Drain treatment device and cleaning method for drain treatment device

Abstract

To clean a separation membrane using wastewater and appropriately remove a polluted matter accumulated on an upper side of the separation membrane.SOLUTION: A wastewater treatment apparatus 1 is assembled with at least two anaerobic wastewater treatment tank 2A, 2B installed neighboring to each other, a separation membrane 10, 10 respectively installed in two anaerobic wastewater treatment tank 2A, 2B for filtration of wastewater, and air diffusion pipe 11, 11 respectively arranged under both separation membrane 10, 10 and supplying gas bubbles toward both separation membrane 10, 10, and is also assembled with a communication passage 5 provided under both separation membrane 10, 10 and communicating two anaerobic wastewater treatment tank 2A, 2B to each other and differential pressure generating means 6 for generating differential pressure between two anaerobic wastewater treatment tank 2A, 2B.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wastewater treatment apparatus and a method for cleaning the wastewater treatment apparatus.

Background Art

[0002] As a wastewater treatment technology for treating wastewater such as industrial wastewater and domestic wastewater, an anaerobic membrane separation method (anaerobic MBR: Membrane Bio Reactor) is known. The anaerobic membrane separation method is an excellent wastewater treatment technology that uses microorganisms and performs solid-liquid separation by a separation membrane to decompose organic substances in wastewater into methane and carbon dioxide.

[0003] Normally, in a wastewater treatment apparatus using the anaerobic membrane separation method, with continuous use, fouling substances such as sludge and dirt adhere to the surface and pores of the separation membrane, causing clogging (fouling). Therefore, cleaning of the separation membrane is necessary. The fouling of the separation membrane reduces the permeation flow rate (flux) and greatly affects the wastewater treatment performance. Conventionally, as methods for cleaning the separation membrane, cleaning by an air diffuser tube, cleaning with a chemical solution, etc. are known (see, for example, Patent Documents 1 and 2).

[0004] Cleaning by an air diffuser tube is to install an air diffuser tube below the separation membrane to generate bubbles, and by bringing the gas-liquid mixed flow of the bubbles and wastewater (water to be treated) formed by the rising of these bubbles into contact with the surface of the separation membrane, the fouling substances attached to the surface of the separation membrane are removed. Usually, cleaning by an air diffuser tube is continuously performed during the operation of the wastewater treatment apparatus. On the other hand, cleaning with a chemical solution is to immerse the separation membrane in a chemical solution of a predetermined concentration, and is performed, for example, periodically. In this case, the separation membrane is also taken out of the tank and immersed in the chemical solution.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, since the cleaning by the above-mentioned diffuser tube utilizes the upward flow of the gas-liquid mixed flow due to the rise of bubbles, there is a problem that contaminants are likely to accumulate on the upper side of the separation membrane and it is difficult to remove the accumulated contaminants. In addition, in the cleaning with a chemical solution, since it affects anaerobic bacteria in the tank during cleaning, the realization of a separation membrane cleaning technique that does not use a chemical solution is expected.

[0007] An object of the present invention is to solve the above-mentioned problems, provide a wastewater treatment apparatus and a cleaning method for the wastewater treatment apparatus that can clean a separation membrane using wastewater (water to be treated) and can suitably remove contaminants accumulated on the upper side of the separation membrane.

Means for Solving the Problems

[0008] In order to solve the above problems, the wastewater treatment apparatus of the present invention includes at least two adjacent anaerobic wastewater treatment tanks, separation membranes installed in each of the two anaerobic wastewater treatment tanks for filtering wastewater, diffuser tubes respectively arranged below the two separation membranes for supplying gas bubbles toward the two separation membranes, a communication passage for communicating the two anaerobic wastewater treatment tanks with each other below the two separation membranes, and pressure difference generating means for generating a pressure difference between the two anaerobic wastewater treatment tanks.

