JP2017056447A - Water treatment system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a water circulatory system applied to fish breeding water tank or the like from becoming larger and a maintenance cost from increasing.SOLUTION: A water treatment system includes filtration treatment parts (3, 5) disposed in a water circulatory path (CM) and biological treatment parts (7, 9) for biologically treating cleaning waste water generated by cleaning of the filtration treatment part. According to this, the biological treatment is applied not to a total amount of water in a circulatory system containing a water storage part such as a water tank but to only a part thereof, that is, reverse washing waste water. Further, when constituting such that the cleaning waste water is anaerobically treated (7), followed by aerobically treating (9) and by returning a part of aerobically treated water to the anaerobically treating part, in the anaerobically treating part, by utilizing an organic substance contained in the introduced cleaning waste water, denitration of nitric acid generated by the aerobic treatment can be performed. Therefore, an addition of methanol or the like can be made unnecessary.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a water treatment system and method, and more particularly to a technology for purifying while circulating water stored in a water storage unit used for breeding organisms, for example, an aquarium for cultivating seafood on land. It is.

  In general, when aquaculture and the like are cultivated on land, in a closed environment such as an aquaculture tank, residual ammonia or an increase in the concentration of excrement is a problem. Therefore, it is conceivable to construct a water circulation system for the aquaculture tank and to perform biological treatment in the course of circulation. As an example of such biological treatment, ammonia is nitrified by performing treatment with aerobic bacteria (aerobic treatment) on water as disclosed in Patent Document 1 or Patent Document 2, and then treatment with anaerobic bacteria. There is a technology to denitrify by applying (anaerobic treatment). Patent Document 1 discloses that methanol is introduced as an organic substance serving as an organic carbon source for the denitrification reaction, and Patent Document 2 similarly discloses an anaerobic treatment of methanol as a hydrogen donor necessary for the denitrification reaction. It is disclosed that it is put in before.

JP 2001-137890 A JP 2011-62653 A

  However, the present inventors have found that the following problems arise when the biological treatment techniques disclosed in these patent documents are simply applied to the circulatory system. That is, performing a biological treatment on the total amount of circulating water or interposing a step of adding methanol between an aerobic treatment step and an anaerobic treatment step is a circulation system including a water storage unit such as a water tank. It is a problem of increasing the size and bringing about an increase in maintenance costs.

  Therefore, an object of this invention is to provide the water treatment system and method which can suppress the enlargement of the circulation system containing water storage parts, such as a water tank, and the increase in maintenance cost.

  For this purpose, the water treatment system of the present invention includes a filtration treatment unit disposed in a water circulation path with respect to the water storage unit, and a biological treatment unit that biologically treats washing wastewater generated by washing of the filtration treatment unit. It is characterized by that.

  Further, the water treatment method of the present invention includes a filtration treatment step for performing filtration treatment by a filtration treatment portion disposed in a water circulation path with respect to a water storage portion, and a biological treatment for biological treatment of washing wastewater generated by washing of the filtration treatment portion. And a processing step.

  According to the present invention, biological treatment is performed not only on the total amount of water in the circulatory system including a water reservoir such as a water tank, but on only a part thereof, that is, backwash waste water. In addition, if anaerobic treatment is performed on the washing wastewater, and then aerobic treatment is performed, and a part of the aerobic treated water is returned to the anaerobic treatment unit, the anaerobic treatment unit may introduce the washing wastewater to be introduced. Since the nitric acid generated by the aerobic treatment can be denitrified using the organic matter contained, it is not necessary to input an electron donor such as methanol. By these, it becomes possible to suppress the enlargement of a circulation system and the increase in maintenance cost.

It is a block diagram showing typically one embodiment of a water treatment system to which the present invention is applied. It is a block diagram which shows the outline of the control system for operating the water treatment system of FIG. It is a flowchart which shows an example of the operation | movement procedure of the water treatment system by the control system of FIG. It is a block diagram which shows typically other embodiment of the water treatment system to which this invention is applied.

Hereinafter, the present invention will be described in detail with reference to the drawings.
In addition to the aquaculture tank (culture tank), ginger, aquarium / zoo display tank, artificial pond, or goldfish or tropical fish at home, Includes small aquarium used. In addition, not only marine organisms that normally stay in the sea, such as fish, shellfish, crustaceans, and whales, but also marine organisms that normally live in the sea, That is, sea animals such as sea lions, fur seals, sea otters, polar bears, penguins, turtles and the like can also be included.

(Outline of water treatment system)
The first embodiment of the water treatment system shown in FIG. 1 is applied to, for example, a fish tank for aquaculture, and mainly includes two circulation paths. One is a normal circulation path CM that recirculates from the water reservoir, that is, the water tank 1 to the water tank 1 through the first filtration processing unit 3 and the second filtration processing unit 5, as indicated by solid arrows. The other reaches the anaerobic treatment unit 7 from the water tank 1 through the first filtration processing unit 3 or further through the second filtration processing unit 5, and further through the aerobic processing unit 9, as indicated by the dashed arrow. This is a biological treatment circulation path CB that returns to the water tank 1. That is, the normal circulation path CM filters the water discharged from the aquarium 1, and physically removes excrement, residual food, bacteria, viruses, and the like of aquatic organisms (hereinafter also collectively referred to as “foreign substances”). This is a circulation path that is recirculated to the water tank 1 after being removed. On the other hand, the biological treatment circulation path CB performs the biological treatment by introducing the washing waste water of the filtration treatment units 3 and 5 together with the foreign matter, and obtains treated water from which excess sludge generated thereby is obtained. 1 is a circulation path that is refluxed to the water tank 1 before the filtration processing unit 3. Thus, it is one of the features of the present embodiment that biological treatment is performed on a part of the circulation system including the water tank 1 instead of the total amount of water. Moreover, this embodiment arrange | positions the aerobic process part 9 in the downstream of the anaerobic process part 7 in the biological treatment circulation path | route CB, and also produces the local circulation via the circulation path CL also among them. Is included as another feature.

  Further, in FIG. 1, reference numeral B <b> 1 is a blower that introduces bubbles into the first filtration processing unit 3 and performs cleaning (back washing) of the filter medium, and reference numeral B <b> 2 introduces bubbles into the second filtration processing unit 5, A blower for backwashing is shown. Moreover, the code | symbol P1 introduce | transduces water into the 2nd filtration process part 5 from the 1st filtration process part 3, and is mainly made to recirculate | reflux to the water tank 1, The code | symbol P2 is the water (backwash drainage) produced by backwashing. The pump for introducing the water from the first and second filtration processing units to the anaerobic processing unit 7, the code P3 is a pump for returning the treated water separated from the excess sludge in the aerobic processing unit 9 to the water tank 1, P4 is a pump for causing local circulation between the anaerobic processing unit 7 on the upstream side and the aerobic processing unit 9 on the downstream side. Furthermore, the code | symbol V1 is an opening / closing valve for opening and closing the flow path between the 2nd filtration process part 5 and the water tank 1 as needed. These units are controlled when the processing procedure shown in FIG. 3 is performed in the control system described later with reference to FIG.

(Normal circulation route)
In the present embodiment, two filtration processing units, a first filtration processing unit 3 and a second filtration processing unit 5 are arranged. If a filtration treatment unit having a fine pore size filter is used, bacteria and viruses can be effectively removed. However, since the water introduced from the aquarium 1 includes excrement and residual food of aquatic organisms, when a filter with a fine pore size is used alone, the pores are likely to be clogged, and the filter is frequently washed. Necessary. Therefore, in the present embodiment, a first filtration processing unit 3 that removes excrement and residual bait and a second filtration processing unit 5 that removes bacteria, viruses, and the like are disposed as a pretreatment. It is assumed that a stage filtration step is performed.

  Examples of the first filtration unit 3 include those that perform sand filtration, foam separation, coagulation precipitation, MF (microfiltration) membrane treatment, fiber filtration, and the like. When sand filtration or fiber filtration is used, it is preferable that microorganisms propagate on the filter medium so that biological treatment can be performed to some extent even in the filtration step. Further, it is more preferable to use fiber filtration because the water passage rate can be increased compared to sand filtration because the porosity of the filter medium is large and the loss head is small. Examples of the fiber filter medium include a sedimentation filter medium, a floatable filter medium, and a long fiber filter medium. It is preferable to use a sedimentation filter medium having high filtration performance.

  Bacteria and many viruses can be removed by using a UF (ultrafiltration) membrane having a pore size of about 0.02 μm for the second filtration processing unit 5. Further, it is more preferable to use an NF (nanofilter) film having a pore size smaller than 0.02 μm because the virus can be completely removed, and protein and coloring components can be removed to some extent. By performing such a membrane treatment in the second filtration processing unit 5, aquatic organisms can be protected from diseases and stably bred without contamination of bacteria in the aquarium 1.

(Biological treatment circulation route)
In the biological treatment of the present embodiment, the anaerobic treatment unit 7 is disposed on the upstream side, the aerobic treatment unit 9 is disposed on the downstream side, and water is partially circulated between them. Thereby, denitrification is performed in the anaerobic treatment unit 7, and residual food and excrement that have not been treated in the anaerobic treatment unit 7 are decomposed and nitrification of ammonia is performed in the aerobic treatment unit 9. In detail, when the biological treatment is started, residual filtration and wastes are introduced into the anaerobic treatment unit 7 together with the backwash waste water containing ammonia from the filtration treatment units 3 and 5, but the ammonia is anaerobic treatment unit. 7 is passed through and is nitrified in the aerobic treatment unit 9. Therefore, immediately after the biological treatment is started, treated water containing nitric acid flows out from the aerobic treatment unit 9, but there is no problem as long as this does not affect the breeding organisms. Conceivable. Moreover, since denitrification is performed by returning a part of the treated water containing nitric acid to the anaerobic treatment unit 7, the content of nitric acid contained in the treated water flowing out from the aerobic treatment unit 9 in the next stage is a problem. It can be reduced to a level that does not become.

  In addition, since the residual feed and excreta containing the organic substance serving as the electron donor are introduced into the anaerobic treatment unit 7, a good denitrification reaction can be caused without separately adding methanol or the like.

  Furthermore, when the configuration disclosed in Patent Document 2 is applied, the amount of dissolved oxygen is low in the water after biological treatment, so re-aeration is required to dissolve oxygen when refluxed to the water tank 1. It becomes. On the other hand, in this embodiment, the dissolved oxygen concentration after the aerobic treatment is sufficiently higher than the dissolved oxygen after the anaerobic treatment, and the biological treatment compared with the normal circulation path CM circulating at a large flow rate. Since the amount of circulating water in the circulation path CB is small, even if aerobic treated water is allowed to flow into the water tank without re-aeration, the dissolved oxygen in the water tank does not drop significantly. Therefore, it is not necessary to install a water tank or blower for re-aeration.

  In this embodiment, the treated water returns from the aerobic treatment unit 9 to the water tank 1. The treated water to be recirculated generally needs to be separated from surplus organisms (surplus sludge) through a solid-liquid separation step after biological treatment. Examples of means for performing the solid-liquid separation step include coagulation sedimentation, pressurized flotation, sand filtration, membrane separation, and the like. From the viewpoint of water quality to be refluxed to the water tank 1, membrane separation is preferable. The membrane used is preferably a UF membrane that can remove bacteria and most viruses. In particular, it is more preferable to use a membrane separation activated sludge method (MBR) that can perform a biological treatment step and a solid-liquid separation step at the same time, because a stable treated water can be obtained in a small space. It is assumed that the method is adopted as the unit 9. However, the use of solid-liquid separation means other than the UF membrane is not excluded, and in that case, a sterilization step by introducing UV sterilization or ozone or hydrogen peroxide may be added.

(Control of water treatment system)
FIG. 2 is a block diagram showing a simplified control system applicable to the water treatment system of FIG. The illustrated control system is mainly configured by a controller CNT that executes a control procedure described later with reference to FIG. Control targets of the controller CNT are pumps P1 to P4, blowers B1 and B2, and a valve V1, which are driven via driving units PD1 to PD4, BD1, BD2, and VD1, respectively. Information for determining whether to perform normal circulation or biological treatment circulation is input to the controller CNT, and on / off of each control target is controlled based on the determination.

  The biological treatment circulation can be performed based on time, and at that time, the first filtration processing unit 3 and the second filtration processing unit 5 may be accompanied by backwashing simultaneously. However, in this embodiment, the biological treatment circulation of a different aspect shall be implemented based on the conditions of the water tank 1, the 1st filtration process part 3, and the 2nd filtration process part 5. FIG. The conditions of the water tank 1 are related to the quality of the water stored in the water tank 1, and for this purpose, the in-water tank state sensor TS1 is used, and the detection information is notified to the controller CNT. The water tank state sensor TS1 may be, for example, a sensor that detects the ammonia concentration in water, but is not limited thereto. The conditions of the first and second filtration processing units 3 and 5 relate to a decrease in filtration performance due to clogging of the filter medium or the membrane used in these, and for that purpose, the first filtration processing unit state sensor FS3 and The second filtration processing unit state sensor FS5 is used, and the detection information thereof is notified to the controller CNT. As these sensors FS3 and FS5, for example, a pressure sensor or a flow rate sensor can be used, but is not limited thereto.

FIG. 3 is a flowchart showing an example of an operation procedure of the water treatment system by the control system of FIG.
In the initial stage when this procedure is started, first, in step S1, the valve V1 is opened, the pump P1 is turned on, the pumps P2 to P4 are turned off, and the blowers B1 and B2 are turned off. Then, water returns to the water tank 1 from the water tank 1 through the first filtration processing unit 3 and the second filtration processing unit 5. That is, a flow along the normal circulation path CM in FIG. 1 occurs.

  This state is maintained until it is determined in step S3 that biological treatment circulation is necessary. The determination is based on the information notified from the in-water tank state sensor TS1, the first filtration processing unit state sensor FS3, and the second filtration processing unit state sensor FS5. This is done when a decline is recognized. Accordingly, in step S5, the valve V1 is closed, the pump P1 is turned off, and the pumps P3 and P4 are turned on. Then, the normal circulation path CM is interrupted, and biological treatment circulation including local circulation becomes possible.

  Next, in step S <b> 7, it is determined which of the conditions of the water tank 1, the first filtration processing unit 3, and the second filtration processing unit 5 is to perform the biological treatment circulation. If it is determined that the water quality is deteriorated, the process proceeds to step S9, the blowers B1 and B2 are activated, and the first filtration unit 3 and the second filtration unit 5 are backwashed. P2 is turned on. Then, the backwash waste water from these filtration processing units is introduced into the anaerobic processing unit 7. In step S7, when it is determined that the first filtration processing unit 3 is based on the performance degradation, the process proceeds to step S13, and only the blower B1 is activated to perform the back washing of the first filtration processing unit 3, The pump P2 is turned on. Then, only the backwash waste water from the first filtration processing unit 3 is introduced into the anaerobic processing unit 7. In Step S7, when it is determined that the second filtration processing unit 5 is based on the performance degradation, the process proceeds to Step S17, where the pump P2 is turned on and only the blower B2 is activated to start the second filtration processing unit. Perform 5 backwash. Then, only the backwash waste water from the second filtration processing unit 5 is introduced into the anaerobic processing unit 7. In any case, after only the backwash wastewater is introduced into the anaerobic treatment unit 7, the biological treatment as described above is performed, and the treated water is returned to the water tank 1.

  Steps S9, S13, or S17 are set at step S11, when the water quality is good, at step S15, the performance of the first filtration unit 3 is restored, or at step S19, the second setting. It is maintained until it is determined that the performance of the filtration processing unit 5 has been recovered, and when the determination is made, the process returns to step S1. That is, the water flow in the water treatment system returns to the normal one along the circulation path CM.

  Instead of branching from step S7 to step S9, S13, and S17 in FIG. 3 based on conditions, the water tank 1, the first filtration processing unit 3, and the second filtration processing unit 5 are provided with sensors. If the tendency of the decrease in performance and the decrease in performance of the filtration processing unit can be predicted statistically or experimentally, branching may be performed based on time.

  In the water treatment system shown in FIG. 1, treated water containing nitric acid flows out from the aerobic treatment unit 9 immediately after the biological treatment is started. If this is so small that it does not affect the breeding organisms, it is considered that there will be no problem. For example, the pump P3 is activated after a certain amount of local circulation between the aerobic processing unit 9 and the anaerobic processing unit 7 is performed. If it does so, it will become possible to reduce the nitric acid concentration of the water recirculated to the water tank 1 to a level with no problem. In relation to this, a means for detecting the concentration of nitric acid contained in the treated water may be provided.

(Second Embodiment)
FIG. 4 is a block diagram schematically showing a second embodiment of the water treatment system to which the present invention is applied. In the second embodiment, a pump P11 and a valve V11 are disposed in a flow path connecting the water tank 1 and the first filtration processing unit 3, and the first filtration processing unit 3 and the second filtration processing unit 5 are each a valve. It is connected to the anaerobic processing unit 7 via V14 and V20. A first filtration water tank 33 for storing the filtered water is disposed at the subsequent stage of the first filtration processing unit 3, and these are connected via a valve V13. A second filtration water tank 53 is also arranged at the subsequent stage of the second filtration processing unit 5, and these are connected via a valve V15.

  A pump P12 is disposed downstream of the first filtration water tank 33, and an outlet side of the pump P12 is connected to the second filtration processing unit 5 through the valve V15 and to the first filtration processing unit 3 through the valve V12. It is connected. Accordingly, the water stored in the first filtration water tank 33 is supplied to the second filtration unit 5 when the pump P12 is operated with the valve V15 opened and the valve V12 closed, and the valve V15 is closed and the valve V15 is closed. If the pump P12 is operated with the valve V14 opened and the valve V14 opened, the pump P12 is supplied to the first filtration processing unit 3, and the cleaning wastewater is transferred to the anaerobic processing unit 7 after washing the first filtration processing unit. A pump P13 is also disposed downstream of the second filtration water tank 53, and the outlet side thereof is connected to the water tank 1 via a valve V19 and is connected to the second filtration part 5 via a valve V18. . Accordingly, the water stored in the second filtered water tank 53 is supplied to the water tank 1 when the pump P13 is operated with the valve V19 opened and the valve V18 closed, and the valve V19 is closed and the valve V18 is opened. If the pump P13 is operated with the valve V20 open, the pump P13 is supplied to the second filtration processing unit 5, and the cleaning wastewater is transferred to the anaerobic processing unit 7 after washing the second filtration processing unit.

  In the second embodiment, unlike the first embodiment, a single blower B11 is provided, which is connected to the first filtration unit 3 and the valves V16 and V22, respectively. The second filtration processing unit 5 is connected. Therefore, air bubbles can be selectively introduced into the first filtration processing unit 3 and the second filtration processing unit 5 by driving the blower B11 with the valves V16 and V22 opened and closed appropriately. The pumps P14 and P15 are the same as the pumps P3 and P5 of the first embodiment, respectively. That is, the pump P14 recirculates treated water from the aerobic treatment unit 9 to the water tank 1, while the pump P15 recirculates a part of the treated water to the anaerobic treatment unit 7 so as to be locally between the aerobic treatment unit 9. A good cycle.

  Each of the above units can be positioned as a control target of the controller CNT, as in the first embodiment, but the outline of the water treatment performed in the present embodiment is as follows.

During normal circulation, the valves V11, V13, V15, V17 and V19 are opened, the valves V12, V14, V16, V18, V20 and V22 are closed, the pumps P11, P12 and P13 are turned on, and the blower B11 is turned off. Then, water flows back from the water tank 1 to the water tank 1 through the first filtration processing unit 3, the first filtration processing water tank 33, the second filtration processing unit 5, and the second filtration processing water tank 53.

It is carried out when the conditions of the first filtration processing unit 3 at the time of the first filtration processing unit backwashing , for example, when the pressure difference before and after the filter medium arranged in the first filtration processing unit 3 reaches a set value or more, the valves V12, V14. And V16 are opened, the other valves are closed, the pump P12 is turned on, the pumps P11 and P13 are turned off, and the blower B11 is turned on. Then, the supply of water from the water tank 1 to the first filtration treatment unit 3 and the transfer of water from the first filtration treatment water tank 33 to the second filtration treatment unit 5 are stopped. On the other hand, with the supply of water from the first filtration water tank 33 to the first filtration treatment unit 3 and the introduction of bubbles from the blower B11, the first filtration treatment unit 3 is backwashed, and the backwash drainage is It is transferred to the anaerobic processing unit 7.

