JP2000325758A - Method for cleaning separation member module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently clean a separation membrane module by a small amount of a chemical liquid by exposing the outer surface of a module membrane section in air and then applying the liquid from the secondary side of the separating membrane module to the outer surface of the membrane section in the case of cleaning and separating the membrane module for filling a liquid to be cleaned by using the chemical liquid. SOLUTION: In the case of cleaning a separating membrane module 13, the operations of a pump 15 and a compressed air pump 18a are discontinued when the differential pressure rise measured by a pressure gauge 16 set on a filtrate piping 14 is higher than the set value. Then the end 14a of the filtrate piping 14 is cut off from the end 17a of a filtrate discharge outlet 17, and the separating membrane module 13 is lifted from a tank 12 for the liquid to be treated by a chain block 19 to expose a membrane section of the separating membrane module 13 in the air. Then the end 41a of a chemical liquid piping 41 connected with a chemical liquid tank 40 is connected with the end 17a of the filtrate discharge outlet 17, and an on-off valve 42 of the chemical liquid pipe 41 is opened to feed the chemical liquid into the separating membrane module 13, and the liquid is applied from the secondary side to the outer surface of the membrane section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a separation membrane module used for filtration of a highly polluting liquid, such as solid-liquid separation in wastewater treatment or industrial wastewater treatment.

[0002]

2. Description of the Related Art Conventionally, a large number of membrane separation techniques have been used for producing sterile water, drinking water, highly purified water, purifying air, and the like. In addition to these uses, in recent years, high-contamination water has been used in secondary and tertiary treatment in sewage treatment plants, solid-liquid separation in septic tanks, and solid-liquid separation of suspended solids (SS) in industrial wastewater. It is used for processing purposes.

FIG. 7 is a schematic diagram showing an example of a filtration device using a separation membrane module. This filtering device 50
Is a liquid tank 52 for processing the liquid to be processed supplied from the liquid supply line 51, a separation membrane module 53 disposed in the liquid tank 52, and a filtrate piping 54 for the separation membrane. Pump 55 connected to module 53
And is schematically configured. The liquid to be treated filled in the liquid to be treated tank 52 is filtered by the separation membrane module 53 by operating the pump 55 to make the inside of the separation membrane module 53 a negative pressure.
Through the inside, it is discharged out of the system.

[0006] Filtration device 5 using separation membrane module 53
At 0, if the filtration operation is performed for a long time, the membrane surface of the separation membrane module 53 will be blocked by the suspended solids (SS) and the like. The decrease in the separation ability of the separation membrane module 53 due to the membrane surface blockage is caused by the pressure gauge 56 provided in the filtrate pipe 54.
It can be known from the differential pressure rise at the time of filtration measured by the above method. Especially in the treatment of highly polluting liquids,
The separation membrane module 53 is likely to be blocked, which causes a problem that the life of the separation membrane module 53 is shortened.

[0005] Therefore, the separation membrane module 53 whose membrane surface is closed is moved to a cleaning tank filled with a chemical solution to remove the clogging substance adhering to the membrane surface of the separation membrane module 53, and its separation ability is restored. Has been done.

[0006]

However, the method in which the separation membrane module 53 is moved to a cleaning tank filled with a chemical solution and immersed in the chemical solution has a problem that a large amount of the chemical solution is required. Further, the liquid to be treated in the liquid to be treated tank 52 is once discharged, and instead, the liquid to be treated is filled in the liquid to be treated 52 so that the membrane of the separation membrane module 53 can be moved without moving the separation membrane module 53. Although a method of cleaning the surface with a chemical solution is conceivable, a large amount of the chemical solution is similarly required.

In the liquid to be treated, the separation membrane module 5
A method of washing by passing a chemical solution from the secondary side through the secondary side has also been proposed. However, at the same time that the chemical solution oozes into the membrane surface of the separation membrane module 53, the surrounding liquid to be treated and the chemical solution react with each other. Is consumed, so that there is a problem that the cleaning effect is reduced. In order to enhance the cleaning effect, a method of applying a chemical solution by applying pressure has been proposed, but as a result, a large amount of the chemical solution has been used. In addition, the properties of the liquid to be treated deteriorate due to the chemical solution, and there is a possibility that the filtration treatment using the separation membrane module 53 may be affected.

The present invention has been made in view of the above circumstances, and a method for cleaning a separation membrane module for filtering a liquid to be treated by a chemical solution is provided. It is an object of the present invention to provide a method for cleaning a separation membrane module that can perform cleaning of a separation membrane module.

[0009]

That is, a method for cleaning a separation membrane module according to the present invention is a method for cleaning a separation membrane module for filtering a liquid to be treated by using a chemical solution. After exposing the outer surface of the membrane portion to the air, a chemical solution is passed from the secondary side of the separation membrane module to the outer surface of the membrane portion. Further, in the method for cleaning a separation membrane module of the present invention, the separation membrane module is arranged so that at least one of the filtrate outlets of the separation membrane module is located above the membrane part of the separation membrane module, It is more preferable to supply a chemical solution.

In the method for cleaning a separation membrane module according to the present invention, the chemical is spread out from at least a part of the membrane portion of the separation membrane module so that the chemical solution travels along the outer surface of the membrane portion and spreads over the entire membrane. Preferably.
In the method for cleaning a separation membrane module of the present invention, it is preferable to use a hollow fiber membrane as the membrane part of the separation membrane module. In the method for cleaning a separation membrane module of the present invention, it is preferable to pass 1 to 5 L of a chemical solution per 1 m ² of the membrane area within a range of 1 to 5 hours.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating an example of a filtration device using a separation membrane module. This filtration device 10
Is a filtrate provided with a liquid tank 12 for processing the liquid supplied from the liquid supply line 11, a separation membrane module 13 disposed in the liquid tank 12, and a pressure gauge 16. This separation membrane module 1
3, a pump 15 connected to the filtrate outlet 17, a diffuser 18 for membrane cleaning air bubbling connected to a compressed air pump 18a, and a chain block for lifting the separation membrane module 13 connected to the end of a chain 19a. 19
And is schematically configured.

The separation membrane module 13 is not particularly limited as long as it has a filtration membrane (separation membrane) having a plurality of fine pores. For example, a flat membrane type, a hollow fiber membrane type, a tubular Known separation membrane modules such as a membrane type and a bag type membrane type can be applied. Above all, from the viewpoint of increasing the film area per volume and increasing the processing efficiency,
It is preferable to use a hollow fiber membrane. In addition, as its material, cellulose, polyolefin, polysulfone,
Examples include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ceramics, and polyacrylonitrile (PAN). Separation membrane module 13
Can be selected arbitrarily according to the purpose of the filtration, and usually a fraction of 0.01 to 1 μm can be applied.

For example, the separation membrane module 13 shown in FIG.
And two flat membranes 21 and 21 arranged in parallel as shown in FIG.
And frame members 22, 22, and frame members 23, 23,
A flat membrane module having a frame-shaped support for supporting the flat membranes 21 and 21, a hollow fiber membrane 31 composed of a plurality of hollow fibers as shown in FIG. A hollow fiber membrane module having a tubular water collecting member 32 provided at both ends of the hollow fiber membrane 31 can be applied.

The cleaning of the separation membrane module 13 is performed as follows. When the differential pressure rise at the time of filtration measured by the pressure gauge 16 provided in the filtrate pipe 14 becomes equal to or larger than a set value, the operation of the pump 15 and the compressed air pump 18a is stopped, and the filtration operation is temporarily stopped. . After the filtration operation is stopped, the distal end portion 14a of the filtrate pipe 14 and the distal end portion 17a of the filtrate outlet 17 are cut off, and the chain block 1 is removed.
At 9, the separation membrane module 13 is lifted from the liquid tank 12 to be treated, and the membrane of the separation membrane module 13 is exposed to air.

After lifting the separation membrane module 13, as shown in FIG. 4, the tip 41 a of the chemical pipe 41 connected to the chemical tank 40 filled with the chemical and the tip 17 a of the filtrate outlet 17 are connected. I do. Next, the opening / closing valve 42 of the chemical liquid pipe 41 is opened to supply the chemical liquid into the separation membrane module 13 and to flow the liquid from the secondary side of the separation membrane module 13 to the outer surface of the membrane part. After a predetermined amount of the chemical is passed for a predetermined time, the distal end 41 a of the chemical pipe 41 and the distal end 1 of the filtrate outlet 17 are removed.
7a, and the separation membrane module 13 is returned to the liquid tank 12 to be treated again. Next, the tip portion 14 of the filtrate pipe 14 is
After connecting a to the tip 17a of the filtrate outlet 17, the pump 15 and the pneumatic pump 18a are operated to restart the filtration operation.

The chemical solution may be passed while the separation membrane module 13 is lifted above the liquid tank 12 to be treated. However, the chemical liquid that has oozed from the membrane portion of the separation membrane module 13 may enter the treatment liquid tank 12 and react with the treatment liquid, adversely affecting the filtration process using the separation membrane module 13 when the filtration operation is restarted. Therefore, it is preferable that the separation membrane module 13 be moved to a place other than the liquid tank 12 to be treated and then subjected to the washing by passing through.

As the method of passing the chemical solution, a known method can be used in addition to a natural fall due to a difference in head. For example, a method of sending a chemical solution from a chemical solution tank 40 filled with a chemical solution to the separation membrane module 13 by a pump, a method of using a pressurized container as the chemical solution tank 40, and sending a chemical solution to the separation membrane module 13 by pressure from a compressor or the like are used. Can be.

It is desirable that the chemical solution and the concentration used for the washing be appropriately selected according to the material of the separation membrane module 13 to be washed, the purpose of the filtration thereof, and the closed state. As the chemical solution, usually, an aqueous solution of an oxidizing compound such as hypochlorite, percarbonate, hydrogen peroxide, an aqueous solution of an alkali such as sodium hydroxide, hydrochloric acid, sulfuric acid, oxalic acid, citric acid, etc. An aqueous solution of an acid, an aqueous solution of a surfactant, alcohol, or the like is used. Further, when various treatments are required for the membrane portion of the separation membrane module 13 after the passage of these chemicals,
An appropriate treatment agent may be passed in the same manner as described above after the above-mentioned chemical solution.

Separation membrane module 13 for passing a chemical solution
Is not particularly limited, but is preferably arranged such that the filtrate outlet 17 is located above the membrane. By arranging the separation membrane module 13 so that the filtrate outlet 17 is located above the membrane, and allowing the chemical to pass through, the chemical oozing from the membrane close to the filtrate outlet 17 is
Gravity flows down the outer surface of the membrane from top to bottom, so that almost the entire outer surface of the membrane can be brought into contact with the chemical.

In the case of a flat membrane type or bag type separation membrane module, as shown in FIG. 2, it is preferable to arrange the separation membrane module with the filtrate outlet 17 upward, and to pass a chemical solution. At this time, the flat film 21 may be disposed so as to be vertical or oblique.

In the case of a hollow fiber membrane type separation membrane module as well, it is preferable to arrange the separation membrane module with the filtrate taking-out port 17 upward as shown in FIG. 3, for example. At this time, the water collecting member 32 may be arranged vertically or obliquely.

Further, as shown in FIG.
May be arranged above and the other water collecting member 32 may be arranged below. In addition, the membrane surface of the hollow fiber membrane 31 may be arranged to be vertical or oblique. Further, when the water collecting members 32 having the filtrate outlets 17 are provided at both ends, it is preferable that the liquid is passed through the upper filtrate outlet 17.

Further, as shown in FIG. 6, two water collecting members 32 may be arranged substantially horizontally. In the case of this arrangement, the hollow fiber membrane 31 has the water collecting member 3 having the filtrate outlet 17.
It is preferable to dispose it so that it is lower than 2. Even in the case of a hollow fiber membrane module having a cylindrical shape or the like, as in the case of a flat hollow fiber membrane module, an effective washing is performed by arranging the filtrate outlet so as to face upward and passing a chemical solution. Can be.

The flow rate of the chemical solution is 1 to 1 per m ² of the membrane area.
Preferably it is 5L. If the flow rate is less than 1 L, the cleaning of the separation membrane module 13 is insufficient. Further, even if the flow rate exceeds 5 L, there is no significant change in the cleaning efficiency. Therefore, the flow rate is preferably 5 L or less. In addition, it is preferable to set the liquid passing time within a range of 1 to 5 hours. If the flow time is less than 1 hour, the separation membrane module 13
It is difficult to spread the chemical solution throughout, and cleaning is insufficient. When the liquid passing time exceeds 5 hours, a large amount of the chemical solution is put into the liquid tank 12 to be treated, which may cause deterioration of the properties of the liquid to be treated. In addition, from the viewpoint of cost, it is preferable to perform the treatment in a range of 1 to 5 hours.

According to such a method for cleaning the separation membrane module, since the chemical solution is passed by exposing the outer surface of the membrane portion of the separation membrane module 13 to the air, the liquid to be treated and the chemical solution are separated. The chemical solution is consumed by the reaction, and the effect of cleaning is not reduced. Therefore, by a simple operation of exposing the outer surface of the membrane portion of the separation membrane module 13 to the air and passing the chemical solution, the clogging substance on the outer surface of the membrane portion of the separation membrane module 13 can be reduced with a small amount of the chemical solution. Efficient and reliable removal from the separation membrane module 13 is possible.

[0026]

The present invention will be described below in further detail with reference to examples. (Example 1) As the separation membrane module 13, a flat hollow fiber membrane module having a polyethylene hollow fiber membrane fixed in a sheet shape (manufactured by Mitsubishi Rayon Co., Ltd., trademark Stellapore LF,
It used a laminate of fractionation performance 0.1 [mu] m) 3 present (8m ^2/1 present) in parallel, and placed into the treated liquid tank 12. As the liquid to be treated, activated sludge water having an SS of 10,000 mg / L was used, and filtration was performed at LV (processing amount per m ² of separation membrane module per day) = 0.3 m / D and air amount of 15 m ³ / h. Was. Initial pressure difference at the start of filtration is 5 kP
What was “a” became a differential pressure of 35 kPa after 6 months. This module was cleaned as follows.

First, the filtration process was stopped, and air bubbling for membrane cleaning was stopped. Next, the separation membrane module 13 was taken out of the liquid tank 12 to be treated by the chain block 19, and was arranged so that the longitudinal direction of the water collecting member 32 was vertical as shown in FIG. Sodium hypochlorite 30
36 L of a 00 mg / L solution was prepared, and the solution was passed through the filtrate outlet 17 at 0.6 L / min for 60 minutes. The time required to pass the chemical solution in this cleaning was 80 minutes including the preparation. Thereafter, filtration was performed again using activated sludge water having an SS of 10000 mg / L at an LV of 0.3 m / D and an air amount of 15 m ³ / h. As a result, the differential pressure was 5 kPa.

Comparative Example 1 The separation membrane module obtained in the same manner as in Example 1 and having been subjected to the filtration treatment for 6 months was washed as follows. First, the filtration process was stopped, and air bubbling for membrane cleaning was stopped. Next, 40 L of a 3000 mg / L sodium hypochlorite solution was prepared, and the flow rate was set to 0.5 L / min for 80 minutes while the separation membrane module 13 was installed in the liquid tank 12 to be treated. went. The liquid passing time in this cleaning was 90 minutes including the preparation. Thereafter, SS was 10,000 mg / L
When the filtration treatment was carried out again using activated sludge water at LV = 0.3 m / D and air amount 15 m ³ / h, the differential pressure was 1
It was 8 kPa.

[0029]

As described above, according to the method for cleaning a separation membrane module of the present invention, after exposing the outer surface of the membrane portion of the separation membrane module to the air, the chemical solution is removed from the secondary membrane of the separation membrane module. Since the liquid is passed from the side to the outer surface of the membrane, the clogging substance on the outer surface of the membrane of the separation membrane module can be efficiently and reliably washed and removed with a small amount of a chemical solution. Further, when the separation membrane module is arranged such that at least one of the filtrate outlets of the separation membrane module is located above the membrane portion of the separation membrane module, and a chemical solution is supplied from the filtrate outlet, a smaller amount of the chemical solution is used. The separation membrane module can be washed.

Further, when the chemical liquid is oozed to the outside from at least a part of the membrane part of the separation membrane module so that the chemical liquid propagates along the outer surface of the membrane part and spreads over the entire membrane, a smaller amount of the chemical liquid is used to separate the separation membrane. The module can be cleaned. Further, when a hollow fiber membrane is used as the membrane part of the separation membrane module, the chemical solution retained in the membrane and the exuded chemical solution can be efficiently washed with a small amount of the chemical solution. In addition, when 1 to 5 L of a chemical solution per 1 m ^{2 of} the membrane area is allowed to flow within a range of 1 to 5 hours, sufficient washing can be performed with a smaller amount of the chemical solution.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a filtration device before washing a separation membrane module.

FIG. 2 is a perspective view showing an example of a flat membrane module.

FIG. 3 is a perspective view showing an example of a hollow fiber membrane module.

FIG. 4 is a schematic view showing one example of a method for cleaning a separation membrane module of the present invention.

FIG. 5 is a diagram showing an example of an arrangement state of a hollow fiber membrane module during washing.

FIG. 6 is a view showing another example of the arrangement state of the hollow fiber membrane modules during washing.

FIG. 7 is a schematic configuration diagram illustrating an example of a filtration device using a separation membrane module.

[Explanation of symbols]

 13 Separation membrane module 17 Filtrate outlet 21 Flat membrane (membrane) 31 Hollow fiber membrane (membrane)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenji Honjo 4-160 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Inside Mitsubishi Rayon Co., Ltd. Product Development Laboratory (72) Inventor Osamu Kato 4-chome Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture No. 1-60 F term in Mitsubishi Rayon Co., Ltd. Product Development Laboratory (reference) 4D006 GA02 HA02 HA19 HA42 HA93 JA16A JA55A KA43 KC03 KC07 KC16 KD04 KD11 KD17 KD22 KD24 KD28 KE01Q KE01R KE05Q KE06Q KE11P KE12P03 KE22P03 MC22X MC29 MC30 MC39 MC62 PA01 PA02 PB08 PC64

Claims (5)

[Claims] 1. A method for cleaning a separation membrane module for cleaning a separation membrane module for filtering a liquid to be treated with a chemical solution, comprising exposing an outer surface of a membrane portion of the separation membrane module to air, and then removing the chemical solution. A method for cleaning a separation membrane module, comprising passing a liquid from the secondary side of the separation membrane module to the outer surface of the membrane part. 2. The method according to claim 1, wherein the separation membrane module is arranged so that at least one of the filtrate outlets of the separation membrane module is located above the membrane portion of the separation membrane module, and a chemical solution is supplied from the filtrate outlet. The method for cleaning a separation membrane module according to claim 1. 3. The method according to claim 1, wherein the chemical solution is oozed out from at least a part of the membrane portion of the separation membrane module so that the chemical solution travels along the outer surface of the membrane portion and spreads over the entire membrane. Item 3. The method for cleaning a separation membrane module according to Item 2. 4. The method for cleaning a separation membrane module according to claim 1, wherein a hollow fiber membrane is used as a membrane portion of the separation membrane module. 5. A chemical solution of 1 to 5 L per 1 m ^{2 of} membrane area,
The method for cleaning a separation membrane module according to any one of claims 1 to 4, wherein the solution is passed for 1 to 5 hours.