[0009] In the wastewater treatment apparatus of the present invention, a water level difference can be formed by generating a pressure difference between one anaerobic wastewater treatment tank and the other anaerobic wastewater treatment tank, and a water flow can be formed that flows from the anaerobic wastewater treatment tank with a higher water head to the anaerobic wastewater treatment tank with a lower water head through a communication passage. Due to this water flow, in the anaerobic wastewater treatment tank with a higher water head, a downward water flow opposite to the upward flow of the gas-liquid mixed flow caused by the rising of the bubbles in the air diffuser pipe is vigorously formed, and the contaminants accumulated on the upper side of the separation membrane are stripped downward. Thereby, the contaminants accumulated on the upper side of the separation membrane can be suitably removed using the wastewater (water to be treated). Therefore, the frequency of cleaning with chemicals can be reduced.

[0010] Further, it is preferable that the pressure difference generating means includes a gas recovery pipe connected to each of the two anaerobic wastewater treatment tanks, a recovery side on-off valve provided in the gas recovery pipe, a gas supply pipe connected to each of the two air diffuser pipes, a supply side on-off valve provided in each of the two gas supply pipes, and a control unit that controls the opening and closing of the two recovery side on-off valves and the two supply side on-off valves.

[0011] In this configuration, by controlling the opening and closing of the two recovery side on-off valves and the two supply side on-off valves by the control unit, cleaning using the water head pressure can be easily performed. For example, when cleaning one anaerobic wastewater treatment tank, the recovery side on-off valve of that tank is opened by the control unit and the supply side on-off valve is closed. Then, the recovery side on-off valve in the other anaerobic wastewater treatment tank is closed by the control unit and the supply side on-off valve is opened. Then, the air pressure continues to increase in the other anaerobic wastewater treatment tank, and the water level in the other tank decreases due to the increased gas. Along with this decrease in the water level, wastewater (water to be treated) flows from the other anaerobic wastewater treatment tank to one anaerobic wastewater treatment tank through the communication passage, and the water level of one anaerobic wastewater treatment tank rises. When the water level of one anaerobic wastewater treatment tank rises to a predetermined height, the recovery side on-off valve in the other anaerobic wastewater treatment tank is opened by the control unit. Thereby, wastewater (water to be treated) flows vigorously from one anaerobic wastewater treatment tank to the other anaerobic wastewater treatment tank through the communication passage, and the contaminants accumulated on the upper side of the separation membrane of one anaerobic wastewater treatment tank are suitably removed by the wastewater (water to be treated).

[0012] Further, it is preferable that the gas recovered by the two gas recovery pipes is supplied to the two gas supply pipes through a blower device.

[0013] With this configuration, since the gas recovered by the two gas recovery pipes is recycled and supplied to the two anaerobic wastewater treatment tanks again, efficient cleaning of the separation membrane can be achieved.

[0014] A method for cleaning a wastewater treatment apparatus according to the present invention for solving the above problems includes at least two adjacent anaerobic wastewater treatment tanks, separation membranes installed in each of the two anaerobic wastewater treatment tanks for filtering wastewater, diffuser pipes disposed below the two separation membranes for supplying gas bubbles toward the two separation membranes, and a communication passage communicating the two anaerobic wastewater treatment tanks below the two separation membranes. A water level difference forming step of forming a water level difference between the two anaerobic wastewater treatment tanks by generating a pressure difference between the two anaerobic wastewater treatment tanks, and a water flow forming step of forming a water flow flowing from the anaerobic wastewater treatment tank on the side with a higher water head to the anaerobic wastewater treatment tank on the side with a lower water head through the communication passage.

