein each filtering sub-assemblies can be optionally disposed between both walls.

[0458] The filtration system 400 is further shown to comprises an intake pipe 460, which is coupled to the rotatable filtering assembly 402 and optionally extends therethrough, such as through a central sealed opening 408. The intake pipe 460 includes at least one pipe inflow opening 462 which is in fluid communication with the medium apertures 452.

[0459] In some examples, the filtration system 400 further comprises a sealed intake chamber 470, which is sealed from the outer environment (e.g., raw water of the water sources 20), and is in fluid communication with the intake pipe 460 (for example, via pipe inflow opening 462) and with at least some of the filtering sub-assemblies 420.

[0460] The intake chamber 470 can be defined between the rotatable support wall 406 and a stationary wall portion 472 that includes a stationary transverse wall 474, such that the rotatable support wall is rotatable around main axis Ym, while stationary wall portion 472 is a non- rotatable component of the filtration system 400. In some examples, the filtration system can further include a circumferential wall portion 476 defining the external perimeter of the intake chamber 470. In some examples, as in the illustrated examples, the circumferential wall portion 476 is affixed or integrally formed with the stationary transverse wall 474, such that the circumferential wall portion 476 and the stationary transverse wall 474 together define the stationary wall portion 472. The rotatable support wall 406 can then be movably coupled, in a sealed manner, to the edges of the circumferential wall portion 476. In other examples, the circumferential wall portion can be affixed to or integrally formed with the rotatable support wall, configured to rotate therewith while stationary transverse wall 474 remains immovable. In such examples, the circumferential wall portion 476 can be movably coupled, in a sealed manner, to the edges of the stationary transverse wall 474.

[0461] In some examples, the intake pipe 460 extends into the intake chamber 470. In some examples, the one or more pipe inflow openings 462 are disposed within the intake chamber 470. In some examples, the pipe inflow openings 462 are disposed around the circumference of the portion of the intake pipe 460 which is disposed in the intake chamber 470, and are offset from the main axis Ym, facing the circumferential wall portion 476. While four pipe inflow openings 462 are illustrated in the example shown in Figs. 32-33, it is to be understood that any other number, such as a single pipe inflow opening, two, three, or more than four pipe inflow openings, is contemplated. Any reference to "pipe inflow openings 462" throughout this specification, unless otherwise stated, refers also to implementation of a single pipe inflow opening 462.

[0462] The intake pipe 460 can be an independent component of a suction line 60, attached thereto and in fluid communication therewith, or can be formed as an integral part or extension of the suction line 60. Intake pipe 460 is coupled to rotatable support wall 406 in a manner that allows it to rotate around intake pipe 460, while intake pipe 460 remain stationary in position, that is to say that intake pipe 460 is a non-rotatable component of the filtration system 400. Intake pipe 460 can extend, for example along main axis Ym, away from the rotational support wall, and terminate with a pipe outflow opening 466 that can be coupled, for example by a pipe coupler 68, to a suction line inlet 62 as described above with respect to filtration systems 200.

[0463] In some examples, the stationary transverse wall 474 is affixed to the intake pipe 460. For example, the stationary transverse wall 474 can include a stationary wall sealed opening 478 that can be aligned with the central sealed opening 408 of the rotatable support wall 406, such that the intake pipe 460 can extend, in a sealed manner, through both openings 408 and 478.

[0464] In some examples, the filtration system 400 further comprises a frame 30. Both the rotatable filtering assembly 402 and the watertight drive motor 72 can be coupled to the frame 30, wherein the rotatable filtering assembly 402 is movably coupled to the frame 30 (i.e., can rotate around main axis Ym while being supported, directly or indirectly, by frame 30). In some implementations, as in the illustrated example, one or both of the frame transverse walls 32 include pipe through openings 34, which are coaxial with, and preferably similarly dimensioned to, the corresponding central sealed opening 408, allowing the intake pipe 460 to extends through the frame transverse walls 32 and the rotatable support wall 406. Thus, in the illustrated examples, the rotatable filtering assembly 402 is indirectly coupled to the frame 30 by intake pipe 460 coupled to, and extending both through, the rotatable support wall 406 and the frame transverse walls 32b.

[0465] While shown, for example in the illustration of Figs. 32-33, to extend through both the central sealed opening 408 of the rotatable support wall 406 and the sealed opening 478 of the stationary transverse wall 474, and optionally further on through a pipe through opening 34 of the corresponding frame transverse wall 32 (wall 32a in the illustrated example), other configurations are available for keeping fluid communication between the intake pipe 460 and the intake chamber 470. For example, the intake pipe 460 can terminate at any point within the intake chamber 470, without further extending through the stationary transverse wall 474, while at least one pipe inflow opening is still exposed to the intake chamber 470. The stationary transverse wall can be affixed to a different component of the filtration system other than the intake pipe, such as a frame transverse wall 32. In other examples, an end portion of the intake pipe 460 can terminate at the stationary transverse wall 474, affixed thereto, without necessarily further extending therethrough.

[0466] In yet other alternative examples, the intake pipe can include a single pipe inflow opening 462 coaxial with main axis Ym, defined by an open end of the intake pipe 460, which can either partially extend into the intake chamber 470, or alternatively terminate at the level of the rotatable support wall 406, having its edges attached to the edges of the central sealed opening 408 in a manner that retain fluid communication of the intake pipe 460 with the intake chamber 470 via central sealed opening 408.

[0467] The rotatable support wall 406 can include, in some examples, at least one offset opening 410, each offset opening 410 is coupled to a respective hub outlet end 426, aligned with a corresponding filtering sub-assembly 420 and its sub-assembly axis Ys, offset from main axis Ym. Each offset opening 410 is in fluid communication with the hub lumen 430 via hub outlet end 424, wherein the connection between hub outlet end 424 and offset opening 410 is sealed from the surrounding environment (e.g., sealed from the raw water of the water source 20), at least during a filtering mode of the respective filtering sub-assembly 420.

[0468] The intake pipe 460 and suction line 60 together define a fluid-communication line between the pipe inflow openings 462 and a suction line outlet 64 (same outlet 64 described hereinabove and shown, for example, in Fig. 1A) which can be placed onshore. This fluidcommunication line is intended to direct filtrate from the rotatable filtering assembly 402 to a target location, which can be onshore, for example by applying suction force at the pipe inflow openings 462. This may be accomplished by creating a negative pressure difference between the pipe inflow openings 462 and the suction line outlet. The negative pressure difference can be created by gravitational forces, or a pump (e.g., pump 66) in the same manner described above with respect to filtration systems 200. This pressure difference facilitates flow from the water source 20, through the filter medium 444, via internal spaces 450 and hub lumen 430, into the intake chamber 470, toward the pipe inflow openings 462 and into the intake pipe 460.

[0469] In some examples, the rotatable filtering assembly 402 is partially submerged, such that only some of the filtering sub-assemblies 420 are immersed in the water source 20. In such examples, any filtering sub-assembly 420 which is not immersed in the water source 20 cannot be in a filtering mode, such that all of its non-submerged medium apertures 452 are nonfiltration apertures 456. Any filtering sub-assembly 420 which is immersed within the water source 20, can optionally transition between filtering and cleaning modes, as will be elaborated below. In some examples, the rotatable filtering assembly 402 is fully submerged, such that all of the filtering sub-assemblies 420 are immersed in the water source 20. In such examples, similar to the partially immersed configurations, any filtering sub-assembly 420 can optionally transition between filtering and cleaning modes, as will be elaborated below.

[0470] As mentioned above, the internal space 450 of each coiled-thread unit 432 is in fluid communication with the hub lumen 430, which in turn is in fluid communication with a corresponding offset opening 410 at the region of attachment of the hub outlet end 424 to the rotatable support wall 406. During filtration mode, raw water which is in direct contact with the coiled threads outer surface 446, flow through the coiled threads 444 into the internal space 450, becoming filtrate that flows therefrom, through the internal space 450 and hub lumen 430, via offset opening 410, into the intake chamber 470, and therefrom, through the pipe inflow openings 462, into intake pipe 460. [0471] Similar to filtration system 200, the filtration system 400 comprises a watertight drive motor 72 configured to rotate the filtering assembly 402 around main axis Ym. As shown, the watertight drive motor 72 can be secured to the frame 30, such as to one of the frame transverse walls 32. When the intake pipe 460 extends through one or both frame transverse walls 32, the drive motor 72 can be offset from the main axis Ym, so as not to interfere with the intake pipe 460. Thus, since the axis of rotation of the watertight drive motor 72 is offset from the main axis Ym in such a case, the filtration system 400 can include a transmission assembly 80, configured to transmit the torque produced by the drive motor 72 to the corresponding rotatable support wall 406, thereby rotating the entire filtering assembly 402 there-along.

[0472] The transmission assembly 80 can include a gear train with one or more gears. For example, the transmission assembly 80 can be implemented is a manner similar to that described above for filtration system 300 with respect to Fig. 25, including a driving gear 84 attached to a shaft 82 driven directly by the watertight drive motor 72, and a driven gear 86 attached to the surface of the rotatable support wall 406 and meshed with the driving gear 84, wherein the size of the gears dictates the transmission ratio between the angular speed of rotation of the motor and the resulting angular speed W of the filtering assembly 402, such that the transmission assembly 80 can also serve as a motor speed reduction mechanism.

[0473] In some examples, at least a portion of the transmission assembly 80, such as gears 84, 86, and optionally shaft 82, is disposed within the intake chamber 470. In other examples, part or all of the transmission assembly 80 can be sealed from the filtrate flowing in the intake chamber 470, for example by the addition of a housing or other type of enclosure around components of the transmission assembly 80.

[0474] The rotatable support walls 406 can also include a plurality of rollers 70 rotatable around axes that are parallel to the main axis Ym, each configured to contact and roll over the outer surface of the intake pipe 460, for example at the portion extending out of the respective central sealed opening 408 away from the intake chamber 470 (though in other configurations, the rollers 70 can be also situation within the intake chamber). While the illustrated example shows three rollers 70 attached to the rotatable support wall 406, it is to be understood that any other number of rollers is contemplated.

[0475] The watertight drive motor 72 can be either an electric motor or a water motor. Utilization of a water motor as the watertight drive motor 72, requires adaptation of the filtration system 400 to include at least one motor line 92 (see for example Fig. 32) fluidly coupled to the motor 72, configured to provide water (or other suitable liquid) to operate the water motor 72. In some implementations, the motor line 92 can extend from a source of water onshore, all the way to the water motor 72 positioned offshore, coupled to the frame 30. This is an unconventional adaptation that can be implemented for utilization of an immersible water drive motor 72 for facilitating rotation of the filtering assembly 202, as most conventional water motors do not include feed lines extending over a length of several meters from a source that can be onshore, to a motor that can be placed offshore. In other implementations, the motor line 92 can be adapted to pump water from the surrounding water source 20 and into the water motor 72. In some examples, the at least one motor line 92 includes two lines, one motor inflow line 92a configured to direct feed water into the water motor 72, and the other motor outflow line 92b configured to direct water out of the water motor 72.

[0476] In contrast to water motors, a conventional electric motor that may be used for rotating onshore rotatable filtering assemblies, is not necessarily watertight as it is usually placed in a dry environment. Thus, when the drive motor 72 is an electric motor, it needs to be watertight to prevent any damage to its operation when immersed within, or otherwise being contacted by, water from the water source 20. An electric drive motor 72 can be, for example, a DC servo motor, a pneumatic actuator, a step motor, and the like. In some implementations, the electric drive motor 72 is a brushless DC (BLDC) motor. The electric drive motor 72 may further be a slotted or slotless BLDC motor. An electric drive motor 72 can become a watertight drive motor 72 by being encased within a watertight motor housing 74, which can be similarly attached to the frame 30, such as to a frame transverse wall 32, as in the illustrated example. When implemented as an electric motor, a motor line 92 can be utilized for transmitting power to the motor, such as cables for transmitting energy.

[0477] As mentioned above, the filtration system 400 further includes at least one controller 76 (see for example Fig. 32), which can be also referred to as a motor controller, configured to control functionality of the drive motor 72. In some implementations, the filtration system 400 also includes a speed sensor, such as an encoder (not shown) that may be attached to the drive motor's shaft. This can be implemented as an absolute encoder, configured to generate a signal commensurate with the angular speed of rotation and angular displacement of the motor's shaft 82. The controller 76 can receive signals from the absolute encoder, and can include software for interpreting sensed signals and readjusting the motor's functioning accordingly. [0478] The controller 76 can include a dedicated processor and/or other component of a control circuitry, including a wireless receiver or transmitter, which, for the same reasons described above of an electric drive motor, should be also watertight to prevent any damage to such components when immersed or otherwise contacted by water from the water source 20. Thus, the controller 76 should be also a watertight controller 76. This can be achieved, for example, by placing the controller 76 in its own watertight controller housing 78. Alternatively, when the drive motor 72 is placed within a watertight motor housing 74, the controller can be placed next to the motor 72, within the same housing 74, such that housing 74 it utilized to seal in a watertight manner both the drive motor 72 and the controller 76 at the same time.

[0479] In some implementations, the frame 30 can include legs 38 terminating below the rotatable filtering assembly 402, for supporting the frame 30 and the rotatable filtering assembly 402 over the water source bed 24, for example when placed in a shallow natural water source 20 or when lowered enough to completely immerse the rotatable filtering assembly 402 within the water source 20. Water source bed 24, as described above in conjunction with Fig. 12A for example, can include a variety of rocks, small stones, mud, algae and the like, which, absent of any protective means, can contact the coiled-thread units 432 and damage them, or clog the medium apertures 452, when the rotatable filtering assembly 402 is immersed deep enough to rest over the or in close proximity to the water source bed 24. Thus, in some implementations, the frame 30 further includes a bottom plate 40 (Fig. 31), which can be in the form of a horizontal plate positioned below the rotatable filtering assembly 402, but preferably somewhat above the lower ends of legs 38. The bottom plate 40 preferably extends over an area which is larger than the horizontal projection of the filtering sub-assemblies 420, to protect them entirely from their bottom side.

[0480] In some implementations, the filtration system 400 comprises a backwash self-cleaning mechanism, which includes flushing a cleaning fluid (e.g., cleaning water) in the opposite direction to that of the flow during the filtering mode, in order to remove accumulated filtride from the filter medium 444.

[0481] Coiled thread-type filters, including such that implement backwash self-cleaning mechanisms, are conventionally known to be adapted for inland utilization, wherein coiled- thread units are placed within a pressure vessel that is sealed from the surrounding environment, except for a dedicate inlet for unfiltered liquid entering the enclosed housing that defined the pressure vessel. This liquid flows through an intermediary passageway defined between the walls of the vessel's housing and the coiled-thread units, toward and through the layers of coiled threads, into the internal spaces defined within these units, and toward a dedicated outlet of the resulting filtrate. Such vessels can further include dedicated inlets and outlets for backwash. In contrast, the coiled thread-type filtration system 400 disclosed herein includes filtering sub-assemblies 420 which are devoid of such a pressure vessels. Specifically, the coiled threads 444 of the coiled-thread units 432 are configured to be directly exposed to the environment such that raw water 10 of the environment is in direct contact with the coiled threads outer surface 446, without passing through an intermediary passageway. Thus, the disclosed coiled thread-type filtration system 400 implements utilization of filter mediums in the form of coiled threads 445 wound around support blanks 434, with optional backwash-type self-cleaning mechanisms, in an unconventional manner which is devoid of pressure vessels enclosed around the coiled-thread units 432.

[0482] In some examples, the filtration system 400 includes a backwash mechanism that includes at least one flush tube 490, optionally at least one flush tube flange 494, and optionally at least one flush tube valve actuator 492, as illustrated in Fig. 33. Each flush tube 490 is branched from, or continuously extends from, and is in fluid communication with, the cleaning feed line 94. Each flush tube 490 is generally aligned with a sub-assembly axis Ys of a corresponding filtering sub-assembly 420. Each sealing flange 494 is disposed over a respective flush tube 490, aligned with a corresponding offset opening 410, movable between a closed position and an open position.

[0483] In the closed position, the sealing flange 494 pressed against the offset opening 410 in a manner that seals the offset opening 410, and therefore the hub lumen 430 of the filtering sub-assembly 420, from the intake chamber 470, allowing for fluid communication of the hub lumen 430 and corresponding internal spaces 450, only with the flush tube 490. In the open position, the sealing flange 494 is spaced away from the offset opening 410, exposing it (along with hub outlet end 424) to the intake chamber 470.

[0484] Each flush tube valve actuator 492 can be operable to move the corresponding sealing flange 494 toward or away from the corresponding offset opening 410, to transition between the closed and open positions.

[0485] In order to transition a filtering sub-assembly 420 from a filtering mode to a cleaning mode, and apply backwash procedure thereto, the flush tube valve actuator 492 can be actuated to advance the sealing flange 494 toward the offset opening, to the closed position, at which point washing fluid such as water (or any other liquid or gas), supplied by the cleaning feed line 94, flows from the flush tube 490 into the hub lumen 430 and corresponding internal spaces 450. The washing fluid is introduced at a relatively high pressure, flowing in a "reverse" direction from the internal spaces 450 toward the coiled threads inner surface 446, substantially displacing any particles trapped within the medium apertures 452. Once backwash is no longer required, cleaning fluid flow terminates and the flush tube valve actuator 492 can be actuated to retract the sealing flange 494 away from the offset opening, to the open position.

[0486] In the examples illustrated in Fig. 33, two flush tubes 490 are shown to be branched from the cleaning feed line 94, such that two filtering sub-assemblies 420, shown as subassemblies 420b and 420d, may transition to a cleaning mode. However, it is to be understood that this is merely shown by way of illustration and not limitation, and that a single flush tube 490 (with a single valve actuator 492 and sealing flange 494) can be similarly implemented, as well as more than two flush tubes 490, for example to enable more than two filtering subassemblies 420 to be simultaneously backwashed.

[0487] Four filtering sub-assemblies 420 are shown in the illustrated example, with filtering sub-assemblies 420a and 420c positioned against corresponding offset openings 410 which are fully exposed to the intake chamber 470, meaning that both of these filtering sub-assemblies 420 can be in a filtering mode in this position. Two filtering sub-assemblies 420d and 420b are aligned with flush tubes 490a and 490b. As long as the sealing flanges 494 are in the open position, these two sub-assemblies can also be in a filtering mode. However, when the sealing flanges 494 transition to the closed position, filtering sub-assemblies 420d and 420b are in a cleaning mode.

[0488] When cleaning of filtering sub-assemblies 420d and 420b is no longer required, the sealing flanges 494 can transition back to the open position. The rotatable support wall 406 can then rotate, by the drive motor 72 and transmission assemble 80, around main axis Ym, such that filtering sub-assemblies 420a and 420c, for example, can be positioned in front of the flush tubes 490a and 490b, at which point rotation is terminated, and the sealing flanges 494 can transition to the sealed mode, allowing these two filtering sub-assemblies 420 to be cleaned in a similar manner. [0489] This procedure can be repeated as required, advantageously allowing the filtering procedure to be continuous such that at least some of the filtering sub-assemblies 420 (one or more) remain in a filtering mode, while others (one or more) are in a cleaning mode.

[0490] In some examples, one or more controllers 76 are utilized to control the tube valve actuators, such as controllers 76a and 76b that can be used for controlling the transition between the closed and open positions of the sealing flanges 494a and 494b, and a separate controller 76c can be used for controlling motor 72 as described above. Each controller 76a, 76b, 76c can be a watertight controller. In such implementations, all of the separate controllers are referred to as a controller 76 of the filtration system (e.g., systems 200, 300, 400 and/or 500), which can include separate control sub-units, such as control sub-units 76a and 76b for controlling the sealing flanges 394a and 394b, and control sub-unit 76c for controlling the drive motor. In other examples, instead of providing separate controllers, a single controller (for example, the controller or control sub-unit designated 76c) can be used to control both the drive motor 72 and any of the flush tube valve actuators 492.

[0491] In the illustrated examples, while the filtering sub-assemblies 420d and 420b are in the cleaning mode, their medium apertures 452 are non-filtration apertures 456, and as long as all other two filtering sub-assemblies 420a and 420c, are fully immersed and are in a filtering mode, all of their medium apertures 452 are filtration apertures 454, the total sum of their aperture open areas Aa constituting the effective area of filtration Ae. When the filtering subassemblies 420d and 420b are aligned with flush tubes 490, but the sealing flanges 494 are in the open position and both filtering sub-assemblies 420d and 420b are in a filtering mode, their medium apertures 452 are also filtration apertures 454, such that in such situations, the effective area of filtration Ae can be equal to the total area of medium apertures At.

[0492] Rotational movement of the rotatable filtering assembly 402 can be periodical, such that it rotates only when repositioning of other filtering sub-assemblies 420 is required, as described above. In alternative implementations, rotational movement of the rotatable filtering assembly 402 can be continuous, wherein the angular speed of rotation W is slow enough to allow adequate backflow self-cleaning of each of the filtering sub-assemblies 420 as it passes along a corresponding flush tube 490.

[0493] In the illustrated configuration, the flush tubes 490 are preferably positioned to align with the left-most and right-most filtering sub-assemblies 420. These positions are advantageous in that the sub-assemblies, such as filtering sub-assemblies 420d and 420b shown in the illustrated example, are not positioned above any portion of any other filtering subassembly, such that when they are backwashed, any filtride disposed and washed away therefrom, will tend to sink downward without interacting with any of the other filtering subassemblies 420. If, alternatively, flush tubes 490 would have been positioned elsewhere, such as the position of filtering sub-assembly 420a in the illustrated example, particles dislodged from this filtering sub-assembly could sink downward and land on portions of medium outer surfaces 446 of other filtering sub-assemblies 420.

[0494] While four filtering sub-assemblies 420 are illustrated throughout Figs. 31-33, it is to be understood that a rotatable filtering assembly 402 can include any other number of filtering sub-assemblies 420, such as more or less than four filtering sub-assemblies 420, and in some implementations, even a single filtering sub-assembly 420.

[0495] In some implementations, filtration system 400 also includes a spray assembly 480 (not illustrated separately), configured to spray liquid or gas toward a portion of filter medium 444 to dislodge filtride that may be clung thereto. Spray assembly 380 can be implemented similar to any example described above for spray assembly 380 of filtration system 300 with respect to Fig. 27, including a spray conduit 482 with one or more nozzles 484 attached thereto (not illustrated separately for filtration system 400, but similar to spray conduit 382 and nozzle 384 illustrated in Fig. 27), optionally directed toward a target region of the filter medium 444. The spray conduit 482 can be attached to, or otherwise fluidly connected to, a cleaning feed line 94 which can provide cleaning liquid or gas, including cleaning water, through the spray conduit 482, toward one or more nozzles 484.

[0496] One example of a spray assembly 480 can include a spray conduit 482 extending into the rotatable filtering assembly 402, with a plurality of nozzles 484 facing coiled threads outer surfaces 446 of any one of the filtering sub-assemblies 420 aligned against it, the nozzles 484 configured to spray water toward the filter medium 444 from the outside. The cleaning feed line 94 can extend from outside of the frame 30 into the intake pipe 460, and at a specific point, it may define a spray conduit 482 by continuously extending radially outward out of the intake pipe 460 (for example, through a corresponding sealed opening formed at the wall of the intake pipe 460), and then assume a longitudinal orientation (e.g., parallel to main axis Ym) with a plurality of nozzles 484 (only one is illustrated for simplicity) directed toward the filter medium 444, and more particularly, toward coiled threads outer surfaces 446. [0497] Filtration system 400 can be partially immersed, such that the nozzles 484 are positioned above the water level 22, designed to spray against a filtering sub-assembly 420 which is also positioned above the water level 22. Alternatively, filtration system 400 can be fully immersed, with the nozzles 484 positioned within the water source 20, designed to spray high-pressure liquid jets, or alternatively, spray air or other suitable gas, while being immersed within the water source.

[0498] The spray assembly 480 can also be a non-rotatable, stationary assembly, similar to the stationary nature of intake pipe 460, such that due to rotation of the support wall 406, the nozzles 484 spray water (or other liquid or gas) impinging against different filtering subassemblies 420. The rotatable filtering assembly 402 may rotate such that it aligns each time a different filtering sub-assembly 420 against the nozzles 484. Rotational movement of the rotatable support wall 406 can be periodical or continuous. For example, periodical rotational movement can be employed when it is desired to align a specific filtering sub-assembly 420 against the nozzles 484, at which point rotation is halted to allow the jets sprayed from the nozzles 484 to clean the corresponding filter medium 444. Alternatively, rotation can be continuous, such that each filtering sub-assembly 420 may be cleaned by the jets sprayed from the nozzles 484 as it passes them during such continuous rotational movement.

[0499] When any filtering sub-assembly 420 is sprayed by nozzles 484, it is in a cleaning mode, meaning that no internal pressure is applied thereto to apply suction toward and into intake pipe 460. It is to be understood that backwash, as disclosed above, can be combined with a spray-assembly 480, such that any filtering sub-assembly 420 can be backwashed by pressurized fluid flowing into its hub lumen 430 and internal spaces 450, and be simultaneously sprays by nozzles 484 from the outside, thereby applying self-cleaning mechanisms directing cleaning fluid both from the medium inner surface 448 outward, and from the medium outer surface 446 inward.

[0500] If a spray assembly 480 is in a relatively upper position, above other filtering subassembly 420, it may pose a risk that filtride particles dislodged therefrom may find their way to the outer surfaces 446 of other filtering sub- assemblies 420, or otherwise fall back into the water of the water source 20 and contaminate the raw water in the immediate vicinity of the other filtering sub-assemblies 420. In some examples, a tray (not shown) may be added below the position of the nozzles 484 and/or the position at which a filtering sub-assembly 420 is being cleaned, so that any filtrate particles dislodged therefrom can fall into the tray, which can be periodically cleaned.

[0501] While designed to minimize filtride accumulation over or in the filter mediums 444, filtration system 400 may still include self-cleaning mechanisms, such as flush tubes 490 or spray assembly 480, which can be utilized as safety measures, or as additional measures that can be utilized in implementations in which the aperture size D is not greater than 350 microns (including being optionally not greater than 300 microns, not greater than 200 microns, not greater than 100 microns, not greater than 40 microns, not greater than 10 microns, not greater than 5 microns, and/or not greater than 1 micron), which can still require certain self-cleaning measured to be employed for such fine filter densities.

[0502] In some implementations, the cleaning feed line 94 can extend from a source of water or compressed air onshore. In other implementations, the cleaning feed line 94 can be adapted to pump water from the surrounding water source 20 and into the spray conduit 482 and nozzles 484, and/or into the flush tubes 490.

[0503] In some implementations, the same water (or other liquid) can be used for the spray assembly 480 and/or the flush tubes 490, and for operating a water motor 72. In such implementations, a unified feed line, or a feed line manifold, can be branched into a one or more motor lines 92 and a cleaning feed line 94, optionally with appropriate controllable valves for controlling adequate flow through each as necessary.

[0504] In some implementations, the frame 30 can include one or more wall windows 42 that can be closed or opened by one or more corresponding window covers 44 (see Fig. 31 for example). For example, the frame 30 can includes two wall windows 42 formed in each frame transverse wall 32, wherein the windows 42 of each frame transverse wall 32 are aligned with each other, and are formed along portion of the frame transverse walls 32 that are at least partially facing a portion of the filter mediums 444 of one or more filtering sub-assemblies 420. The wall windows 42 can be covered, in some examples, by window covers 44 that can transition between closed and open positions.

[0505] The wall windows 42 and window covers 44 may serve as an additional or alternative self-cleaning mechanism, that can be used, for example, with a partially immersible rotatable filtering assembly 402. The wall windows 42 are designed to be at a height of the water level 22 when the rotatable filtering assembly 402 is partially immersed. When placed in a natural water source 20 that includes moving water, such as sea waves or running water of a river, opening the window covers 44 will expose the windows 42 to such waves or moving river water, which will flow therethrough from side to side, along the filter mediums 444 of filtering sub-assemblies 420 aligned therewith, dislodging any accumulated filtride and cleaning the filter mediums along with the flow.

[0506] The windows covers 44 can be hinged to pivot about their hinged connection between the closed and open states as in the illustrated example, though any other mechanism for moving such covers between open and closed position, as known in the art, is contemplated. Moving the window covers 44 between closed and open positions can be performed either manually, or by implementation of electrically controlled (including remote-controlled) mechanisms. The window covers 44 may be opened to expose the wall windows 42 to a surrounding water flow during a cleaning mode of the filtering sub-assemblies 420 aligned therewith, and may be closed to prevent such flow from interfering during filtering mode.

[0507] While described for use with a partially immersible rotatable filtering assembly 402, it is to be understood that wall windows 42 with window covers 44 can be also utilized as a cleaning mechanism for a fully immersible rotatable filtering assembly 402. For example, a rotatable filtering assembly 402 can be fully immersed during a filtering mode, while the window covers 44 are in the closed position. When at least some of the filtering sub-assemblies 420, aligned with windows 42, transition to the cleaning mode, the rotatable filtering assemblies 402 can be raised upward to be partially immersible, for example placing the wall windows 42 at the height of the water level 22, at which point the window covers 44 may be opened. When cleaning is no longer required, the window covers 44 can be closed again, and the rotatable filtering assembly 402 can be lowered downward back to the fully immersible position, as the same filtering sub-assemblies 420 transition back to the filtering mode. Furthermore, wall windows 42 can be exposed to the surrounding water and utilized in a cleaning mode also when the rotatable filtering assembly 402 is fully immersed, taking advantage of water streams occurring not only at the water level 22, but also below water level 22.

[0508] Wall windows 42 can be provided in various shapes and sizes, such as a trapezoid shape shown in Fig. 31, an hourglass shape similar to that shown in Figs. 39A-C, or any other suitable shape. In some examples, particularly for wall windows 42 provided with irregular shapes such as the hourglass-shape in Figs. 39A-C, the frame 30 can be devoid of window covers, leaving the wall windows 42 exposed to the surrounding environment at all times.

[0509] In some examples, frame 30 further comprises funneling extensions 48, each funneling extension 48 circumscribing a corresponding wall window 42, thus generally shaped in the same shape defined by the borders of the wall window 42, and extending from the frame transverse wall 32 in a direction opposite to the filter medium 444. Each funneling extension 48 can include a tapering inner surface 49 that forms a funnel-like guide for streaming the water toward the opening of wall window 42. When placed in a water source 20 with moving water, such as sea waves or streaming river, the funneling extensions 48 can serve to funnel the streaming water toward and through the wall windows 42, wherein the tapering inner surfaces can increase the flow speed of the streaming water toward filter medium 444, thus improving the surrounding water's capability of effectively washing away filtride that may have accumulated over filter medium 444. While not illustrated as such, it is to be understood that in some examples, wall windows 42 of any size and shape can be provided with any combination of window covers 44 and/or funneling extensions 48.

[0510] In some implementations, the filtration system 400 also includes at least one float 50 attached to the frame 30, such as the couple of floats 50 shown in Fig. 31 to extend through float opening 36 formed in both frame transverse walls 32. Floats 50 can be utilized to keep the rotatable filtering assembly 402 fully or partially submersible at a desired height relative to the water level 22. While two floats 50^a, 50^b are illustrated in Fig. 31, it is to be understood that any other number, such as a single float or more than two, are contemplated, and that the plural use of the term "floats 50" is not limiting, and may similarly refer to a single float.

[0511] In some implementations, the floats are adjustable floats 50, meaning that the weight of the floats 50 can be adjusted to control their buoyancy. In some implementations, the adjustable floats 50 may be provided in the form of ballast tanks, with at least one port for controlling the level of ballast water. In some implementations, each adjustable float comprises a float water port or liquid port 52 through which water (or other suitable liquid), such as ballast water, can be poured to fill the internal volume of the float 50, thereby increasing its weight, and an air port or gas port 54, through which air (or other suitable gas) may flow into the float 50 while water may exit through the water port 52. [0512] Adjustable floats 50 can be utilized, by increasing and decreasing the weight of the floats 50, to control the buoyancy of the rotatable filtering assembly 402 and its height, relative to the water level 22. Such implementations can be used in combination with cleaning mechanisms that rely on opening and closing window covers 44 of wall windows 42 and/or funneling water through wall windows 42 provided with funneling extensions 48 as described above, for example by being filled with water (or other suitable liquid) to increase their weight and allow the rotatable filtering assembly 402 to be fully submerged during the filtration phase, and filling air (or other suitable gas) to raise the rotatable filtering assembly 402 and the wall windows 42 to the water source level 22 during the cleaning mode.

[0513] In some examples, floats 50 can be positioned such that, when inflated, their bottom edges are below the level of the upper edges of the top-side filtering sub-assemblies 420, such that if these floats 50 are retained at the water level 22 of the water source 20 when inflated, at least some portions of at least some filtering sub-assemblies 420 are not immersed in the water source 20, but are rather exposed to the atmosphere.

[0514] In some examples, as shown in Fig. 31, the floats 50 are positioned above all filtering sub-assemblies 420, such that the upper edges of any of the filtering sub-assemblies 420 are below the lower edges of any of the floats 50. In such implementations, when the floats are inflated and retained at the water level 22 of the water source 20, all of the filtering subassemblies 420 can remain fully immersed, below the water level 22.

[0515] In some examples, filtration system 400 comprises one or more movable floats (50), that can be either adjustable or non-adjustable floats, configured to raise or lower the rotatable filtering assembly 402 relative to water level 22. The movable floats (50) can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 44A-45B. The same examples of movable floats (50) can be adapted for use with filtration system 400, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0516] In some implementations, the filtration system 400 can include an anchoring structure 120 attached to the frame 30, which can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 9A-9B. The same examples of anchoring structure 120 can be adapted for use with filtration system 400, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0517] In some implementations, filtration system 400 comprises an elevation assembly 130 to which at least one frame 30 and rotatable filtering assembly 402 are movably mounted, wherein the elevation assembly 130 is configured to control the height of the rotatable filtering assembly 402, for example relative to water level 22. The elevation assembly 130 can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 10-12B. The same examples of elevation assembly 130 can be adapted for use with filtration system 400, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0518] In some implementations, filtration system 400 comprises an offshore platform connection assembly 154 for coupling the frame 30 to an offshore platform 150 according to any of the examples described above in combination with filtration system 200 with respect to Fig. 13. The same examples of offshore platform connection assembly 154 can be adapted for use with filtration system 400, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0519] Another self-cleaning mechanism that can be implemented for filtration system 400 relies on changing the height of the rotatable filtering assembly 402 relative to the water level 22, at a speed high enough during which the impact of a filter mediums 444 of at least one of the filtering sub-assemblies 420 against the surface of the water at the water level 22 will dislodge filtride from the respective filter mediums 444. For example, the rotatable filtering assembly 402 can be positioned such that filter medium 444 of at least one filtering subassembly 420, and in some implementations, the filter mediums 444 of all filtering subassemblies 420, are above the water level 22. Then, lowering the rotatable filtering assembly 402 into the water at a high-enough speed, will cause the filter medium 444 to impact the water surface at the water level 22 at a force which is sufficient to dislodge filtride therefrom.

[0520] Any of the above-mentioned height-control mechanisms, including movable and/or adjustable floats 50, elevation assembly 130, and/or offshore platform connection assembly 154, can be utilized to elevate and lower the height of the rotatable filtering assembly 402 to forcibly impact filter mediums 444 of at least one of the filtering sub-assemblies 420 against the surface of the water at the water level 22. In some implementations, alteration of the height of the rotatable filtering assembly 402 to impact filter mediums 444 against the surface of the water at the water level 22 is performed during a cleaning mode of the filtering sub-assemblies 420 to be impacted. In some implementations, more than one cycle of raising and lowering the rotatable filtering assembly 402 can be sequentially performed, wherein each subsequent cycle can serve to further dislodge filtride that remained stuck against the corresponding filter mediums 444. In some implementations, rotatable support wall 406 can be rotated so as to position, each time, different filtering sub-assemblies 420 (one or more) above the water level 22, to be impacted.

[0521] Another self-cleaning mechanism that can be implemented for filtration system 400 relies on accelerating the angular speed of rotation of rotatable filtering assembly 402 while being partially submerged in the water source 20. While filtration is performed at a very low angular speed of rotation W during filtering mode, to minimize accumulation of particles over filter mediums 444, the rotatable filtering assembly 402 can be accelerated for a limited time period to a significantly higher angular speed of rotation, such as an angular speed higher than 60 degrees per second (i.e., more than 10 revolutions per minute), causing filter mediums 444 (of at least one filtering sub-assembly 420) that hit against the water at the water level 22, to hit at an impact force high enough so as to dislodge filtride therefrom. All filtering subassemblies 420, including those that may be still immersed prior to angular speed acceleration, are preferably switched to the cleaning mode (i.e., terminating suction into intake pipe 460 from all) prior to angular speed acceleration, as even filtration sub-assemblies that do not necessarily hit against water level 22, will still experience the elevated angular speed of rotation that can disturb the water in their vicinity. In some implementations, the direction of rotation can be also altered between subsequent cycles.

[0522] The controller 76 (e.g., motor control sub-unit 76c) can be configured to transition the drive motor's 72 angular speed of rotation between low speeds during a filtering mode, and high speeds during a cleaning mode, as well as optional alteration of the direction of rotation during the cleaning mode. The controller 76 can be configured to control the acceleration and deceleration rates during the transition between higher and lower angular speeds of rotation.

[0523] In some implementations, the filtration system 400 can further include an additional vibration motor 73, that can be coupled to the rotatable filtering assembly 402 and configured to vibrate, and more specifically, apply vibrational movement to the filter medium 444, which will serve to dislodge filtride accumulated thereon. The vibration motor 73 is a watertight motor, and can be optionally sealed by being encompassed by a watertight housing, similar to housing 74. A filtration system 400 can be equipped with both a watertight drive motor 72 and a watertight vibration motor 73, similar to the example described above for filtration system 200 with respect to Fig. 17A, wherein both motors can be attached to the same component of a frame 30, such as both being coupled to frame transverse wall 32a as illustrated, or to different components of the frame 30 or other components of the filtration system 400. Operation of the vibration motor 73 can be controlled by a separate controller, or the same controller 76 of the drive motor 72.

[0524] The controller 76 can be adapted to control the operation of the drive motor 72 and the vibration motor 73, such that the drive motor 72 is activated to rotate the rotatable filtering assembly 402 during the filtering mode (either periodically or continuously), while the vibration motor 73 is inactive, and the vibration motor 73 is activated, while the drive motor 72 is non-active, during a cleaning mode. The vibration motor 73 can be implemented, in some examples, as an eccentric rotating mass vibration motor. In some implementations, the same motor 72 can be used to apply both rotational movement for rotating filtering assembly 402, and vibrational movement to facilitate vibration of the filter mediums 444. The controller 76 can control the operation of such a multi-purpose motor 72, to transition between rotational movement during the filtering mode and vibrational movement during the cleaning mode.

[0525] In some examples, filtration system 400 can include one or more ultrasonic transducer(s) 96, positioned to apply ultrasonic energy directed at the filter medium 444, similar to the manner described above for filtration system 200 with respect to Fig. 17A. The ultrasonic transducer(s) 96 can apply ultrasonic energy that can disintegrate and/or create ultrasonic waves that will impact against the filter medium 444 in a manner that will dislodge filtride therefrom. Advantageously, the desire ultrasonic waves, directed at the filter medium, do not require high energy, enabling utilization of the ultrasonic transducer as low-energy longterm self-cleaning mechanism.

[0526] In some examples, the intake pipe 460 further comprises an expansion chamber 464 (not illustrated separately for filtration system 400), similar to the manner described above for filtration system 200 with respect to Fig. 16. An expansion chamber 464 is disposed upstream from the rotatable filtering assembly 402, and is formed as a portion of the intake pipe which expands to an expansion chamber diameter De which is at least twice as great as the minimal pipe diameter Dp, and in some example, at least three times as great as the minimal pipe diameter Dp. The minimal pipe diameter Dp is the diameter of intake pipe 460 at its minimal intake pipe cross-sectional area Ap, which can be measured at a portion of the intake pipe 460 extending into the rotatable filtering assembly 402, or at least extending through or disposed at the level of, a rotatable support wall 406.

[0527] The expansion chamber 464 can be either integrally formed with the remainder of intake pipe 460, or provided as a separate component attached in a sealed manner to the remainder of intake pipe 460. The expansion chamber 464 can include a gradually tapering inflow portion, expanding gradually radially outward from minimal pipe diameter Dp to expansion chamber De, a main expanded portion having a uniform diameter De along a length Lc, and a gradually tapering outflow portion, narrowing gradually radially inward from expansion chamber diameter De back to minimal pipe diameter Dp, after which the pipe may further extend along a certain length and terminate with pipe outflow opening 466. In some examples, the length of expanded main portion Lc is at least twice as great as the expansion chamber diameter De.

[0528] In some examples, a filtration system 400 can be oriented in a vertical orientation, such that its main axis Ym is substantially orthogonal to a plane of the water level 22. In examples of filtration systems that include one or more floats 50, including any of the movable and/or adjustable floats disclosed herein, the orientation of the float(s) 50 is adjusted to allow for vertical orientation of the rotatable filtering assembly 402. In some examples, the float(s) 50 extends along a plane which is substantially orthogonal to the main axis Ym. For example, float(s) 50 illustrated in Fig. 31 extend longitudinally along an axis which is substantially parallel to the main axis Ym, which will result in a horizontal orientation of the rotatable filtering assembly 202. In contrast, a float 50 can be implemented in a similar manner to that described above for filtration system 200 with respect to Fig. 16, defining a plane which is substantially orthogonal to main axis Ym, resulting in a vertical orientation of the rotatable filtering assembly 402.

[0529] In some examples, the intake pipe 460 extend from the rotatable filtering assembly 402 downward, toward water source bed 24, such that the pipe outflow opening 466 is positioned lower than the rotatable filtering assembly 402.

[0530] In some examples, the filtration system 400 is equipped with a weight 160 opposite to float 50. Any of the float 50 and/or weight(s) 160 can be coupled to the frame 30 and/or to the filtering assembly 402, preferably on opposite sides, via one or more coupling means such as cables, chains, and the like, in a manner similar to that described above for filtration system 200 with respect to Fig. 17A. The combination of float(s) 50, and in some examples, movable and/or adjustable float(s) 50, with weight(s) 160, can serve to control the height of rotatable filtering assembly 402 within the water source 20 (i.e., relative to water level 22), for example by adjusting the degree of floatation of float(s) 50, while weight(s) 160 pull the rotatable filtering assembly 402 gravitationally downward. Moreover, the combination of float(s) 50 from above, and weight(s) 160 from below the rotatable filtering assembly 402, can together stabilize the rotatable filtering assembly 402 in a vertical orientation, substantially orthogonal to the plane defined by water level 22.

[0531] In some implementations, the threads 445 forming filter medium 444 comprise copper, for example by being completely made of copper or coated by a copper layer. Embedding copper into the threads 445, or forming them from copper, can significantly reduce the likelihood of algae and other microorganisms from clinging to the filter medium 444 and clogging medium apertures 452 when immersed in a natural water source 20.

[0532] As mentioned, minimal ratio Ra and/or maximal flow velocity across the filtration apertures Ve depend on the effective area of filtration Ae, such that for a given maximal flow rate Qm, a minimal effective area of filtration Ae is required to result in the minimal desired Ra and/or maximal desire Ve. Furthermore, as also mentioned above, the filtration apertures 454, which in some cases can constitute only a subset of the medium apertures 452 of some of the filtering sub-assemblies 420, contribute to the effective area of filtration Ae. A filtration system 400 configured to have at least one of its filtering sub-assemblies 420 in a filtering mode, while at least one other filtering sub-assembly 420 is in a cleaning mode, can be designed such that the minimal number of filtering sub-assemblies 420 that continue to operate in a filtering mode at all times, including when one or more filtering sub-assemblies 420 are in a cleaning mode, provide a sufficient minimal effective area of filtration Ae.

[0533] In the example illustrated in Fig. 33, two flush tubes 490 are provided to allow backwash of two corresponding filtering sub-assemblies 420, such that even during this cleaning mode, at least two other filtering sub-assemblies 420 continue to operate in a filtering mode. Thus, while in some instances, all four filtering sub-assemblies 420 can operate in a filtering mode, the minimal number of filtration apertures 454 includes all medium apertures 452 of at least two filtering sub-assemblies 420. The minimal effective area of filtration Ae, based on the filtration apertures of two filtering sub-assemblies 420 in such an example, can be designed to result in the minimally desired Rq and/or Ra.

[0534] In examples of a partially immersible filtration system 400, the medium apertures 452 of any filtering sub-assemblies 420 that can be at any instant of time above the water level 22 are non-filtration apertures, such that only the minimal number of filtering sub-assemblies 420 which always remain submerged in the water source 20 at any given time, will contribute to the effective area of filtration Ae. In such cases, the filtration system 400 can include an immersion depth marking 46 that can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Fig. 7. The same examples of immersion depth markings 46 can be adapted for use with filtration system 400, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0535] In some examples, filtration system 400 can include at least one camera 56 configured to take images of at least a portion of filter medium(s) 444, optionally mounted on a camera mount 58 that can be an adjustable arm, wherein each of the camera 56 and/or mount 58 can be controlled by control sub-unit 76e. Any of the at least one camera 56 and camera mount 58, as well as control sub-unit 76e, can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 39A-C. The same examples of camera(s) 56, camera mount(s) 58, and/or controller sub-unit 76e, can be adapted for use with filtration system 400, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0536] In some examples, each filtering sub-assembly 420 is not only revolvable around the main axis Ym, but is also rotatable around its sub-assembly axis Ys. For example, filtration system 400 can include a planetary transmission mechanism, configured to allow simultaneous rotation of the rotatable support wall 406 around main axis Ym, as well as rotation of the filtering sub-assemblies 420 - each around its own sub-assembly axis Ys. Any implementation of a simultaneous revolvable and rotational movement of the filtering sub-assemblies, including a planetary gear that includes a driving gear 84 and driven gears 86 having first 86' and second 86" gear portions, and planetary gears 88, can be implemented according to any of the examples described above in combination with filtration system 300 with respect to Fig. 41. [0537] Each planetary gear 88 can be attached to another component of the corresponding filtering sub-assembly, such as the hollow hub 422. Thus, the same examples for implementation of simultaneous rotation of the rotatable support wall around main axis Ym, and the plurality of filtering sub-assemblies around their axes Ys, including any implementation of driven gears 86 and planetary gears 88, can be adapted for use with filtration system 400, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0538] In other examples, each filtering sub-assembly 420 is independently rotatable around its own sub-assembly axis Ys, irrespective of its resolvability around main axis Ym or rotatability of any other filtering sub-assemblies of the filtration system 400. Any of the sub assembly drive motors 180, sub assembly transmission 184, internal pressure sensor 182, external pressure sensors 183, as well as control sub-units 76s, can be implemented according to any of the examples described above in combination with filtration system 300 with respect to Figs. 42-43.

[0539] Each sub-assembly transmission 184 can include a sub-assembly driver gear 186 and a sub-assembly main gear 188, wherein the main gear 188 can be attached to a component of the filtering sub-assembly 420, such as the hollow hub 422. Internal pressure sensor 182 can be disposed within hub lumen 430 or internal space 450, configured to measure pressure within hub lumen 430 or internal space 450, for example by being attached to an inner surface of the hollow hub 422 or to an inner surface of any of its support blanks 434. Thus, the same examples for implementation of independent rotation of the rotatable support wall around main axis Ym, and any of the plurality of filtering sub-assemblies around their axes Ys, including any implementation of sub-assembly drive motors 180, sub-assembly transmissions 184, drive gears 186, main gears 188, internal pressure sensor 182, and external pressure sensors 183, can be adapted for use with filtration system 400, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0540] In some examples, filtration system 400 comprises a bubble generator (140) that includes a hollow enclosure 142 with bubble apertures 144 facing at least one filter medium 444 of at least one rotatable filtering sub-assembly 420, configured to generate bubble (28) that can float toward coiled threads of the corresponding one or more filter medium(s) 444 during a cleaning mode. The filtration system 400 can further comprise a guiding chamber (190) extending upward from the bubble generator (140). The bubble generator (140), with or without a guiding chamber (190), can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 47A-51. The same examples of bubble generator (140), with or without a guiding chamber (190), can be adapted for use with filtration system 400, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0541] Another possible implementation of a filtration system, referred to as sheaf-type filtration system 500, provided with a sheaf-type rotatable filtering assembly 502, will now be described in detail with reference to Figs. 34A-38 of the accompanying drawings. Fig. 34A shows a view in perspective an example of a sheaf-like unit 532. Fig. 34B shows a sectional view in perspective of the sheaf-like unit 532 of Fig. 34A. Fig. 35A shows a view in perspective of a sheaf-type filtering sub-assembly 520. Fig. 35B shows a sectional view of sheaf-type filtering sub-assembly 520 of Fig. 35A. Figs. 36 and 37 show views in perspective of one example of a sheaf-type filtration system 500. Fig. 38 shows a sectional view in perspective of an exemplary sheaf-type filtering sub-assembly 520. Figs. 34A-38 are described herein together.

[0542] A sheaf-type filtration system 500 comprises a sheaf-type rotatable filter assembly 502, that includes at least one, and preferably a plurality of, revolvable filtering sub-assemblies 520. Each filtering sub-assembly 520 includes a filter medium 544, implemented as longitudinally extending threads 545 arranged in a sheaf-like configuration within support blanks 534.

[0543] Figs. 34A-B show views of a sheaf-like unit 532, that includes threads 545 extending substantially in parallel to each other in a sheaf-like configuration within a support blank 534. An example of a support blank 534 can include a blank base 536 with a blank outlet 538, a blank inflow end 542 which is an open end opposite to the blank base 536, and a blank tubular housing 540 extending between the blank base 536 and blank inflow end 542, within which multiple threads 545 extend, such as in a sheaf-like configuration. The blank tubular housing 540 is shown with partial transparency to expose the threads 545 contained therein. The threads 545 are attached on one end to the sheaf base 535, and terminate on their opposite free ends at the blank inflow end 542. All threads 545 contained within each support blank 534 together form the filter medium 544, defining a medium outer surface 546 at their free ends, at the level of the blank inflow end 542. [0544] The term "threads 545" can relate to any kind of strings, yarns, fabric stripes, etc., and may be made of any suitable rigid or flexible material, such as metal, plastic, fabric and the like. The threads 545 are arranged tightly lengthwise between blank base 536 and blank inflow end 542, surrounded by blank tubular housing 540 in a manner that allows water flow along their lengths, at spacings formed between adjacent threads 545. The blank tubular housing 540 can have a uniform cross-sectional area along its length, or can be tapering from the blank base 536 to the blank inflow end 542. The lateral spacing between adjacent threads 445 is defined as the medium aperture 552, further defining the aperture size D. The aperture open area Aa is defined as the cross-sectional area of a medium aperture 552 at the medium outer surface 546 (i.e., at the surface defined by the free ends of the threads 545).

[0545] During a filtering mode, raw water flow from blank inflow end 542, lengthwise along the spacings between the threads 545 (i.e., through medium apertures 552 of filter medium 544), toward blank outlet 538. The spacings between adjacent threads are adapted to trap particles contaminating the water during flow there-through, as well as restrict entry of relatively larger particles (i.e., larger than aperture open area Aa) into these spacings to begin with.

[0546] Figs. 35A-B show an example of a sheaf-type filtering sub assembly 520, which includes a plurality of sheaf-like units 532 mounted on a hollow hub 522. Hollow hub 522 can be a tubular structure that includes an open ended hub outlet end 524, and an opposite hub closed end 526, and defining a hub lumen 530, with a plurality of hub openings 528 disposed around its circumference, corresponding to in number to the number of sheaf-like units 532 of the filtering sub assembly 520. Each blank outlet 538 is coupled in a sealed manner to a corresponding hub opening 528, so as to maintain fluid communication between filter medium 544 of the corresponding sheaf-like unit 532 and the hub lumen 530.

[0547] In the illustrated example, a ring-like arrangement is shown with several sheaf-like units 532 disposed around the circumference of the hollow hub 522 at each specific distance from the hub outlet end 524, in a manner that forms a ring-like arrangement at this specific position, with a plurality of ring-like arrangements disposed along the length of the hollow hub 522. It is to be understood that other arrangements may be provided for the sheaf-like units 532 along a hollow hub 522. [0548] As shown throughout Figs. 36-38, a sheaf-type filtration system 500 includes a sheaftype rotatable filtering assembly 502, at least one watertight drive motor 72 and at least one controller 76. The sheaf-type rotatable filtering assembly 502 defines a main axis Ym (indicated for example in Fig. 38) around which it is configured to rotate by the corresponding watertight drive motor 72. Sheaf-type rotatable filtering assembly 502 further comprises at least one rotatable support wall 506, and at least one, and preferably a plurality of, sheaf-type revolvable filtering sub-assemblies 520, attached to the at least one rotatable support wall 506. Each revolvable sub-assembly 520 defines a sub-assembly axis Ys which is parallel to, and offset from, main axis Ym (see, for example, Fig. 38). For simplicity, any reference to a component of filtration system 500 (such as filtering sub-assembly 520, rotatable support wall 506, controller 76, and so on) in a single form throughout the current specification, will similarly refer to "one or more" of said components for implementations that include a plurality of said components, unless otherwise stated.

[0549] The terms "sheaf-type filtration system 500" and "filtration system 500" are interchangeable, the terms "sheaf-type rotatable filtering assembly 502" and "filtering assembly 502" are interchangeable, and the terms "sheaf-type filtering sub-assembly 520" and "filtering sub-assembly 520" are also interchangeable, for system, assembly, and sub-assembly numerals 500, 502 and 520 throughout the specification, and particularly with respect to Figs. 35A-33, unless otherwise stated.

[0550] For a filtration system 500 that includes a sheaf-type rotatable filtering assembly 502 equipped with sheaf-type filtering sub-assemblies 520, the terms "filter medium 544" and "elongated threads 544" are interchangeable, and refer to a filter medium which is implemented as a multitude of threads 545 arranged lengthwise, side by side, within support blanks 534.

[0551] In the illustrated examples, the filtration system 500 comprises a single rotatable support wall 506 extending along a plane substantially orthogonal to the main axis Ym. However, this is not meant to be limiting, and in alternative examples, two rotatable support walls can be provided, wherein each filtering sub-assemblies can be optionally disposed between both walls.

[0552] The filtration system 500 is further shown to comprises an intake pipe 560, which is coupled to the rotatable filtering assembly 502 and optionally extends therethrough, such as through a central sealed opening 508. The intake pipe 560 includes at least one pipe inflow opening 562 which is in fluid communication with the medium apertures 552.

[0553] In some examples, the filtration system 500 further comprises a sealed intake chamber 570, which is sealed from the outer environment (e.g., raw water of the water sources 20), and is in fluid communication with the intake pipe 560 (for example, via pipe inflow opening 562) and with at least some of the filtering sub-assemblies 520.

[0554] The intake chamber 570 can be defined between the rotatable support wall 506 and a stationary wall portion 572 that includes a stationary transverse wall 574, such that the rotatable support wall is rotatable around main axis Ym, while stationary wall portion 572 is a non- rotatable component of the filtration system 500. In some examples, the filtration system can further include a circumferential wall portion 576 defining the external perimeter of the intake chamber 570. In some examples, as in the illustrated examples, the circumferential wall portion 576 is affixed or integrally formed with the stationary transverse wall 574, such that the circumferential wall portion 576 and the stationary transverse wall 574 together define the stationary wall portion 572. The rotatable support wall 506 can then be movably coupled, in a sealed manner, to the edges of the circumferential wall portion 576. In other examples, the circumferential wall portion can be affixed to or integrally formed with the rotatable support wall, configured to rotate therewith while stationary transverse wall 574 remains immovable. In such examples, the circumferential wall portion 576 can be movably coupled, in a sealed manner, to the edges of the stationary transverse wall 574.

[0555] In some examples, the intake pipe 560 extends into the intake chamber 570. In some examples, the one or more pipe inflow openings 562 are disposed within the intake chamber 570. In some examples, the pipe inflow openings 562 are disposed around the circumference of the portion of the intake pipe 560 which is disposed in the intake chamber 570, and are offset from the main axis Ym, facing the circumferential wall portion 576. While four pipe inflow openings 562 are illustrated in the example shown in Fig. 38, it is to be understood that any other number, such as a single pipe inflow opening, two, three, or more than four pipe inflow openings, is contemplated. Any reference to "pipe inflow openings 562" throughout this specification, unless otherwise stated, refers also to implementation of a single pipe inflow opening 562. [0556] The intake pipe 560 can be an independent component of a suction line 60, attached thereto and in fluid communication therewith, or can be formed as an integral part or extension of the suction line 60. Intake pipe 560 is coupled to rotatable support wall 506 in a manner that allows it to rotate around intake pipe 560, while intake pipe 560 remain stationary in position, that is to say that intake pipe 560 is a non-rotatable component of the filtration system 500. Intake pipe 560 can extend, for example along main axis Ym, away from the rotational support wall, and terminate with a pipe outflow opening 566 that can be coupled, for example by a pipe coupler 68, to a suction line inlet 62 as described above with respect to filtration systems 200.

[0557] In some examples, the stationary transverse wall 574 is affixed to the intake pipe 560. For example, the stationary transverse wall 574 can include a stationary wall sealed opening 578 that can be aligned with the central sealed opening 508 of the rotatable support wall 506, such that the intake pipe 560 can extend, in a sealed manner, through both openings 508 and 578.

[0558] In some examples, the filtration system 500 further comprises a frame 30. Both the rotatable filtering assembly 502 and the watertight drive motor 72 can be coupled to the frame 30, wherein the rotatable filtering assembly 502 is movably coupled to the frame 30 (i.e., can rotate around main axis Ym while being supported, directly or indirectly, by frame 30). In some implementations, as in the illustrated example, one or both of the frame transverse walls 32 include pipe through openings 34, which are coaxial with, and preferably similarly dimensioned to, the corresponding central sealed opening 508, allowing the intake pipe 560 to extends through the frame transverse walls 32 and the rotatable support wall 506. Thus, in the illustrated examples, the rotatable filtering assembly 502 is indirectly coupled to the frame 30 by intake pipe 560 coupled to, and extending both through, the rotatable support wall 506 and the frame transverse walls 32b.

[0559] While shown, for example in the illustration of Figs. 36-38, to extend through both the central sealed opening 508 of the rotatable support wall 506 and the sealed opening 578 of the stationary transverse wall 574, and optionally further on through a pipe through opening 34 of the corresponding frame transverse wall 32 (wall 32a in the illustrated example), other configurations are available for keeping fluid communication between the intake pipe 560 and the intake chamber 570. For example, the intake pipe 560 can terminate at any point within the intake chamber 570, without further extending through the stationary transverse wall 574, while at least one pipe inflow opening is still exposed to the intake chamber 570. The stationary transverse wall can be affixed to a different component of the filtration system other than the intake pipe, such as a frame transverse wall 32. In other examples, an end portion of the intake pipe 560 can terminate at the stationary transverse wall 574, affixed thereto, without necessarily further extending therethrough.

[0560] In yet other alternative examples, the intake pipe can include a single pipe inflow opening 562 coaxial with main axis Ym, defined by an open end of the intake pipe 560, which can either partially extend into the intake chamber 570, or alternatively terminate at the level of the rotatable support wall 506, having its edges attached to the edges of the central sealed opening 508 in a manner that retain fluid communication of the intake pipe 560 with the intake chamber 570 via central sealed opening 508.

[0561] The rotatable support wall 506 can include, in some examples, at least one offset opening 510, each offset opening 510 is coupled to a respective hub outlet end 526, aligned with a corresponding filtering sub-assembly 520 and its sub-assembly axis Ys, offset from main axis Ym. Each offset opening 510 is in fluid communication with the hub lumen 530 via hub outlet end 524, wherein the connection between hub outlet end 524 and offset opening 510 is sealed from the surrounding environment (e.g., sealed from the raw water of the water source 20), at least during a filtering mode of the respective filtering sub-assembly 520.

[0562] The intake pipe 560 and suction line 60 together define a fluid-communication line between the pipe inflow openings 562 and a suction line outlet 64 (same outlet 64 described hereinabove and shown, for example, in Fig. 1A) which can be placed onshore. This fluidcommunication line is intended to direct filtrate from the rotatable filtration assembly 502 to a target location, which can be onshore, for example by applying suction force at the pipe inflow openings 562. This may be accomplished by creating a negative pressure difference between the pipe inflow openings 562 and the suction line outlet. The negative pressure difference can be created by gravitational forces, or a pump (e.g., pump 66) in the same manner described above with respect to filtration systems 200. This pressure difference facilitates flow from the water source 20, through the filter medium 544, via blank outlets 538 and hub lumen 530, into the intake chamber 570, toward the pipe inflow openings 562 and into the intake pipe 560.

[0563] In some examples, the rotatable filtering assembly 502 is partially submerged, such that only some of the filtering sub-assemblies 520 are immersed in the water source 20. In such examples, any filtering sub-assembly 520 which is not immersed in the water source 20 cannot be in a filtering mode, such that all of its non-submerged medium apertures 552 are nonfiltration apertures 556. Any filtering sub-assembly 520 which is immersed within the water source 20, can optionally transition between filtering and cleaning modes, as will be elaborated below. In some examples, the rotatable filtering assembly 502 is fully submerged, such that all of the filtering sub-assemblies 520 are immersed in the water source 20. In such examples, similar to the partially immersed configurations, any filtering sub-assembly 520 can optionally transition between filtering and cleaning modes, as will be elaborated below.

[0564] As mentioned above, the blank outlet 538 of each sheaf-like unit 532 is in fluid communication with the hub lumen 530, which in turn is in fluid communication with a corresponding offset opening 510 at the region of attachment of the hub outlet end 524 to the rotatable support wall 506. During filtration mode, raw water which is in direct contact with the medium outer surface 546, flow through the filter medium 544 (lengthwise along threads 545) into blank outlet 538, becoming filtrate that flows therefrom, through hub lumen 530, via offset opening 510, into the intake chamber 570, and therefrom, through the pipe inflow openings 562, into intake pipe 560.

[0565] Similar to filtration system 200, the filtration system 500 comprises a watertight drive motor 72 configured to rotate the filtering assembly 502 around main axis Ym. As shown, the watertight drive motor 72 can be secured to the frame 30, such as to one of the frame transverse walls 32. When the intake pipe 560 extends through one or both frame transverse walls 32, the drive motor 72 can be offset from the main axis Ym, so as not to interfere with the intake pipe 560. Thus, since the axis of rotation of the watertight drive motor 72 is offset from the main axis Ym in such a case, the filtration system 500 can include a transmission assembly 80, configured to transmit the torque produced by the drive motor 72 to the corresponding rotatable support wall 406, thereby rotating the entire filtering assembly 502 there-along.

[0566] The transmission assembly 80 can include a gear train with one or more gears. For example, the transmission assembly 80 can be implemented is a manner similar to that described above for filtration system 300 with respect to Fig. 25, including a driving gear 84 attached to a shaft 82 driven directly by the watertight drive motor 72, and a driven gear 86 attached to the surface of the rotatable support wall 406 and meshed with the driving gear 84, wherein the size of the gears dictates the transmission ratio between the rotation speed of the motor and the resulting angular speed of rotation W of the filtering assembly 502, such that the transmission assembly 80 can also serve as a motor speed reduction mechanism. [0567] In some examples, at least a portion of the transmission assembly 80, such as gears 84, 86, and optionally shaft 82, is disposed within the intake chamber 570. In other examples, part or all of the transmission assembly 80 can be sealed from the filtrate flowing in the intake chamber 570, for example by the addition of a housing or other type of enclosure around components of the transmission assembly 80.

[0568] The rotatable support walls 506 can also include a plurality of rollers 70 rotatable around axes that are parallel to the main axis Ym, each configured to contact and roll over the outer surface of the intake pipe 560, for example at the portion extending out of the respective central sealed opening 508 away from the intake chamber 570 (though in other configurations, the rollers 70 can be also situation within the intake chamber). While the illustrated example shows three rollers 70 attached to the rotatable support wall 506, it is to be understood that any other number of rollers is contemplated.

[0569] The watertight drive motor 72 can be either an electric motor or a water motor. Utilization of a water motor as the watertight drive motor 72, requires adaptation of the filtration system 400 to include at least one motor line 92 (see for example Fig. 37) fluidly coupled to the motor 72, configured to provide water (or other suitable liquid) to operate the water motor 72. In some implementations, the motor line 92 can extend from a source of water onshore, all the way to the water motor 72 positioned offshore, coupled to the frame 30. This is an unconventional adaptation that can be implemented for utilization of an immersible water drive motor 72 for facilitating rotation of the filtering assembly 202, as most conventional water motors do not include feed lines extending over a length of several meters from a source that can be onshore, to a motor that can be placed offshore. In other implementations, the motor line 92 can be adapted to pump water from the surrounding water source 20 and into the water motor 72. In some examples, the at least one motor line 92 includes two lines, one motor inflow line 92a configured to direct feed water into the water motor 72, and the other motor outflow line 92b configured to direct water out of the water motor 72.

[0570] In contrast to water motors, a conventional electric motor that may be used for rotating onshore rotatable filtering assemblies, is not necessarily watertight as it is usually placed in a dry environment. Thus, when the drive motor 72 is an electric motor, it needs to be watertight to prevent any damage to its operation when immersed within, or otherwise being contacted by, water from the water source 20. An electric drive motor 72 can be, for example, a DC servo motor, a pneumatic actuator, a step motor, and the like. In some implementations, the electric drive motor 72 is a brushless DC (BLDC) motor. The electric drive motor 72 may further be a slotted or slotless BLDC motor. An electric drive motor 72 can become a watertight drive motor 72 by being encased within a watertight motor housing 74, which can be similarly attached to the frame 30, such as to a frame transverse wall 32, as in the illustrated example. When implemented as an electric motor, a motor line 92 can be utilized for transmitting power to the motor, such as cables for transmitting energy.

[0571] As mentioned above, the filtration system 500 further includes at least one controller 76 (see for example Fig. 37), which can be also referred to as a motor controller, configured to control functionality of the drive motor 72. In some implementations, the filtration system 500 also includes a speed sensor, such as an encoder (not shown) that may be attached to the drive motor's shaft. This can be implemented as an absolute encoder, configured to generate a signal commensurate with the angular speed of rotation and angular displacement of the motor's shaft 82. The controller 76 can receive signals from the absolute encoder, and can include software for interpreting sensed signals and readjusting the motor's functioning accordingly.

[0572] The controller 76 can include a dedicated processor and/or other component of a control circuitry, including a wireless receiver or transmitter, which, for the same reasons described above of an electric drive motor, should be also watertight to prevent any damage to such components when immersed or otherwise contacted by water from the water source 20. Thus, the controller 76 should be also a watertight controller 76. This can be achieved, for example, by placing the controller 76 in its own watertight controller housing 78. Alternatively, when the drive motor 72 is placed within a watertight motor housing 74, the controller can be placed next to the motor 72, within the same housing 74, such that housing 74 it utilized to seal in a watertight manner both the drive motor 72 and the controller 76 at the same time.

[0573] In some implementations, the frame 30 can include legs 38 terminating below the rotatable filtering assembly 502, for supporting the frame 30 and the rotatable filtering assembly 502 over the water source bed 24, for example when placed in a shallow natural water source 20 or when lowered enough to completely immerse the rotatable filtering assembly 402 within the water source 20. Water source bed 24, as described above in conjunction with Fig. 12A for example, can include a variety of rocks, small stones, mud, algae and the like, which, absent of any protective means, can contact the sheaf-like units 532 and damage them, or clog the medium apertures 552, when the rotatable filtering assembly 502 is immersed deep enough to rest over the or in close proximity to the water source bed 24. Thus, in some implementations, the frame 30 further includes a bottom plate 40 (Fig. 36), which can be in the form of a horizontal plate positioned below the rotatable filtering assembly 502, but preferably somewhat above the lower ends of legs 38. The bottom plate 40 preferably extends over an area which is larger than the horizontal projection of the filtering sub-assemblies 520, to protect them entirely from their bottom side.

[0574] In some implementations, the filtration system 500 comprises a backwash self-cleaning mechanism, which includes flushing a cleaning fluid (e.g., cleaning water) in the opposite direction to that of the flow during the filtering mode, in order to remove accumulated filtride from the filter medium 544.

[0575] Sheaf-type filters, including such that implement backwash self-cleaning mechanisms, are conventionally known to be adapted for inland utilization, wherein sheaf-like units are placed within a pressure vessel that is sealed from the surrounding environment, except for a dedicate inlet for unfiltered liquid entering the enclosed housing that defined the pressure vessel. This liquid flows through an intermediary passageway defined between the walls of the vessel's housing and the coiled-thread units, toward and through the layers of coiled threads, into the internal spaces defined within these units, and toward a dedicated outlet of the resulting filtrate. Such vessels can further include dedicated inlets and outlets for backwash. In contrast, the sheaf-type filtration system 500 disclosed herein includes filtering sub-assemblies 520 which are devoid of such a pressure vessels. Specifically, the filter mediums 544 of the sheaflike units 532, and more specifically, the free ends of threads 545 defining medium outer surfaces 546, are configured to be directly exposed to the environment such that raw water 10 of the environment is in direct contact with the medium outer surface 546, without passing through an intermediary passageway. Thus, the disclosed sheaf-type filtration system 500 implements utilization of filter mediums in the form of threads 545 arranged lengthwise side- by-side within blanks 534, with optional backwash-type self-cleaning mechanisms, in an unconventional manner which is devoid of pressure vessels enclosed around the sheath-like units 532.

[0576] In some examples, the filtration system 500 includes a backwash mechanism that includes at least one flush tube 590, optionally at least one flush tube flange 594, and optionally at least one flush tube valve actuator 592, as illustrated in Fig. 38. Each flush tube 590 is branched from, or continuously extends from, and is in fluid communication with, the cleaning feed line 94. Each flush tube 590 is generally aligned with a sub-assembly axis Ys of a corresponding filtering sub-assembly 520. Each sealing flange 594 is disposed over a respective flush tube 590, aligned with a corresponding offset opening 510, movable between a closed position and an open position.

[0577] In the closed position, the sealing flange 594 pressed against the offset opening 510 in a manner that seals the offset opening 510, and therefore the hub lumen 530 of the filtering sub-assembly 520, from the intake chamber 570, allowing for fluid communication of the hub lumen 530 and corresponding blank outlet 538, only with the flush tube 590. In the open position, the sealing flange 594 is spaced away from the offset opening 510, exposing it (along with hub outlet end 524) to the intake chamber 570.

[0578] Each flush tube valve actuator 592 can be operable to move the corresponding sealing flange 594 toward or away from the corresponding offset opening 510, to transition between the closed and open positions.

[0579] In order to transition a filtering sub-assembly 520 from a filtering mode to a cleaning mode, and apply backwash procedure thereto, the flush tube valve actuator 592 can be actuated to advance the sealing flange 594 toward the offset opening, to the closed position, at which point washing fluid such as water (or any other liquid or gas), supplied by the cleaning feed line 94, flows from the flush tube 590 into the hub lumen 530 and corresponding blank outlets 538. The washing fluid is introduced at a relatively high pressure, flowing in a "reverse" direction from the blank outlets 538 toward the medium outer surface 546, substantially displacing any particles trapped within the medium apertures 552. Once backwash is no longer required, cleaning fluid flow terminates and the flush tube valve actuator 592 can be actuated to retract the sealing flange 594 away from the offset opening, to the open position.

[0580] In the examples illustrated in Fig. 38, two flush tubes 590 are shown to be branched from the cleaning feed line 94, such that two filtering sub-assemblies 520, shown as subassemblies 520b and 520d, may transition to a cleaning mode. However, it is to be understood that this is merely shown by way of illustration and not limitation, and that a single flush tube 590 (with a single valve actuator 592 and sealing flange 594) can be similarly implemented, as well as more than two flush tubes 490, for example to enable more than two filtering subassemblies 520 to be simultaneously backwashed.

[0581] Four filtering sub-assemblies 520 are shown in the illustrated example, with filtering sub-assemblies 520a and 520c positioned against corresponding offset openings 510 which are fully exposed to the intake chamber 570, meaning that both of these filtering sub-assemblies 520 can be in a filtering mode in this position. Two filtering sub-assemblies 520d and 520b are aligned with flush tubes 590a and 590b. As long as the sealing flanges 594 are in the open position, these two sub-assemblies can also be in a filtering mode. However, when the sealing flanges 594 transition to the closed position, filtering sub-assemblies 520d and 520b are in a cleaning mode.

[0582] When cleaning of filtering sub-assemblies 520d and 520b is no longer required, the sealing flanges 594 can transition back to the open position. The rotatable support wall 506 can then rotate, by the drive motor 72 and transmission assemble 80, around main axis Ym, such that filtering sub-assemblies 520a and 520c, for example, can be positioned in front of the flush tubes 590a and 590b, at which point rotation is terminated, and the sealing flanges 594 can transition to the sealed mode, allowing these two filtering sub-assemblies 520 to be cleaned in a similar manner.

[0583] This procedure can be repeated as required, advantageously allowing the filtering procedure to be continuous such that at least some of the filtering sub-assemblies 520 (one or more) remain in a filtering mode, while others (one or more) are in a cleaning mode.

[0584] In some examples, one or more controllers 76 are utilized to control the tube valve actuators, such as controllers 76a and 76b that can be used for controlling the transition between the closed and open positions of the sealing flanges 594a and 594b, and a separate controller 76c can be used for controlling motor 72 as described above. Each controller 76a, 76b, 76c can be a watertight controller. In such implementations, all of the separate controllers are referred to as a controller 76 of the filtration system (e.g., systems 200, 300, 400 and/or 500), which can include separate control sub-units, such as control sub-units 76a and 76b for controlling the sealing flanges 394a and 394b, and control sub-unit 76c for controlling the drive motor. In other examples, instead of providing separate controllers, a single controller (for example, the controller or control sub-unit designated 76c) can be used to control both the drive motor 72 and any of the flush tube valve actuators 592.

[0585] In the illustrated examples, while the filtering sub-assemblies 520d and 520b are in the cleaning mode, their medium apertures 552 are non-filtration apertures 556, and as long as all other two filtering sub-assemblies 520a and 520c, are fully immersed and are in a filtering mode, all of their medium apertures 552 are filtration apertures 554, the total sum of their aperture open areas Aa constituting the effective area of filtration Ae. When the filtering subassemblies 520d and 520b are aligned with flush tubes 590, but the sealing flanges 594 are in the open position and both filtering sub-assemblies 520d and 520b are in a filtering mode, their medium apertures 552 are also filtration apertures 554, such that in such situations, the effective area of filtration Ae can be equal to the total area of medium apertures At.

[0586] Rotational movement of the rotatable filtering assembly 502 can be periodical, such that it rotates only when repositioning of other filtering sub-assemblies 520 is required, as described above. In alternative implementations, rotational movement of the rotatable filtering assembly 502 can be continuous, wherein the angular speed of rotation W is slow enough to allow adequate backflow self-cleaning of each of the filtering sub-assemblies 520 as it passes along a corresponding flush tube 590.

[0587] In the illustrated configuration, the flush tubes 590 are preferably positioned to align with the left-most and right-most filtering sub-assemblies 520. These positions are advantageous in that the sub-assemblies, such as filtering sub-assemblies 520d and 520b shown in the illustrated example, are not positioned above any portion of any other filtering subassembly, such that when they are backwashed, any filtride disposed and washed away therefrom, will tend to sink downward without interacting with any of the other filtering subassemblies 520. If, alternatively, flush tubes 590 would have been positioned elsewhere, such as the position of filtering sub-assembly 520a in the illustrated example, particles dislodged from this filtering sub-assembly could sink downward and land on portions of medium outer surfaces 546 of other filtering sub-assemblies 520.

[0588] While four filtering sub-assemblies 520 are illustrated throughout Figs. 36-38, it is to be understood that a rotatable filtering assembly 502 can include any other number of filtering sub-assemblies 520, such as more or less than four filtering sub-assemblies 520, and in some implementations, even a single filtering sub-assembly 520.

[0589] In some implementations, filtration system 500 also includes a spray assembly 580 (not illustrated separately), configured to spray liquid or gas toward a portion of filter medium 544 to dislodge filtride that may be clung thereto. Spray assembly 580 can be implemented similar to any example described above for spray assembly 380 of filtration system 300 with respect to Fig. 27, including a spray conduit 582 with one or more nozzles 584 attached thereto (not illustrated separately for filtration system 500, but similar to spray conduit 382 and nozzle 384 illustrated in Fig. 27), optionally directed toward a target region of the filter medium 544. The spray conduit 582 can be attached to, or otherwise fluidly connected to, a cleaning feed line 94 which can provide cleaning liquid or gas, including cleaning water, through the spray conduit 582, toward one or more nozzles 584.

[0590] One example of a spray assembly 580 can include a spray conduit 582 extending into the rotatable filtering assembly 502, with a plurality of nozzles 584 facing coiled threads outer surfaces 546 of any one of the filtering sub-assemblies 520 aligned against it, the nozzles 584 configured to spray water toward the filter medium 544 from the outside. The cleaning feed line 94 can extend from outside of the frame 30 into the intake pipe 560, and at a specific point, it may define a spray conduit 582 by continuously extending radially outward out of the intake pipe 560 (for example, through a corresponding sealed opening formed at the wall of the intake pipe 560), and then assume a longitudinal orientation (e.g., parallel to main axis Ym) with a plurality of nozzles 584 (only one is illustrated for simplicity) directed toward the filter medium 544, and more particularly, toward coiled threads outer surfaces 546.

[0591] Filtration system 500 can be partially immersed, such that the nozzles 584 are positioned above the water level 22, designed to spray against a filtering sub-assembly 520 which is also positioned above the water level 22. Alternatively, filtration system 500 can be fully immersed, with the nozzles 584 positioned within the water source 20, designed to spray high-pressure liquid jets, or alternatively, spray air or other suitable gas, while being immersed within the water source.

[0592] The spray assembly 580 can also be a non-rotatable, stationary assembly, similar to the stationary nature of intake pipe 560, such that due to rotation of the support wall 506, the nozzles 584 spray water (or other liquid or gas) impinging against different filtering subassemblies 520. The rotatable filtering assembly 502 may rotate such that it aligns each time a different filtering sub-assembly 520 against the nozzles 584. Rotational movement of the rotatable support wall 506 can be periodical or continuous. For example, periodical rotational movement can be employed when it is desired to align a specific filtering sub-assembly 520 against the nozzles 584, at which point rotation is halted to allow the jets sprayed from the nozzles 584 to clean the corresponding filter medium 544. Alternatively, rotation can be continuous, such that each filtering sub-assembly 520 may be cleaned by the jets sprayed from the nozzles 584 as it passes them during such continuous rotational movement. [0593] When any filtering sub-assembly 520 is sprayed by nozzles 584, it is in a cleaning mode, meaning that no internal pressure is applied thereto to apply suction toward and into intake pipe 560. It is to be understood that backwash, as disclosed above, can be combined with a spray-assembly 580, such that any filtering sub-assembly 520 can be backwashed by pressurized fluid flowing into its hub lumen 530 and blank outlets 538, and be simultaneously sprays by nozzles 584 from the outside, thereby applying self-cleaning mechanisms directing cleaning fluid both from the stack inner surface 548 outward, and from the medium outer surface 546 inward.

[0594] If a spray assembly 580 is in a relatively upper position, above other filtering subassembly 520, it may pose a risk that filtride particles dislodged therefrom may find their way to the outer surfaces 546 of other filtering sub- assemblies 520, or otherwise fall back into the water of the water source 20 and contaminate the raw water in the immediate vicinity of the other filtering sub-assemblies 520. In some examples, a tray (not shown) may be added below the position of the nozzles 584 and/or the position at which a filtering sub-assembly 520 is being cleaned, so that any filtrate particles dislodged therefrom can fall into the tray, which can be periodically cleaned.

[0595] While designed to minimize filtride accumulation over or in the filter mediums 544, filtration system 500 may still include self-cleaning mechanisms, such as flush tubes 590 or spray assembly 580, which can be utilized as safety measures, or as additional measures that can be utilized in implementations in which the aperture size D is not greater than 200 microns (including being optionally not greater than 200 microns, not greater than 100 microns, not greater than 40 microns, not greater than 10 microns, and/or not greater than 5 microns), which can still require certain self-cleaning measured to be employed for such fine filter densities.

[0596] In some implementations, the cleaning feed line 94 can extend from a source of water or compressed air onshore. In other implementations, the cleaning feed line 94 can be adapted to pump water from the surrounding water source 20 and into the spray conduit 582 and nozzles 584, and/or into the flush tubes 590.

[0597] In some implementations, the same water (or other liquid) can be used for the spray assembly 580 and/or the flush tubes 590, and for operating a water motor 72. In such implementations, a unified feed line, or a feed line manifold, can be branched into a one or more motor lines 92 and a cleaning feed line 94, optionally with appropriate controllable valves for controlling adequate flow through each as necessary.

[0598] In some implementations, the frame 30 can include one or more wall windows 42 that can be closed or opened by one or more corresponding window covers 44 (see Fig. 36 for example). For example, the frame 30 can includes two wall windows 42 formed in each frame transverse wall 32, wherein the windows 42 of each frame transverse wall 32 are aligned with each other, and are formed along portion of the frame transverse walls 32 that are at least partially facing a portion of the filter mediums 544 of one or more filtering sub-assemblies 520. The wall windows 42 can be covered, in some examples, by window covers 44 that can transition between closed and open positions.

[0599] The wall windows 42 and window covers 44 may serve as an additional or alternative self-cleaning mechanism, that can be used, for example, with a partially immersible rotatable filtering assembly 502. The wall windows 42 are designed to be at a height of the water level 22 when the rotatable filtering assembly 502 is partially immersed. When placed in a natural water source 20 that includes moving water, such as sea waves or running water of a river, opening the window covers 44 will expose the windows 42 to such waves or moving river water, which will flow therethrough from side to side, along the filter mediums 544 of filtering sub-assemblies 520 aligned therewith, dislodging any accumulated filtride and cleaning the filter mediums along with the flow.

[0600] The windows covers 44 can be hinged to pivot about their hinged connection between the closed and open states as in the illustrated example, though any other mechanism for moving such covers between open and closed position, as known in the art, is contemplated. Moving the window covers 44 between closed and open positions can be performed either manually, or by implementation of electrically controlled (including remote-controlled) mechanisms. The window covers 44 may be opened to expose the wall windows 42 to a surrounding water flow during a cleaning mode of the filtering sub-assemblies 520 aligned therewith, and may be closed to prevent such flow from interfering during filtering mode.

[0601] While described for use with a partially immersible rotatable filtering assembly 502, it is to be understood that wall windows 42 with window covers 44 can be also utilized as a cleaning mechanism for a fully immersible rotatable filtering assembly 502. For example, a rotatable filtering assembly 502 can be fully immersed during a filtering mode, while the window covers 44 are in the closed position. When at least some of the filtering sub-assemblies 520, aligned with windows 42, transition to the cleaning mode, the rotatable filtering assemblies 502 can be raised upward to be partially immersible, for example placing the wall windows 42 at the height of the water level 22, at which point the window covers 44 may be opened. When cleaning is no longer required, the window covers 44 can be closed again, and the rotatable filtering assembly 502 can be lowered downward back to the fully immersible position, as the same filtering sub-assemblies 520 transition back to the filtering mode. Furthermore, wall windows 42 can be exposed to the surrounding water and utilized in a cleaning mode also when the rotatable filtering assembly 502 is fully immersed, taking advantage of water streams occurring not only at the water level 22, but also below water level 22.

[0602] Wall windows 42 can be provided in various shapes and sizes, such as a trapezoid shape shown in Fig. 36, an hourglass shape similar to that shown in Figs. 39A-C, or any other suitable shape. In some examples, particularly for wall windows 42 provided with irregular shapes such as the hourglass-shape in Figs. 39A-C, the frame 30 can be devoid of window covers, leaving the wall windows 42 exposed to the surrounding environment at all times.

[0603] In some examples, frame 30 further comprises funneling extensions 48, each funneling extension 48 circumscribing a corresponding wall window 42, thus generally shaped in the same shape defined by the borders of the wall window 42, and extending from the frame transverse wall 32 in a direction opposite to the filter medium 544. Each funneling extension 48 can include a tapering inner surface 49 that forms a funnel-like guide for streaming the water toward the opening of wall window 42. When placed in a water source 20 with moving water, such as sea waves or streaming river, the funneling extensions 48 can serve to funnel the streaming water toward and through the wall windows 42, wherein the tapering inner surfaces can increase the flow speed of the streaming water toward filter medium 544, thus improving the surrounding water's capability of effectively washing away filtride that may have accumulated over filter medium 544. While not illustrated as such, it is to be understood that in some examples, wall windows 42 of any size and shape can be provided with any combination of window covers 44 and/or funneling extensions 48.

[0604] In some implementations, the filtration system 500 also includes at least one float 50 attached to the frame 30, such as the couple of floats 50 shown in Fig. 36 to extend through float opening 36 formed in both frame transverse walls 32. Floats 50 can be utilized to keep the rotatable filtering assembly 502 fully or partially submersible at a desired height relative to the water level 22. While two floats 50^a, 50^b are illustrated in Fig. 36, it is to be understood that any other number, such as a single float or more than two, are contemplated, and that the plural use of the term "floats 50" is not limiting, and may similarly refer to a single float.

[0605] In some implementations, the floats are adjustable floats 50, meaning that the weight of the floats 50 can be adjusted to control their buoyancy. In some implementations, the adjustable floats 50 may be provided in the form of ballast tanks, with at least one port for controlling the level of ballast water. In some implementations, each adjustable float comprises a float water port or liquid port 52 through which water (or other suitable liquid), such as ballast water, can be poured to fill the internal volume of the float 50, thereby increasing its weight, and an air port or gas port 54, through which air (or other suitable gas) may flow into the float 50 while water may exit through the water port 52.

[0606] Adjustable floats 50 can be utilized, by increasing and decreasing the weight of the floats 50, to control the buoyancy of the rotatable filtering assembly 502 and its height, relative to the water level 22. Such implementations can be used in combination with cleaning mechanisms that rely on opening and closing window covers 44 of wall windows 42 and/or funneling water through wall windows 42 provided with funneling extensions 48 as described above, for example by being filled with water (or other suitable liquid) to increase their weight and allow the rotatable filtering assembly 502 to be fully submerged during the filtration phase, and filling air (or other suitable gas) to raise the rotatable filtering assembly 502 and the wall windows 42 to the water source level 22 during the cleaning mode.

[0607] In some examples, floats 50 can be positioned such that, when inflated, their bottom edges are below the level of the upper edges of the top-side filtering sub-assemblies 520, such that if these floats 50 are retained at the water level 22 of the water source 20 when inflated, at least some portions of at least some filtering sub-assemblies 520 are not immersed in the water source 20, but are rather exposed to the atmosphere.

[0608] In some examples, as shown in Fig. 36, the floats 50 are positioned above all filtering sub-assemblies 520, such that the upper edges of any of the filtering sub-assemblies 520 are below the lower edges of any of the floats 50. In such implementations, when the floats are inflated and retained at the water level 22 of the water source 20, all of the filtering subassemblies 520 can remain fully immersed, below the water level 22. [0609] In some examples, filtration system 500 comprises one or more movable floats (50), that can be either adjustable or non-adjustable floats, configured to raise or lower the rotatable filtering assembly 502 relative to water level 22. The movable floats (50) can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 44A-45B. The same examples of movable floats (50) can be adapted for use with filtration system 500, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0610] In some implementations, the filtration system 500 can include an anchoring structure 120 attached to the frame 30, which can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 9A-9B. The same examples of anchoring structure 120 can be adapted for use with filtration system 500, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0611] In some implementations, filtration system 500 comprises an elevation assembly 130 to which at least one frame 30 and rotatable filtering assembly 502 are movably mounted, wherein the elevation assembly 130 is configured to control the height of the rotatable filtering assembly 502, for example relative to water level 22. The elevation assembly 130 can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 10-12B. The same examples of elevation assembly 130 can be adapted for use with filtration system 500, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0612] In some implementations, filtration system 500 comprises an offshore platform connection assembly 154 for coupling the frame 30 to an offshore platform 150 according to any of the examples described above in combination with filtration system 200 with respect to Fig. 13. The same examples of offshore platform connection assembly 154 can be adapted for use with filtration system 500, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0613] Another self-cleaning mechanism that can be implemented for filtration system 500 relies on changing the height of the rotatable filtering assembly 502 relative to the water level 22, at a speed high enough during which the impact of a filter mediums 544 of at least one of the filtering sub-assemblies 520 against the surface of the water at the water level 22 will dislodge filtride from the respective filter mediums 544. For example, the rotatable filtering assembly 502 can be positioned such that filter medium 544 of at least one filtering subassembly 520, and in some implementations, the filter mediums 544 of all filtering subassemblies 520, are above the water level 22. Then, lowering the rotatable filtering assembly 502 into the water at a high-enough speed, will cause the filter medium 544 to impact the water surface at the water level 22 at a force which is sufficient to dislodge filtride therefrom.

[0614] Any of the above-mentioned height-control mechanisms, including movable and/or adjustable floats 50, elevation assembly 130, and/or offshore platform connection assembly 154, can be utilized to elevate and lower the height of the rotatable filtering assembly 502 to forcibly impact filter mediums 544 of at least one of the filtering sub-assemblies 520 against the surface of the water at the water level 22. In some implementations, alteration of the height of the rotatable filtering assembly 502 to impact filter mediums 544 against the surface of the water at the water level 22 is performed during a cleaning mode of the filtering sub-assemblies 520 to be impacted. In some implementations, more than one cycle of raising and lowering the rotatable filtering assembly 502 can be sequentially performed, wherein each subsequent cycle can serve to further dislodge filtride that remained stuck against the corresponding filter mediums 544. In some implementations, rotatable support wall 506 can be rotated so as to position, each time, different filtering sub-assemblies 520 (one or more) above the water level 22, to be impacted.

[0615] Another self-cleaning mechanism that can be implemented for filtration system 500 relies on accelerating the angular speed of rotatable filtering assembly 502 while being partially submerged in the water source 20. While filtration is performed at a very low angular speed of rotation W during filtering mode, to minimize accumulation of particles over filter mediums 544, the rotatable filtering assembly 502 can be accelerated for a limited time period to a significantly higher angular speed of rotation, such as an angular speed higher than 60 degrees per second (i.e., more than 10 revolutions per minute), causing filter mediums 544 (of at least one filtering sub-assembly 420) that hit against the water at the water level 22, to hit at an impact force high enough so as to dislodge filtride therefrom. All filtering sub-assemblies 520, including those that may be still immersed prior to angular speed acceleration, are preferably switched to the cleaning mode (i.e., terminating suction into intake pipe 560 from all) prior to angular speed acceleration, as even filtration sub-assemblies that do not necessarily hit against water level 22, will still experience the elevated angular speed of rotation that can disturb the water in their vicinity. In some implementations, the direction of rotation can be also altered between subsequent cycles.

[0616] The controller 76 (e.g., motor control sub-unit 76c) can be configured to transition the drive motor's 72 angular speed of rotation between low speeds during a filtering mode, and high speeds during a cleaning mode, as well as optional alteration of the direction of rotation during the cleaning mode. The controller 76 can be configured to control the acceleration and deceleration rates during the transition between higher and lower angular speeds of rotation.

[0617] In some implementations, the filtration system 500 can further include an additional vibration motor 73, that can be coupled to the rotatable filtering assembly 502 and configured to vibrate, and more specifically, apply vibrational movement to the filter medium 544, which will serve to dislodge filtride accumulated thereon. The vibration motor 73 is a watertight motor, and can be optionally sealed by being encompassed by a watertight housing, similar to housing 74. A filtration system 500 can be equipped with both a watertight drive motor 72 and a watertight vibration motor 73, similar to the example described above for filtration system 200 with respect to Fig. 17A, wherein both motors can be attached to the same component of a frame 30, such as both being coupled to frame transverse wall 32a as illustrated, or to different components of the frame 30 or other components of the filtration system 500. Operation of the vibration motor 73 can be controlled by a separate controller, or the same controller 76 of the drive motor 72.

[0618] The controller 76 can be adapted to control the operation of the drive motor 72 and the vibration motor 73, such that the drive motor 72 is activated to rotate the rotatable filtering assembly 502 during the filtering mode (either periodically or continuously), while the vibration motor 73 is inactive, and the vibration motor 73 is activated, while the drive motor 72 is non-active, during a cleaning mode. The vibration motor 73 can be implemented, in some examples, as an eccentric rotating mass vibration motor. In some implementations, the same motor 72 can be used to apply both rotational movement for rotating filtering assembly 502, and vibrational movement to facilitate vibration of the filter mediums 544. The controller 76 can control the operation of such a multi-purpose motor 72, to transition between rotational movement during the filtering mode and vibrational movement during the cleaning mode.

[0619] In some examples, filtration system 500 can include one or more ultrasonic transducer(s) 96, positioned to apply ultrasonic energy directed at the filter medium 544, similar to the manner described above for filtration system 200 with respect to Fig. 17A. The ultrasonic transducer(s) 96 can apply ultrasonic energy that can disintegrate and/or create ultrasonic waves that will impact against the filter medium 544 in a manner that will dislodge filtride therefrom. Advantageously, the desire ultrasonic waves, directed at the filter medium, do not require high energy, enabling utilization of the ultrasonic transducer as low-energy longterm self-cleaning mechanism.

[0620] In some examples, the intake pipe 560 further comprises an expansion chamber 564 (not illustrated separately for filtration system 500), similar to the manner described above for filtration system 200 with respect to Fig. 16. An expansion chamber 564 is disposed upstream from the rotatable filtering assembly 502, and is formed as a portion of the intake pipe which expands to an expansion chamber diameter De which is at least twice as great as the minimal pipe diameter Dp, and in some example, at least three times as great as the minimal pipe diameter Dp. The minimal pipe diameter Dp is the diameter of intake pipe 560 at its minimal intake pipe cross-sectional area Ap, which can be measured at a portion of the intake pipe 560 extending into the rotatable filtering assembly 502, or at least extending through or disposed at the level of, a rotatable support wall 506.

[0621] The expansion chamber 564 can be either integrally formed with the remainder of intake pipe 560, or provided as a separate component attached in a sealed manner to the remainder of intake pipe 560. The expansion chamber 564 can include a gradually tapering inflow portion, expanding gradually radially outward from minimal pipe diameter Dp to expansion chamber De, a main expanded portion having a uniform diameter De along a length Lc, and a gradually tapering outflow portion, narrowing gradually radially inward from expansion chamber diameter De back to minimal pipe diameter Dp, after which the pipe may further extend along a certain length and terminate with pipe outflow opening 566. In some examples, the length of expanded main portion Lc is at least twice as great as the expansion chamber diameter De.

[0622] In some examples, a filtration system 500 can be oriented in a vertical orientation, such that its main axis Ym is substantially orthogonal to a plane of the water level 22. In examples of filtration systems that include one or more floats 50, including any of the movable and/or adjustable floats disclosed herein, the orientation of the float(s) 50 is adjusted to allow for vertical orientation of the rotatable filtering assembly 502. In some examples, the float(s) 50 extends along a plane which is substantially orthogonal to the main axis Ym. For example, float(s) 50 illustrated in Fig. 31 extend longitudinally along an axis which is substantially parallel to the main axis Ym, which will result in a horizontal orientation of the rotatable filtering assembly 502. In contrast, a float 50 can be implemented in a similar manner to that described above for filtration system 200 with respect to Fig. 16, defining a plane which is substantially orthogonal to main axis Ym, resulting in a vertical orientation of the rotatable filtering assembly 502.

[0623] In some examples, the intake pipe 560 extend from the rotatable filtering assembly 502 downward, toward water source bed 24, such that the pipe outflow opening 566 is positioned lower than the rotatable filtering assembly 502.

[0624] In some examples, the filtration system 500 is equipped with a weight 160 opposite to float 50. Any of the float 50 and/or weight(s) 160 can be coupled to the frame 30 and/or to the filtering assembly 502, preferably on opposite sides, via one or more coupling means such as cables, chains, and the like, in a manner similar to that described above for filtration system 200 with respect to Fig. 17A. The combination of float(s) 50, and in some examples, movable and/or adjustable float(s) 50, with weight(s) 160, can serve to control the height of rotatable filtering assembly 502 within the water source 20 (i.e., relative to water level 22), for example by adjusting the degree of floatation of float(s) 50, while weight(s) 160 pull the rotatable filtering assembly 502 gravitationally downward. Moreover, the combination of float(s) 50 from above, and weight(s) 160 from below the rotatable filtering assembly 502, can together stabilize the rotatable filtering assembly 502 in a vertical orientation, substantially orthogonal to the plane defined by water level 22.

[0625] In some implementations, the threads 545 forming filter medium 544 comprise copper, for example by being completely made of copper or coated by a copper layer. Embedding copper into the threads 545, or forming them from copper, can significantly reduce the likelihood of algae and other microorganisms from clinging to the filter medium 544 and clogging medium apertures 552 when immersed in a natural water source 20.

[0626] As mentioned, the minimal ratio Ra and/or maximal flow velocity across the filtration apertures Ve depend on the effective area of filtration Ae, such that for a given maximal flow rate Qm, a minimal effective area of filtration Ae is required to result in the minimal desired Ra and/or maximal desire Ve. Furthermore, as also mentioned above, the filtration apertures 554, which in some cases can constitute only a subset of the medium apertures 552 of some of the filtering sub-assemblies 520, contribute to the effective area of filtration Ae. A filtration system 500 configured to have at least one of its filtering sub-assemblies 520 in a filtering mode, while at least one other filtering sub-assembly 520 is in a cleaning mode, can be designed such that the minimal number of filtering sub-assemblies 520 that continue to operate in a filtering mode at all times, including when one or more filtering sub-assemblies 520 are in a cleaning mode, provide a sufficient minimal effective area of filtration Ae.

[0627] In the example illustrated in Fig. 38, two flush tubes 590 are provided to allow backwash of two corresponding filtering sub-assemblies 520, such that even during this cleaning mode, at least two other filtering sub-assemblies 520 continue to operate in a filtering mode. Thus, while in some instances, all four filtering sub-assemblies 520 can operate in a filtering mode, the minimal number of filtration apertures 554 includes all medium apertures 552 of at least two filtering sub-assemblies 520. The minimal effective area of filtration Ae, based on the filtration apertures of two filtering sub-assemblies 520 in such an example, can be designed to result in the minimally desired Rq and/or Ra.

[0628] In examples of a partially immersible filtration system 500, the medium apertures 552 of any filtering sub-assemblies 520 that can be at any instant of time above the water level 22 are non-filtration apertures, such that only the minimal number of filtering sub-assemblies 520 which always remain submerged in the water source 20 at any given time, will contribute to the effective area of filtration Ae. In such cases, the filtration system 500 can include an immersion depth marking 46 that can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Fig. 7. The same examples of immersion depth markings 46 can be adapted for use with filtration system 500, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0629] In some examples, filtration system 500 can include at least one camera 56 configured to take images of at least a portion of filter medium(s) 544, optionally mounted on a camera mount 58 that can be an adjustable arm, wherein each of the camera 56 and/or mount 58 can be controlled by control sub-unit 76e. Any of the at least one camera 56 and camera mount 58, as well as control sub-unit 76e, can be implemented according to any of the examples described above in combination with filtration system 200 with respect to Figs. 39A-C. The same examples of camera(s) 56, camera mount(s) 58, and/or controller sub-unit 76e, can be adapted for use with filtration system 500, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0630] In some examples, each filtering sub-assembly 520 is not only revolvable around the main axis Ym, but is also rotatable around its sub-assembly axis Ys. For example, filtration system 500 can include a planetary transmission mechanism, configured to allow simultaneous rotation of the rotatable support wall 506 around main axis Ym, as well as rotation of the filtering sub-assemblies 520 - each around its own sub-assembly axis Ys. Any implementation of a simultaneous revolvable and rotational movement of the filtering sub-assemblies, including a planetary gear that includes a driving gear 84 and driven gears 86 having first 86' and second 86" gear portions, and planetary gears 88, can be implemented according to any of the examples described above in combination with filtration system 300 with respect to Fig. 41.

[0631] Each planetary gear 88 can be attached to another component of the corresponding filtering sub-assembly, such as the hollow hub 522. Thus, the same examples for implementation of simultaneous rotation of the rotatable support wall around main axis Ym, and the plurality of filtering sub-assemblies around their axes Ys, including any implementation of driven gears 86 and planetary gears 88, can be adapted for use with filtration system 500, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

[0632] In other examples, each filtering sub-assembly 520 is independently rotatable around its own sub-assembly axis Ys, irrespective of its resolvability around main axis Ym or rotatability of any other filtering sub-assemblies of the filtration system 500. Any of the sub assembly drive motors 180, sub assembly transmission 184, internal pressure sensor 182, external pressure sensors 183, as well as control sub-units 76s, can be implemented according to any of the examples described above in combination with filtration system 300 with respect to Figs. 42-43.

[0633] Each sub-assembly transmission 184 can include a sub-assembly driver gear 186 and a sub-assembly main gear 188, wherein the main gear 188 can be attached to a component of the filtering sub-assembly 520, such as the hollow hub 522. Internal pressure sensor 182 can be disposed within hub lumen 530, configured to measure pressure within hub lumen 530, for example by being attached to an inner surface of the hollow hub 522. Thus, the same examples for implementation of independent rotation of the rotatable support wall around main axis Ym, and any of the plurality of filtering sub-assemblies around their axes Ys, including any implementation of sub-assembly drive motors 180, sub-assembly transmissions 184, drive gears 186, main gears 188, internal pressure sensor 182, and external pressure sensors 183, can be adapted for use with filtration system 500, mutatis mutandis, and in the interest of brevity will not be separately illustrated or further described.

Some Examples of the Disclosed Implementations

[0634] Some examples of above-described implementations are enumerated below. It should be noted that one feature of an example in isolation or more than one feature of the example taken in combination and, optionally, in combination with one or more features of one or more examples below are examples also falling within the disclosure of this application.

[0635] Example Al. A filtration system, comprising: at least one rotatable filtering assembly, comprising: at least one rotatable support wall configured to rotate around a main axis; and a filter medium coupled to the at least one rotatable support wall, the filter medium comprising a plurality of medium apertures, the plurality of medium apertures comprising a plurality of filtration apertures; an intake pipe defining a minimal intake pipe cross-sectional area, wherein the intake pipe comprises at least one pipe inflow opening in fluid communication with the filter medium; a watertight drive motor in mechanical communication with the at least one rotatable filtering assembly; and a watertight controller for controlling the watertight drive motor to rotate the at least one rotatable filtering assembly around the main axis, the angular speed of rotation not exceeding 6 degrees per second at any moment when the watertight controller is in a filtering mode.

[0636] Example A2. The filtration system of any example herein, particularly example Al, wherein each filtration aperture has an aperture size that is not greater than 350 microns. [0637] Example A3. The filtration system of any example herein, particularly example Al, wherein each filtration aperture has an aperture size that is not greater than 200 microns.

[0638] Example A4. The filtration system of any example herein, particularly example Al, wherein each filtration aperture has an aperture size that is not greater than 40 microns.

[0639] Example A5. The filtration system of any example herein, particularly example Al, wherein each filtration aperture has an aperture size that is not greater than 5 microns.

[0640] Example A6. The filtration system of any example herein, particularly example Al, wherein each filtration aperture has an aperture size that is not greater than 1 micron.

[0641] Example A7. The filtration system of any example herein, particularly any one of examples Al to A6, wherein each filtration aperture defines an aperture area, wherein a ratio between a sum of the aperture areas of all of the filtration apertures to the minimal intake pipe cross-sectional area is greater than 4.

[0642] Example A8. The filtration system of any example herein, particularly any one of examples Al to A6, wherein each filtration aperture defines an aperture area, wherein a ratio between a sum of the aperture areas of all of the filtration apertures to the minimal intake pipe cross-sectional area is greater than 7.

[0643] Example A9. The filtration system of any example herein, particularly any one of examples Al to A6, wherein each filtration aperture defines an aperture area, wherein a ratio between a sum of the aperture areas of all of the filtration apertures to the minimal intake pipe cross-sectional area is greater than 8.

[0644] Example A10. The filtration system of any example herein, particularly any one of examples Al to A6, wherein each filtration aperture defines an aperture area, wherein a ratio between a sum of the areas of all of the filtration apertures to the minimal intake pipe cross- sectional area is greater than 10.

[0645] Example Al l. The filtration system of any example herein, particularly any one of examples Al to A10, wherein at least 50% of the medium apertures are filtration apertures.

[0646] Example A12. The filtration system of any example herein, particularly any one of examples Al to A 10, wherein at least 70% of the medium apertures are filtration apertures. [0647] Example A13. The filtration system of any example herein, wherein all of the medium apertures are filtration apertures.

[0648] Example A14. The filtration system of any example herein, particularly any one of examples Al to A13, further comprising a frame, wherein the at least one rotatable filtering assembly is coupled to the frame.

[0649] Example A15. The filtration system of any example herein, particularly example A14, wherein the watertight drive motor is attached to the frame.

[0650] Example A16. The filtration system of any example herein, particularly any one of examples A 14 or A 15, further comprising at least one float.

[0651] Example A17. The filtration system of any example herein, particularly example A16, wherein each float is an adjustable float.

[0652] Example A18. The filtration system of any example herein, particularly example A17, wherein each adjustable float comprises a float water port and a float air port.

[0653] Example A19. The filtration system of any example herein, particularly example A17, wherein each adjustable float comprises a float liquid port and a float gas port.

[0654] Example A20. The filtration system of any example herein, particularly any one of examples A16 to A19, wherein the float defines a plane which is orthogonal to the main axis.

[0655] Example A21. The filtration system of any example herein, particularly any one of examples A16 to A20, further comprising at least one weight coupled to the frame, opposite to the at least one float.

[0656] Example A22. The filtration system of any example herein, particularly any one of examples A14 to A21, wherein the frame comprises a bottom plate disposed below the at least one rotatable filtering assembly.

[0657] Example A23. The filtration system of any example herein, particularly any one of examples A14 to A22, wherein the frame further comprises at least one immersion depth marking. [0658] Example A24. The filtration system of any example herein, particularly any one of examples A 14 to A23, wherein the frame further comprises at least one frame transverse wall, wherein each frame transverse wall comprises at least one frame window which at least partially faces a portion of the filter medium.

[0659] Example A25. The filtration system of any example herein, particularly example 24, wherein the frame further comprises at least one window cover covering a respective frame window, wherein each window cover is configured to transition between a closed position and an open position.

[0660] Example A26. The filtration system of any example herein, particularly any one of examples A 14 to A25, further comprising an anchoring structure, the anchoring structure comprising at least one anchoring arm coupled to the frame at an arm coupling end thereof, and configured to be ground to a shore at an opposite arm grounding end thereof.

[0661] Example 1. The filtration system of any example herein, particularly any one of examples A14 to A25, further comprising an elevation assembly comprising: a vertical column; and a height adjustment assembly configured to elevate or lower one or more of the at least one rotatable filtering assemblies along the vertical column.

[0662] Example A28. The filtration system of any example herein, particularly any one of examples A14 to A25, further comprising an offshore platform connection assembly comprising: at least one winch; and at least one elongated flexible member coupled to the frame, and rotatable around the at least one winch.

[0663] Example A29. The filtration system of any example herein, particularly any one of examples 1 to 28, wherein the watertight drive motor is a water motor.

[0664] Example A30. The filtration system of any example herein, particularly any one of examples Al to A29, further comprising a watertight vibration motor. [0665] Example A31. The filtration system of any example herein, particularly any one of examples Al to A30, further comprising at least one ultrasonic transducer.

[0666] Example A32. The filtration system of any example herein, particularly any one of examples Al to A31, wherein the filter medium comprises copper.

[0667] Example A33. The filtration system of any example herein, particularly any one of examples Al to A32, wherein the intake pipe comprises an expansion chamber having an expansion chamber diameter that is at least twice as great as a minimal diameter of the intake pipe.

[0668] Example A34. The filtration system of any example herein, particularly example A33, wherein the expansion chamber diameter is at least three times as great as the minimal diameter of the intake pipe.

[0669] Example A35. The filtration system of any example herein, particularly any one of examples Al to A34, wherein the filtration system is a drum-type filtration system, wherein the rotatable filtering assembly is a drum-type filtering assembly, wherein the at least one rotatable support wall comprises two rotatable support walls, and wherein the filter medium comprises a screen mesh disposed between both rotatable support walls.

[0670] Example A36. The filtration system of any example herein, particularly example A35, further comprising a spray assembly, the spray assembly comprising a spray conduit and a plurality of nozzles, wherein the spray conduit is disposed within the filter medium, and wherein the plurality of nozzles are facing an inner surface of the filter medium..

[0671] Example A37. The filtration system of any example herein, particularly any one of examples A35 or A36, wherein the at least one rotatable filtering assembly comprises a plurality of rotatable filtering assemblies.

[0672] Example A38. The filtration system of any example herein, particularly example A37, wherein the intake pipe comprises a plurality of pipe branches, wherein each of the pipe branches is in fluid communication with a respective one of the plurality of rotatable filtering assemblies.

[0673] Example A39. The filtration system of any example herein, particularly any one of examples A37 or A38, wherein the watertight drive motor comprises a single watertight drive motor configured to apply rotational movement to any of the plurality of rotatable filtering assemblies.

[0674] Example A40. The filtration system of any example herein, particularly any one of examples Al to A34, wherein the filtration system is a disc-type filtration system, wherein the rotatable filtering assembly is a disc-type filtering assembly comprising a plurality of disc-type filtering sub-assemblies, each defining a sub-assembly axis, each sub-assembly axis being offset from and parallel to the main axis, wherein each disc-type filtering sub-assembly comprises a stack of discs, wherein the filter medium is formed by the at least one stack of discs, and wherein the medium apertures are defined by channels formed between adjacent discs.

[0675] Example A41. The filtration system of any example herein, particularly example A40, further comprising an intake chamber defined between the rotatable support wall and a stationary wall portion, wherein the stack of discs of each disc-type filtering sub-assembly defines an internal space which is in fluid communication with an offset opening defined along the rotatable support wall, wherein at least one offset opening is in fluid communication with the intake chamber, and wherein the intake chamber is in fluid communication with the at least one pipe inflow opening.

[0676] Example A42. The filtration system of any example herein, particularly example 41, further comprising at least one flush tube equipped with at least one flush tube sealing flange, wherein each flush tube sealing flange is movable between an open position, spaced away from the rotatable support wall, and a closed position, sealing a respective offset opening from the intake chamber while enabling fluid communication between the flush tube and the respective internal space.

[0677] Example A43. The filtration system of any example herein, particularly any one of examples Al to A34, wherein the filtration system is a coiled thread-type filtration system, wherein the rotatable filtering assembly is a coiled thread-type filtering assembly comprising a plurality of coiled thread-type filtering sub-assemblies, each defining a sub-assembly axis, each sub-assembly axis being offset from and parallel to the main axis, wherein each coiled thread-type filtering sub-assembly comprises a hollow hub defining a hub lumen and fluidly connected to a plurality of coiled-thread units, wherein the filter medium is formed by coiled threads of the plurality of coiled-thread units, and wherein the medium apertures are defined by spacings formed between adjacent threads.

[0678] Example A44. The filtration system of any example herein, particularly example A43, further comprising an intake chamber defined between the rotatable support wall and a stationary wall portion, wherein each hub lumen is in fluid communication with an offset opening defined along the rotatable support wall, wherein at least one offset opening is in fluid communication with the intake chamber, and wherein the intake chamber is in fluid communication with the at least one pipe inflow opening.

[0679] Example A45. The filtration system of any example herein, particularly example A44, further comprising at least one flush tube equipped with at least one flush tube sealing flange, wherein each flush tube sealing flange is movable between an open position, spaced away from the rotatable support wall, and a closed position, sealing a respective offset opening from the intake chamber while enabling fluid communication between the flush tube and the respective hub lumen.

[0680] Example A46. The filtration system of any example herein, particularly any one of examples Al to A34, wherein the filtration system is a sheaf-type filtration system, wherein the rotatable filtering assembly is a sheaf-type filtering assembly comprising a plurality of sheaf-type filtering sub-assemblies, each defining a sub-assembly axis, each sub-assembly axis being offset from and parallel to the main axis, wherein each sheaf-type filtering sub-assembly comprises a hollow hub defining a hub lumen and fluidly connected to a plurality of sheaf-like units, wherein the filter medium is formed by longitudinally extending threads arranged in a sheaf-like configuration within the plurality of sheaf-like units, and wherein the medium apertures are defined by spacings formed between adjacent threads.

[0681] Example A47. The filtration system of any example herein, particularly example A46, further comprising an intake chamber defined between the rotatable support wall and a stationary wall portion, wherein each hub lumen is in fluid communication with an offset opening defined along the rotatable support wall, wherein at least one offset opening is in fluid communication with the intake chamber, and wherein the intake chamber is in fluid communication with the at least one pipe inflow opening.

[0682] Example A48. The filtration system of any example herein, particularly example 47, further comprising at least one flush tube equipped with at least one flush tube sealing flange, wherein each flush tube sealing flange is movable between an open position, spaced away from the rotatable support wall, and a closed position, sealing a respective offset opening from the intake chamber while enabling fluid communication between the flush tube and the respective hub lumen.

[0683] Example A49. The filtration system of any example herein, particularly any one of examples 1 to 48, wherein the filtration system is devoid of a pressure vessel disposed around any of the at least one filter medium.

[0684] Example A50. The filtration system of any example herein, particularly any one of examples 1 to 48, further comprising a driving gear attached to a shaft extending from the drive motor, and a driven gear meshed with the driving gear, wherein the driven gear is attached to the rotatable support wall.

[0685] Example A51. A method, comprising: disposing a filtration assembly within a water source, such that at least a portion of medium apertures of at least one filter medium of the filtration system are immersed within the water source; applying suction force through at least one at least one pipe inflow opening of an intake pipe which is in fluid communication with the filter medium, wherein the suction force is selected so as not to exceed a maximal flow rate through the filter medium, and actuating a watertight motor of the filtration assembly to rotate the at least one filter medium around a main axis, at an angular speed of rotation that does not exceed 6 degrees per second.

[0686] Example A52. The method of any example herein, particularly example A51, wherein each medium aperture defines an aperture open area, and wherein the maximal flow rate and the sum of aperture areas of the immersed portion of the medium apertures are selected so as not to exceed a maximal flow velocity of 0.7 m/s through the immersed portion of the medium apertures.

[0687] Example Bl. A filtration system, comprising: at least one rotatable filtering assembly, comprising: two rotatable support walls configured to rotate around a main axis; a screen mesh extending between and coupled to the two rotatable support walls, the screen mesh comprising a plurality of medium apertures; an intake pipe comprising at least one pipe inflow opening in fluid communication with the screen mesh, wherein the screen mesh defines an internal space between an inner surface thereof and the intake pipe; a spray assembly comprising a spray conduit, one or more flexible portions extending from the spray conduit and in fluid communication therewith, and at least one nozzle residing in the internal space, each nozzle attached to an end of a corresponding one of the one or more flexible portions.

[0688] Example B2. The filtration system of any example herein, particularly example Bl, further comprising a watertight drive motor in mechanical communication with the at least one rotatable filtering assembly.

[0689] Example B3. The filtration system of any example herein, particularly example B2, further comprising a watertight controller for controlling the watertight drive motor to rotate the at least one rotatable filtering assembly around the main axis.

[0690] Example B4. The filtration system of any example herein, particularly any one of examples B2 or B3, wherein the watertight drive motor is a water motor.

[0691] Example B5. The filtration system of any example herein, particularly example B4, further comprising a feed line manifold branched into at least one motor line and a cleaning feed line, wherein the at least one motor line is in fluid communication with the water motor, configured to direct water from the feed line manifold into the water motor, and wherein the cleaning feed line is in fluid communication with the spray conduit, configured to direct water from the feed line manifold toward the at least one nozzle.

[0692] Example B6. The filtration system of any example herein, particularly any one of examples Bl to B5, wherein each medium aperture has an aperture size that is not greater than 350 microns. [0693] Example B7. The filtration system of any example herein, particularly any one of examples Bl to B5, wherein each medium aperture has an aperture size that is not greater than 300 microns.

[0694] Example B8. The filtration system of any example herein, particularly any one of examples Bl to B5, wherein each medium aperture has an aperture size that is not greater than 200 microns.

[0695] Example B9. The filtration system of any example herein, particularly any one of examples Bl to B5, wherein each medium aperture has an aperture size that is not greater than 100 microns.

[0696] Example B10. The filtration system of any example herein, particularly any one of examples Bl to B5, wherein each medium aperture has an aperture size that is not greater than 40 microns.

[0697] Example B 11. The filtration system of any example herein, particularly any one of examples Bl to B5, wherein each medium aperture has an aperture size that is not greater than 5 microns.

[0698] Example B 12. The filtration system of any example herein, particularly any one of examples Bl to B5, wherein each medium aperture has an aperture size that is not greater than 1 micron.

[0699] Example B 13. The filtration system of any example herein, particularly any one of examples Bl to B12, further comprising a watertight vibration motor.

[0700] Example B 14. The filtration system of any example herein, particularly any one of examples Bl to B13, further comprising at least one ultrasonic transducer.

[0701] Example B 15. The filtration system of any example herein, particularly any one of examples Bl to B14, wherein the screen mesh comprises copper.

[0702] Example B 16. The filtration system of any example herein, particularly any one of examples Bl to B15, wherein the intake pipe comprises an expansion chamber having an expansion chamber diameter that is at least twice as great as a minimal diameter of the intake pipe. [0703] Example B17. The filtration system of any example herein, particularly example B16, wherein expansion chamber diameter is at least three times as great as the minimal diameter of the intake pipe.

[0704] Example Bl 8. The filtration system of any example herein, particularly any one of examples Bl to B17, further comprising a frame, wherein the at least one rotatable filtering assembly is coupled to the frame.

[0705] Example B19. The filtration system of any example herein, particularly example B17, wherein the watertight drive motor is attached to the frame.

[0706] Example B20. The filtration system of any example herein, particularly any one of examples B 18 or Bl 9, further comprising at least one float.

[0707] Example B21. The filtration system of any example herein, particularly example B20, wherein each float is an adjustable float.

[0708] Example B22. The filtration system of any example herein, particularly example B21, wherein each adjustable float comprises a float liquid port and a float gas port.

[0709] Example B23. The filtration system of any example herein, particularly example B21, wherein each adjustable float comprises a float water port and a float air port.

[0710] Example B24. The filtration system of any example herein, particularly any one of examples B20 to B23, wherein the float defines a plane which is orthogonal to the main axis.

[0711] Example B25. The filtration system of any example herein, particularly any one of examples B20 to B24, further comprising at least one weight coupled to the frame, opposite to the at least one float.

[0712] Example B26. The filtration system of any example herein, particularly any one of examples B18 to B25, wherein the frame comprises a bottom plate disposed below the at least one rotatable filtering assembly.

[0713] Example B27. The filtration system of any example herein, particularly any one of examples B18 to B26, further comprising an anchoring structure, the anchoring structure comprising at least one anchoring arm coupled to the frame at an arm coupling end thereof, and configured to be ground to a shore at an opposite arm grounding end thereof. [0714] Example B28. The filtration system of any example herein, particularly any one of examples B18 to B26, further comprising: a vertical column; and a height adjustment assembly configured to elevate or lower one or more of the at least one rotatable filtering assemblies along the vertical column.

[0715] Example B29. The filtration system of any example herein, particularly any one of examples B18 to B26, further comprising: at least one winch; and at least one elongated flexible member coupled to the frame, and rotatable around the at least one winch.

[0716] Example B30. The filtration system of any example herein, particularly any one of examples Bl to B29, wherein the filtration system is devoid of a pressure vessel disposed around any of the at least one screen mesh.

[0717] Example Cl. A filtration system, comprising: at least one rotatable filtering assembly, comprising: two rotatable support walls configured to rotate around a main axis; a screen mesh extending between and coupled to the two rotatable support walls, the screen mesh comprising a plurality of medium apertures; an intake pipe comprising at least one pipe inflow opening in fluid communication with the screen mesh, wherein the screen mesh defines an internal space between an inner surface thereof and the intake pipe; a spray assembly comprising a spray conduit, and at least one nozzle attached to the spray conduit and in fluid communication therewith, the at least one nozzle residing in the internal space; a cleaning feed line fluidly connected to the spray conduit and configured to deliver compressed air or gas to the spray conduit; an air or gas release mechanism comprising a baffle residing within the screen mesh and a release tube, wherein the baffle extends from a circumference of the screen mesh to an opening of the release tube, and wherein the release tube extends from the baffle and beyond at least one of the rotatable support walls.

[0718] Example C2. The filtration system of any example herein, particularly example Cl, wherein the baffle is tapering from the screen mesh to the opening of the release tube.

[0719] Example C3. The filtration system of any example herein, particularly any one of examples Cl or C2, wherein the air or gas release mechanism further comprises a unidirectional valve positioned within the release tube.

[0720] Example C4. The filtration system of any example herein, particularly example C3, wherein the unidirectional valve is a ball valve.

[0721] Example C5. The filtration system of any example herein, particularly any one of examples C3 or C4, wherein the unidirectional valve is positioned at an end of the release tube which is opposite to the baffle.

[0722] Example C6. The filtration system of any example herein, particularly any one of examples Cl to C5, further comprising a watertight drive motor in mechanical communication with the at least one rotatable filtering assembly.

[0723] Example C7. The filtration system of any example herein, particularly example C6, further comprising a watertight controller for controlling the watertight drive motor to rotate the at least one rotatable filtering assembly around the main axis.

[0724] Example C8. The filtration system of any example herein, particularly any one of examples Cl to C7, wherein the release tube extends along the main axis or an axis parallel to the main axis.

[0725] Example C9. The filtration system of any example herein, particularly any one of examples Cl to C7, wherein each medium aperture has an aperture size that is not greater than 350 microns. [0726] Example CIO. The filtration system of any example herein, particularly any one of examples Cl to C7, wherein each medium aperture has an aperture size that is not greater than 300 microns.

[0727] Example Cl 1. The filtration system of any example herein, particularly any one of examples Cl to C7, wherein each medium aperture has an aperture size that is not greater than 200 microns.

[0728] Example C 12. The filtration system of any example herein, particularly any one of examples Cl to C7, wherein each medium aperture has an aperture size that is not greater than 100 microns.

[0729] Example C 13. The filtration system of any example herein, particularly any one of examples Cl to C7, wherein each medium aperture has an aperture size that is not greater than 40 microns.

[0730] Example C 14. The filtration system of any example herein, particularly any one of examples Cl to C7, wherein each medium aperture has an aperture size that is not greater than 5 microns.

[0731] Example C 15. The filtration system of any example herein, particularly any one of examples Cl to C7, wherein each medium aperture has an aperture size that is not greater than 1 micron.

[0732] Example C16. A method, comprising: providing the filtration system of any one of examples Cl to C15; positioning the at least one rotatable filtering assembly within a water source, such that at least a portion of the screen mesh is immersed within the water source, and such that at least a portion of the release tube extends above the water level;

[0733] Example C17. The method of any example herein, particularly example C16, wherein the main axis is orthogonal to the water level.

[0734] Example Cl 8. The method of any example herein, particularly example Cl 6, wherein the at least one pipe inflow opening is below the water level, and wherein the baffle is above the at least one pipe inflow opening. [0735] Example DI. A filtration system, comprising a rotatable filtering assembly, comprising: a rotatable support wall configured to rotate around a main axis; a plurality of filtering sub-assemblies attached to the rotatable support wall, wherein the filtering sub-assemblies are revolvable around the main axis, and wherein each revolvable sub-assembly comprises a filter medium that comprises a plurality of medium apertures; an intake chamber defined between the rotatable support wall and a stationary wall portion; an intake pipe comprising at least one pipe inflow opening in fluid communication with the intake chamber; a watertight drive motor in mechanical communication with the rotatable support wall; and a watertight controller for controlling the watertight drive motor to rotate the rotatable support wall around the main axis.

[0736] Example D2. The filtration system of any example herein, particularly example DI, wherein the rotatable support wall comprises a plurality of offset openings, and wherein each offset opening is aligned with a sub-assembly axis of a corresponding filtering sub-assembly.

[0737] Example D3. The filtration system of any example herein, particularly example D2, further comprising a cleaning feed line, and at least one flush tube extending from the cleaning feed line and in fluid communication therewith, wherein each flush tube is aligned with a corresponding sub-assembly axis.

[0738] Example D4. The filtration system of any example herein, particularly example D3, further comprising at least one sealing flange disposed over the flush tube, and movable between a closed position and an open position.

[0739] Example D5. The filtration system of any example herein, particularly any one of examples DI to D4, wherein each filtering sub-assembly comprises a plurality of discs which are normally pressed against each other, and wherein the medium apertures are channels formed by grooves extending along at least one side of each of the plurality of discs.

[0740] Example D6. The filtration system of any example herein, particularly example D5, wherein each filtering sub-assembly further comprises a spine disposed along the corresponding sub-assembly axis, such that the plurality of discs are disposed along the length of the spine.

[0741] Example D7. The filtration system of any example herein, particularly example D6, wherein each filtering sub-assembly further comprises a compression plate mounted to the spine, opposite to the rotatable support wall, such that the plurality of discs are stacked between the compression plate and the rotatable support wall.

[0742] Example D8. The filtration system of any example herein, particularly any one of examples DI to D4, wherein each filtering sub-assembly comprises a hollow hub defining a hub lumen, and a plurality of hub openings disposed around a circumference of the hollow hub.

[0743] Example D9. The filtration system of any example herein, particularly example D8, wherein each filtering sub-assembly further comprises a plurality of coiled-thread units mounted on the hollow hub, each coiled-thread unit comprising: a support blank comprising a blank first end with a blank outlet, and a close-ended blank second end opposite to the blank first end; and one or more threads coiled around the support blank, so as to form an internal space between the coiled threads, the blank first end, and the blank second end; wherein the medium apertures are defined by spacings between adjacent portions of the threads; and wherein the blank outlets are coupled in a sealed manner to the hub openings, maintaining fluid communication between the internal spaces and the hub lumen.

[0744] Example D10. The filtration system of any example herein, particularly example D9, wherein each blank further comprises one or more blank arms extending between the blank first end and the blank second end, wherein the threads are coiled around the blank arms. [0745] Example Dl l. The filtration system of any example herein, particularly example D8, wherein each filtering sub-assembly further comprises a plurality of sheaf-like units mounted on the hollow hub, each sheaf-like unit comprising: a support blank comprising a blank base with a blank outlet, an open-ended blank inflow end opposite to the blank base, and a blank tubular housing extending between the blank base and the blank inflow end; and a plurality of threads disposed within the blank tubular housing in a sheaf-like configuration, the threads extending from the blank base toward the blank inflow end; wherein the medium apertures are defined by lateral spacings between adjacent threads; and wherein the blank outlets are coupled in a sealed manner to the hub openings, maintaining fluid communication between the lateral spacings formed between the threads, and the hub lumen.

[0746] Example Dl l. The filtration system of any example herein, particularly example D8, wherein the threads are attached to the blank base, extending longitudinally therefrom to opposite free ends of the threads.

[0747] Example DI 2. The filtration system of any example herein, particularly any one of examples DI to DI 1, wherein the watertight drive motor is a water motor.

[0748] Example DI 3. The filtration system of any example herein, particularly any one of examples DI to D12, wherein each medium aperture has an aperture size that is not greater than 350 microns.

[0749] Example DI 4. The filtration system of any example herein, particularly any one of examples DI to D12, wherein each medium aperture has an aperture size that is not greater than 300 microns.

[0750] Example DI 5. The filtration system of any example herein, particularly any one of examples DI to D12, wherein each medium aperture has an aperture size that is not greater than 200 microns. [0751] Example DI 6. The filtration system of any example herein, particularly any one of examples DI to D12, wherein each medium aperture has an aperture size that is not greater than 100 microns.

[0752] Example DI 7. The filtration system of any example herein, particularly any one of examples DI to D12, wherein each medium aperture has an aperture size that is not greater than 40 microns.

[0753] Example DI 8. The filtration system of any example herein, particularly any one of examples DI to D12, wherein each medium aperture has an aperture size that is not greater than 5 microns.

[0754] Example DI 9. The filtration system of any example herein, particularly any one of examples DI to D12, wherein each medium aperture has an aperture size that is not greater than 1 micron.

[0755] Example D20. The filtration system of any example herein, particularly any one of examples DI to DI 9, further comprising a watertight vibration motor.

[0756] Example D21. The filtration system of any example herein, particularly any one of examples DI to D20, further comprising at least one ultrasonic transducer.

[0757] Example D22. The filtration system of any example herein, particularly any one of examples DI to D21, wherein the discs comprise copper.

[0758] Example D23. The filtration system of any example herein, particularly any one of examples DI to D22, wherein the intake pipe comprises an expansion chamber having an expansion chamber diameter that is at least twice as great as a minimal diameter of the intake pipe.

[0759] Example D24. The filtration system of any example herein, particularly example D23, wherein the expansion chamber diameter is at least three times as great as the minimal diameter of the intake pipe.

[0760] Example D25. The filtration system of any example herein, particularly any one of examples DI to D24, wherein the filtration system is devoid of a pressure vessel disposed around any of the filtering sub-assemblies. [0761] Example D26. The filtration system of any example herein, particularly any one of examples DI to D25, further comprising a driving gear attached to a shaft extending from the drive motor, and a driven gear meshed with the driving gear, wherein the driven gear is attached to the rotatable support wall.

[0762] Example D27. The filtration system of any example herein, particularly example D26, wherein each filtering sub-assembly further comprises a planetary gears, and wherein the driven gear comprises a first gear portion meshed with the driving gear, and a second gear portion meshed with the planetary gears.

[0763] Example D28. The filtration system of any example herein, particularly example D26, further comprising a plurality of sub-assembly drive motors, each sub-assembly drive motor configured to rotate a corresponding one of the plurality of filtering sub-assemblies via a corresponding sub-assembly transmission.

[0764] Example D28. The filtration system of any example herein, particularly example D27, wherein each sub-assembly transmission comprises a sub-assembly drive gear attached to the sub-assembly drive motor and rotatable thereby, and a sub-assembly main gear attached to the filtering sub-assembly and meshed with the sub-assembly drive gear.

[0765] Example D29. The filtration system of any example herein, particularly any one of examples D27 or D28, wherein each filtering sub-assembly further comprises an internal pressure sensor, disposed within an internal space defined between the filter medium and the sub-assembly axis.

[0766] Example D30. The filtration system of any example herein, particularly example D29, further comprising at least one external pressure sensor, attached to a component of the filtration system and configured to measure pressure in an environment surrounding the filter medium.

[0767] Example El. A filtration system, comprising: a frame comprising at least one frame transverse wall, the at least one frame transverse wall comprising at least one wall window; at least one rotatable filtering assembly attached to the frame and comprising: at least one rotatable support wall configured to rotate around a main axis; and a filter medium coupled to the at least one rotatable support wall, the filter medium comprising a plurality of medium apertures; an intake pipe comprising at least one pipe inflow opening in fluid communication with the filter medium; wherein the at least one window is at least partially facing the filter medium.

[0768] Example E2. The filtration system of any example herein, particularly example El, wherein the at least one frame transverse wall comprises at least two frame transverse walls, positioned on opposite sides of the rotatable filtering assembly along the main axis.

[0769] Example E3. The filtration system of any example herein, particularly any one of examples El or E2, wherein the at least one frame transverse wall comprises at least two wall windows, each facing a different portion of the filter medium.

[0770] Example E4. The filtration system of any example herein, particularly any one of examples El to E3, wherein each wall window further comprises a window cover attached thereto, wherein the window cover is configured to transition between an open position, in which the corresponding wall window is exposed, to a closed position, in which the wall window is covered by the corresponding window cover.

[0771] Example E5. The filtration system of any example herein, particularly example E4, wherein each window cover is hinged to the wall window.

[0772] Example E6. The filtration system of any example herein, particularly any one of examples El to E5, wherein each wall window is shaped as a trapezoid.

[0773] Example E7. The filtration system of any example herein, particularly any one of examples El to E5, wherein each wall window is hourglass-shaped.

[0774] Example E8. The filtration system of any example herein, particularly any one of examples El to E7, wherein each wall window comprises a funneling extension.

[0775] Example E9. The filtration system of any example herein, particularly example E8, wherein each funneling extension comprises a tapering inner surface. [0776] Example E 10. The filtration system of any example herein, particularly any one of examples El to E9, wherein each medium aperture has an aperture size that is not greater than 350 microns.

[0777] Example El l. The filtration system of any example herein, particularly any one of examples El to E9, wherein each medium aperture has an aperture size that is not greater than 300 microns.

[0778] Example E 12. The filtration system of any example herein, particularly any one of examples El to E9, wherein each medium aperture has an aperture size that is not greater than 200 microns.

[0779] Example E 13. The filtration system of any example herein, particularly any one of examples El to E9, wherein each medium aperture has an aperture size that is not greater than 100 microns.

[0780] Example E 14. The filtration system of any example herein, particularly any one of examples El to E9, wherein each medium aperture has an aperture size that is not greater than 40 microns.

[0781] Example E15. The filtration system of any example herein, particularly any one of examples El to E9, wherein each medium aperture has an aperture size that is not greater than 5 microns.

[0782] Example El 6. The filtration system of any example herein, particularly any one of examples El to E9, wherein each medium aperture has an aperture size that is not greater than 1 micron.

[0783] Example E 17. The filtration system of any example herein, particularly any one of examples El to El 6, further comprising a watertight vibration motor.

[0784] Example El 8. The filtration system of any example herein, particularly any one of examples El to E17, further comprising at least one ultrasonic transducer.

[0785] Example El 9. The filtration system of any example herein, particularly any one of examples El to El 8, wherein the filter medium comprises copper. [0786] Example E20. The filtration system of any example herein, particularly any one of examples El to El 9, wherein the intake pipe comprises an expansion chamber having an expansion chamber diameter that is at least twice as great as a minimal diameter of the intake pipe.

[0787] Example E21. The filtration system of any example herein, particularly example E20, wherein expansion chamber diameter is at least three times as great as the minimal diameter of the intake pipe.

[0788] Example E22. The filtration system of any example herein, particularly any one of examples El to E21, further comprising at least one float.

[0789] Example E23. The filtration system of any example herein, particularly example E22, wherein each float is an adjustable float.

[0790] Example E24. The filtration system of any example herein, particularly example E23, wherein each adjustable float comprises a float liquid port and a float gas port.

[0791] Example E25. The filtration system of any example herein, particularly example E23, wherein each adjustable float comprises a float water port and a float air port.

[0792] Example E26. The filtration system of any example herein, particularly any one of examples E22 to E25, wherein the float defines a plane which is orthogonal to the main axis.

[0793] Example E27. The filtration system of any example herein, particularly any one of examples E22 to E26, further comprising at least one weight coupled to the frame, opposite to the at least one float.

[0794] Example E28. The filtration system of any example herein, particularly any one of examples El to E27, wherein the frame comprises a bottom plate disposed below the at least one rotatable filtering assembly.

[0795] Example E29. The filtration system of any example herein, particularly any one of examples El to E28, further comprising an anchoring structure, the anchoring structure comprising at least one anchoring arm coupled to the frame at an arm coupling end thereof, and configured to be ground to a shore at an opposite arm grounding end thereof. [0796] Example E30. The filtration system of any example herein, particularly any one of examples El to E28, further comprising: a vertical column; and a height adjustment assembly configured to elevate or lower one or more of the at least one rotatable filtering assemblies along the vertical column.

[0797] Example E31. The filtration system of any example herein, particularly any one of examples El to E28, further comprising: at least one winch; and at least one elongated flexible member coupled to the frame, and rotatable around the at least one winch.

[0798] Example E32. The filtration system of any example herein, particularly any one of examples El to E31, wherein the filtration system is devoid of a pressure vessel disposed around any of the at least one filter medium.

[0799] Example Fl. A filtration system, comprising: at least one rotatable filtering assembly comprising: at least one rotatable support wall configured to rotate around a main axis; and a filter medium coupled to the at least one rotatable support wall, the filter medium comprising a plurality of medium apertures; an intake pipe comprising at least one pipe inflow opening in fluid communication with the filter medium; at least one adjustable float configured to control the buoyancy of the rotatable filtering assembly, relative to a water level of a water source, when the rotatable filtering assembly is at least partially submersed within the water source.

[0800] Example F2. The filtration system of any example herein, particularly example Fl, further comprising a frame, wherein the at least one rotatable filtering assembly is attached to the frame, and wherein the at least one adjustable float is attached to the frame. [0801] Example F3. The filtration system of any example herein, particularly example F2, wherein the frame comprises two frame transverse walls on opposite sides of the rotatable filtering assembly, and wherein the at least one float extends through the frame transverse walls.

[0802] Example F4. The filtration system of any example herein, particularly any one of examples Fl to F3, wherein the at least one adjustable float comprises a float water or liquid port and a float air or gas port.

[0803] Example F5. The filtration system of any example herein, particularly any one of examples Fl to F4, wherein the at least one adjustable float defines a plane which is orthogonal to the main axis.

[0804] Example F6. The filtration system of any example herein, particularly any one of examples Fl to F5, further comprising at least one weight coupled to the frame, opposite to the at least one adjustable float.

[0805] Example F7. The filtration system of any example herein, particularly any one of examples Fl to F6, wherein the at least one adjustable float comprises at least two adjustable floats.

[0806] Example F8. The filtration system of any example herein, particularly any one of examples Fl to F7, wherein each medium aperture has an aperture size that is not greater than 350 microns.

[0807] Example F9. The filtration system of any example herein, particularly any one of examples Fl to F7, wherein each medium aperture has an aperture size that is not greater than 300 microns.

[0808] Example F10. The filtration system of any example herein, particularly any one of examples Fl to F7, wherein each medium aperture has an aperture size that is not greater than 200 microns.

[0809] Example Fl 1. The filtration system of any example herein, particularly any one of examples Fl to F7, wherein each medium aperture has an aperture size that is not greater than 100 microns. [0810] Example F12. The filtration system of any example herein, particularly any one of examples Fl to F7, wherein each medium aperture has an aperture size that is not greater than 40 microns.

[0811] Example F13. The filtration system of any example herein, particularly any one of examples Fl to F7, wherein each medium aperture has an aperture size that is not greater than 5 microns.

[0812] Example F14. The filtration system of any example herein, particularly any one of examples Fl to F7, wherein each medium aperture has an aperture size that is not greater than 1 micron.

[0813] Example F15. The filtration system of any example herein, particularly any one of examples Fl to Fl 4, further comprising a watertight vibration motor.

[0814] Example Fl 6. The filtration system of any example herein, particularly any one of examples Fl to Fl 5, further comprising at least one ultrasonic transducer.

[0815] Example F17. The filtration system of any example herein, particularly any one of examples Fl to Fl 6, wherein the filter medium comprises copper.

[0816] Example F18. The filtration system of any example herein, particularly any one of examples Fl to F17, wherein the filtration system is devoid of a pressure vessel disposed around any of the at least one filter medium.

[0817] Example Gl. A filtration system, comprising: a vertical column; at least one frame movable along the vertical column; at least one rotatable filtering assembly coupled to the at least one frame and comprising: at least one rotatable support wall configured to rotate around a main axis; and a filter medium coupled to the at least one rotatable support wall, the filter medium comprising a plurality of medium apertures; an intake pipe comprising at least one pipe inflow opening in fluid communication with the filter medium; and a height adjustment assembly configured to elevate or lower one or more of the at least one rotatable filtering assemblies along the vertical column.

[0818] Example G2. The filtration system of any example herein, particularly example Gl, wherein the at least one frame comprises a single frame movable along the vertical column, and wherein the at least one filtering assembly comprises at least two filtering assemblies coupled to the single frame.

[0819] Example G3. The filtration system of any example herein, particularly example Gl, wherein the at least one frame comprises at least two frames, and wherein the at least one filtering assembly comprises at least two filtering assemblies, each coupled to a separate one of the at least two frames.

[0820] Example G4. The filtration system of any example herein, particularly example G3, wherein the height adjustment assembly is configured to separately elevate or lower each of the at least two frames.

[0821] Example G5. The filtration system of any example herein, particularly any one of examples Gl to G4, wherein the height adjustment assembly comprises at least one of: one or more hydraulic pistons, one or more pneumatic pistons, one or more rack and pinion assemblies, one or more electric actuators, and/or one or more pulleys.

[0822] Example G6. The filtration system of any example herein, particularly any one of examples Gl to G5, wherein each medium aperture has an aperture size that is not greater than 350 microns.

[0823] Example G7. The filtration system of any example herein, particularly any one of examples Gl to G5, wherein each medium aperture has an aperture size that is not greater than 300 microns.

[0824] Example G8. The filtration system of any example herein, particularly any one of examples Gl to G5, wherein each medium aperture has an aperture size that is not greater than 200 microns. [0825] Example G9. The filtration system of any example herein, particularly any one of examples G1 to G5, wherein each medium aperture has an aperture size that is not greater than 100 microns.

[0826] Example GIO. The filtration system of any example herein, particularly any one of examples G1 to G5, wherein each medium aperture has an aperture size that is not greater than 40 microns.

[0827] Example Gi l. The filtration system of any example herein, particularly any one of examples G1 to G5, wherein each medium aperture has an aperture size that is not greater than 5 microns.

[0828] Example G12. The filtration system of any example herein, particularly any one of examples G1 to G5, wherein each medium aperture has an aperture size that is not greater than 1 micron.

[0829] Example G 13. The filtration system of any example herein, particularly any one of examples G1 to G12, further comprising at least one ultrasonic transducer.

[0830] Example G14. The filtration system of any example herein, particularly any one of examples G1 to G13, wherein the filter medium comprises copper.

[0831] Example G15. The filtration system of any example herein, particularly any one of examples G1 to G14, wherein the filtration system is devoid of a pressure vessel disposed around any of the at least one filter medium.

[0832] Example Hl. A filtration system, comprising: a plurality of filtering assemblies, each filtering assembly comprising: two rotatable support walls configured to rotate around a main axis of the corresponding filtering assembly; a screen mesh extending between and coupled to the two rotatable support walls, the screen mesh comprising a plurality of medium apertures; an intake pipe comprising at least one pipe inflow opening in fluid communication with each screen mesh of the plurality of filtering assemblies; at least one drive motor in mechanical communication with at least one of the plurality of filtering assemblies.

[0833] Example H2. The filtration system of any example herein, particularly example Hl, wherein the intake pipe comprises a plurality of pipe branches, wherein each pipe branch comprises at least one pipe inflow opening which is in fluid communication with one of the plurality of screen meshes.

[0834] Example H3. The filtration system of any example herein, particularly any one of examples Hl or H2, wherein the at least one drive motor comprises a single drive motor, configured to simultaneously rotate all of the plurality of filtering assemblies.

[0835] Example H4. The filtration system of any example herein, particularly any one of examples Hl or H2, wherein the at least one drive motor comprises a plurality of drive motors, each of which is configured to rotate a different one of the plurality of filtering assemblies.

[0836] Example H5. The filtration system of any example herein, particularly any one of examples Hl to H4, wherein the main axes of at least two of the plurality of filtering assemblies are parallel to each other, and are offset from each other.

[0837] Example H6. The filtration system of any example herein, particularly any one of examples Hl to H4, wherein all of the main axes of all of the plurality of filtering assemblies coincide with each other, together forming a single continuous main axis.

[0838] Example H7. The filtration system of any example herein, particularly any one of examples Hl to H4, wherein the plurality of filtering assemblies are vertically arranged.

[0839] Example H8. The filtration system of any example herein, particularly any one of examples Hl to H6, wherein the at least one drive motor is a watertight drive motor.

[0840] Example H9. The filtration system of any example herein, particularly example H8, wherein the at least one watertight drive motor is a water motor.

[0841] Example H10. The filtration system of any example herein, particularly any one of examples Hl to H9, further comprising a frame, wherein the plurality of filtering assemblies are attached to the frame. [0842] Example Hl l. The filtration system of any example herein, particularly example H10, wherein the frame comprises an immersion depth marking.

[0843] Example H12. The filtration system of any example herein, particularly example Hl l, wherein the immersion depth marking comprises a printed marking.

[0844] Example Hl 3. The filtration system of any example herein, particularly any one of examples Hl 1 or H12, wherein the immersion depth marking comprises a slot and/or a groove.

[0845] Example H14. The filtration system of any example herein, particularly any one of examples Hl to H13, wherein each medium aperture has an aperture size that is not greater than 350 microns.

[0846] Example H15. The filtration system of any example herein, particularly any one of examples Hl to H13, wherein each medium aperture has an aperture size that is not greater than 350 microns.

[0847] Example H16. The filtration system of any example herein, particularly any one of examples Hl to H13, wherein each medium aperture has an aperture size that is not greater than 300 microns.

[0848] Example H17. The filtration system of any example herein, particularly any one of examples Hl to H13, wherein each medium aperture has an aperture size that is not greater than 200 microns.

[0849] Example Hl 8. The filtration system of any example herein, particularly any one of examples Hl to H14, wherein each medium aperture has an aperture size that is not greater than 100 microns.

[0850] Example H19. The filtration system of any example herein, particularly any one of examples Hl to H13, wherein each medium aperture has an aperture size that is not greater than 40 microns.

[0851] Example H20. The filtration system of any example herein, particularly any one of examples Hl to H13, wherein each medium aperture has an aperture size that is not greater than 5 microns. [0852] Example H21. The filtration system of any example herein, particularly any one of examples Hl to H13, wherein each medium aperture has an aperture size that is not greater than 1 micron.

[0853] Example H22. The filtration system of any example herein, particularly any one of examples Hl to H21, wherein each screen mesh comprises copper.

[0854] Example H23. The filtration system of any example herein, particularly any one of examples Hl to H22, further comprising at least one float.

[0855] Example H24. The filtration system of any example herein, particularly example H23, wherein each float is an adjustable float.

[0856] Example H25. The filtration system of any example herein, particularly example H24, wherein each adjustable float comprises a float liquid port and a float gas port.

[0857] Example H26. The filtration system of any example herein, particularly example H24, wherein each adjustable float comprises a float water port and a float air port.

[0858] Example H27. The filtration system of any example herein, particularly any one of examples Hl to H26, wherein the filtration system is devoid of a pressure vessel disposed around any screen mesh.

[0859] Example II. A filtration system, comprising: at least one rotatable filtering assembly comprising: at least one rotatable support wall configured to rotate around a main axis; and a filter medium coupled to the at least one rotatable support wall, the filter medium comprising a plurality of medium apertures; an intake pipe comprising at least one pipe inflow opening in fluid communication with the filter medium; a drive motor in mechanical communication with the at least one rotatable filtering assembly; a controller for controlling the drive motor to rotate the at least one rotatable filtering assembly around the main axis; and a camera configured to acquire images of at least a portion of the filter medium.

[0860] Example 12. The filtration system of any example herein, particularly example II, further comprising a camera mount, wherein the camera is attached to the camera mount.

[0861] Example 13. The filtration system of any example herein, particularly example 12, further comprising a frame, wherein the at least one rotatable filtering assembly is attached to the frame, and wherein the camera mount is attached to the frame.

[0862] Example 14. The filtration system of any example herein, particularly any one of examples 12 or 13, wherein the camera mount comprises a stationary support member.

[0863] Example 15. The filtration system of any example herein, particularly any one of examples 12 to 14, wherein the camera mount is an adjustable camera mount, comprising at least one link member which is movable relative to at least one joint thereof.

[0864] Example 16. The filtration system of any example herein, particularly any one of examples II to 15, wherein each medium aperture has an aperture size that is not greater than 350 microns.

[0865] Example 17. The filtration system of any example herein, particularly any one of examples II to 15, wherein each medium aperture has an aperture size that is not greater than 300 microns.

[0866] Example 18. The filtration system of any example herein, particularly any one of examples II to 15, wherein each medium aperture has an aperture size that is not greater than 200 microns.

[0867] Example 19. The filtration system of any example herein, particularly any one of examples II to 15, wherein each medium aperture has an aperture size that is not greater than 100 microns.

[0868] Example 110. The filtration system of any example herein, particularly any one of examples II to 15, wherein each medium aperture has an aperture size that is not greater than 40 microns. [0869] Example Il l. The filtration system of any example herein, particularly any one of examples II to 15, wherein each medium aperture has an aperture size that is not greater than 5 microns.

[0870] Example 112. The filtration system of any example herein, particularly any one of examples II to 15, wherein each medium aperture has an aperture size that is not greater than 1 micron.

[0871] Example 113. The filtration system of any example herein, particularly any one of examples II to 112, wherein the drive motor is a watertight motor.

[0872] Example 114. The filtration system of any example herein, particularly example 113, wherein the watertight motor is a water motor.

[0873] Example 115. The filtration system of any example herein, particularly any one of examples II to 114, wherein the controller is a watertight controller.

[0874] Example 116. The filtration system of any example herein, particularly any one of examples II to 115, further comprising a vibration motor.

[0875] Example 117. The filtration system of any example herein, particularly any one of examples II to 116, further comprising at least one ultrasonic transducer.

[0876] Example 118. The filtration system of any example herein, particularly any one of examples II to 117, wherein the filter medium comprises copper.

[0877] Example 119. The filtration system of any example herein, particularly any one of examples II to 118, further comprising at least one float.

[0878] Example 120. The filtration system of any example herein, particularly example 119, wherein each float is an adjustable float.

[0879] Example 121. The filtration system of any example herein, particularly example 120, wherein each adjustable float comprises a float liquid port and a float gas port.

[0880] Example 122. The filtration system of any example herein, particularly example 120, wherein each adjustable float comprises a float water port and a float air port. [0881] Example 123. The filtration system of any example herein, particularly any one of examples II to 122, further comprising an anchoring structure, the anchoring structure comprising at least one anchoring arm coupled to the frame at an arm coupling end thereof, and configured to be ground to a shore at an opposite arm grounding end thereof.

[0882] Example 124. The filtration system of any example herein, particularly any one of examples II to 122, at least one winch; and at least one elongated flexible member coupled to the frame, and rotatable around the at least one winch.

[0883] Example 125. The filtration system of any example herein, particularly any one of examples II to 122, a vertical column; and a height adjustment assembly configured to elevate or lower one or more of the at least one rotatable filtering assemblies along the vertical column.

[0884] Example 126. The filtration system of any example herein, particularly any one of examples II to 125, wherein the filtration system is devoid of a pressure vessel disposed around any of the at least one filter medium.

[0885] Example JI. A filtration system, comprising: at least one rotatable filtering assembly comprising: at least one rotatable support wall configured to rotate around a main axis; and a filter medium coupled to the at least one rotatable support wall, the filter medium comprising a plurality of medium apertures; an intake pipe comprising at least one pipe inflow opening in fluid communication with the filter medium; at least one movable float; a float driving gear in mechanical communication with the at least one movable float via a float transmission assembly, configured to control the position of the at least one movable float relative to the main axis.

[0886] Example J2. The filtration system of any example herein, particularly example JI, further comprising a frame, wherein the at least one rotatable filtering assembly is attached to the frame, and wherein the at least one movable float is pivotably attached to the frame.

[0887] Example J3. The filtration system of any example herein, particularly example J2, wherein the at least one movable float comprises two movable floats.

[0888] Example J4. The filtration system of any example herein, particularly example J3, further comprising two float arms, each float arms comprising an engagement end which is attached to the frame at a float arm pivot, and a support end to which a corresponding movable float is attached.

[0889] Example J5. The filtration system of any example herein, particularly example J4, wherein both float arm pivots are laterally disposed on opposite sides of the main axis.

[0890] Example J6. The filtration system of any example herein, particularly any one of examples J4 or J5, wherein both float arm pivots are laterally aligned.

[0891] Example J7. The filtration system of any example herein, particularly any one of examples J4 to J6, wherein both float arm pivots are aligned with the main axis.

[0892] Example J8. The filtration system of any example herein, particularly any one of examples J4 to J7, wherein the float transmission assembly comprises a float driving gear rotatable by the float displacement motor, a first transfer gear meshed with the float driving gear, and a second transfer gear aligned with the first transfer gear, wherein the first transfer gear and the second transfer gear are configured to rotate in opposite directions.

[0893] Example J9. The filtration system of any example herein, particularly example J8, wherein the first transfer gear and the second transfer gear are disposed around the intake pipe.

[0894] Example J10. The filtration system of any example herein, particularly any one of examples J8 or J9, wherein the first transfer gear and the second transfer gear are rotatable around the main axis. [0895] Example JI 1. The filtration system of any example herein, particularly any one of examples J8 to J10, wherein the first transfer gear further comprises a first gear extension, and wherein the float transmission assembly further comprises one or more planetary gears meshed with extension teeth of the first gear extension, and with second gear inner teeth of the second transfer gear.

[0896] Example J12. The filtration system of any example herein, particularly example JI 1, wherein both float arm pivots are laterally disposed on opposite sides of the first transfer gear and the second transfer gear.

[0897] Example J13. The filtration system of any example herein, particularly any one of examples JI 1 or J12, wherein each engagement end comprises engagement teeth which are meshed with outer teeth of a different one of the first transfer gear and the second transfer gear.

[0898] Example J14. The filtration system of any example herein, particularly any one of examples J4 to J13, wherein both movable floats are rotatable in opposite directions to each other, around their respective float arm pivots.

[0899] Example J15. The filtration system of any example herein, particularly any one of examples JI to J14, wherein the float drive motor is a watertight float drive motor.

[0900] Example J16. The filtration system of any example herein, particularly any one of examples JI to J15, wherein the at least one movable float is a movable adjustable float that comprises a float water or liquid port and a float air or gas port.

[0901] Example J17. The filtration system of any example herein, particularly any one of examples JI to J 16, wherein each medium aperture has an aperture size that is not greater than 350 microns.

[0902] Example JI 8. The filtration system of any example herein, particularly any one of examples JI to J 16, wherein each medium aperture has an aperture size that is not greater than 300 microns.

[0903] Example J19. The filtration system of any example herein, particularly any one of examples JI to J 16, wherein each medium aperture has an aperture size that is not greater than 200 microns. [0904] Example J20. The filtration system of any example herein, particularly any one of examples JI to J 16, wherein each medium aperture has an aperture size that is not greater than 100 microns.

[0905] Example J21. The filtration system of any example herein, particularly any one of examples JI to J 16, wherein each medium aperture has an aperture size that is not greater than 40 microns.

[0906] Example J22. The filtration system of any example herein, particularly any one of examples JI to J 16, wherein each medium aperture has an aperture size that is not greater than 5 microns.

[0907] Example J23. The filtration system of any example herein, particularly any one of examples JI to J 16, wherein each medium aperture has an aperture size that is not greater than 1 micron.

[0908] Example J24. The filtration system of any example herein, particularly any one of examples JI to J23, further comprising a watertight vibration motor.

[0909] Example J25. The filtration system of any example herein, particularly any one of examples JI to J24, further comprising at least one ultrasonic transducer.

[0910] Example J26. The filtration system of any example herein, particularly any one of examples JI to J25, wherein the filter medium comprises copper.

[0911] Example J27. The filtration system of any example herein, particularly any one of examples JI to J26, wherein the filtration system is devoid of a pressure vessel disposed around any of the at least one filter medium.

[0912] Example KI. A filtration system, comprising: at least one rotatable filtering assembly comprising: at least one rotatable support wall configured to rotate around a main axis; and a filter medium coupled to the at least one rotatable support wall, the filter medium comprising a plurality of medium apertures; an intake pipe comprising at least one pipe inflow opening in fluid communication with the filter medium; a bubble generator comprising: a hollow enclosure defining a lumen and a plurality of bubble apertures in fluid communication with the lumen; and a hose in fluid communication with the lumen; wherein the plurality of bubble apertures are facing the filter medium of the at least one rotatable filtering assembly.

[0913] Example K2. The filtration system of any example herein, particularly example JI, wherein the bubble apertures span across the entire horizontal planar projection of the filter medium.

[0914] Example K3. The filtration system of any example herein, particularly any one of examples KI or K2, wherein the hose is flexible.

[0915] Example K4. The filtration system of any example herein, particularly any one of examples KI to K3, further comprising at least one tether attached to the hollow enclosure..

[0916] Example K5. The filtration system of any example herein, particularly any one of examples KI to K3, wherein the at least one rotatable filtering assembly comprises a plurality of filtering assemblies;

[0917] Example K6. The filtration system of any example herein, particularly example K5, wherein the intake pipe comprises a plurality of pipe branches, wherein each pipe branch is in fluid communication with one of the plurality of filter mediums.

[0918] Example K7. The filtration system of any example herein, particularly example K6, wherein each pipe branch is flexible.

[0919] Example K8. The filtration system of any example herein, particularly any one of examples K5 to K7, wherein the plurality of filtering plurality of filtering assemblies are coupled to each other via flexible connectors. [0920] Example K9. The filtration system of any example herein, particularly any one of examples KI to K8, wherein the at least one rotatable support wall of each of the at least one filtering assemblies comprises two rotatable support walls, and wherein each filter medium comprises a screen mesh extending between and coupled to the two corresponding rotatable support walls.

[0921] Example K10. The filtration system of any example herein, particularly any one of examples KI to K9, wherein each medium aperture has an aperture size that is not greater than 350 microns.

[0922] Example KI 1. The filtration system of any example herein, particularly any one of examples KI to K9, wherein each medium aperture has an aperture size that is not greater than 300 microns.

[0923] Example K12. The filtration system of any example herein, particularly any one of examples KI to K9, wherein each medium aperture has an aperture size that is not greater than 200 microns.

[0924] Example K14. The filtration system of any example herein, particularly any one of examples KI to K9, wherein each medium aperture has an aperture size that is not greater than 100 microns.

[0925] Example K15. The filtration system of any example herein, particularly any one of examples KI to K9, wherein each medium aperture has an aperture size that is not greater than 40 microns.

[0926] Example K16. The filtration system of any example herein, particularly any one of examples KI to K9, wherein each medium aperture has an aperture size that is not greater than 5 microns.

[0927] Example K17. The filtration system of any example herein, particularly any one of examples KI to K9, wherein each medium aperture has an aperture size that is not greater than 1 micron.

[0928] Example KI 8. The filtration system of any example herein, particularly any one of examples KI to K17, further comprising at least one drive motor in mechanical communication with the at least one rotatable filtering assembly. [0929] Example K19. The filtration system of any example herein, particularly example K8, wherein the at least one drive motor is a watertight motor.

[0930] Example K20. The filtration system of any example herein, particularly example K19, wherein the watertight motor is a water motor..

[0931] Example K21. The filtration system of any example herein, particularly any one of examples KI to K20, further comprising a vibration motor.

[0932] Example K22. The filtration system of any example herein, particularly any one of examples KI to K21, further comprising at least one ultrasonic transducer.

[0933] Example K23. The filtration system of any example herein, particularly any one of examples KI to K22, wherein the at least one filter medium comprises copper.

[0934] Example K24. The filtration system of any example herein, particularly any one of examples KI to K23, wherein the hollow enclosure comprises copper.

[0935] Example K25. The filtration system of any example herein, particularly any one of examples KI to K24, further comprising a guiding chamber having a chamber wall disposed around the at least one rotatable filtering assembly and extending upward from a chamber lower end to a chamber upper end.

[0936] Example K26. The filtration system of any example herein, particularly example K25, wherein the chamber lower end is attached to the bubble generator.

[0937] Example K27. The filtration system of any example herein, particularly example K25 or K26, wherein the chamber wall defines a rectangular cross sectional shape.

[0938] Example K28. The filtration system of any example herein, particularly example K25 or K26, wherein the chamber wall defines a circular cross sectional shape.

[0939] Example K29. The filtration system of any example herein, particularly any one of examples K25 to K28, wherein the guiding chamber has a wider cross-sectional area at the chamber lower end, and a narrower cross-sectional area at the chamber upper end. [0940] Example K30. The filtration system of any example herein, particularly any one of examples KI to 9 wherein the filtration system is devoid of a pressure vessel disposed around any of the at least one filter medium.

[0941] It is appreciated that certain features of the disclosure, which are, for clarity, described in the context of separate examples, may also be provided in combination in a single example. Conversely, various features of the disclosure, which are, for brevity, described in the context of a single example, may also be provided separately or in any suitable sub-combination or as suitable in any other described example of the disclosure. No feature described in the context of an example is to be considered an essential feature of that example, unless explicitly specified as such.

[0942] In view of the many possible examples to which the principles of the disclosure may be applied, it should be recognized that the illustrated examples are only preferred examples and should not be taken as limiting the scope. Rather, the scope is defined by the following claims. We therefore claim all that comes within the scope and spirit of these claims.

Claims

1. A filtration system, comprising: at least one rotatable filtering assembly, comprising: at least one rotatable support wall configured to rotate around a main axis; and a filter medium coupled to the at least one rotatable support wall, the filter medium comprising a plurality of medium apertures, the plurality of medium apertures comprising a plurality of filtration apertures; an intake pipe defining a minimal intake pipe cross-sectional area, wherein the intake pipe comprises at least one pipe inflow opening in fluid communication with the filter medium; a watertight drive motor in mechanical communication with the at least one rotatable filtering assembly; and a watertight controller for controlling the watertight drive motor to rotate the at least one rotatable filtering assembly around the main axis, the angular speed of rotation not exceeding 6 degrees per second at any moment when the watertight controller is in a filtering mode.

2. The filtration system of claim 1, wherein each filtration aperture has an aperture size that is not greater than 350 microns.

3. The filtration system of claim 1, wherein each filtration aperture has an aperture size that is not greater than 200 microns.

4. The filtration system of claim 1, wherein each filtration aperture has an aperture size that is not greater than 40 microns.

5. The filtration system of claim 1, wherein each filtration aperture has an aperture size that is not greater than 5 microns.

6. The filtration system of claim 1, wherein each filtration aperture has an aperture size that is not greater than 1 micron.

7. The filtration system of any one of claims 1 to 6, wherein each filtration aperture defines an aperture area, wherein a ratio between a sum of the aperture areas of all of the filtration apertures to the minimal intake pipe cross-sectional area is greater than 4. The filtration system of any one of claims 1 to 6, wherein each filtration aperture defines an aperture area, wherein a ratio between a sum of the aperture areas of all of the filtration apertures to the minimal intake pipe cross-sectional area is greater than 7. The filtration system of any one of claims 1 to 6, wherein each filtration aperture defines an aperture area, wherein a ratio between a sum of the aperture areas of all of the filtration apertures to the minimal intake pipe cross-sectional area is greater than 8. The filtration system of any one of claims 1 to 6, wherein each filtration aperture defines an aperture area, wherein a ratio between a sum of the aperture areas of all of the filtration apertures to the minimal intake pipe cross-sectional area is greater than 10. The filtration system of any one of claims 1 to 10, wherein at least 50% of the medium apertures are filtration apertures. The filtration system of any one of claims 1 to 10, wherein at least 70% of the medium apertures are filtration apertures. The filtration system of any one of claims 1 to 10, wherein all of the medium apertures are filtration apertures. The filtration system of any one of claims 1 to 13, further comprising a frame, wherein the at least one rotatable filtering assembly is coupled to the frame. The filtration system of claim 14, wherein the watertight drive motor is attached to the frame. The filtration system of claim 14 or 15, further comprising at least one float. The filtration system of claim 16, wherein each float is an adjustable float. The filtration system of claim 17, wherein each adjustable float comprises a float liquid port and a float gas port. The filtration system of any one of claims 16 to 18, wherein the float defines a plane which is orthogonal to the main axis. The filtration system of any one of claims 16 to 19, further comprising at least one weight coupled to the frame, opposite to the at least one float. The filtration system of any one of claims 14 to 20, wherein the frame comprises a bottom plate disposed below the at least one rotatable filtering assembly. The filtration system of any one of claims 14 to 21, wherein the frame further comprises at least one immersion depth marking. The filtration system of any one of claims 14 to 22, wherein the frame further comprises at least one frame transverse wall, wherein each frame transverse wall comprises at least one frame window which at least partially faces a portion of the filter medium. The filtration system of claim 23, wherein the frame further comprises at least one window cover covering a respective frame window, wherein each window cover is configured to transition between a closed position and an open position. The filtration system of any one of claims 14 to 24, further comprising an anchoring structure, the anchoring structure comprising at least one anchoring arm coupled to the frame at an arm coupling end thereof, and configured to be ground to a shore at an opposite arm grounding end thereof. The filtration system of any one of claims 14 to 24, further comprising an elevation assembly comprising: a vertical column; and a height adjustment assembly configured to elevate or lower one or more of the at least one rotatable filtering assemblies along the vertical column. The filtration system of any one of claims 14 to 24, further comprising an offshore platform connection assembly comprising: at least one winch; and at least one elongated flexible member coupled to the frame, and rotatable around the at least one winch. The filtration system of any one of claims 1 to 27, wherein the watertight drive motor is a water motor. The filtration system of any one of claims 1 to 28, further comprising a watertight vibration motor. The filtration system of any one of claims 1 to 29, further comprising at least one ultrasonic transducer. The filtration system of any one of claims 1 to 30, wherein the filter medium comprises copper. The filtration system of any one of claims 1 to 31, wherein the intake pipe comprises an expansion chamber having an expansion chamber diameter that is at least twice as great as a minimal diameter of the intake pipe. The filtration system of claim 32, wherein the expansion chamber diameter is at least three times as great as the minimal diameter of the intake pipe. The filtration system of any one of claims 1 to 33, wherein the filtration system is a drum-type filtration system, wherein the rotatable filtering assembly is a drum-type filtering assembly, wherein the at least one rotatable support wall comprises two rotatable support walls, and wherein the filter medium comprises a screen mesh disposed between both rotatable support walls. The filtration system of claim 34, further comprising a spray assembly, the spray assembly comprising a spray conduit and a plurality of nozzles, wherein the spray conduit is disposed within the filter medium, and wherein the plurality of nozzles are facing an inner surface of the filter medium. The filtration system of claim 34 or 35, wherein the at least one rotatable filtering assembly comprises a plurality of rotatable filtering assemblies. The filtration system of claim 36, wherein the intake pipe comprises a plurality of pipe branches, wherein each of the pipe branches is in fluid communication with a respective one of the plurality of rotatable filtering assemblies. The filtration system of claim 36 or 37, wherein the watertight drive motor comprises a single watertight drive motor configured to apply rotational movement to any of the plurality of rotatable filtering assemblies. The filtration system of any one of claims 1 to 33, wherein the filtration system is a disc-type filtration system, wherein the rotatable filtering assembly is a disctype filtering assembly comprising a plurality of disc-type filtering sub-

202 assemblies, each defining a sub-assembly axis, each sub-assembly axis being offset from and parallel to the main axis, wherein each disc-type filtering subassembly comprises a stack of discs, wherein the filter medium is formed by the stacks of discs, and wherein the medium apertures are defined by channels formed between adjacent discs. The filtration system of claim 39, further comprising an intake chamber defined between the rotatable support wall and a stationary wall portion, wherein the stack of discs of each disc-type filtering sub-assembly defines an internal space which is in fluid communication with an offset opening defined along the rotatable support wall, wherein at least one offset opening is in fluid communication with the intake chamber, and wherein the intake chamber is in fluid communication with the at least one pipe inflow opening. The filtration system of claim 40, further comprising at least one flush tube equipped with at least one flush tube sealing flange, wherein each flush tube sealing flange is movable between an open position, spaced away from the rotatable support wall, and a closed position, sealing a respective offset opening from the intake chamber while enabling fluid communication between the flush tube and the respective internal space. The filtration system of any one of claims 1 to 33, wherein the filtration system is a coiled thread-type filtration system, wherein the rotatable filtering assembly is a coiled thread-type filtering assembly comprising a plurality of coiled threadtype filtering sub-assemblies, each defining a sub-assembly axis, each subassembly axis being offset from and parallel to the main axis, wherein each coiled thread-type filtering sub-assembly comprises a hollow hub defining a hub lumen and fluidly connected to a plurality of coiled-thread units, wherein the filter medium is formed by coiled threads of the plurality of coiled-thread units, and wherein the medium apertures are defined by spacings formed between adjacent threads. The filtration system of claim 42, further comprising an intake chamber defined between the rotatable support wall and a stationary wall portion, wherein each hub lumen is in fluid communication with an offset opening defined along the rotatable support wall, wherein at least one offset opening is in fluid

203 communication with the intake chamber, and wherein the inner chamber is in fluid communication with the at least one pipe inflow opening. The filtration system of claim 43, further comprising at least one flush tube equipped with at least one flush tube sealing flange, wherein each flush tube sealing flange is movable between an open position, spaced away from the rotatable support wall, and a closed position, sealing a respective offset opening from the intake chamber while enabling fluid communication between the flush tube and the respective hub lumen. The filtration system of any one of claims 1 to 33, wherein the filtration system is a sheaf-type filtration system, wherein the rotatable filtering assembly is a sheaf-type filtering assembly comprising a plurality of sheaf-type filtering subassemblies, each defining a sub-assembly axis, each sub-assembly axis being offset from and parallel to the main axis, wherein each sheaf-type filtering subassembly comprises a hollow hub defining a hub lumen and fluidly connected to a plurality of sheaf-like units, wherein the filter medium is formed by longitudinally extending threads arranged in a sheaf-like configuration within the plurality of sheaf-like units, and wherein the medium apertures are defined by spacings formed between adjacent threads. The filtration system of claim 45, further comprising an intake chamber defined between the rotatable support wall and a stationary wall portion, wherein each hub lumen is in fluid communication with an offset opening defined along the rotatable support wall, wherein at least one offset opening is in fluid communication with the intake chamber, and wherein the intake chamber is in fluid communication with the at least one pipe inflow opening. The filtration system of claim 46, further comprising at least one flush tube equipped with at least one flush tube sealing flange, wherein each flush tube sealing flange is movable between an open position, spaced away from the rotatable support wall, and a closed position, sealing a respective offset opening from the intake chamber while enabling fluid communication between the flush tube and the respective hub lumen.

204 The filtration system of any one of claims 1 to 47, wherein the filtration system is devoid of a pressure vessel disposed around any of the at least one filter medium. A method, comprising: disposing a filtration assembly within a water source, such that at least a portion of medium apertures of at least one filter medium of the filtration system are immersed within the water source; applying suction force through at least one at least one pipe inflow opening of an intake pipe which is in fluid communication with the filter medium, wherein the suction force is selected so as not to exceed a maximal flow rate through the filter medium, and actuating a watertight motor of the filtration assembly to rotate the at least one filter medium around a main axis, at an angular speed of rotation that does not exceed 6 degrees per second. The method of claim 49, wherein each medium aperture defines an aperture open area, and wherein the maximal flow rate and the sum of aperture areas of the immersed portion of the medium apertures are selected so as not to exceed a maximal flow velocity of 0.7 m/s through the immersed portion of the medium apertures.

205