JP2000210542A - Method and apparatus for washing membrane unit in waste water treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply wash a membrane unit without hanging up or transferring the same. SOLUTION: An activated sludge stand-by tank 13 is arranged outside an activated sludge tank 4 having a membrane unit 1 arranged therein and both tanks are connected by an activated sludge transfer pipe 15 equipped with a pump 14 and an activated sludge return pipe 17 equipped with a pump 16. Activated sludge 4a in the activated sludge tank 4 is transferred to the activated sludge stand-by tank 13 through the activated sludge transfer pipe 15 to be stored therein and the membrane unit 1 is then washed in the activated sludge tank 4. After a washing soln. is withdrawn, activated sludge in the activated sludge stand-by tank 13 is returned to the activated sludge tank 4 through the activated sludge return pipe 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for cleaning a membrane unit in a wastewater treatment facility in which wastewater is treated by a high-concentration activated sludge method in an activated sludge tank.

[0002]

2. Description of the Related Art As an example of a wastewater treatment system employing an activated sludge method, as shown in FIGS.
A membrane unit 1 formed by assembling a plurality of separation membranes 2 made of hollow fiber membranes at required intervals and connecting a filtration water pipe 3 to the separation membranes 2 is immersed in activated sludge 4 a in an activated sludge tank 4. The filtration water pipe 3 is connected to a treated water suction pipe 6 equipped with a treated water suction pump 5, and diffuser pipes 7 are arranged in multiple rows below the membrane unit 1. 7
Is connected to the blower 8 via the air supply pipe 9 and the activated sludge tank 4 is equipped with an aeration device.
Is supplied into the activated sludge tank 4 through a raw water supply pipe 12 by driving a raw water supply pump 11.
The raw water and the activated sludge 4a are mixed and stirred by blowing air through the air diffuser 7 to remove the organic matter in the raw water into the activated sludge 4a.
Then, the treated water as the filtered water filtered through the separation membrane 2 is sucked by the treated water suction pump 5 into the filtered water pipe 3 and the treated water suction pipe 6.
The microorganisms and suspended substances are separated on the surface of the separation membrane 2 by being collected through the separation membrane 2.

In the case of such a wastewater treatment facility, as described above, only the clarified filtered water is sucked by the separation membrane 2 of the membrane unit 1, and microorganisms and suspended substances are maintained in the activated sludge tank 4. However, in order to efficiently maintain the activated sludge treatment, the solid membrane is clogged by depositing a solid on the surface of the separation membrane 2 as a cake layer. Need to be washed.

Conventionally, the membrane unit 1 is entirely lifted from the activated sludge tank 4 and washed with water, or the lifted membrane unit 1 is transferred and immersed in a chemical tank. Has been adopted.

[0005]

However, when the membrane unit 1 is lifted, the connection between the filtered water pipe 3 and the treated water suction pipe 6 of the membrane unit 1 must be separated or reconnected each time. In addition, the operation becomes complicated, and the separation membrane 2 may be damaged.
When transferring the water, not only there is a problem that sludge containing water adhering to the separation membrane 2 drops and stains the surroundings, but also there is a problem that the entire configuration of the cleaning device becomes large-scale.

[0006] Therefore, an object of the present invention is to enable the membrane unit to be easily washed without being lifted or transferred.

[0007]

According to the present invention, in order to solve the above problems, raw water and activated sludge are mixed and agitated by aeration in an activated sludge tank, and the treated water is discharged out of the activated sludge tank through a membrane unit. During the washing of the membrane unit in the wastewater treatment facility that is configured to perform wastewater treatment, the activated sludge in the activated sludge tank is transferred to another tank and stored therein, and then the activated sludge is removed from the activated sludge tank. Washing the membrane unit in the activated sludge tank by draining the washing liquid from the activated sludge tank and returning the activated sludge stored in another tank to the activated sludge tank. The activated sludge in a wastewater treatment facility wherein the raw water and the activated sludge are mixed and agitated by aeration in the activated sludge tank, and the treated water is discharged outside the activated sludge tank through the membrane unit. In addition, an activated sludge standby tank and a washing liquid tank are installed, and an activated sludge transfer pipe and an activated sludge return pipe are connected between the activated sludge standby tank and the activated sludge tank, respectively. A membrane unit cleaning device in a wastewater treatment facility in which a cleaning liquid supply pipe is connected to an activated sludge tank.