[0015] In the method for cleaning a wastewater treatment apparatus according to the present invention, a water level difference can be formed between two anaerobic wastewater treatment tanks by the water level difference forming step, and a water flow flowing from the higher water head side to the lower water head side through the communication passage can be formed by the water flow forming step. Since this water flow is a downward flow opposite to the upward flow of the gas-liquid mixed flow caused by the rising of the bubbles in the diffuser pipe, it acts to scrape off the contaminants accumulated on the upper side of the separation membrane downward. Thereby, the contaminants accumulated on the upper side of the separation membrane can be suitably removed using the wastewater (water to be treated). Therefore, the frequency of cleaning with a chemical solution can be reduced.

Effects of the Invention

[0016] In the wastewater treatment apparatus and the method for cleaning a wastewater treatment apparatus according to the present invention, the separation membrane can be cleaned using wastewater, and the contaminants accumulated on the upper side of the separation membrane can also be suitably removed.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0018] Embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, the up and down directions are the vertical directions perpendicular to the surface on which the anaerobic wastewater treatment tank of the wastewater treatment device is installed.

[0019] As shown in FIG. 1, the wastewater treatment device 1 includes anaerobic wastewater treatment tanks 2A and 2B, membrane units 10 and 10, and diffuser pipes 11 and 11. Further, the wastewater treatment device 1 includes pressure difference generating means 6 for generating a pressure difference between the two anaerobic wastewater treatment tanks 2A and 2B. Details of the pressure difference generating means 6 will be described later.

[0020] The anaerobic wastewater treatment tanks 2A and 2B (hereinafter referred to as "treatment tanks 2A and 2B") are adjacently arranged via a partition wall 2a formed in the central part of the left and right. Each treatment tank 2A and 2B is sealed and configured such that wastewater W1 flows in as the water to be treated. The wastewater W1 is supplied to the treatment tanks 2A and 2B by a liquid feeding pump (not shown) provided in the middle of the wastewater supply path. Examples of the wastewater W1 include industrial wastewater and domestic wastewater (sewage) discharged from factories and the like. In each of the treatment tanks 2A and 2B, the water level W1a of the wastewater W1 is set to a height at which the entire membrane units 10 and 10 are immersed.

[0021] Below the lower part of the partition wall 2a, a communication path 5 that connects the treatment tanks 2A and 2B to each other is formed. The communication path 5 enables the flow of the drainage water W1 between the treatment tanks 2A and 2B and has an opening area that does not pose a resistance to the flow of the drainage water W1 between the treatment tanks 2A and 2B. The communication path 5 is formed to open at a position below the membrane units 10, 10 of each treatment tank 2A, 2B. Note that, above the inner space of the treatment tanks 2A and 2B, a space that allows the water level of the drainage water W1 to rise is formed. Also, the treatment tanks 2A and 2B are provided with a discharge path (not shown) for discharging excess sludge.

[0022] The membrane unit 10 includes a plurality of membrane elements made of a known separation membrane. The same specifications of membrane units 10 are used in each of the treatment tanks 2A and 2B. The membrane elements exhibit a flat shape with high integration. Note that those with different shapes such as cylindrical shapes may also be used. As the separation membrane, it is preferable to use a microfiltration membrane (MF membrane). Examples of the shape of the separation membrane include a hollow fiber membrane, a flat membrane, a tubular membrane, and a bag-shaped membrane. Among these, a hollow fiber membrane with a large membrane area is preferable when compared on a volume basis. Examples of the material of the separation membrane include organic materials (cellulose, polyolefin, polysulfone, polyvinyl alcohol, polymethyl methacrylate, polyvinylidene fluoride, polytetrafluoroethylene, etc.). The material of the separation membrane is appropriately selected according to the properties of the water to be treated.

[0023] The membrane unit 10 is formed, for example, by holding a plurality of membrane elements in a frame-shaped frame. At the upper part of the membrane unit 10, a permeate discharge path 12 for discharging the permeate water W2 from the plurality of membrane elements is connected. The permeate discharge paths 12, 12 of each of the membrane units 10, 10 merge into one on the downstream side. A suction pump (not shown) is provided in the middle of the merged path. The permeate water W2 is sucked by the suction pump and discharged to the outside, and is sent to a subsequent advanced treatment facility (nitrogen treatment method, not shown) or an anammox treatment device to remove nitrogen.

[0024] The air diffuser pipes 11 are respectively arranged below each of the membrane units 10, 10. The air diffuser pipes 11 discharge biogas, which is the gas supplied from the blower device 19, toward the membrane elements of the membrane unit 10. A plurality of discharge holes for gas discharge are provided in the air diffuser pipes 11. Gas supply pipes 13 are respectively connected to each of the air diffuser pipes 11, 11. Each of the gas supply pipes 13, 13 is connected to a main pipe 18 connected to the blower device 19 and is configured to receive gas supply through the main pipe 18. The bubbles generated in the air diffuser pipes 11 form a gas-liquid mixed flow of bubbles and drainage W1 by rising. Note that the biogas is a gas containing methane gas, carbon dioxide, nitrogen, hydrogen sulfide, etc.

[0025] The pressure difference generating means 6 includes gas recovery pipes 15, 15, recovery side on-off valves 16, 16, gas supply pipes 13, 13, supply side on-off valves 14, 14, and a control unit 30. One end of each of the gas recovery pipes 15, 15 is connected to the treatment tanks 2A, 2B, and biogas is recovered from the internal space of the treatment tanks 2A, 2B. The recovery side on-off valves 16, 16 are provided in the middle of the gas recovery pipes 15, 15 and operate under the control of the control unit 30. When the recovery side on-off valve 16 is open, it allows the biogas to be recovered, and when it is closed, it blocks the recovery of the biogas. The other ends of the gas recovery pipes 15, 15 are connected to a recovery side main pipe 17. The downstream end of the recovery side main pipe 17 is connected to a gas holder 20. The gas holder 20 has a function of storing surplus biogas when it occurs. The end of the main pipe 18 is connected to the recovery side main pipe 17.

[0026] One end of each of the gas supply pipes 13, 13 is connected to the air diffuser pipes 11, 11 and supplies biogas to the air diffuser pipes 11, 11. The other ends of the gas supply pipes 13, 13 are connected to the main pipe 18. The supply side on-off valves 14, 14 are provided in the middle of the gas supply pipes 13, 13 and operate under the control of the control unit 30. When the supply side on-off valve 14 is open, it allows the biogas to be supplied to the air diffuser pipe 11, and when it is closed, it blocks the supply to the air diffuser pipe 11. The upstream side of the main pipe 18 is connected to the recovery side main pipe 17.

[0027] The control unit 30 is a device that controls the opening and closing of the recovery-side on-off valves 16, 16 and the supply-side on-off valves 14, 14. The control unit 30 is configured to include, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an input / output circuit, and the like. The control unit 30 executes control by performing various processes based on inputs from input devices, programs stored in the ROM, data, and the like.

[0028] Next, a cleaning method for the wastewater treatment device executed by the control of the control unit 30 will be described. FIG. 2 is a diagram showing the cleaning method of the wastewater treatment device and is a diagram showing the water level difference forming step. FIG. 3 is a diagram showing the cleaning method of the wastewater treatment device and is a diagram showing the water flow forming step.

[0029] During normal operation without a pressure difference, as shown in FIG. 1, the water levels W1a, 1a are set such that the entire membrane units 10, 10 are immersed in the treatment tanks 2A, 2B. During normal operation, under the control of the control unit 30, all of the recovery-side on-off valves 16, 16 and the supply-side on-off valves 14, 14 are opened, and the biogas discharged from the blower device 19 is diffused into the treatment tanks 2A, 2B from the diffuser pipes 11, 11 through the main pipe 18 and the gas supply pipes 13, 13. Then, the biogas diffused into the treatment tanks 2A, 2B is discharged into the internal space of the treatment tanks 2A, 2B and then recovered by the gas recovery pipes 15, 15, flows from the recovery-side main pipe 17 into the main pipe 18, and is discharged again into the main pipe 18 by the blower device 19. That is, during normal operation, the biogas circulates along such a circulation path, and the treatment tanks 2A, 2B are maintained in an environment suitable for the growth of anaerobic microorganisms.

[0030] The cleaning method of the wastewater treatment device 1 includes a water level difference forming step and a water flow forming step. Hereinafter, the left treatment tank 2A will be described as the cleaning target. The water level difference forming process is a process of generating a pressure difference between treatment tank 2A and treatment tank 2B to form a water level difference. Specifically, on the treatment tank 2A side, the recovery side on-off valve 16 is opened and the supply side on-off valve 14 is closed. On the other hand, on the treatment tank 2B side, the recovery side on-off valve 16 is closed and the supply side on-off valve 14 is opened. By doing so, on the treatment tank 2B side, since biogas is continuously supplied from the air diffuser pipe 11 with the gas recovery pipe 15 closed, the volume of the internal space of treatment tank 2B increases due to the retention of biogas, and the pressure of the internal space becomes higher. As a result, the water level W1a of treatment tank 2B, which was at the height shown in Fig. 1 during normal operation, is pushed down to the low water level W1c shown in Fig. 2.

[0031] Then, the drainage water W1 stored in treatment tank 2B flows into treatment tank 2A through the communication path 5, and the water level W1a of treatment tank 2A, which was at the height shown in Fig. 1 during normal operation, is pushed up to the high water level W1b shown in Fig. 2. As a result, a water level difference is formed between treatment tank 2A and treatment tank 2B.

[0032] The water flow forming process is a process of forming a water flow that flows from treatment tank 2A on the side with a higher water head to treatment tank 2B on the side with a lower water head through the communication path 5 based on the water level difference formed between treatment tank 2A and treatment tank 2B by the water level difference forming process. The peak of the water level difference can be detected, for example, by monitoring the water level of treatment tank 2A with a sensor or the like. In the water flow forming process, the recovery side on-off valve 16 on the treatment tank 2A side is maintained in an open state, and the supply side on-off valve 14 is maintained in a closed state. On the other hand, on the treatment tank 2B side, the recovery side on-off valve 16 is switched to an open state, and the supply side on-off valve 14 is maintained in an open state. By doing so, the biogas retained in the internal space of treatment tank 2B is recovered through the gas recovery pipe 15, and the pressure of the internal space of treatment tank 2B rapidly decreases. As a result, the water level of treatment tank 2B rises from the low water level W1c to the water level W1a during normal operation.

[0033] Then, the wastewater W1 stored in the treatment tank 2A at the high water level W1b returns to the treatment tank 2B through the communication passage 5. At this time, since the water flow generated in the treatment tank 2A is a downward flow opposite to the upward flow of the gas-liquid mixed flow by the bubbles of the air diffuser pipe 11, it acts to strip off the pollutants accumulated on the upper side of the membrane unit 10 downward. Thereby, in the treatment tank 2A, the pollutants accumulated on the upper side of the membrane unit 10 and the upper side of the membrane element can be suitably removed by using the wastewater W1 (water to be treated).

[0034] When cleaning the membrane unit 10 of the treatment tank 2B, conversely to the above-described cleaning method, the pressure in the inner space of the treatment tank 2A is increased to form a water level difference, and a water flow is formed that flows from the treatment tank 2B with a higher water head to the treatment tank 2A with a lower water head through the communication passage 5. Thereby, on the treatment tank 2B side, the pollutants accumulated on the upper side of the membrane unit 10 and the upper side of the membrane element can be suitably removed by using the wastewater W1 (water to be treated).

[0035] In the wastewater treatment apparatus 1 of the present embodiment described above, a water level difference can be formed by generating a pressure difference between the treatment tank 2A and the treatment tank 2B. For example, a water flow can be formed that flows from the treatment tank 2A with a higher water head to the treatment tank 2B with a lower water head through the communication passage 5. In the treatment tank 2A, since this water flow is a downward flow opposite to the upward flow of the gas-liquid mixed flow by the bubbles of the air diffuser pipe 11, it acts to strip off the pollutants accumulated on the upper side of the membrane unit 10 and the membrane element downward. Thereby, the pollutants accumulated on the upper side of the membrane unit 10 and the membrane element can be suitably removed by using the wastewater W1 (water to be treated). Therefore, the frequency of cleaning with chemicals can be reduced.

[0036] Further, by controlling the opening and closing of both recovery side on-off valves 16, 16 and both supply side on-off valves 14, 14 by the control unit 30, cleaning using the water head pressure can be easily performed. For example, the control unit 30 can perform cleaning at a predetermined cycle such as once a day or once a week. Note that the suction pressure of the suction pump may be detected by a sensor or the like, and when the suction pressure becomes greater than a predetermined value, it may be determined that the membrane unit 10 is contaminated, and the control unit 30 may be configured to automatically perform cleaning.

[0037] In addition, since the biogas recovered by the two gas recovery pipes 15, 15 is supplied to the two gas supply pipes 13, 13 through the blower device 19, efficient cleaning of the membrane unit 10 can be achieved.

[0038] In addition, in the cleaning method of the wastewater treatment apparatus 1 of the present embodiment, a water level difference can be formed between the treatment tanks 2A and 2B by the water level difference forming step, and a water flow flowing from the higher water head side to the lower water head side through the communication path 5 can be formed by the water flow forming step. Since this water flow is a downward flow opposite to the upward flow of the gas-liquid mixed flow by the bubbles of the air diffuser pipe 11, it acts to scrape off the contaminants accumulated on the upper side of the membrane unit 10 and the membrane element downward. Thereby, the contaminants accumulated on the upper side of the membrane unit 10 and the membrane element can be suitably removed using the wastewater W1 (water to be treated). Therefore, the cleaning frequency with the chemical solution can be reduced.

[0039] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and can be appropriately modified without departing from the spirit thereof. For example, in the above embodiment, the configuration is such that a water level difference is formed between the treatment tank 2A and the treatment tank 2B by the biogas sent to the air diffuser pipe 11 by the blower device 19. However, the present invention is not limited thereto, and the internal air pressure may be increased by storing the biogas naturally generated from the stored wastewater W1 without using the blower device 19.

[0040] In addition, in the above embodiment, the cleaning is performed by forming a water level difference between two adjacent treatment tanks 2A and 2B. However, the present invention is not limited thereto, and in a wastewater treatment apparatus 60 having three treatment tanks 61 to 63 and a preliminary tank 55 as shown in FIG. 4, the membrane unit 10 can also be suitably cleaned using the water level difference. The treatment tanks 61 to 63 shown in Fig. 4 each include a membrane unit 10 and each include a communication passage 5 in two partition walls 2a, 2a. Further, the treatment tanks 61 to 63 are similarly provided with a gas recovery pipe 15, a recovery side on-off valve 16, a gas supply pipe 13, and a supply side on-off valve 14, and are provided with a control unit 30 for controlling the opening and closing of these valves.

[0041] In such a wastewater treatment apparatus 60, for example, when cleaning the membrane unit 10 of the treatment tank 61, in the water level difference forming step, the supply side on-off valve 14 of the treatment tank 61 is closed, and the recovery side on-off valves 16 of the treatment tanks 62 and 63 are closed to increase the pressure in each internal space of the treatment tanks 62 and 63. As a result, the water levels of the treatment tanks 62 and 63 each drop, and instead, the water level of the treatment tank 61 rises, forming a water level difference between the treatment tank 61 and the treatment tanks 62 and 63.

[0042] When the water level difference is formed, in the water flow forming step, on the treatment tank 61 side, the recovery side on-off valve 16 is maintained in an open state, and the supply side on-off valve 14 is maintained in a closed state. On the other hand, on the treatment tank 62, 63 side, each recovery side on-off valve 16 is switched to an open state, and each supply side on-off valve 14 is maintained in an open state. As a result, the pressure in the internal space of each of the treatment tanks 62 and 63 decreases, and the water levels of the treatment tanks 62 and 63 rise from the low water level to the water level during normal operation. Due to this rise, the wastewater W1 vigorously flows into the treatment tanks 62 and 63 through the communication passage 5 from the treatment tank 61. At this time, the water flow generated in the treatment tank 61 is a downward flow opposite to the upward flow of the gas-liquid mixed flow by the bubbles of the air diffuser pipe 11, so it acts to strip off the contaminants accumulated on the upper side of the membrane unit 10 downward. Thereby, in the treatment tank 61, the contaminants accumulated on the upper side of the membrane unit 10 and the upper side of the membrane element can be suitably removed using the wastewater W1 (water to be treated). Note that, regarding the cleaning of the membrane units 10, 10 of the treatment tanks 62 and 63, the contaminants can be suitably removed by similarly forming a water level difference. As described above, the wastewater treatment apparatus 60 having the three treatment tanks 61 to 63 and the preliminary tank 55 has been explained. However, the present invention is not limited thereto, and the cleaning of the membrane unit 10 can be suitably performed by using the water level difference also for a wastewater treatment apparatus having four or more treatment tanks and preliminary tanks.

Explanation of Signs

[0043] 1 Wastewater treatment apparatus 2A, 2B Anaerobic wastewater treatment tank (treatment tank) 5 Communication path 6 Pressure difference generating means 10 Membrane unit 11 Diffuser tube 13 Gas supply pipe 14 Supply side on-off valve 15 Gas recovery pipe 16 Recovery side on-off valve 30 Control unit 60 Wastewater treatment apparatus 61 to 63 Treatment tanks W1 Wastewater

Claims

1. At least two adjacent anaerobic wastewater treatment tanks, Separation membranes installed in each of the two anaerobic wastewater treatment tanks for filtering wastewater, Diffuser pipes respectively arranged below the two separation membranes for supplying gas bubbles toward the two separation membranes, A communication passage connecting the two anaerobic wastewater treatment tanks below the two separation membranes, A pressure difference generating means for generating a pressure difference between the two anaerobic wastewater treatment tanks, characterized in that the wastewater treatment apparatus comprises the above components.

2. The pressure difference generating means includes gas recovery pipes respectively connected to the two anaerobic wastewater treatment tanks, a recovery side on-off valve provided on the gas recovery pipes, gas supply pipes respectively connected to the two diffuser pipes, supply side on-off valves provided on the two gas supply pipes, and a control unit for controlling the opening and closing of the two recovery side on-off valves and the two supply side on-off valves. The wastewater treatment apparatus according to Claim 1 is characterized by comprising the above components.

3. The two gas recovery pipes are connected to the two gas supply pipes through a blower device. The wastewater treatment apparatus according to Claim 2 is characterized by this.

4. A cleaning method for a wastewater treatment apparatus comprising at least two adjacent anaerobic wastewater treatment tanks, separation membranes installed in each of the two anaerobic wastewater treatment tanks for filtering wastewater, diffuser pipes respectively arranged below the two separation membranes for supplying gas bubbles toward the two separation membranes, and a communication passage connecting the two anaerobic wastewater treatment tanks below the two separation membranes, the method comprising: A water level difference forming step of forming a water level difference between the two anaerobic wastewater treatment tanks by generating a pressure difference between the two anaerobic wastewater treatment tanks; A water flow forming step of forming a water flow flowing from the anaerobic wastewater treatment tank on the side with a higher water head to the anaerobic wastewater treatment tank on the side with a lower water head through the communication passage. The cleaning method for a wastewater treatment apparatus is characterized by including the above steps.

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