JP2007061787A - Separation membrane module, water treatment apparatus and water treatment method using the apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separation membrane module in which a uniform gas-liquid-mixed flow can be sent to each of membrane elements even when the separation membrane module is short and the power of scraping stains on the surfaces of membrane elements can be kept and to provide a water treatment apparatus and a water treatment method. <P>SOLUTION: The separation membrane module is provided with: a plurality of membrane elements arrayed horizontally in a box unit; an air diffuser arranged below the membrane elements in the box unit; and hoods arranged below the box unit to guide the air discharged from the air diffuser into the box unit. The hood facing the arrayed direction of the membrane elements is extended to the position lower than those of the hoods other than the hood facing the arrayed direction of the membrane elements. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a separation membrane module, a water treatment apparatus, and a water treatment method using them, particularly suitable for use in wastewater treatment and water purification treatment.

  The membrane separation method is a technology that is widely used while expanding its application field because it has features such as energy saving, space saving, labor saving, and product quality improvement. Membrane separation methods include methods such as reverse osmosis, ultrafiltration, and microfiltration, and filtration membranes in the form of hollow fiber membranes, flat membranes, tubular membranes, and the like are used. As this application field, it has been used for seawater desalination, water purification, gas separation, blood purification, etc., but recently, it has been applied to wastewater treatment from the viewpoint of environmental conservation.

  As a membrane separation technology applied to wastewater treatment, the module is immersed in a treatment tank filled with wastewater such as activated sludge, and the permeate side of the module is filtered by suction using a pump or using a water level difference like a siphon. Techniques for obtaining water are known. In the activated sludge treatment, aeration is required to keep aerobic microorganisms in the treatment tank. If this diffuser is installed at the bottom of multiple membrane elements loaded in the module, solid-liquid separation can be performed while scrubbing the membrane surface of the membrane with a gas-liquid mixed flow caused by aeration. Operation at cost is possible.

  As such an immersion type module, for example, in Patent Document 1, the casing 102 includes hoods 105 and 106 having a length of 500 to 2000 mm below the membrane element 103, and the casing 102 has a lower end. A device in which an air diffuser 104 is installed is disclosed. 7 and 8 are schematic views showing an example of the module described in Patent Document 1. FIG.

Normally, when the air is discharged from the air diffuser 104 into the module 101, the apparent density of the activated sludge in the module 101 decreases, so that a phenomenon in which activated sludge outside the module flows from the opening on the lower side surface of the module 101 is seen. , Swirl flows 109 and 110 are generated. Since the swirl flows 109 and 110 push the air 108 discharged from the air diffuser 104 to the central portion of the module 101, it is difficult for the air 108 to reach the membrane elements 113 installed at both ends. If the hoods 105 and 106 having a length of 500 to 2000 mm are installed as in the module described in 1, the effect of redistributing the air 108 collected in the central portion is obtained, and the membrane elements 103 are relatively uniform. A gas-liquid mixed stream can be sent.
JP-A-5-277345

  However, even when such a configuration is adopted, the influence of the inflow from the arrangement direction of the membrane elements 103 cannot be completely eliminated. Therefore, air is difficult to disperse in both outermost membrane elements 113, and each membrane element 103 However, there is a problem that the outermost membrane elements are attracted to the central part of the module where the apparent density of the activated sludge is reduced and damaged. Moreover, when taking such a structure, since the module 101 becomes long, the water depth of a treated water tank must be taken large. Therefore, there is a problem that it cannot be installed in a treated water tank having a low water depth, and there is a problem that a cost for newly producing the treated water tank is required.

  FIG. 9 shows an example in which the module is shortened by reducing the opening at the bottom of the hood while maintaining the length of the hood of Patent Document 1. In this case, since the openings at the lower ends of the hoods 205 and 206 are narrowed, the flow of activated sludge is extremely reduced, the rising speed of the gas-liquid mixed flow is reduced, and the force for scraping the film surface is reduced. .

  An object of the present invention is to provide a separation membrane module and a water treatment device that can send a uniform gas-liquid mixed flow to each membrane element and maintain the ability to scrape off the membrane surface even when the module is short And providing a water treatment method.

In order to achieve the above object, the present invention comprises the following configurations. That is,
(1) A plurality of membrane elements arranged in a horizontal direction in a housing, an air diffuser disposed below the membrane elements in the housing, and discharged from the air diffuser below the housing A separation membrane module having a hood configured such that air is guided into the housing, wherein the hood facing the arrangement direction of the membrane elements of the hood faces the arrangement direction of the membrane elements A separation membrane module, characterized in that the separation membrane module is installed below a hood other than the above.

  (2) The separation membrane module according to (1) above, wherein the distance between the lower end of the membrane element and the air diffuser is less than 500 mm.

  (3) The separation membrane module as described in (1) or (2) above, wherein the plurality of membrane elements are arranged in the horizontal direction at intervals of 4 to 10 mm.

  (4) The separation membrane module according to any one of (1) to (3) above, wherein the membrane element is a flat membrane element using a flat membrane.

  (5) The separation membrane module according to any one of (1) to (4) above, wherein the air diffuser is not included in the hood.

  (6) A water treatment apparatus, wherein the separation membrane module according to any one of (1) to (5) is immersed in a treatment tank.

  (7) A water treatment method using the water treatment apparatus according to (6) above, wherein the water to be treated in the treatment tank is subjected to solid-liquid separation using a separation membrane module immersed in the treatment tank. A water treatment method characterized by guiding air discharged from a diffuser into a housing.

  According to the present invention, by installing the hood in the arrangement direction of the plurality of membrane elements arranged in the horizontal direction in the housing to the lower side than the other hoods, the activity from the opening at the lower end of the hood in the arrangement direction It is possible to provide a separation membrane module capable of suppressing the flow of sludge and sending a gas-liquid mixed flow uniformly to each membrane element.

  In addition, this makes it possible to reduce the length of the hood for redistributing the air collected in the center, so that the module can be shortened.

  Hereinafter, the present invention will be described in more detail based on embodiments shown in the drawings. FIG. 1 is a schematic perspective view showing an embodiment of the module of the present invention.

  The module of the present invention basically includes a plurality of membrane elements 3, a casing 2 in which the membrane elements 3 are arranged and inserted in the horizontal direction, and an air diffuser 4 disposed below the membrane elements 3 in the casing 2. The casing 2 has hoods 5 and 6 configured such that air discharged from the air diffuser 4 is guided into the casing 2 below, and the casing 2 faces in the arrangement direction of the membrane elements 3 in the hood. The hood 5 to be operated is installed below the other hoods 6.

  Here, the arrangement direction is a direction in which a plurality of membrane elements 3 are arranged, and indicates the direction AB in FIG. The hood refers to a lid between C and D in FIG. 2 from the lower end of the membrane element 3 in the housing 2 to the opening. The hood in the arrangement direction refers to a hood facing in the A-B direction, and corresponds to the hood 5.

  According to the present invention, by installing the hood 5 facing the arrangement direction of the membrane elements 3 below the hood 6, the flow of the swirling flow 9 from the arrangement direction can be prevented and discharged from the air diffuser 4. The air 8 is not uniformly collected in the center of the module 1 but is uniformly dispersed in both outermost membrane elements 13 (FIG. 2A). Further, by keeping the opening of the hood 6 large, the flow path of the swirling flow 10 can be secured, and a gas-liquid mixed flow having a sufficient speed can be supplied to each membrane element 3 (FIG. 2B).

  The housing 2 can accommodate and hold a plurality of membrane elements 3 therein, and has hoods 5 and 6 integrally or connected below the hood 5 in the arrangement direction of the membrane elements 3. However, there is no particular limitation as long as it is installed below the other hoods 6. As the shape, various shapes such as a cylindrical shape and a rectangular parallelepiped can be selected. However, when the plate-like flat membrane element 3 is used, it is preferable to select the rectangular parallelepiped so as to increase the packing density. It is preferable to open the upper and lower ends so that the swirl flow 10 by the gas passes through the housing 2 and passes between the flat membrane elements 3. Further, the casing 2 may be provided with a water collection pipe for collecting the filtrate from each membrane element 2.

  If the hood 5 is installed below the hood 6, the effect of the present invention can be obtained, but the greatest effect can be obtained when the hood 5 is installed to the lowest end of the housing 2. The length of the hood 5 is not particularly limited, but it is preferable that the hood 5 is installed from the lowermost end of the housing 2 to 300 mm. When a rectangular parallelepiped is selected as the shape of the housing 2, there are two hoods 5 in the arrangement direction of the membrane elements 3. These hoods 5 are not particularly limited in height as long as they are installed below the hood 6, but are set at the same height in order to uniformly disperse the air 8 in the direction AB. Preferably it is done.

  The hood 6 is not particularly limited as long as the hood 6 is installed above the hood 5, but the total area of the openings below the hood 6 corresponds to each of the modules 1 in which the gas-liquid mixed flow flows. It is preferable to be provided so as to be larger than the sum of the flow paths between the membrane elements 3.

  Further, in order to further uniformly disperse the air 8, in the arrangement direction of the membrane elements 3, the housing of the portion where the hood is installed is larger than the inner dimension of the portion where the plurality of membrane elements 3 are installed. A structure as shown in FIG. 3 having an increased internal dimension can also be preferably used.

  As long as the membrane element 3 is provided with a separation membrane capable of filtering activated sludge and has a nozzle capable of discharging filtrate water outside the membrane element 3, any type such as a flat membrane, a hollow fiber membrane, and a tubular membrane may be used. The effect of the present invention can be obtained. In particular, when a flat membrane type, which is important for stable operation, is used for cleaning the membrane surface by circulating flow, a particularly great effect can be obtained.

  The structure of the flat membrane type membrane element 3 is not particularly limited, and various structures can be selected and used. As an example, a structure in which a flow path material 22 and a sheet-like separation membrane 23 are sequentially installed on both surfaces of a plate-like support plate 21 having a filtrate outlet port 24 as shown in FIG. Further, as shown in FIG. 5, the membrane element 31 is manufactured with a support plate having ribs 33 on both edges, the adjacent membrane element 31 and the rib 33 are brought into contact with each other, and a function as a lid on the side surface of the housing 32 The thing of the shape which has can also be used preferably.

  The membrane element 3 is preferably installed so that the flow path for flowing a gas-liquid mixed flow formed between the membrane elements in the housing 2 is substantially uniform. In addition, each membrane element 3 is preferably installed in the horizontal direction so that the gas-liquid mixed flow rises smoothly. The horizontal direction represents a range of ± 20 ° with respect to the horizontal. The width of the flow path can be set as appropriate depending on the amount of air 8 discharged from the diffuser 4. As an example, 7 to 25 L / min of air per membrane element is discharged from the diffuser 4. In this case, the width is preferably 4 to 10 mm.

  The support plate 21 is not particularly limited as long as it has a substantially flat plate shape, and the material is not particularly limited as long as the Young's modulus in ASTM test method D638 has a rigidity of about 300 MPa or more. Metals such as stainless steel, acrylonitrile butadiene styrene rubber (ABS resin), resins such as vinyl chloride, composite materials such as fiber reinforced resin (FRP), and other materials can be appropriately selected and used.

  The flow path material 22 is not particularly limited as long as it has a thickness capable of forming a gap through which filtered water flows between the separation membrane 23 and the support plate 21. As an example, the porosity is 40% to About 96% of a porous material such as a net, non-woven fabric, ceramic or metal can be preferably used. Moreover, the shape which gave the function of this flow-path material 22 to the support plate can also be preferably used by making the surface of the support plate 21 into an uneven shape.

  The separation membrane 23 is not particularly limited, and polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinyl alcohol, cellulose acetate, polyacrylonitrile, chlorinated polyethylene, polyvinylidene fluoride, polyvinyl fluoride, and other materials may be used. It can be appropriately selected and used. When used in an environment that continuously diffuses, highly durable polyolefin-based and fluorine-based materials can be particularly preferably used, and the MLSS (Mixed Liquor and Suspended Solid) concentration is 1000 mg / liter or less. In the case of relatively clear raw water, polyacrylonitrile, cellulose acetate, polysulfone and the like can be particularly preferably used. The pore size of the flat membrane is not particularly limited as long as it is porous, but when the activated sludge water is subjected to solid-liquid separation, the pore size of the pore that determines the filtration performance of the membrane is 0. What exists in the range of about 01-20 micrometers is preferable.

  A diffuser 4 that discharges air is installed at the lower part of the membrane element 3, but this diffuser 4 may be fixed to the casing 2, and is installed separately from the casing 2. Also good. The arrangement and form of the air diffuser 4 are not particularly limited as long as the arrangement is such that air can be uniformly fed to the plurality of membrane elements 3 and the form of the air diffuser is sufficient. As an example, as shown in FIG. 1, a plurality of pipes are arranged below the membrane element 3, and the upper and lower surfaces of the pipes are provided with air holes at regular intervals. The number and size of the air diffuser holes are not particularly limited, and can be appropriately set according to the amount of air. In the present invention, although the flow of the swirl flow 109 can be reduced, air bias due to the circulation flow 110 cannot be prevented. Therefore, a plurality of pipes are installed so that the distance between the pipes is 100 to 300 mm. Thus, it is preferable to minimize the deviation of air.

  The effect of the present invention is particularly significant when the distance between the lower end of the membrane element 3 and the air diffuser 4 is less than 500 mm. The distance between the membrane element 3 and the air diffuser 4 indicates the distance of the lowermost end of the portion where the air of the air diffuser 4 is discharged from the lowermost end of the membrane element. Although a great effect is obtained at less than 500 mm, it is more preferable to install in the range of 200 to 500 mm.

  The effect of the present invention is significant when the air diffuser 4 is not included in the hood. The inside of the hood is a space surrounded by the hood 5 and the hood 6 and indicates a situation where the air diffuser 4 is installed above the lowermost end of the hood 6. Since the air diffuser 4 is not included in the hood, the height of the module can be set low.

  The material of the housing 2 and the air diffuser 4 is not particularly limited as long as the material has a rigidity with a tensile strength of about 15 MPa or more in D638 of the ASTM test method, but metals such as stainless steel, acrylonitrile A butadiene styrene rubber (ABS resin), a resin such as polyethylene, polypropylene, and vinyl chloride, a composite material such as a fiber reinforced resin (FRP), and other materials can be preferably used.

  The module 1 described above is used by being immersed in a treatment tank in which treated water is stored. FIG. 6 shows an example of a water treatment apparatus using the module 1. The module 1 is immersed in the treatment tank 41 in which the water to be treated 44 is stored, and a suction pump 43 for sucking filtered water 45 and a blower 42 for sending air to the air diffuser are connected to the module. Yes. In FIG. 6, the suction pump 43 is used to take out the filtered water from the treatment tank 41, but in addition, gravity using the water head difference between the water surface of the treatment tank and the filtered water extraction portion is not used. Filtration can also be performed.

  In the water treatment apparatus configured as described above, the water to be treated such as waste water passes through the separation membrane 23 installed in the membrane element 2 by the suction force of the pump 43. At this time, suspended substances such as microbial particles and inorganic particles contained in the water to be treated are filtered. Then, the water that has passed through the separation membrane 23 is taken out to the outside of the processing tank 41 through the filtered water channel formed by the channel material 22 and the nozzle 24. On the other hand, the air supplied from the blower 42 in parallel with the filtration is discharged from the diffuser 4, and this air is guided to each hood and enters the housing 2. The upward flow of gas-liquid mixing parallel to the membrane surface separates the filtrate deposited on the membrane surface. The air that has passed through the module disappears into the atmosphere above the treatment tank, but the treated water that has risen at the same time descends outside the module and forms a swirling flow that enters the module again from the opening at the bottom of the hood.

  At this time, according to the module 1 of the present invention, since the gas-liquid mixed flow by air can be uniformly dispersed in each part of the film surface, the film surface can be efficiently cleaned. Moreover, the height of the module 1 can be lowered without obstructing the flow of the swirling flow, and as a result, the water depth of the treated water tank can be lowered.

  Then, the module 1 of the present invention has a MLSS (Mixed Liquor and Suspended Solid) concentration indicating the SS concentration in the liquid to be treated for filtering the water to be treated having a concentration of 1000 mg / liter or more because of its good cleanability. The removability of the filtrate by air is high, and it can be used particularly preferably.

Example 1
100 membrane elements 3 having a separation membrane 23 installed on an ABS support plate 21 having a height of 1500 mm, a width of 500 mm, and a thickness of 6 mm, having irregularities as substitutes for the flow path material on both surfaces were prepared.

  Next, a housing 2 having an inner dimension of about 2000 mm in height, 505 mm in width, and 1350 mm in depth was opened at the top and bottom. The casing 2 has openings so that the length of the hood when the membrane element is installed is C (height of the hood 5) = 400 mm and D (height of the hood 6) = 200 mm, respectively. It has been. Further, as the air diffuser 4, two 40 A SUS pipes were arranged below the membrane element and fixed to the lower end of the hood 5. Each SUS pipe is provided with 6 mm holes at a pitch of 30 mm on the lower surface, and the SUS pipes are arranged in parallel so that the interval between the SUS pipes is 230 mm.

  The 100 membrane elements 3 described above were loaded into the housing 2 to manufacture the module 1 shown in FIG.

  The module 1 was immersed in a transparent acrylic treatment tank filled with tap water, and air of 15 L / min per membrane element was discharged from the air diffuser 4.

  At this time, as a result of observing the rise of air from the opening on the hood 6 side, it can be confirmed that the air is uniformly distributed between the membrane elements and that the air reaches the membrane elements 13 on both ends. It was.

(Comparative Example 1)
Other than providing openings so that the length of the hood when the membrane element is installed in the housing is C (height of the hood 305) = 200 mm and D (height of the hood 306) = 200 mm, respectively. 10 was produced in the same manner as in Example 1, and a module 301 shown in FIG. 10 was produced. In addition, a plurality of acrylic windows were installed in the hood 306 so that air dispersion could be visually confirmed later.

  This module 301 was immersed in a transparent acrylic treatment tank filled with tap water in the same manner as in Example 1, and air of 15 L / min per membrane element was discharged from the diffuser 4.

  At this time, as a result of observing the rise of air from the acrylic window of the hood 306, it was confirmed that there was little air in the membrane elements 313 on both ends.

It is a schematic perspective view which shows an example of the module used for this invention. (A) is the schematic diagram which looked at FIG. 1 from the hood 6 side, and has shown partial sectional drawing, (b) is the cross-sectional schematic diagram which looked at FIG. 1 from the hood 5 side. It is the schematic diagram seen from the food | hood 6 side which shows another example of the module used for this invention, and has shown partial sectional drawing. It is a schematic perspective view which shows an example of the membrane element used for this invention. It is a schematic perspective view which shows another example of the membrane element and module used for this invention. It is a schematic diagram which shows an example of the water treatment apparatus used for this invention. It is a schematic perspective view which shows an example of the conventional module. (A) is the schematic diagram which looked at FIG. 7 from the food | hood 106 side, and has shown partial sectional drawing, (b) is the cross-sectional schematic diagram which looked at FIG. 7 from the food | hood 105 side. It is a schematic perspective view which shows another example of the conventional module. It is a schematic perspective view which shows another example of the conventional module.

Explanation of symbols

1 Module 2 Housing 3 Membrane Element 4 Air Diffuser 5 Hood 6 Hood 8 Air 9 Swirling Flow
DESCRIPTION OF SYMBOLS 10 Swirling flow 13 Membrane element 21 installed in both ends Support plate 22 Channel material 23 Separation membrane 24 Nozzle 31 Membrane element 32 Case 33 Rib 41 Treatment tank 42 Blower 43 Suction pump 44 Water to be treated 45 Filtration water 101 Module 102 Housing 103 Membrane element 104 Air diffuser 105 Hood 106 Hood
108 Air 109 Swirling Flow 110 Swirling Flow 113 Membrane Element 201 Installed at Both Ends Module 202 Case 203 Membrane Element 304 Aeration Device 205 Hood 206 Hood 213 Membrane Element Installed at Both Ends 301 Module 302 Case 303 Membrane Element 304 Air diffuser 305 Hood 306 Hood 313 Membrane elements installed at both ends

Claims (7)

A plurality of membrane elements arranged in a horizontal direction in the housing, an air diffuser disposed below the membrane elements in the housing, and air discharged from the air diffuser below the housing A separation membrane module having a hood configured to be guided into a housing, wherein the hood facing the arrangement direction of the membrane elements in the hood is a hood other than the hood facing the arrangement direction of the membrane elements A separation membrane module, wherein the separation membrane module is installed to the lower side. The separation membrane module according to claim 1, wherein a distance between a lower end of the membrane element and the air diffuser is less than 500 mm. The separation membrane module according to claim 1 or 2, wherein the plurality of membrane elements are arranged in a horizontal direction at intervals of 4 to 10 mm. The separation membrane module according to claim 1, wherein the membrane element is a flat membrane element using a flat membrane. The separation membrane module according to claim 1, wherein the air diffuser is not included in the hood. A water treatment apparatus, wherein the separation membrane module according to any one of claims 1 to 5 is immersed in a treatment tank. A water treatment method using the water treatment apparatus according to claim 6, wherein when water to be treated in the treatment tank is subjected to solid-liquid separation using a separation membrane module immersed in the treatment tank, A water treatment method, wherein air discharged from an air diffuser is guided into the housing.

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