Since the activated sludge is transferred to another tank and made to stand by, it is possible to eliminate the trouble of lifting and transferring the membrane unit.

Further, the cleaning liquid after cleaning the membrane unit in the activated sludge tank is drawn out of the activated sludge tank through the above-mentioned membrane unit, thereby saving the trouble of transferring the used cleaning liquid to another place for processing. Can be.

Further, by activating the activated sludge stored in another tank when cleaning the membrane unit, the activity of the activated sludge on standby can be maintained.

Furthermore, by transferring activated sludge from the activated sludge tank to another tank and loading the activated sludge nutrient solution such as raw water into the other tank during storage, the sludge is washed when the membrane unit is washed. Can be prevented from self-decomposing excessively.

On the other hand, a raw water tank for storing raw water flowing into the activated sludge tank is divided into at least a raw water tank dedicated section capable of communicating with and shut off from each other and a raw water tank / active sludge standby tank combined section. When the membrane unit is washed, the activated sludge transferred from the activated sludge tank is stored in the raw water tank / active sludge standby tank dual-purpose part when washing the membrane unit, and the cleaning liquid is supplied to the activated sludge tank from the raw water tank / cleaning liquid tank dual-purpose part By adopting a configuration in which washing is performed, a dedicated activated sludge standby tank can be eliminated.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In a wastewater treatment facility having the same configuration as that shown in FIGS. 6A and 6B, an activated sludge standby tank is provided separately from the activated sludge tank 4. 13 is provided between the activated sludge tank 4 and the activated sludge standby tank 13.
5 and an activated sludge return pipe 17 equipped with a pump 16 are connected to each other, and the activated sludge 4a in the activated sludge tank 4 is transferred into the activated sludge standby tank 13 through the activated sludge transfer pipe 15 by the suction force of the pump 14. At the same time, the activated sludge 4a transferred and stored in the activated sludge standby tank 13 can be returned to the activated sludge tank 4 through the activated sludge return pipe 17 by the suction force of the pump 16.

A cleaning liquid tank 18 is installed near the downstream side of the activated sludge tank 4, and a branch pipe 19 connected to the cleaning liquid tank 18 on the downstream side of the treated water suction pump 5 from the treated water suction pump 5. And an on-off valve 20 is provided at a position downstream of the branch pipe connection of the treated water suction pipe 6, and an on-off valve 21 is provided in the middle of the branch pipe 19.
The processing water sucked into the processing water suction pipe 6 by the suction force of the above is introduced into the cleaning liquid tank 18 through the branch pipe 19 by opening and closing the on-off valves 20 and 21.

Further, a cleaning liquid supply pipe 23 having a pump 22 and a cleaning liquid return pipe 25 having a pump 24 are connected between the activated sludge tank 4 and the cleaning liquid tank 18, respectively.
The treatment water introduced into the cleaning liquid tank 18 can be supplied as a cleaning liquid into the activated sludge tank 4 through the cleaning liquid supply pipe 23 by the suction force of the pump 22 and the activated sludge tank 4
The cleaning liquid used in the inside can be returned to the cleaning liquid tank 18 through the cleaning liquid return pipe 25 by the suction force of the pump 24.

When the membrane unit 11 is to be washed, the on-off valve 20 is closed and the on-off valve 21 is switched on in advance while the treated water suction pump 5 is operating, and the treated water is transferred from the treated water suction pipe 6 to the branch pipe 19. After that, the operation of the treated water suction pump 5 is stopped.

Next, the pump 14 is operated to transfer the activated sludge 4a in the activated sludge tank 4 through the activated sludge transfer pipe 15 to the activated sludge standby tank 13 for storage. When all the activated sludge 4a is transferred to the activated sludge standby tank 13, the pump 2
2 is operated and the treated water in the cleaning liquid tank 18 is supplied to the cleaning liquid supply pipe 2.
The liquid is supplied to the activated sludge tank 4 through 3 as a cleaning liquid, and the activated sludge tank 4 is filled with the cleaning liquid, and the membrane unit 11 is aerated and cleaned for a required time.

When the aeration cleaning of the membrane unit 11 is completed,
The pump 24 is operated to return all of the cleaning liquid in the activated sludge tank 4 to the cleaning liquid tank 18 through the cleaning liquid return pipe 25, and then the pump 16 is operated to remove the activated sludge 4 a in the activated sludge standby tank 13 from the activated sludge return pipe 17. Then, the wastewater is returned to the activated sludge tank 4, and thereafter, the operation of the treated water suction pump 5 is restarted.

The used cleaning liquid returned to the cleaning liquid tank 18 is stored in the cleaning liquid tank 18 as long as it can be used again for cleaning. Depending on the water quality, the wastewater is discharged as it is or the membrane separation activated sludge method is returned to the raw water tank 10 during a low load time period for reprocessing.

As described above, in the present invention, the membrane unit 1
Is washed in the activated sludge tank 4 without being lifted or moved, so that there is no need to separate or connect a connecting portion between the filtered water pipe 3 and the treated water suction pipe 6 of the membrane unit 1 and wash. Since the entire operation can be performed easily, and the membrane unit 1 is not transferred, the problem that sludge containing water drops and contaminates the surroundings can be solved.

In the embodiment shown in FIG. 1, one of the pumps 14 and 16 and one of the pumps 22 and 24 are replaced with valves, and the activated sludge tank 4, the activated sludge standby tank 13 and the cleaning liquid With a configuration in which a height difference is provided between the tank and the tank 18, the activated sludge and the cleaning liquid can be moved.

FIGS. 2 (a) and 2 (b) show another embodiment of the present invention. In the same configuration as shown in FIG. 1, a space between the activated sludge tank 4 and the washing liquid tank 18 is provided. The cleaning liquid return pipe 25 and the pump 24 are omitted. Further, in the activated sludge tank 4, as shown in (b), a suction start level switch 26, a load stop level switch 27, a load start level switch 28, and a suction stop level switch 29 are installed in order from the top. The four levels of suction start, load stop, load start, and suction stop are set, and during normal operation, the operation of the treated water suction pump 5 is controlled based on the signals of the suction start level switch 26 and the suction stop level switch 29. In addition, the raw water supply pump 11 is operated based on the signal of the load start level switch 28, and the operation of the raw water supply pump 11 is stopped based on the signal of the load stop level switch 27. However, only when the cleaning of the membrane unit 1 is completed, the pump 16 is operated by being switched by a switch, a relay, or the like.

In the embodiment shown in FIGS. 2A and 2B,
As in the case of the embodiment shown in FIG.
Is washed in the activated sludge tank 4, but the used washing liquid is not returned to the washing liquid tank 18, and the washing water is sucked from the activated sludge tank 4 through the membrane unit 1 by operating the treated water suction pump 5. The tube 6 is withdrawn as treated water. Thereby, it is possible to save the trouble of transferring the used cleaning liquid to another place for processing.

Next, FIG. 3 shows still another embodiment of the present invention. In the configuration similar to that shown in FIG.
A branch pipe 30 is connected in the middle of the air supply pipe 9 constituting the aeration device of the activated sludge tank 4, and the leading end of the branch pipe 30 is introduced into the bottom of the activated sludge standby tank 13. At the tip, a plurality of diffuser tubes 31 are communicated and connected at required arrangement intervals, and an activated sludge standby tank 13 is provided with an aerator. Further, an on-off valve 32 is provided in the middle of the branch pipe 30,
Further, on-off valves 33 are provided at positions upstream of the branch pipe connection portion of the air supply pipe 9 respectively.

In the case of the embodiment shown in FIG. 3, when the membrane unit 11 is to be washed, as in the case of the embodiment shown in FIG. 20 is closed and the on-off valve 21 is opened, and the treated water is stored in the cleaning liquid tank 18 from the treated water suction pipe 6 via the branch pipe 19, and after the storage, the operation of the treated water suction pump 5 is stopped. Next, the pump 14 is operated to transfer the activated sludge 4 a in the activated sludge tank 4 to the activated sludge standby tank 13 through the activated sludge transfer pipe 15. Thereafter, the pump 22 is operated to move the activated sludge in the washing liquid tank 18. The treated water is supplied as a cleaning liquid into the activated sludge tank 4 through the cleaning liquid supply pipe 23, and the activated sludge tank 4
The inside is filled with the cleaning liquid, and the membrane unit 11 is aerated and cleaned for a required time.

On the other hand, when the membrane unit 1 is washed, the on-off valve 32 is opened and air is blown into the activated sludge standby tank 13 for storing the activated sludge 4a through the air supply pipe 9, the branch pipe 30, and the diffuser pipe 31. Then, the activated sludge 4a on standby is aerated. As a result, the activated sludge 4a on standby
Can maintain the activity of, or can improve the condition by decomposing the adsorbed organic matter, or can reduce the excess sludge by self-digestion,
When the activated sludge 4a is returned to the activated sludge tank 4 after the completion of the washing operation, a higher wastewater treatment capacity can be exhibited as compared with the case where the activated sludge is returned without aeration.

In the embodiment of FIG. 3, a case is shown in which the blower 8 of the aeration device of the activated sludge tank 4 is also used as the aeration device of the activated sludge standby tank 13, but it is separately constituted. An aeration device may be used.

FIG. 4 shows still another embodiment of the present invention. In a configuration similar to that shown in FIG. 3, a branch pipe 34 is provided at a position downstream of the raw water supply pump 11 of the raw water supply pipe 12. Connection, the tip of the branch pipe 34 is connected to the activated sludge standby tank 13, so that the raw water supply pipe 12 and the branch pipe 34 can be used as the activated sludge nutrient solution supply pipe,
Further, an on-off valve 35 is provided in the middle of the branch pipe 34, and an on-off valve 36 is provided at a position downstream of the branch pipe connection portion of the raw water supply pipe 12.

In the embodiment shown in FIG.
At the time of washing, the on-off valve 36 is closed, the on-off valve 35 is opened, and the activated sludge such as raw water is supplied into the activated sludge standby tank 13 for storing the activated sludge through the raw water supply pipe 12 and the branch pipe 34 by the suction force of the raw water pump 11. The nutrient solution is supplied by load, and the raw water and the activated sludge 4a are mixed and agitated by aeration by an aerator. This can prevent the sludge from being excessively self-decomposed during the cleaning operation of the membrane unit 1.

FIG. 5 shows still another embodiment of the present invention. In a configuration similar to that shown in FIGS. 6A and 6B, the raw water tank 10 is provided with a raw water tank dedicated section 10a for directly receiving raw water. And a multi-tank integrated structure comprising a raw water tank / washing liquid tank dual-purpose part 10b and a raw water tank / sludge standby tank dual-purpose part 10c independently disposed at positions sandwiching the raw water tank dedicated part 10a on the left and right. A communication pipe 3 having on-off valves 37a, 37b, 37c is connected to lower portions of 10a, 10b, 10c.
8, a raw water supply pipe 12 provided with a raw water supply pump 11 is connected between the raw water tank / washing liquid tank combined portion 10b of the raw water tank 10 and the activated sludge tank 4.
An activated sludge transfer pipe 15 having a pump 14 and an activated sludge return pipe 17 having a pump 16 are connected between the raw water tank / sludge standby tank 10c of the raw water tank 10 and the activated sludge tank 4; The raw water tank / washing liquid tank 1 of the raw water tank 10
0b, a branch pipe 19 connected to the downstream side of the treated water suction pump 5 of the treated water suction pipe 6 is connected so that the treated water is returned. An on-off valve 20 is provided at a downstream position, and an on-off valve 21 is provided in the branch pipe 19. In addition, each part 10a, 10b, 10c which comprises the raw water tank 10 has the size of one tank of the activated sludge tank 4, respectively.

In FIG. 5, the same parts as those in FIG. 6 are denoted by the same reference numerals.

In the case of the embodiment shown in FIG. 5, during normal operation,
Each open / close valve 37 of the communication pipe 38 attached to the raw water tank 10
The raw water is supplied to the activated sludge tank 4 through the raw water supply pipe 12 from the raw water tank / washing liquid tank 10b with the a, 37b, and 37c opened.

When the membrane unit 1 is to be cleaned, the cleaning is determined to some extent earlier, and the opening / closing valves 37a, 37b, 37 are used during a time period when the flow of raw water into the raw water tank dedicated section 10a is small.
By closing c, the treated water suction pump 5 is operated to store the treated water from the treated water suction pipe 6 through the branch pipe 19 in the independent raw water tank / washing liquid tank combined portion 10b. Further, after the operation of the treated water suction pump 5 is stopped, the activated sludge 4a in the activated sludge tank 4 is transferred to the raw water tank / sludge standby tank combined portion 10c through the activated sludge transfer pipe 15 by the operation of the pump 14. Then, raw water supply pump 1
By the operation of 1, the treated water in the raw water tank / cleaning liquid tank dual-purpose portion 10b is supplied as a cleaning liquid into the activated sludge tank 4 through the raw water supply pipe 12, and the membrane unit 1 is aerated and cleaned.

When the aeration cleaning of the membrane unit 1 is completed, the cleaning water is supplied to the activated sludge tank 4 by operating the treated water suction pump 5.
Through the membrane unit 1 and into the treated water suction pipe 6.
After returning the activated sludge 4a in the sludge standby tank dual-purpose part 10c into the activated sludge tank 4 through the activated sludge return pipe 17, the on-off valves 37a, 37b, 37c are opened to open the respective parts 10a, 10b,
10c is brought into a communication state.

When the embodiment shown in FIG. 5 is adopted, since the raw water tank 10 has a multi-tank structure, it is not necessary to provide a dedicated activated sludge standby tank.

In the above embodiment, the switching between the discharge of the treated water and the transfer as the cleaning liquid is controlled by the on-off valves 20 and 2.
Although the case where the operation is performed by the operation 1 is shown, if the switching between the discharge and storage of the treated water is possible, the on-off valves 20 and 21 are used.
May be performed by moving the treated water suction pipe 6, for example, and the cleaning of the membrane unit 1 may be performed by a method other than the treated water, for example, working water, or based on them. In addition to using a chemical aqueous solution, or in addition to aeration cleaning, for example, surface sludge may be washed off with running water. Further, in the embodiment of FIG.
The case where the communication between the tank portions 10a, 10b, and 10c of the raw water tank 10 is performed using the communication pipe 38 and the on-off valves 37a, 37b, and 37c is shown. Of course, various changes may be made without departing from the spirit of the present invention.

[0038]

As described above, according to the method and apparatus for cleaning a membrane unit in a wastewater treatment facility of the present invention, the following excellent effects are exhibited. (1) In the activated sludge tank, the raw water and the activated sludge are mixed and agitated by aeration, and the treated water is discharged to the outside of the activated sludge tank through the membrane unit. When the unit is washed, the activated sludge in the activated sludge tank is transferred to another tank and stored therein, and then the cleaning liquid is put into the activated sludge tank to wash the membrane unit. The cleaning liquid is drained from the tank, and the activated sludge stored in the other tank is returned to the activated sludge tank.Therefore, every time the membrane unit is washed, lifting of the membrane unit and associated work are not required. As a result, the complexity of the entire cleaning operation and the increase in the size of the cleaning device can be eliminated, and since the membrane unit is not transferred to another place, sludge containing water does not fall and contaminate the surroundings. (2) The cleaning liquid after washing the membrane unit in the activated sludge tank is drawn out of the activated sludge tank through the above-mentioned membrane unit, so that it takes special time to process the cleaning liquid after the membrane unit is washed. No need to multiply. (3) At the time of cleaning the membrane unit, the activated sludge stored in another tank is aerated so that the activated sludge on standby can be kept active, which is advantageous. (4) By transferring activated sludge from the activated sludge tank to another tank and loading the activated sludge nutrient solution into the other tank during storage, the sludge is excessively self-decomposed during washing of the membrane unit. Can be prevented. (5) Raw water and activated sludge are mixed and stirred by aeration in the activated sludge tank, and the raw water flowing into the activated sludge tank in the wastewater treatment facility in which the treated water is discharged to the outside of the activated sludge tank through the membrane unit. The raw water tank for storing has a multi-tank integrated structure that is divided into at least a raw water tank dedicated section that can communicate with each other and can be shut off and a raw water tank / active sludge standby tank combined section. The activated sludge transferred from the tank is stored in the raw water tank / active sludge standby tank dual-purpose section, and the cleaning liquid is supplied to the activated sludge tank from the raw water tank / cleaning liquid tank dual-purpose section to perform cleaning, The need to install a dedicated activated sludge standby tank can be eliminated,
This can contribute to downsizing of equipment.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of a membrane unit cleaning apparatus in a wastewater treatment facility of the present invention.

FIG. 2 shows another embodiment of the present invention.
Is a schematic diagram of the whole, and (b) is a schematic diagram of an activated sludge tank portion.

FIG. 3 is a schematic diagram showing still another embodiment of the present invention.

FIG. 4 is a schematic diagram showing still another embodiment of the present invention.

FIG. 5 is a schematic view showing still another embodiment of the present invention.

FIG. 6 shows an example of a wastewater treatment facility, in which (a) is a schematic plan view of the whole, and (b) is a partially cutaway perspective view showing an enlarged activated sludge tank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Membrane unit 4 Activated sludge tank 4a Activated sludge 6 Treated water suction pipe 7 Aeration pipe (aeration device) 10 Raw water tank 10a Raw water tank dedicated section 10b Raw water tank / washing liquid tank combined section 10c Raw water tank / sludge standby tank shared section 12 Raw water supply Pipe 13 Activated sludge standby tank 15 Activated sludge transfer pipe 17 Activated sludge return pipe 18 Cleaning liquid tank 23 Cleaning liquid supply pipe 38 Communication pipe

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Sakae Fukunaga 1 Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Technical Research Institute, Kawashima-Harima Heavy Industries Co., Ltd. 4D006 GA02 HA16 HA19 HA93 JA34Z JA39Z JA53Z JA55Z JA67Z KA01 KA12 KA44 KA67 KB22 KC02 KC13 KC14 KE21P KE21Q KE22P KE22Q KE23P KE23Q KE24P KE24Q MA01 MB02 PA02 PB08 PB70 PC64 4D028 AB00 BA00 BC17 BC28 BD12 BD17 CA05 CB08 CC05 CD05

Claims (8)

[Claims] 1. A wastewater treatment system in which raw water and activated sludge are mixed and agitated by aeration in an activated sludge tank, and treated water is discharged through a membrane unit to the outside of the activated sludge tank to perform wastewater treatment. At the time of cleaning the membrane unit, the activated sludge in the activated sludge tank is transferred to another tank and stored therein, and then the cleaning unit is put into the activated sludge tank to wash the membrane unit. A method for cleaning a membrane unit in a wastewater treatment facility, wherein a cleaning liquid is drained from an activated sludge tank and activated sludge stored in another tank is returned to the activated sludge tank. 2. The method for cleaning a membrane unit in a wastewater treatment facility according to claim 1, wherein the cleaning liquid after washing the membrane unit in the activated sludge tank is drawn out of the activated sludge tank through the membrane unit. 3. The method for cleaning a membrane unit in wastewater treatment equipment according to claim 1, wherein activated sludge stored in another tank is aerated when the membrane unit is washed. 4. The method for cleaning a membrane unit in a wastewater treatment facility according to claim 3, wherein the activated sludge is transferred from the activated sludge tank to another tank, and the activated sludge nutrient solution is loaded into the other tank during storage. . 5. An activated sludge tank, wherein the raw water and the activated sludge are mixed and agitated by aeration, and the treated water is discharged out of the activated sludge tank through a membrane unit. Installing an activated sludge standby tank and a cleaning liquid tank, connecting an activated sludge transfer pipe and an activated sludge return pipe between the activated sludge standby tank and the activated sludge tank, respectively, and providing a cleaning liquid tank and an activated sludge tank. And a cleaning liquid supply pipe connected between the cleaning unit and the membrane unit cleaning apparatus in a wastewater treatment facility. 6. The membrane unit cleaning device in a wastewater treatment facility according to claim 5, wherein an aeration device is provided in the activated sludge standby tank. 7. The membrane unit cleaning apparatus in a wastewater treatment facility according to claim 6, wherein an activated sludge nutrient solution supply pipe is connected to the activated sludge standby tank. 8. An activated sludge tank, in which raw water and activated sludge are mixed and agitated by aeration, and the treated water flows into the activated sludge tank in a wastewater treatment facility configured to discharge the treated water out of the activated sludge tank through a membrane unit. The raw water tank for storing raw water has a multi-tank integrated structure divided into at least a raw water tank dedicated section and a raw water tank / active sludge standby tank dual-purpose section that can communicate with each other and can be shut off. Activated sludge transferred from the activated sludge tank is stored in the raw water tank / active sludge standby tank dual-purpose section, and the cleaning liquid is supplied to the activated sludge tank from the raw water tank / cleaning liquid tank dual-purpose section to perform cleaning. A membrane unit cleaning device in a wastewater treatment facility, characterized in that: