JP3488535B2 - Chemical solution cleaning method for membrane in immersion type membrane filtration device and chemical solution cleaning device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an immersion type membrane filtration device for filtering raw water with a membrane immersed in an immersion tank, and a method for cleaning a membrane in the immersion tank with a chemical solution and a chemical solution cleaning. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, there is an immersion type membrane filtration device in which a membrane (also referred to as a membrane module) is immersed in an immersion tank in which raw water is stored to purify the raw water by a filtering action of the membrane. In this membrane filtration device, when the membrane filtration is continued, the membrane is clogged with turbidity or the like to lower the filtration efficiency. Therefore, the membrane is washed after a certain period of use.

As this cleaning method, backwashing is carried out in which the treated water is backwashed from the treated water side of the membrane to the raw water side, or the membrane is formed by air bubbles from an air nozzle provided below the membrane in the dipping tank. There are things such as cleaning the surface.

Further, when it is used for a certain period of time, suspended matters and the like enter the inside of the membrane and the effect of the above-mentioned cleaning is remarkably reduced, so that the membrane is cleaned using a cleaning chemical solution. In this case, the membrane is removed from the apparatus and immersed in the chemical cleaning tank in which the cleaning chemical is stored to clean the membrane with the chemical.

[0005]

However, the conventional chemical cleaning has the following problems. Since the membrane is removed from the membrane filtration device and immersed in the chemical cleaning tank, equipment such as a crane for moving and removing / attaching the membrane is required. In addition, since it takes time to remove and attach the work, the mobility of the membrane filtration device is lowered. further,
Since the membrane is immersed in the chemical cleaning bath for cleaning, a large amount of cleaning chemical is required, resulting in high cost.

The present invention has been made in view of the above-mentioned problems, and eliminates the need for equipment such as movement of the membrane, shortens the cleaning time, and can clean the membrane with a small amount of chemical liquid. To provide a device.

[0007]

In order to solve the above problems, the present invention has the following structure. The raw water is filtered by the membrane of the membrane module immersed in the immersion tank to treat the treated water in the membrane module.
Using a submerged membrane filtration device that is extracted from both ends of the membrane module, one end of the membrane module is supplied with a chemical solution for cleaning from a chemical solution supply means through a permeate channel, and the other of the membrane module is supplied. Is a method for cleaning a membrane to discharge the chemical solution to the outside from an end portion of the chemical solution via a chemical solution drainage channel.
With the water channel closed, the permeated water is discharged from the chemical liquid supply means.
A chemical solution is supplied to the inside of the membrane through a channel, and
Suspended in the membrane by permeating the inside of the membrane
After dissolving the solution, push the supplied chemical solution into the membrane.
Then, let the drug solution flow out from the inside to the outside,
Then, the chemical liquid drainage channel is opened to discharge the chemical liquid to the outside, which is a method for cleaning a chemical liquid of a membrane. Also, the above
The chemical liquid supply means is provided in the membrane of the membrane module from the permeate channel.
To the above-mentioned chemical solution and a chemical solution different from this chemical solution,
You may make it replace.

Further, the raw water is filtered by the membrane of the membrane module immersed in the dipping tank so that the treated water is supplied to both the inside of the membrane module.
Is a submerged membrane filtration device taken out from the end of, the permeate channel connected to one end of the membrane module, and a chemical drainage channel connected to the other end of the membrane module,
And a chemical solution supply means for supplying a chemical solution from the permeate channel into the inside of the membrane, the chemical solution supply means washing a large amount.
For supplying a large amount of chemical liquid and a small amount of cleaning liquid
And a small amount liquid medicine supply means for supplying a liquid medicine,
By supplying a large amount of liquid medicine to the inside of the membrane
Permeates the inside of the membrane to dissolve clogged suspended matter, etc.
By pushing the drug solution into the membrane by means of a small amount drug solution supply means
Let the chemical flow out from the inside to the outside
Open the liquid medicine discharge path to discharge the liquid medicine to the outside.
That the the and a chemical cleaning device layer characterized by. still,
Chemical supply means, said supply another drug solution the the drug solution and the drug solution within the membrane from the transmission waterways membrane module may be performed replacement of chemical.

