JP2001009246A - Immersion type flat membrane filtering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to effectively suppress the closure of various membrane modules and further to easily each chemical liquid at a low cost. SOLUTION: This device is disposed with the many membrane modules 16, 16,... stored in the water 14 to be treated in a flat membrane tank 12 in such a manner that the spacings therebetween are larger by every two rows. The membrane modules are enclosed dividedly by two row each by air diffusion induction walls 188. Openings are formed in the lower parts of the air diffusion induction walls 188 and communicating paths of the water 14 to be treated are formed in the upper parts thereof. Swirling flow passages of the water 14 to be treated are sufficiently assured for the respective membrane modules 16. The air diffusion induction walls 188 are so constituted that the openings are freely opened and closed and that the communicating paths can be shut off. Independent washing tanks 86 may be formed by closing the openings and shutting off the communicating paths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an immersion flat membrane filtration apparatus, and more particularly to an immersion flat membrane filtration apparatus used for treating sewage and industrial wastewater.

[0002]

2. Description of the Related Art An immersion flat membrane filtration device is used for the treatment of coagulated sludge in an industrial drainage system and the treatment of activated sludge such as sewage. In this apparatus, a large number of membrane modules are immersed in a treatment tank (for example, a nitrification tank) for a highly concentrated suspension, and the suspension is sucked into the inside of the membrane module by a pump or a siphon to remove treated water. can get. The plurality of membrane modules are vertically installed at intervals, and a diffusion means for diffusing air is provided below the membrane modules. Here, the purpose of the air diffusion is to remove sludge cake deposited on the membrane surface, obtain a cleaning effect of suppressing blockage of the membrane, and to cause a swirling flow in the treatment tank to give a cross flow to the membrane surface. Stirring the inside of the treatment tank, supplying oxygen for aerobic treatment when the water to be treated in the treatment tank contains microorganisms such as activated sludge, and the like.

[0003] Around the plurality of membrane modules,
An air diffusion guide wall is provided, and air bubbles diffused from the air diffusion means are guided toward the membrane module by the air diffusion guide wall. As a result, an upward flow, that is, a cross flow in a direction perpendicular to the filtration direction of the membrane is generated inside the air diffusion guide wall, and a shear force is generated in the sludge on the membrane surface, and the blockage of the membrane surface is suppressed. You. The upward flow turns downward at the liquid level position and descends outside the diffusion guide wall, enters again into the diffusion guide wall from the lower end of the diffusion guide wall, and enters the inside of the diffusion guide wall. Form a swirling flow that swirls with the outside. Even if the sludge adheres to the membrane surface, the sludge is destroyed because bubbles from the air diffuser hit the membrane surface.

[0004] However, even if the membrane surface is constantly cleaned by aeration, even fine particles adhered to the membrane surface cannot be peeled off, so that the membrane surface gradually closes and eventually does not fulfill the filtration function as a membrane. In such a case, cleaning with a chemical solution is required, and depending on the properties of the water to be treated, it is usually several months to 1 hour.
It takes place regularly at annual intervals.

[0005] As described above, in the conventional immersion flat membrane filtration device, the clogging of the membrane surface is suppressed by the cross flow and the air bubbles generated by the air diffusing means, and the membrane module is periodically cleaned by the chemical solution. The filtration function has been restored.

[0006]

However, in the conventional immersion flat membrane filtration apparatus, the membrane modules at both ends of a large number of membrane modules arranged side by side are difficult to close, but the membrane module at the center is closed. There was a drawback that it was easy. This is because the center membrane module is more difficult to secure a swirl flow path for generating an upward flow and easily generates sludge accumulation than the membrane modules at both ends. Once formed, the sludge pool cannot be destroyed even when air bubbles are applied to the membrane surface, and on the contrary, it is compacted and grows gradually, eventually closing the entire membrane surface. For this reason, the membrane module at the center was more likely to be closed than the membrane modules at both ends.

[0007] The closed membrane surface must be cleaned with a chemical solution, but the conventional immersion flat membrane filtration device has the disadvantage that cleaning the chemical solution requires a lot of labor and cost. For example, as a method of chemical cleaning, a method of taking out the membrane module from the processing tank and immersing it in a separately prepared chemical liquid tank, a method of temporarily extracting the suspension in the processing tank and filling the processing tank with the chemical liquid, There is a method of flowing a chemical solution from the inside of the membrane module in a direction opposite to the flow of filtration. However, the method of (1) has a large cost of auxiliary equipment such as a lifting device for removing the membrane module and a chemical solution tank, and the method of (2) also requires a high cost for cleaning because it also cleans a membrane module that does not require cleaning. The method has a drawback that the cleaning solution is not suitable for treatment using an organic film because the cleaning solution flows into the treatment tank through the film.

[0008] For these reasons, there has been a demand for an immersion flat membrane filtration apparatus that can easily and at low cost wash a chemical solution of a membrane module.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is an immersion flat membrane capable of effectively suppressing blockage of each membrane module by diffusing air, and furthermore, performing a simple and low-cost cleaning of a chemical solution. It is an object to provide a filtration device.

[0010]

According to a first aspect of the present invention, in order to achieve the above object, a large number of membrane modules are vertically immersed in water to be treated in a treatment tank and are arranged side by side. In a submerged flat membrane filtration device in which a diffuser is disposed below the membrane module, the plurality of membrane modules are
Adjacent membrane modules are divided into a plurality of groups as one group, and air bubbles diffused from the air diffusing means are guided to the membrane modules by surrounding each of the groups with an enclosing wall having openings vertically. The enclosing walls are arranged at intervals such that a flow path for the water to be treated, which has risen inside the enclosing wall due to the air bubbles, to descend outside the enclosing wall is secured.

According to the present invention, the plurality of modules are divided into a plurality of groups, for example, two rows, and are surrounded by the surrounding wall, and the surrounding walls are arranged at intervals at which a flow path for descending flow is secured. Therefore, a sufficient swirling flow is formed for each membrane module. Therefore, it is possible to prevent the formation of a sludge pool on the membrane surface of the membrane module, and it is possible to effectively suppress the blockage of the membrane module.

According to the third aspect of the present invention, an independent cleaning tank is formed inside the processing tank by closing the lower opening of the enclosure wall. Therefore, by introducing a chemical solution into the cleaning tank, only the membrane module in the cleaning tank can be cleaned. As a result, only the predetermined membrane module can be easily and inexpensively cleaned with the chemical solution.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a submerged flat membrane filtration device according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic structural view of an immersion flat membrane filtration device, and FIG. 2 is a perspective view illustrating the internal structure of the flat membrane tank of FIG.

In a flat membrane tank (corresponding to a treatment tank) 12 of the immersion flat membrane filtration apparatus 10, a water to be treated (suspension) 14 is stored. The modules 16, 16 ... are immersed. Many membrane modules 1
Are arranged vertically and in parallel with each other, and the interval between the membrane modules 16, 16,.
In the Y-axis direction.
The membrane modules 16 are surrounded every two rows by an air diffusion guide wall (corresponding to an enclosure wall) 18 formed in a cylindrical shape. Further, as shown in FIG.
, And by driving the pump 22, a suction force can be applied to the inside of the membrane module 16.

Below the membrane module 16, a flat membrane tank 12 is provided.
A diffuser tube 24 is provided along the bottom surface 12A of the airbag. The diffuser tube 24 has a diffuser hole (not shown) formed on the side surface so that the diffuser can diffuse air from below as much as possible (see FIG. 6). The air diffuser 24 is connected to a blower 30 via an air supply pipe 28 provided with an on-off valve 26. Thereby, blower 3
When “0” is driven, bubbles are diffused from the diffuser tube 24, and the diffused bubbles are guided to the membrane module 16 by the diffusion guide wall 18.

The air diffuser 24 is connected to a pump 34 via a pipe 32, and a tap water supply 36 and a chemical supply 38 are connected to the pump 34. Thus, when the on-off valve 26 provided in the pipe 32 is opened and the pump 34 is driven, the tap water and the chemical are sent to the diffuser 24. A drain pipe 42 is connected to the pump 34, and the liquid in the diffuser pipe 24 is drained to the outside by opening an on-off valve 44 disposed on the drain pipe 42.

FIG. 3 is a perspective view for explaining the structure of the membrane module 16.

As shown in FIG.
A plurality (for example, 10) of membrane bags 46 (only one is shown);
A pair of water collecting portions 48 supporting the left and right ends of the membrane bag 46;
48. The membrane bag 46 is formed by attaching an organic flat membrane 54 to both sides of a hollow support plate (plastic step) 50 via a spacer 52. Binders 56 are attached to the upper and lower ends of each membrane bag 46, whereby the ends of the membrane bags 46 are reinforced. Further, the membrane bags 46 are supported at regular intervals by a gap holding member 58 made of urethane rubber. On the other hand, the water collecting section 48 communicates with the inside of each membrane bag 46 and is connected to the pump 22 of FIG. Thereby, when the pump 22 is driven, each membrane bag 46
A suction force acts inside the membrane bag 46, and the water 14 to be treated outside each membrane bag 46 is sucked into the membrane bag 46 via the organic flat membrane 54 and filtered. The size of the membrane module 16 is, for example, 1116 mm in width (X-axis direction) and thickness (Y-axis direction).
The height is 124 mm and the height (Z-axis direction) is 1152 mm.

FIG. 4 is a side view illustrating the air diffusion guide wall 18, and FIG. 5 is a plan view of FIG. In these figures, the right air diffusion guide wall 18 shows a state where the lower opening 61 is opened, and the left air diffusion guide wall 18 shows a state where the lower opening 61 is closed.

As shown in these figures, the air diffusing guide wall 18
Is formed in a rectangular cylindrical shape by a pair of side walls 18A, 18A orthogonal to the film surface of the film module 16 and a pair of side walls 18B, 18B parallel to the film surface of the film module 16. The diffusion guide walls 18 are arranged so as to surround the membrane module 16 every two rows, and are arranged at a predetermined interval from the adjacent diffusion guide walls 18. Here, the predetermined interval is an interval at which a flow path of a descending flow descending between the adjacent diffusion guide walls 18 is sufficiently secured.

The side walls 18A, 18A are formed such that the lower end is in close contact with the bottom surface 12A of the flat membrane tank 12 and the upper end is above the liquid level of the water 14 to be treated. on the other hand,
The side walls 18B, 18B are formed shorter in the height direction than the side walls 18A, and are erected on the side walls 18A, 18A such that an opening 61 is formed below and a communication path for the water 14 to be formed is formed above. Is done. As a result, the water to be treated 14 rises inside the diffusion guide wall 18 and flows out of the diffusion guide wall 18 via the communication passage, and further descends between the diffusion guide walls 18. A swirling flow path of the water to be treated 14 that enters the inside through the opening 61 is formed.

A partition wall 20 is provided between the membrane modules 16 so that the swirling channels formed in each membrane module 16 are symmetrical.

Below the side wall 18B, a swing wall 60 is rotatably attached to the bottom surface 12A of the flat membrane tank 12 by a hinge 62 or the like. The swing wall 60 is connected to the lever 74 via the link mechanism shown in FIGS. Regarding the structure of the link mechanism, three links 66, 66...
Are provided rotatably on a horizontal plane by pins 68. Both ends of the link 66 are attached to the mounting plate 7
It is rotatably supported at zero. And the link 66
In addition, a lever 74 is provided via an L-shaped support rod 72. Therefore, when the lever 74 is pushed and pulled in the direction of the arrow in FIG. 5, the link 66 rotates and the interval between the upper ends of the swing walls 60 fluctuates, and the swing wall 60 swings. For example,
When the lever 74 is slid upward as shown on the right side of FIG. 5, the swing wall 60 is at a predetermined angle, and the swirling flow path of the water to be treated is sufficiently secured through the opening 61. When the lever 74 is slid downward, the swing wall 60 swings and comes into contact with the side wall 18B, and the lower opening 61 is closed. A seal rubber 76 is attached to the swing wall 60 at a contact portion with the side wall 18B.
1 is securely sealed. The hinge 62 is covered with a rubber sheet 78, and the rubber sheet 7
8 prevents leakage from the connecting part.

Further, the air diffusion guide wall 18 is formed by the side wall 18B.
It is configured to be able to shut off the communication passage above. That is, like the air diffusion guide wall 18 on the left side of FIG.
By mounting a separate slide wall 80 above the side wall 18B, the substantial upper end of the side wall 18B is positioned above the liquid level of the water 14 to be treated. Sliding wall 8
0 is configured to be guided by guide portions 84 formed on both side portions of the side wall 18A and to slide vertically.
After sliding the sliding wall 80 downward by its own weight,
The taper block 82 is attached by dropping it into the guide portion 84. Tapered surfaces are formed at the upper and lower ends of the slide wall 80, of which the lower tapered surface is in contact with the tapered surface of the side wall 18B, and the upper tapered surface is in contact with the taper of the tapered block 82. . A seal rubber 81 is attached to the upper and lower ends of the slide wall 80, and a seal rubber (not shown) is attached to a contact surface with the side wall 18A. As a result, the slide wall 80 is pressed inward by the weight of the slide wall 80 and the tapered block 82, and is securely adhered to the seal rubber, thereby blocking the communication path above the side wall 18B.

Next, the operation of the immersion flat membrane filtration device 10 configured as described above will be described with reference to FIG. FIG. 6 is a schematic diagram illustrating the operation of the immersion flat membrane filtration device 10. In the case where the membrane modules 16 are divided into three groups, two of the groups perform a filtration operation, and the remaining group performs chemical cleaning. It is.

First, a description will be given of the membrane module 16 which performs a normal filtration operation. In this case, the lever 74 shown in FIG. 5 is slid upward. As a result, the swing wall 60 swings inward at a predetermined angle, and the lower opening 6 of the side wall 18B.
1 is released. Therefore, when air is diffused from the diffuser tube 24, the diffused air bubbles are guided below the membrane module 16 by the swing wall 60 and the diffusion guide wall 18, and rise along the membrane module 16. As a result, air bubbles hit the membrane surface, and the sludge attached to the membrane surface is destroyed. At this time, an ascending flow is formed in the diffusion guide wall 18 as the bubbles rise, and a descending flow wrapping around from the communication path above the side wall 18B is formed outside the diffusion guide wall 18. As a result, a swirling flow swirling between the inside and the outside of the air diffusion guide wall 18 is formed, and the sludge attached to the membrane of the membrane module 16 is separated by the shearing force due to the swirling flow.

In the present embodiment, a large number of membrane modules 16 are surrounded by the diffusion guide walls 18 every two rows, and the diffusion guide walls 18, 18... Are arranged at predetermined intervals. The swirling flow path of the swirling flow descending between the air diffusion guide walls 18 is sufficiently secured for each membrane module 16. Comparing this with the conventional apparatus, in the conventional apparatus, since the entire membrane module is surrounded by one diffuser introduction wall, the swirling flow descending beyond the wall surface parallel to the membrane surface in the membrane modules at both ends. While a sufficient path is ensured, the central membrane module has only a swirl flow path descending beyond a wall surface perpendicular to the membrane surface, and the swirl flow path for the downward flow is narrow. As described above, when the flow path for the downward flow is narrow, the swirling flow that rises when entering the inside of the air diffusion guide wall is disturbed, and the shearing force acting on the sludge on the membrane surface becomes uneven on the membrane surface. For this reason, the membrane modules at the center of the conventional apparatus are easily blocked by the membrane modules at both ends. In the present embodiment, all the membrane modules 16 correspond to the membrane modules at both ends of the conventional apparatus, and a sufficient swirling flow path is secured. Therefore, each membrane module 16
Since the shear force due to the swirling flow acts evenly on the membrane surface of (1), blockage of the membrane surface of each membrane module can be effectively suppressed. Thereby, the life of each membrane module 16 can be improved.

In this embodiment, since the openings 61 are formed over the entire width of the membrane module 16, the effect of preventing the membrane from being blocked by the swirling flow in the width direction of the membrane module 16 is equalized. Blockage of the membrane can be effectively prevented.

The swirling flow is applied to each of the membrane modules 16.
Are formed substantially uniformly in each of the membrane modules 16.
The shearing force acting on the sludge pool adhering to the surface of the membrane becomes substantially uniform. Therefore, variation in the effect of suppressing the blockage of each membrane module 16 is reduced, and variation in the life of each membrane module 16 is eliminated.

In the present embodiment, since the diffuser tube 24 is disposed along the bottom surface 12A of the flat membrane tank 12, the flat membrane tank 1
No stagnation area is formed at the bottom of 2. Therefore, it is possible to prevent the water to be treated from becoming anaerobic and decay, and to stabilize the liquid properties.

Further, in the present embodiment, since the swing wall 60 is swung at a predetermined angle, bubbles diffused from the diffuser tube 24 leak out of the opening 61 to the outside of the diffuser guide wall 18. Instead, it is guided to the membrane module 16. Therefore, the swirling flow is generated stably, and the effect of suppressing the blockage of the membrane surface of the membrane module 16 is also stabilized.

Next, a description will be given of the membrane module 16 for chemical cleaning. In this case, the lever 74 shown in FIG. 5 is slid downward, and the slide wall 80 is attached to the upper portion of the side wall 18B. As a result, the opening 61 below the side wall 18B is closed, and the communication path above the side wall 18B is shut off, so that a cleaning tank 86 independent from the surroundings is formed inside the flat membrane tank 12.

Next, the on-off valve 26 shown in FIG. 1 is closed and the on-off valves 40 and 44 are opened. Thus, the water 14 to be treated inside the cleaning tank 86 is discharged to the outside. next,
By driving the pump 34 by closing the on-off valve 44,
A chemical solution and tap water are supplied to the cleaning tank 86. This allows
The membrane module 16 in the cleaning tank 86 in FIG. 8 can be cleaned.

As described above, in the present embodiment, since the independent cleaning tank 86 is formed to clean the membrane module 16, only a predetermined membrane module 16 can be cleaned with the chemical solution. Therefore, we do not use chemicals more than necessary,
The cost for chemical cleaning can be greatly reduced. In addition, since the chemical solution can be washed while performing a normal filtration operation in the membrane modules 16 of another group, the filtration efficiency of the immersion flat membrane filtration device 10 can be improved. In addition, in this method, it is not necessary to take out the membrane module 16, and therefore, the chemical solution can be easily washed. Further, since the liquid medicine is supplied from the air diffuser 24, an effect of cleaning the inside of the air diffuser 24 can be obtained.

In the above-described embodiment, the membrane modules 16 are surrounded by the air diffusing walls 18 every two rows. However, the present invention is not limited to this, and a large number of membrane modules 16, 16. By arranging the air diffusion guide walls 18 at predetermined intervals and enclosing the air diffusion guide walls 18 at predetermined intervals, the swirling flow path for each membrane module 16 can be widened. Can be effectively suppressed. Note that a large number of membrane modules 16 may be surrounded one by one by the air diffusion guide wall 18.

The oscillating means of the oscillating wall 60 is not limited to the above-described embodiment, but may be oscillated by a driving device such as a cylinder.

The means for opening and closing the opening 61 below the side wall 18B and the means for shutting off the communication path above the side wall 18B are not limited to the above-described embodiment. For example, FIG.
Is a sliding wall 9 having a two-stage side wall.
2, 94. Sliding walls 92, 9
The structure of No. 4 is the same as that of the slide wall 80 described above, and the description is omitted. In the case of filtering by the air diffusion guide wall 90 (the case on the left side in FIG. 7), the slide wall 92 is fixed at a predetermined position by a pin (not shown) or the like. In the case of cleaning with a chemical solution (in the case of the right side in FIG. 7), the pins are removed, and the taper block 96, the slide wall 94, and the taper block 98 are sequentially dropped above the slide wall 92. As a result, both the slide walls 92 and 94 are pressed inward by the taper, and the seal rubbers 95 provided at the upper and lower ends of each of the slide walls 92 and 94 come into close contact with each other, so that an independent cleaning tank 86 is formed.

A cylindrical enclosure wall 99 as shown in FIG.
The opening 61 and the communication path may be closed by attaching the upper and lower portions of the air diffusion guide wall 18.

In this embodiment, the slide wall 80
The communication passage is closed by the treatment water 14 in the flat membrane tank 12.
May be lowered.

Further, in the present embodiment, the opening 61 and the communication path are formed only on the side wall 18B side, but the present invention is not limited to this, and the opening and the communication path are also formed on the side wall 18A side. You may comprise so that it can be shut off.

[0042]

As described above, according to the immersion flat membrane filtration device of the present invention, the large number of modules are divided into a plurality of groups and surrounded by the surrounding walls, and the surrounding walls are separated by the downward flow path. Are arranged at intervals enough to ensure a sufficient swirl flow path for each membrane module, and blockage of the membrane module can be effectively suppressed. Further, according to the present invention, since the lower opening of the enclosure wall is closed, an independent washing tank can be formed in the processing tank, and a predetermined membrane module can be easily washed.

[Brief description of the drawings]

FIG. 1 is a schematic structural diagram of an immersion flat membrane filtration device according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating the internal structure of the flat membrane tank in FIG.

FIG. 3 is a perspective view of the membrane module of FIG. 2;

FIG. 4 is a side sectional view of the air diffusion guide wall of FIG. 2;

5 is a cross-sectional view of the air diffusion guide wall of FIG. 4 as viewed from above.

FIG. 6 is a diagram illustrating the operation of the immersion flat membrane filtration device according to the embodiment of the present invention.

FIG. 7 is a side cross-sectional view of an air diffusion guide wall having a shape different from that of FIG. 4;

FIG. 8 is a perspective view showing a part of an air diffusion guide wall having a shape different from that of FIG. 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Immersion flat membrane filtration device, 12 ... Flat membrane tank, 14 ... Water to be treated, 16 ... Membrane module, 18 ... Aeration guide wall, 24 ... Aeration tube, 60 ... Oscillating wall, 61 ... Opening, 80 ... Slide wall

Continued on front page F term (reference) 4D006 GA02 HA48 HA93 JA03Z JA04Z JA18A JA29A JA30A JA31A JA39A JA53Z JA71 KA12 KA44 KA67 KC02 KC14 KC16 MA03 MB02 MC07 PA02 PA05 PB08 PB70 PC64

Claims (3)

[Claims] 1. A submerged flat membrane filtration apparatus in which a number of membrane modules are vertically immersed in water to be treated in a treatment tank and juxtaposed, and a diffuser is provided below the plurality of membrane modules. In the above, a large number of the membrane modules are divided into a plurality of groups with adjacent membrane modules as one group, and each of the groups is surrounded by an enclosure wall having openings at upper and lower sides and diffused from the air diffuser. The bubbles are guided to the membrane module, and the surrounding walls are arranged at intervals at which a flow path for the water to be treated, which has risen inside the surrounding wall due to the bubbles, to fall outside the surrounding wall is secured. An immersion flat membrane filtration device characterized by the following. 2. The immersion flat membrane filter according to claim 1, wherein said one group comprises two rows of membrane modules. 3. An opening / closing means for opening and closing the lower opening is provided at a lower opening of the enclosure wall, and when the lower opening is closed by the opening / closing means, the inside of the enclosure wall is isolated from the processing tank. The immersion flat membrane filtration device according to claim 1 or 2, wherein the filtration is performed.