JPH0356192A - Washing of membrane module with chemical - Google Patents

Abstract

PURPOSE:To enable a membrane module to be washed with chemicals without taking out either of the module and activated sludge by connecting a microbial treatment tank with a filtration tank so that these two tanks can be either communicated or cut off one another and by washing the membrane module after storing all the activat ed sludge in the microbial treatment tank and cutting off this tank from the filtration tank when the module is washed with chemicals. CONSTITUTION:In case of washing a membrane module 15 with chemicals, an operation of apparatus is shut down, part of mixed solution in a microbial treatment tank 11 is transferred into a filtration tank 12 by a pump 2, this solution is separated into a condensed solution and a filtrate and the filtrate is discharged outside, resulting in a reduction of liquid holdup by a quantity of discharged filtrate. Next, the microbial treatment tank 11 is cut off, all the condensed solution remaining in the filtration tank 12 is transferred into the microbial treatment tank 11 through a transfer pipe 25 to empty the filtration tank 12, then washing water is poured into the filtration tank 12 and the membrane module 15 is washed with water while air is blown from an air diffuser 17. After the washing water is discharged, liquid chemicals are poured into the filtration tank 12 and the membrane module 15 is washed with the chemicals. Furthermore, a neutralizer is introduced after the washing so as to prevent microorgan ism from dying out when the operation is resumed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for chemically cleaning a membrane module in a sewage treatment apparatus in which a mixed solution after microbial treatment of raw water is filtered through a filtration membrane.

Conventionally, in the above-mentioned sewage treatment equipment, for example, as shown in FIG. A diffuser pipe 3 for aeration was installed. The raw sewage water 4 is then supplied into the microbial treatment tank 1 and treated with microorganisms to form a mixed solution 5 with microorganisms. This mixed solution 5 becomes an upward flow due to the bubbles of the aeration air 6 blown out from the aeration pipe 3, is filtered by the membrane module 2, and is separated into a concentrated liquid and a permeated liquid, and the concentrated liquid further rises to form a permeated liquid. The permeate in the membrane module 2 circulates in the direction of the arrow in Figure 2, and is discharged to the outside by a suction pump (not shown).

Problems to be Solved by the Invention By the way, as the membrane module 2 is used, it gradually becomes clogged with the solid content in the mixed solution 5, so it is necessary to periodically clean it with a chemical solution.

However, in the conventional configuration described above, when cleaning the membrane module 2, it is necessary to remove the membrane module 2 or the microorganisms from the tank so that the microorganisms in the activated sludge are not killed by the chemical solution, so cleaning only takes time. Without,
There was a problem in that the sewage treatment equipment was out of operation for a long time.

It is an object of the present invention to provide a method that eliminates these conventional problems and allows chemical cleaning to be performed without taking out either the membrane module or the microorganisms to the outside.

Means for Solving the Problems In order to achieve the above object, the chemical cleaning method for membrane modules of the present invention includes a microbial treatment tank for microbial treatment of raw water;
A filtration treatment tank in which a mixed solution after microbial treatment is filtered by a membrane module having a filtration membrane is installed so as to be able to communicate with it through a partition wall, and a first filter is installed at the bottom of the microbial treatment tank.
A valve is connected, and a plurality of membrane modules and an aeration diffuser pipe below the membrane module are installed inside the filtration treatment tank.
A second valve and a third valve are connected in series to the bottom of the filtration treatment tank, and a fourth valve is connected between the first valve and the second valve.
A first communication pipe having a valve and a second communication pipe having a pump are connected between the third valve and a transfer pipe having a fifth pulp between the pump of the second communication pipe and the third pulp. and a drain pipe having a drainage valve, and the other end of the transfer pipe is opened above the microbial treatment tank to constitute a sewage treatment device, and the supply of raw water to the microbial treatment tank is stopped, and the first valve is opened. , a first step of closing valves other than the second valve and the third valve, and a part of the mixed solution in the microbial treatment tank is sent into the filtration treatment tank by a pump, and the mixed solution is filtered and concentrated by a membrane module. A second step in which the mixed solution in the microbial treatment tank is reduced by separating the liquid and the permeated liquid and discharging the permeated liquid in the membrane module to the outside; The third valve opens the fourth valve and the fifth valve, and the pump transfers all the concentrated liquid in the filtration treatment tank to the microbial treatment tank.
After closing all valves and washing the membrane module by pouring washing water into the filtration tank and blowing air through the air diffuser, open the second valve, the third valve, and the drain valve to release the washing water. A fourth step of discharging the water, a fifth step of closing all valves, putting a chemical solution into the filtration treatment tank to wash the membrane module with a chemical, and then adding a neutralizing agent into the chemical solution to neutralize the chemical solution. and a sixth step of restarting operation of the sewage treatment apparatus by opening the first valve, the second valve, and the fourth valve.

Effect In the configuration of the present invention described above, during operation, the first valve, the second valve, and the fourth valve are opened, and the mixed solution in the filtration treatment tank rises due to the bubbles of aeration air blown out from the aeration pipe. The resulting liquid is filtered by a membrane module and separated into a concentrated liquid and a permeated liquid. The concentrated liquid further rises, enters the activated sludge treatment tank over the partition wall, mixes with the mixed solution in the cypress, descends, returns to the filtration treatment tank via the first communication pipe, and circulates. On the other hand, the permeate inside the membrane module is discharged to the outside by a suction pump.

When cleaning the membrane module with chemicals, in the first step, the operation of the sewage treatment equipment is stopped, and the supply of raw water is also stopped. When all valves other than the first valve, second valve, and third valve are closed, the activated sludge treatment tank and the filtration treatment tank are communicated via the second communication pipe. In the second step, while operating the pump to send a part of the mixed solution in the microbial treatment tank into the filtration treatment tank, the mixed solution is filtered by the membrane module and separated into a concentrated liquid and a permeated liquid. When the permeate in the module is discharged to the outside, the mixed solution in the microbial treatment tank is reduced by the amount of the discharged permeate. In the third step,
When the first valve and the third pulp are closed and the second valve, the fourth valve, and the fifth valve are opened, the microbial treatment tank is shut off and the filtration treatment tank is transferred from the first communication pipe to the second communication pipe. It communicates with the transfer pipe. Therefore, when the pump is operated, all the concentrated liquid remaining in the filtration tank is transferred from the transfer pipe to the microbial treatment tank, and the filtration tank becomes empty. In the fourth step, all valves are closed, cleaning water is poured into the filtration treatment tank, and air is blown through the aeration pipe, which agitates the cleaning water and washes the membrane module. After opening the second valve, third valve, and drain valve to discharge the cleaning water, in the fifth step, all the valves are closed and a chemical solution is poured into the filtration treatment tank to chemically clean the membrane module. The chemical solution is
Since it is usually acidic, if the chemical solution remains in the filtration treatment tank when restarting operation later, there is a risk that microorganisms will be killed. Therefore, a neutralizing agent is added to the chemical solution to neutralize the chemical solution and prevent the microorganisms from dying.

Since the chemical cleaning is now completed, in the sixth step, the first valve, the second valve, and the fourth valve are opened to restart the operation of the sewage treatment equipment. The neutralized water in the filtration treatment tank is
Mixed with the concentrate from the microbial treatment tank, this concentrate returns to its original concentration.

As described above, according to the configuration of the present invention, chemical cleaning is easy without taking out either the membrane module or the activated sludge to the outside, and the downtime of the sewage treatment equipment can be shortened. .

Example An embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 1, the sewage treatment apparatus in this embodiment has an activated sludge treatment tank 11 and a filtration treatment tank 12 installed side by side through a partition wall 13 so as to be able to communicate with each other through the partition wall. At the bottom of the activated sludge treatment tank 11, a first valve 1 is installed.
4 are connected. The filtration treatment tank 12 is provided with a plurality of membrane modules 15 having ultrafiltration membranes therein, an aeration diffuser pipe 17 having a blower 16 below the membrane modules, and a second valve 18 and a second valve 18 at the bottom. Three valves 19 are connected in series. 1st valve 1
4, a first communication pipe 21 having a fourth valve 20 between it and the second valve 18 and a pump 2 between it and the third valve 19.
2 are connected to the second communication pipes 23 having the second communication pipes 23 and 23, respectively. A transfer pipe 25 having a fifth valve 24 and a drain pipe 27 having a drain valve 26 are connected to the second communication pipe 23 between the pump 22 and the third valve 19, respectively. The other end of the transfer pipe 25 opens above the activated sludge treatment tank 11. 28 is a raw water supply pipe.

Next, the operation of the above configuration will be explained.

During operation of the sewage treatment apparatus, the first valve 14, the second valve 18, and the fourth valve 20 are opened, and both tanks 11 and 12 are communicated through the first communication pipe 21. The raw water 29 of sewage is supplied from the raw water supply pipe 28 into the activated sludge treatment tank 11 and subjected to activated sludge treatment to become a mixed solution 30 with activated sludge. This mixed solution 30 enters the filtration treatment tank 12 via the first communication pipe 21, becomes an upward flow due to the bubbles of the aeration air 31 blown out from the diffuser pipe 17 by the blower 16, and is filtered by the membrane module 15. The liquid is separated into a concentrated liquid and a permeated liquid. The concentrated liquid further rises, crosses the partition wall 13 and enters the activated sludge treatment tank 11, mixes with the mixed solution 3o in the tank, descends, and enters the filtration treatment tank 12 via the first communication pipe 21. It returns and circulates in the direction of the arrow in the figure. On the other hand, the permeate in the membrane module 15 is discharged to the outside by a suction pump (not shown).

When cleaning the membrane module 15 with chemicals, in the first step, the operation of the sewage treatment device is stopped and the supply of raw water 29 is also stopped. When the first valve 14, the second valve l8 and the third valve 19 are opened and all other valves are closed,
Both tanks 11. ．． 12 are communicated via a second communication pipe 23. In the second step, while operating the pump 22 to send a part of the mixed solution 30 in the activated sludge treatment tank 11 into the filtration treatment tank 12, the mixed solution 30 is filtered through the membrane module 15 and passed through the concentrated liquid. When the permeated liquid in the membrane module 15 is discharged to the outside by a suction pump (not shown), the mixed solution 30 in the activated sludge treatment tank 11 is reduced by the amount of the discharged permeated liquid. In this case, the volume of the trunk-≠bell i mixed solution 30 is kept to such an extent that all of the mixed liquid in the activated sludge treatment tank 11 remains in the tank 11 without exceeding the partition wall 13. In the third step, the first valve 14 and the third valve 19 are closed, and the second valve 18 and the fourth valve are closed.
When the valve 20 and the fifth valve 24 are opened, the filtration treatment tank 12 is cut off from the activated sludge treatment tank 11 and communicated with the transfer pipe 25 via the first communication pipe 21 and the second communication pipe 23. Therefore, when the pump 22 is operated, the filtration treatment tank 1
All the concentrated liquid remaining in the filter 2 is transferred from the transfer pipe 25 to the activated sludge treatment tank 11, and the filtration treatment tank 12 becomes empty. In the fourth step, all valves are closed and the filtration treatment tank 12
Cleaning water 32 is poured into the air diffuser pipe 17 using the blower 16.
When air 31 is blown into the washing water 32, the washing water 32 is stirred and the membrane module 15 is washed with water. In this case, the cleaning water 32
The amount of air 31 is kept to such an extent that it does not exceed the partition wall 13 even if the air 31 is blown.

After washing, the second valve 18, the third valve 19, and the drain valve 26 are opened, and the washing water 32 is discharged from the drain pipe 27 to the outside. In the fifth step, all valves are closed, and a chemical solution 33 such as HC/ is put into the filtration treatment tank, and the membrane module 15 is
Clean with chemicals. In this case, the amount of the chemical solution 33 is
prevent it from exceeding the partition W13. After chemical cleaning, when restarting operation later, if the chemical solution 33 remains in the filtration treatment tank 12, the microorganisms in the activated sludge may be killed, so a neutralizing agent is added to the chemical solution 33 to neutralize it. and prevent the death of microorganisms.

In addition, after the above chemical cleaning and neutralization, N
In some cases, further chemical cleaning is performed using a chemical solution such as aCIO, followed by neutralization. Since the chemical cleaning is completed in the above steps, in the sixth step, the first valve 14, the second valve 18 and the fourth valve
The valve 20 is opened to communicate the two tanks 11 and 12 through the first communication pipe 21, raw water 29 is supplied, and the operation of the sewage treatment apparatus is restarted. The neutralized water 34 remaining in the filtration treatment tank 12 mixes with the concentrated liquid from the activated sludge treatment tank 11, and this concentrated liquid returns to its original concentration.

As described above, according to the configuration of this embodiment, the membrane module 1
5 and activated sludge can be cleaned with chemicals without taking them out to the outside, which not only makes cleaning easier, but also shortens the downtime of the sewage treatment equipment.

Effects of the Invention As explained above, in the present invention, an activated sludge treatment tank and a filtration treatment tank of a sewage treatment device are connected to each other so as to be able to communicate and shut off by a partition wall and first and second communication pipes, and the second communication A transfer pipe is connected to the pipe, and when cleaning the membrane module with chemicals, the filtration treatment tank is isolated from the activated sludge treatment tank, and all activated sludge is temporarily stored in the activated sludge treatment tank in a concentrated state before cleaning. With this configuration, chemical cleaning can be performed without taking out either the membrane module or the activated sludge to the outside. Therefore, there is an advantage that not only the chemical cleaning process is facilitated, but also the downtime of the sewage treatment equipment due to chemical cleaning is shortened.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a sewage treatment apparatus according to an embodiment of the present invention, and FIG. 2 is a sectional view of an example of a conventional sewage treatment apparatus. 11... activated sludge treatment tank, 12... filtration treatment tank, 1
3... Partition wall, 14... First valve, 15... Membrane module, 17... Diffusion tube, 18... Second valve, 19... Third valve, 2o... Third valve 4 valves, 21
... first communication pipe, 22 ... pump, 23 ... second
Communication pipe, 24... Fifth valve, 25... Transfer pipe, 2
6... Drain valve. 27... Drain pipe, 29... Raw water, 30... Mixed solution, 31... Air, 32...
Washing water, 33...chemical solution.

Claims (1)

[Claims] 1. A microbial treatment tank that microbially treats raw water and a filtration tank that filters a mixed solution after microbial treatment using a membrane module having a filtration membrane are communicated through a partition wall. A first valve is connected to the bottom of the microbial treatment tank, a plurality of membrane modules and an aeration diffuser pipe below the membrane modules are provided inside the filtration treatment tank, and a first valve is connected to the bottom of the filtration treatment tank. The second valve and the third valve are connected in series, and the first valve has a first communicating pipe having a fourth valve between it and the second valve, and a second communicating pipe having a pump between the third valve. A transfer pipe having a fifth valve and a drain pipe having a drain valve are connected between the pump and the third valve of the second communication pipe, and the other end of the transfer pipe is opened above the microbial treatment tank. A first step of stopping the supply of raw water to the microbial treatment tank and closing valves other than the first valve, second valve, and third valve, and a pump to configure the sewage treatment equipment. While sending a part of the mixed solution into the filtration treatment tank, the mixed solution is filtered through a membrane module and separated into a concentrated liquid and a permeated liquid, and the permeated liquid in the membrane module is discharged to the outside for microbial treatment. The second step is to reduce the amount of mixed solution in the tank, close the first and third valves, open the second, fourth and fifth valves, and remove all the concentrated liquid in the filtration tank with microorganisms using a pump. The third to be transferred into the treatment tank
After closing all valves and washing the membrane module by pouring washing water into the filtration tank and blowing air through the air diffuser, open the second valve, the third valve, and the drain valve to release the washing water. A fourth step of discharging the water, a fifth step of closing all valves, putting a chemical solution into the filtration treatment tank to wash the membrane module with the chemical, and then adding a neutralizing agent into the chemical solution to neutralize the chemical solution; A method for cleaning a membrane module with chemicals, comprising: a sixth step of restarting operation of the sewage treatment equipment by opening the valve, the second valve, and the fourth valve.