[0009]

According to the present invention, it operates as follows. The chemical liquid supply means supplies the cleaning chemical liquid to the membrane from the treated water side of the membrane through the permeate water passage at one end of the membrane module, and the chemical liquid permeates the membrane. This will wash the membrane. Then, it is discharged from the chemical liquid drainage channel at the other end of the membrane module. Further, since a large amount of chemical liquid supply means and a small amount of chemical liquid supply means are provided , after the chemical liquid permeates the membrane, the chemical liquid to be supplied is switched to a small amount and flowed to the raw water side for washing. As a result, the chemical liquid flowing out to the raw water side can be kept small and the cleaning effect can be improved. Wash
After cleaning, the chemical liquid in the membrane module is the chemical liquid discharge path at the other end.
Is discharged from the outside. At that time , a chemical solution different from the previously supplied chemical solution may be pressure-fed into the membrane of the membrane module, and the previous chemical solution may be discharged to the outside so that the chemical solution is replaced with another chemical solution .

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show an immersion type membrane filtration device 2 provided with a chemical liquid cleaning device 1 of this embodiment.

The submerged membrane filtration device 2 is roughly constructed by including a submerged tank 3 in which raw water is stored, and a membrane module 4 submerged in the raw water in the submerged tank 3. This membrane module 4 is a hollow fiber membrane 4a (hereinafter referred to as membrane 4a).
A large number of these are integrated, and they are placed side by side and two are arranged above and below. Each of the membranes 4a has both ends connected to each other, and both ends communicate with each other inside. This membrane 4a is a raw water membrane 4a.
Permeate from the outside (raw water side) to the inside (treated water side) of the membrane 4a to become permeated water (treated water).

Pipes 5 and 6 are connected to both ends of the membrane module 4, and the open / close valve V1 is connected to one pipe 6.
Is intervening. The pipes 5 and 6 are connected to each other on the membrane module 4 side of the on-off valve V1 provided on the pipe 6 via the on-off valve V4. The pipe 6 is further extended from the on-off valve V1 to form a permeate channel.

The chemical liquid cleaning apparatus 1 comprises a chemical liquid supply means 10 for supplying a cleaning chemical liquid to the membrane 4a from the inside of the membrane 4a, and a large capacity pump P1 for supplying a large amount of chemical liquid to the chemical liquid supply means 10. It is provided with (a large amount liquid medicine means) and a small capacity pump P2 (a small amount liquid medicine means) for supplying a small amount of the liquid medicine. Further, the tip of the pipe 5 is bifurcated, and an opening / closing valve V2 is provided in one branch passage to form an air drainage passage, and an opening / closing valve V3 is provided in the other branch passage to drain chemical liquid. It is a road.

A pipe 7 is connected to a pipe 6 on the membrane module 4 side of the on-off valve V1, and a pump P3 for backwash water and an on-off valve V5 are connected in series to this pipe 7. There is. Further, a chemical tank 8 for storing a chemical liquid for cleaning the membrane 4a is provided, and a pipe 9 is provided from the chemical tank 8 toward the pipe 7. A pump P1 is installed in series in the pipe 9, and the pump P1
A pump P2 is connected in parallel with. These pumps P
An on-off valve V6 is interposed between the pipes 1 and P2 and the pipe 7.

Next, the operation of the submerged membrane filtration device 2 and the membrane 4a.
The cleaning method and the chemical cleaning method will be described.

First, referring to FIGS. 4 (a) and 4 (b), a case where a normal filtration step is performed by the immersion type membrane filtration device 2 of the present embodiment will be described.

That is, the pumps P1, P2, P3 are stopped, the opening / closing valves V2, V3, V5, V6 are closed, and the opening / closing valves V1, V4 are opened. When a suction pump (not shown) provided in the permeate channel is operated, raw water permeates from the outside of the membrane 4a through the membrane 4a to the inside of the membrane 4a and is filtered. The permeated water inside the membrane 4a is stored in a permeated water tank (not shown) through the permeated water passage.

In this way, after the filtration step has passed a predetermined time (for example, a filtration time of 30 to 60 minutes), the back washing step is performed for a predetermined time (for example, 3 times) in order to eliminate clogging of the membrane 4a.
(0 to 60 seconds).

That is, the pumps P1 and P2 are stopped, the pump P3 is driven, and the on-off valve V
1, V2, V3, V6 are closed and the on-off valve V
Open V4 and V5. As a result, the backwash water is pumped into the inside of the membrane 4a by the pump P3, flows out from the inside of the membrane 4a toward the outside, and the clogging of the membrane 4a is eliminated. As the backwash water, the permeated water from the above-mentioned permeated water tank is usually used, but water from another backwash water tank may be used.

Further, since air may accumulate in the pipe, an air venting process is provided. This puts the pumps P1 and P2 into the stopped state, puts the pump P3 into the driven state, closes the on-off valves V1, V3, V4 and V6, and opens the on-off valves V2 and V5. Thereby, the permeated water from the permeated water tank circulates and the air in the pipe is removed.

If filtration is carried out for a long time (for example, one month to several months) by the immersion type membrane filtration device 2, the clogging of the membrane 4a cannot be eliminated even by back washing, so that a cleaning chemical solution is used. The chemical solution cleaning process that was performed. This chemical cleaning step will be described with reference to FIGS.

First, the pumps P2 and P3 are stopped,
The on-off valves V1, V2, V3, V4 and V5 are closed, and the on-off valve V6 is opened. When the pump P1 is driven, as shown in FIG. 1A, the chemical liquid in the chemical liquid tank 8 is supplied into the inside of the membrane 4a through the pipes 9 and 6. The supplied chemical solution permeates from the inside of the film 4a into the inside of the film 4a, and dissolves suspended substances and the like that are clogged inside the film 4a.

Next, the pumps P1 and P3 are stopped,
When the pump P2 is driven, the chemical liquid is pushed into the inside of the membrane 4a of the membrane module 4 as shown in FIG.
As shown in, the chemical solution flows out from the inside of the film 4a to the outside through the inside of the film 4a. At this time, turbid substances and the like that have entered the inside of the film 4a are almost completely removed.

When the pump P2 is driven for a certain time,
The pumps P2 and P3 are stopped, the pump P1 is driven, and the on-off valve V3 is opened. As a result, as shown in FIG. 3A, another chemical solution stored in the chemical solution tank 8 is pressure-fed into the membrane of the membrane module 4 and is discharged to the outside through the on-off valve V3 to replace the chemical solution. Done.

When the chemical cleaning step is completed in this way, the process proceeds to the normal filtration step. However, since the inside of the membrane 4a is still filled with the chemical liquid, the permeated water mixes with the permeated water in the initial stage of the normal filtration process, so the permeated water in the initial stage of the filtration process cannot be put into the permeated water tank. Then put it in another tank.

An appropriate type of chemical solution is used depending on the type of membrane and the type of clogging substance, and sodium hydroxide solution, hydrochloric acid solution, sodium hypochlorite solution, etc. are used. Further, one kind of chemical solution may be used, or plural kinds of chemical solutions may be divided into two stages and used. In this case, it is preferable that the alkaline chemical solution is first introduced, and then the acid chemical solution is introduced.

According to the chemical cleaning device and the chemical cleaning method for the membrane 4a of the present embodiment, the chemical is filled inside the membrane 4a of the membrane module 4 with the chemical for cleaning, and the filled chemical is filled in the membrane 4a.
Since the membrane 4a is washed out by flowing out from the inside to the outside of the membrane 4a, the clogging of the membrane 4a can be almost completely washed by using an appropriate chemical solution. Moreover, it is not necessary to remove the membrane module 4 since the membrane 4a installed in a ready-to-use state is only filled with the chemical liquid and washed, and the period of suspension of the submerged membrane filtration device 2 is minimized. You can

As shown in FIG. 5, a plurality of water channels (seven sets in the figure) may be provided in parallel as in the above embodiment.

The present invention is not limited to the above embodiment,
For example, a flat membrane, a spiral membrane, a tubular membrane, or the like may be used instead of the hollow fiber membrane. Further, the chemical liquid supply means may be a single pump whose flow rate can be changed, or may be a combination of a fixed amount of metering pump and a flow rate control valve. Further, the chemical solution may be supplied by only one pump, or the chemical solution may be circulated through the membrane.