When the second filtration processing unit backwashing condition of the second filtration processing unit 3, for example, the pressure difference before and after the filter medium arranged in the second filtration processing unit 5 reaches a set value or more, valves V18 and V20 And V22 are opened, the other valves are closed, the pump P13 is turned on, the pumps P11 and P12 are turned off, and the blower B11 is turned on. Then, the transfer of water from the first filtration water tank 33 to the second filtration part 5 and the reflux of water from the second filtration water tank 53 to the water tank 1 are stopped. On the other hand, with the supply of water from the second filtration treatment water tank 53 to the second filtration treatment unit 5 and the introduction of bubbles from the blower B11, the second filtration treatment unit 5 is backwashed, and the backwash wastewater is anaerobic. It is transferred to the processing unit 7.

  In consideration of the fact that the first and second filtration treatment units 3 and 5 are regularly backwashed, and the backwash wastewater is supplied to the anaerobic treatment unit 7 and biologically treated, it is gradually returned to the water tank. P14 and P15 are basically always on.

(Other)
The present invention is not limited to the first and second embodiments described above and the modifications described in various places, but according to the scale and amount of water tank or water treatment system, or the kind and breeding density of breeding organisms. Various changes, replacements, deletions or additions of components, and the like can be performed, and control according to the changes can be performed.

  For example, in the water treatment system shown in FIG. 1 and FIG. 4, a two-stage filtration process is performed. If the amount of foreign matter is not a problem, the first filtration process is performed. The arrangement of the part 3 can be omitted.

  Further, the pump may be disposed at an appropriate position. If water is smoothly transferred from the upstream processing unit to the downstream processing unit due to overflow, the pump is not necessarily disposed between them. Further, the valve may be arranged at a position where the flow path needs to be blocked. Conversely, when the biological treatment circulation is performed in the water treatment system shown in FIG. 1, the valve V <b> 1 is not necessary if it is not necessary to block the normal circulation path. Further, the means for backwashing is not limited to the blower. For example, if a pump capable of reverse rotation is used and sufficient backwashing is performed by the reverse rotation, the blower can be omitted. For example, in the water treatment system shown in FIG. 1, if the pump 4 is such, the blower B1 can be omitted.

  Furthermore, the amount of water to be refluxed from the aerobic processing unit 9 to the anaerobic processing unit 7 can be determined according to conditions such as the number of backwashing times or the amount of backwash drainage of the filtration processing unit depending on the organism to be reared and the rearing density, The maximum amount of water to be refluxed from the aerobic treatment unit 9 to the water tank 1 can be 5%.

In addition, if a sensor that detects the concentration of ammonium ions (NH ₄ ⁻ ) or nitrate ions NO ₃ ⁻ ) is used as a sensor that detects the conditions of the water tank 1, the detected value reaches an abnormal value. A configuration can be added to automatically replenish new breeding water or prompt the administrator.

  In addition, the water treatment method may be automatically performed using a control system as shown in FIG. 2 or may be manually performed at least partially.

DESCRIPTION OF SYMBOLS 1 Water tank 3 1st filtration process part 5 2nd filtration process part 7 Anaerobic process part 9 Aerobic process part 33 1st filtration process water tank 53 2nd filtration process water tank P1-P3, P11-P15 Pump B1, B2, B11 Blower V1 , V11 to V22 Open / close valve CM Main circulation route CB Biological treatment circulation route CL Local circulation route

Claims (6)

A filtration processing unit disposed in a water circulation path with respect to the water storage unit;
A biological treatment unit that biologically treats washing wastewater generated by washing the filtration unit;
A water treatment system comprising: The biological treatment unit is an anaerobic treatment unit for anaerobically treating the washing waste water;
An aerobic treatment unit that performs an aerobic treatment after the anaerobic treatment;
The water treatment system according to claim 1, comprising:   The water treatment system according to claim 2, further comprising a path for returning a part of the water treated by the aerobic treatment unit to the anaerobic treatment unit.   The water treatment system according to any one of claims 1 to 3, further comprising a path for returning a part of the biologically treated water to the water storage unit.   The water treatment system according to any one of claims 2 to 4, wherein the aerobic treatment unit performs aerobic treatment and solid-liquid separation simultaneously by a membrane separation activated sludge method. A filtration treatment step of performing filtration by a filtration treatment unit disposed in a water circulation path with respect to the water storage unit;
A biological treatment process for biologically treating washing wastewater generated by washing of the filtration unit;
A water treatment method comprising: