JPH1147562A - Membrane cleaning method and membrane unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the constitution and cleaning work for a cleaning equipment of a separating membrane for solid-liquid separation. SOLUTION: A membrane unit is constituted of a main body section 10 with a separating membrane and a casing 20, and the casing 20 is constituted of a peripheral wall section 21 with open upper and lower sections and a bottom plate section 25 with a blocked lower opening. The main body section 10 is made to be hung down integrally with the casing 20. The membrane unit is set in a treatment tank in the state of removing the bottom plate section 25 from the casing 20. For cleaning the separating membrane, the casing 20 is lifted together with the main body section 10 and then the bottom plate section 25 is set on and a lower opening 21a of the peripheral wall section 21 is blocked, and a chemical liquid S is introduced into the casing 20 and left as it is for the required time. Then the chemical liquid S is neutralized and drained, and the bottom plate section 25 is removed again and then the membrane unit is set in the treatment tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a unit for cleaning a separation membrane for solid-liquid separation of purified treated water in a wastewater, rainwater or other water treatment facility.

[0002]

2. Description of the Related Art In a water treatment facility for drainage and rainwater, drainage and
After purifying rainwater or the like, it is necessary to remove solids by performing solid-liquid separation using a separation membrane before discharging or reusing the treated water. For example, in a water treatment facility that purifies wastewater by biological treatment with activated sludge, it is necessary to remove the activated sludge from the treated water.

As a separation membrane to be used for solid-liquid separation in a water treatment facility, a microfiltration membrane having an average pore diameter of about 0.1 to 1.0 μm formed into a flat membrane shape or a hollow fiber shape is generally used. Further, it is often used as a membrane unit configured in a certain form. Microfiltration membranes have the advantage that they can pass highly solids, such as activated sludge, as well as bacteria, so that they can be advanced with simple equipment. In addition, the unitization of the separation membrane has an advantage that handling is simplified.

[0004] Fig. 10 shows an example of processing equipment for purifying raw water with activated sludge and performing solid-liquid separation using a separation membrane for treated water in the same processing tank. The membrane unit is applied to such processing equipment. In the illustrated processing equipment, a membrane unit 3 having a plurality of separation membranes 2 arranged in parallel is disposed in an aeration treatment tank 1 containing activated sludge, and a secondary side of the membrane unit 3 is connected to a suction pump 4, The suction pump 4
Is led to the outside to discharge or reuse the filtered water. Although not shown, an air supply means such as a blower for stirring the inside of the tank and maintaining an aerobic environment is provided.

[0005] Raw water supplied from a flow control tank or the like is purified in the aeration tank 1 by the biological action of activated sludge. Activated sludge is an aggregate of microorganisms, is present in a floating state in the aeration tank 1, and decomposes organic matter contained in raw water under an aerobic environment. The treated water thus purified is suctioned by the suction pump 4 to be separated into solid and liquid when passing through the separation membrane 2 of the membrane unit 3, and the obtained filtered water is guided to the outside to be discharged or reused. Is done.

By the way, if the filtration of the treated water by the separation membrane 2 is continuously performed, clogging of the separation membrane 2 gradually progresses, and the filtration ability is reduced. Therefore, it is necessary to periodically clean the separation membrane 2. The following method is conventionally known as a method for cleaning the separation membrane 2. One is a method of taking out the entire membrane unit 3 from the processing tank and immersing it in a separately prepared chemical solution tank. The other is a method in which activated sludge is discharged from the treatment tank and replaced with a chemical solution.

[0007]

The former method of transferring the entire membrane unit 3 to a chemical tank and immersing the same requires a separate chemical tank and requires an installation space for the chemical tank. There is.

In the latter method of replacing the inside of the treatment tank with a chemical solution, the activated sludge is discharged from the treatment tank and stored in another place.
After the washing of the membrane unit is completed, an operation of returning the activated sludge to the inside of the treatment tank is required, which requires a lot of trouble. Also,
Since the treatment tank must be filled with the chemical solution, a large amount of the chemical solution is required, which increases the cost.