[0030]

Since the present invention is constructed as described above,
It has the following effects. Since the cleaning chemical is supplied to the membrane from the treated water side of the membrane for cleaning, the membrane can be cleaned while being immersed in the immersion tank. Therefore, equipment for moving and removing / attaching the membrane, such as a crane, becomes unnecessary. In addition, since the time required for the removal / attachment work is unnecessary, the operation rate of the device is improved. Further, since the amount of the chemical liquid for cleaning is supplied to the membrane, the amount of the chemical liquid can be small and the cost can be reduced as compared with the case where the membrane is immersed in the chemical liquid cleaning tank for cleaning. Also, after the drug solution penetrates the membrane,
Change the amount of chemical solution to a small amount and flush it to the raw water side for cleaning
With this, it is possible to reduce the amount of chemical liquid that flows out to the raw water side.
In addition, the cleaning effect can be improved.

[0031]

[Brief description of drawings]

FIG. 1 is a diagram showing one step of a chemical cleaning device for a membrane and a chemical cleaning process using the same according to an embodiment of the present invention.

FIG. 2 is a diagram showing one process of a chemical cleaning process using the chemical cleaning device for the membrane of FIG.

FIG. 3 is a diagram showing one process of a chemical cleaning process using the chemical cleaning device for the membrane of FIG.

FIG. 4 is a diagram showing a normal filtration process by a membrane filtration device provided with the membrane chemical cleaning device of FIG. 1.

FIG. 5 is a diagram showing a chemical cleaning device for a membrane according to another embodiment of the present invention.

[Explanation of symbols]

1: Chemical cleaning device 2: Immersion type membrane filtration device 3: Immersion tank 4: Membrane module 4a: hollow fiber membrane (membrane) 5, 6: Piping 10: Medication supply means V1, V2, V3, V4, V5, V6 open / close valve P1: Pump (Means for high-volume liquid medicine) P2: Pump (Means for small amount liquid medicine) P3: Pump

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-4-225805 (JP, A) JP-A-3-77629 (JP, A) JP-A-5-285354 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B01D 65/02 C02F 1/44

Claims (4)

(57) [Claims] 1. Raw water is filtered by a membrane of a membrane module immersed in a dipping tank to process treated water at both ends in the membrane module.
Using a submerged type membrane filtration device that is taken out from the chamber , one side of the membrane module is connected to the chemical liquid supply means through the permeate channel .
Supplying a chemical solution for al cleaning film for discharging the liquid medicine to the outside through the chemical liquid drainage from the other end of the membrane module
The method for cleaning a chemical solution according to claim 1, wherein the chemical solution drain means closes the chemical solution from the chemical solution supply means.
Supplying the chemical solution inside the membrane through the permeate channel,
The inside of the membrane is permeated from the inside of the membrane to the inside of the membrane.
The above-mentioned chemical liquid to be further supplied after dissolving the clogged suspended matter, etc.
To push the drug solution from the inside to the outside.
The chemical liquid and then drain the chemical liquid to open the chemical liquid drainage channel.
The method of cleaning a membrane in a submerged membrane filtration device with a chemical solution, the method comprising: 2. The chemical liquid supply means is a membrane from the permeate channel.
In the membrane of the module, the above-mentioned chemical solution and another chemical solution different from this chemical solution
Characterized by supplying and replacing chemical liquids
The method for cleaning a membrane with a chemical liquid in the immersion type membrane filtration device according to claim 1 . 3. The raw water is filtered by the membrane of the membrane module immersed in the immersion tank to process the treated water at both ends of the membrane module.
An immersion type membrane filtration device that is taken out from a permeate channel connected to one end of the membrane module, a chemical drainage channel connected to the other end of the membrane module, and a chemical solution from the permeate channel. A chemical solution supply means for supplying the inside of the membrane , wherein the chemical solution supply means supplies a large amount of cleaning chemicals.
A large amount of chemical supply means for supplying liquid and a small amount of cleaning chemical
A small amount of chemical liquid supply means for supplying, and the large amount of chemical liquid supply means supplies the chemical liquid to the inside of the membrane.
Then, it permeates the inside of the membrane and dissolves the suspended substances, etc.
In addition, the drug solution is pushed into the membrane by a small amount drug solution supply means.
Then let the drug solution flow from the inside to the outside, and then
To open the chemical liquid discharge passage to discharge the chemical liquid to the outside
A chemical cleaning device for a membrane in an immersion type membrane filtration device characterized by the above . Wherein said chemical solution supply means, said supply another drug solution the the drug solution and the drug solution within the membrane from the transmission waterways membrane module, according to, characterized in that to perform the replacement of the chemical Item 4. A membrane chemical cleaning device in the immersion type membrane filtration device according to item 3.