[0009]

SUMMARY OF THE INVENTION The present invention provides a method for efficiently cleaning a separation membrane for performing solid-liquid separation of treated water, and a structure of a membrane unit suitable for performing the cleaning method. It is. The feature of the membrane cleaning method according to the present invention is that the separation membrane for performing solid-liquid separation is pulled up from the treatment tank, and after surrounding the separation membrane with a waterproof structure, a chemical solution is supplied into the waterproof structure to form a separation membrane. It is where cleaning is performed.

In the above-mentioned membrane cleaning method, the waterproof structure is constituted by a casing comprising a peripheral wall part surrounding a side periphery of the separation membrane and a bottom plate part covering a bottom surface, and the separation membrane is pulled up from the treatment tank together with the peripheral wall part, After the bottom plate is attached to the bottom surface of the peripheral wall to constitute the casing, a chemical solution can be supplied into the casing to wash the separation membrane.

[0011] Alternatively, the waterproof structure is constituted by a storage case formed using a waterproof sheet. After being lifted from the treatment tank and surrounding the separation membrane with the storage case, a chemical solution is supplied into the storage case. A method for washing the separation membrane is also possible.

The washing of the separation membrane may be performed after the separation membrane is lifted from the processing tank and held in a suspended state, or may be executed by lowering the separation membrane on the floor.

On the other hand, the features of the membrane unit according to the present invention are as follows.
A separation membrane for performing solid-liquid separation, and a casing for accommodating the separation membrane, wherein the casing surrounds a side circumference of the separation membrane, is open at upper and lower sides, and is configured to be able to be suspended integrally with the separation membrane. And a bottom plate for detachably closing the lower opening of the peripheral wall.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIG. 1 shows a membrane unit U according to the present invention.
1 shows a schematic configuration of an example. The membrane unit U includes a main body 10 having a large number of separation membranes M arranged side by side and held by frames 11, 12, and 13, and a casing 20 for accommodating the main body 10.

In the main body 10, a frame 11 to which one end of each separation membrane M is connected is provided with a water collecting section for collecting filtered water obtained by filtration through the separation membrane M, and taking out the collected filtered water to the outside. A discharge unit 14 is provided, and the discharge unit 14 communicates with a suction unit of a separately provided suction pump.

The casing 20 includes a peripheral wall 21 which surrounds the periphery of the main body 10 and is open at the top and bottom, and a bottom plate 25 which is attached to the bottom of the peripheral wall 21 and closes the lower opening. . The peripheral wall portion 21 is formed so that a flange portion 22 projects at a lower end portion, and a hanging structure such as a hook 23 is provided on an upper surface of an outer surface.

The bottom plate 25 closes the lower opening of the peripheral wall portion 21 by fixing the bottom plate portion 25 by abutting the flange portion 22 of the peripheral wall portion 21 with the packing 24 interposed therebetween. As illustrated in FIG. 2A, the fixing means of the bottom plate portion 25 includes:
A structure in which through holes are provided in the bottom plate portion 25 and the flange portion 22 and the two are fastened with bolts 31 and nuts 32, or as shown in FIG. And the like. Further, it is desirable to provide a drain port 26 at an appropriate position of the bottom plate 25 as shown in FIG. Further, when the drain port 26 is provided, a drain valve may be provided, and an inclined surface 27 may be formed on the bottom plate 25 to provide a drain gradient toward the drain port 26.

The main body 10 is housed in the casing 20 so as to be suspended together with the casing 20. Accordingly, when performing a separation membrane cleaning step described later, the casing 20 is pulled up from the treatment tank to thereby remove the main body 10.
Can be taken out. As a storage structure of the main body 10, a structure in which the main body 10 and the casing 20 are integrated by connecting the main body 10 and the casing 20 using an appropriate jig can be considered, and other examples are illustrated in FIG. As described above, a structure is also possible in which a plurality of bars 34 are arranged in the vicinity of the bottom in the casing 20 either vertically or horizontally to provide a lattice structure, and the main body 10 can be mounted thereon. In addition, FIG.
A hook 35 that engages with the upper edge of the casing 20 is provided above the main body 10, and a bracket 3 that supports the bottom surface of the main body 10 near the bottom of the inner surface of the casing 20 as shown in FIG.
6 may be employed.

FIG. 4 shows another embodiment of the membrane unit U. The basic structure of the membrane unit U is the same as described above. That is, the main body 10 formed by holding the separation membrane M by the frames 11 and 13 is housed in the casing 20, and the main body 10 and the peripheral wall 21 of the casing 20 can be integrally hung. The peripheral wall portion 21 of the casing 20 has a flange portion 22 formed on the bottom surface side, and the lower opening is
The bottom plate 25 is closed by fixing the bottom plate portion 25 with 4 interposed therebetween.

The membrane unit U is different from that of FIG.
A point that a separation membrane M is configured by bundling a large number of hollow fiber membranes; and
The difference is that the entire shape is formed in a substantially cylindrical shape. An opening 28 is formed near the upper end of the casing 20, and this is used as a connection means such as a hanging wire rope.

FIG. 5 shows an example of a water treatment facility using the membrane unit U according to the present invention. In the equipment shown in the figure, the membrane unit U except for the bottom plate 25 is installed in the aeration tank 1 containing activated sludge, and the suction pump 4 is connected to the discharge section 14 of the main body 10 in the membrane unit U. Have been. The secondary side of the suction pump 4 communicates with the outside. Further, in order to stir the inside of the aeration tank 1 and maintain an aerobic environment, an air supply means such as a blower 30 is provided.

The water treatment equipment configured as described above decomposes and purifies organic substances contained in raw water introduced into the aeration tank 1 by the biological activity of activated sludge. During this time, usually, air is supplied from the blower 30 to stir the inside of the aeration tank 1 and keep it in an aerobic environment.

The purified treated water is sucked through the membrane unit U by the suction pump 4 and is led out for discharge or reuse. At this time, the solid matter contained in the treated water such as activated sludge is filtered and removed by the separation membrane M of the membrane unit U, and clean filtered water is obtained. The membrane unit U is installed in the aeration tank 1 with the bottom plate 25 (see FIG. 1) removed, and the casing 20 is open at the top and bottom.

When the treatment in the water treatment facility is continued, clogging of the separation membrane M of the membrane unit U gradually progresses, and the solid-liquid separation efficiency decreases. Therefore, it is necessary to clean the membrane unit U to eliminate clogging of the separation membrane M. In this example, the membrane unit U is cleaned by the following procedure.

First, as shown in FIG. 6A, a wire rope R or the like is connected to the casing 20 of the membrane unit U, and the membrane unit U is connected to the casing 20 using an appropriate means such as a chain block or a crane. And lifted up from the aeration tank 1. At this time, the main body 10 is housed integrally with the peripheral wall 21 of the casing 20 so as to be able to be hung.
Can be raised from. It is preferable that the suspension position of the membrane unit U be above the side of the aeration tank 1. However, if there is a restriction on the equipment, it is not precluded that the membrane unit U is directly above the aeration tank 1.

Subsequently, as shown in FIG. 7A, the membrane unit U is held in a suspended state, and a bottom plate portion 25 and a packing 24 to be mounted on the bottom surface side of the peripheral wall portion 21 of the casing 20 are prepared. Then, as shown in FIG. 3B, the bottom plate 25 is fixed to the peripheral wall 21 with the packing 24 interposed therebetween, and the lower opening 21a of the peripheral wall 21 is closed. Subsequently, as shown in FIG. 4C, a cleaning solution S such as a sodium hypochlorite (NaClO) solution is supplied and filled into the casing 20, and the casing 20 is left for a required time. By this treatment, the solid matter adhering to the separation membrane M is dissolved, and clogging of the separation membrane M is eliminated. In supplying the chemical solution, the pump P is operated in the opposite direction, and
It is also possible to reversely feed the chemical solution into the separation membrane M from above, and to exude the chemical solution S into the casing 20 from the inside of the separation membrane M.

After the required time has elapsed, the casing 2
After neutralizing the chemical S by adding a neutralizing agent into the inside of the cylinder 0, the neutralized chemical S is discharged from the casing 20 as shown in FIG. At this time, if the drainage channel 29 provided with the opening / closing valve V is provided in the bottom plate portion 25, the discharging operation of the chemical solution S is easy. After the cleaning of the separation membrane M is completed, the operation reverse to the above is performed to remove the bottom plate portion 25 and the packing 24 and open the lower portion of the casing 20 (FIG. 7).
(See (A)), the membrane unit U in the suspended state is lowered and installed in the aeration tank 1 again (see FIG. 6).

In this embodiment, the separation membrane M is washed while the membrane unit U is held in a suspended state, so there is no room for installing a cleaning chemical tank around the processing tank. It is possible to respond to the case.

[Second Embodiment] In the first embodiment, the cleaning process of the separation membrane M is executed while the membrane unit U is held in a suspended state. However, space is left on the floor around the aeration tank 1. If there is, the cleaning step can be performed by lowering the membrane unit U on the floor. In this case, as illustrated in FIG. 8, legs are integrally provided on the bottom plate 25 of the casing 20 surrounding the separation membrane M, so that the membrane unit U can be stably mounted on the floor. Alternatively, a dedicated stand may be prepared, and the membrane unit U may be placed on the stand.

The procedure for performing the cleaning step will be described. First, the membrane unit U is pulled out of the aeration tank 1,
The membrane unit U is lowered onto the bottom plate 25 placed on a nearby floor, and the bottom plate 25 and the peripheral wall 21 are joined. Alternatively, the membrane unit U may be lifted out of the aeration tank 1, and in a state where the membrane unit U is suspended, the bottom plate 25 may be attached first, and then the membrane unit U may be lowered onto the floor. Continue with casing 2
The cleaning solution is poured into the container 0 to fill it, and the container is left for a required time. If the clogging of the separation membrane M is eliminated, a neutralizing agent is introduced into the casing 20 to neutralize the chemical, and the neutralized chemical is discharged from the casing 20. As shown in FIG. 8, if a drain pipe provided with an open / close valve is provided in the bottom plate 25 in communication with the drain port 26, the discharge operation of the chemical solution S can be easily performed.

After the cleaning of the separation membrane M is completed, the bonding state of the bottom plate 25 is released, and then the membrane unit U is removed.
Is lifted and installed in the aeration tank 1 again.

In this embodiment, the membrane unit U is mounted on the floor near the processing tank to clean the separation membrane M.
The space near the processing tank is occupied only during the cleaning step of the separation membrane M, and does not constantly occupy a certain space unlike a conventional permanent cleaning chemical tank. Therefore, the space around the processing tank can be used for multiple purposes.

[Third Embodiment] FIG. 9 shows another method of cleaning a membrane unit. The unit U in this embodiment does not require the casing 20, and includes the separation membrane M and the frame 15 for maintaining the same in a fixed form.

When cleaning the membrane unit U, first, as shown in FIG. 9A, the membrane unit U is pulled up from the processing tank 1 and held in a suspended state. Next, as shown in FIG. 4B, a storage case 40 is formed in which a waterproof sheet is hung at the peripheral edge to form a bag or a pocket, and as shown in FIG. It is arranged within 40. At this time, it is preferable that the membrane unit U and the storage case 40 are individually suspended and held so that the membrane unit U is suspended in the storage case 40. Subsequently, the cleaning liquid S is supplied into the storage case 40 to immerse the membrane unit U, and the separation unit M is washed by leaving it for a required time.

After the required time has elapsed and the cleaning of the separation membrane M has been completed, a neutralizing agent is added to neutralize the chemical solution S, and then the chemical solution S is discharged from the storage case 40. For this purpose, a valve (not shown) for discharging a chemical solution may be provided at an appropriate position of the storage case 40. After a while, storage case 4
0 is removed from the periphery of the membrane unit U, and the membrane unit U is lowered again into the aeration treatment tank 1 and installed.

[Other Embodiments] The present invention is applicable not only to wastewater purification equipment and rainwater recycling equipment, but also to any equipment capable of performing solid-liquid separation of treated water using a separation membrane. . In addition to the membrane unit provided with the separation membrane, it is also possible to install the membrane unit in a solid-liquid separation tank for transferring and storing the treated water after purification, in addition to the installation in the aeration treatment tank containing activated sludge.

In addition, the embodiments of the present invention do not prevent various applications and modifications other than those described above.

[0038]

According to the present invention, it is not necessary to permanently install a dedicated chemical solution tank for cleaning the separation membrane, so that space can be saved. In addition, since the periphery of the separation membrane is surrounded by a casing or a storage case, and a chemical solution is supplied into the inside of the casing to wash the separation membrane, the usage fee of the chemical solution can be reduced. Further, the cleaning method according to the present invention can be executed by a simple operation, so that the work load is light.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an example of a membrane unit according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part according to the first embodiment of the present invention, illustrating a structure for fixing a peripheral wall portion and a bottom portion in a membrane unit.

FIG. 3 is a cross-sectional view according to the first embodiment of the present invention, illustrating a structure in which a main body of a membrane unit is integrally housed in a casing.

FIG. 4 is an exploded perspective view according to the first embodiment of the present invention, showing a different example of a membrane unit.

FIG. 5 is a cross-sectional view according to the first embodiment of the present invention, showing a schematic configuration of a water treatment facility provided with a membrane unit of the present invention.

FIG. 6 relates to a method for cleaning a membrane unit according to the first embodiment of the present invention, wherein FIG. 6A is a preparation stage for pulling up the membrane unit from a treatment tank, and FIG. It is the schematic which shows the state pulled up from each.

FIG. 7 relates to a method for cleaning a membrane unit according to the first embodiment of the present invention, wherein FIG. 7 (A) is a preparation stage for mounting a bottom plate on a peripheral wall of the membrane unit, and FIG.
Is a schematic view showing a state in which the bottom plate is attached to the peripheral wall, FIG. (C) is a state in which the membrane unit is being washed, and FIG.

FIG. 8 is an exploded perspective view showing an example of a membrane unit according to the second embodiment of the present invention.

9A and 9B relate to a method of cleaning a membrane unit according to a third embodiment of the present invention, wherein FIG. 9A shows a state in which the membrane unit is pulled out of a processing tank, and FIG. (C) is a schematic view showing a state in which the membrane unit is housed in the storage case, and FIG. (D) is a schematic view showing a state in which the membrane unit is being washed.

FIG. 10 is a cross-sectional view illustrating a schematic configuration of a water treatment facility using a conventional membrane unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Aeration tank 4 ... Suction pump 10 ... Body part 1
1, 12, 13 ... Frame 14 ... Discharge part 20 ... Casing 21 ... Peripheral wall part 22 ... Flange part 25 ... Bottom plate part 26 ... Drain outlet M ... Separation membrane S ... Chemical solution U ... Membrane unit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junichi Yamanaka 5-1-1 Koiehonmachi, Tokoname-shi, Aichi Prefecture Inax Corporation (72) Inventor Tatsuro Yamamoto 5-1-1 Koiehonmachi, Tokoname-shi, Aichi Inax Corporation (72) Inventor Junichi Murakoshi 1-19-15 Jiyugaoka, Kumatori-cho, Sennan-gun, Osaka

Claims (6)

[Claims] 1. A separation membrane for performing solid-liquid separation is pulled up from a treatment tank, and after surrounding the separation membrane with a waterproof structure, a chemical solution is supplied into the waterproof structure to wash the separation membrane. Membrane cleaning method. 2. The waterproof structure is constituted by a casing comprising a peripheral wall portion surrounding a side circumference of the separation membrane and a bottom plate portion covering a bottom surface, the separation film is pulled up from the processing tank together with the peripheral wall portion, and the bottom plate portion is removed from the peripheral wall portion. The membrane cleaning method according to claim 1, wherein after the casing is configured by being attached to a bottom surface of the casing, a chemical solution is supplied into the casing to clean the separation membrane. 3. The waterproof structure is constituted by a storage case formed using a waterproof sheet. After being lifted up from the treatment tank and surrounding the separation membrane with the storage case,
2. The membrane cleaning method according to claim 1, wherein a chemical solution is supplied into the storage case to wash the separation membrane. 4. The membrane cleaning method according to claim 1, wherein after the separation membrane is lifted from the processing tank, cleaning is performed while maintaining the suspended state. 5. The method according to claim 1, wherein the separation membrane is lifted from the processing tank, and then lowered on a floor to perform washing.
The method for cleaning a membrane according to any one of the above. 6. A separation membrane for performing solid-liquid separation, and a casing for accommodating the separation membrane, wherein the casing surrounds a side circumference of the separation membrane, is open at the top and bottom, and can be suspended integrally with the separation membrane. A membrane unit comprising: a peripheral wall configured as described above; and a bottom plate that removably closes a lower opening of the peripheral wall.