JP2000288359A - Immersion flat membrane filtration device - Google Patents

Abstract

(57) [Problem] To provide an immersion flat membrane filtration device capable of uniformly cleaning a large number of filtration membranes and maintaining a high filtration efficiency as a whole for a long period of time. A filtration unit is suspended from a beam by a telescopic support member, and a lower end position thereof can be adjusted. In the filtration unit 14 whose lower end position has been adjusted, the filtration units 14A arranged in the lower part and the filtration units 14B arranged in the upper part are alternately arranged.
As a result, the air diffused from the air diffuser cylinder 50 forms an air pocket that is divided by the filter unit 14A disposed below, below the filter unit 14B disposed above.

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 In the field of water treatment, suspended matter such as activated sludge and coagulated sludge contained in wastewater and sewage is generally removed by a membrane separation device. This membrane separation device is mainly
It comprises a tank for storing the water to be treated, a number of filtration units having a filtration membrane, and a suction pump connected to the number of filtration units. Then, by driving the suction pump, the water to be treated stored in the tank is sucked into the filtration unit, and is filtered by the filtration membrane of the filtration unit to remove suspended matter.

[0003] In the above-mentioned membrane separation device, since the filtration membrane is closed with the lapse of time, measures for blocking the filtration membrane are usually taken. For example, in an immersion flat membrane filtration device in which many filtration units are immersed in water to be treated, an air diffuser is provided below the filtration unit, and the water to be treated is diffused by the air diffuser. Then, the air bubbles that have been diffused rise between the filtration units to separate the sludge attached to the filtration membrane from the filtration membrane. Thereby, the filtration membrane is washed, and the filtration performance of the filtration membrane is restored.

[0004]

However, the conventional immersion flat membrane filtration apparatus has a drawback that the filtration performance of the filtration membrane varies greatly in many filtration units. For this reason, the performance of all the filtration membranes could not be recovered sufficiently, and high filtration efficiency could not be obtained as a whole.

The inventors of the present invention have clarified that the variation in the recovery of the filtration performance of the filtration membrane is caused by the following causes. That is, the air diffused by the diffuser is
Instead of rising directly between the filtration units, an air pocket is once formed below the filtration units. And
When the air pool becomes large and the pressure of the air pool becomes large, bubbles are split from the air pool, and the bubbles rise between arbitrary filtration units toward the water surface.

Therefore, when the air reservoir grows unevenly, a large pressure portion and a small pressure portion are generated in the air reservoir, and the large pressure portion causes many bubbles to be split from the air reservoir, and conversely, the pressure increases. The smaller the area, the smaller the number of bubbles to be divided. In this case, above the portion where the pressure is small, the suspension of the filtration membrane is not sufficiently peeled off,
The filtration performance of the filtration membrane deteriorates. Therefore, it is preferable that the plurality of filtration units are arranged so that the lower ends thereof are all equal, and the air reservoir grows uniformly over the entire surface. Was difficult.

[0007] The present invention has been made in view of such circumstances, and provides an immersion flat membrane filtration device capable of uniformly cleaning a large number of filtration membranes and maintaining a high filtration efficiency as a whole for a long period of time. With the goal.

[0008]

According to the present invention, in order to achieve the above-mentioned object, the present invention is immersed vertically in water to be treated in a tank at an interval, and the water to be treated is sucked in through a filtration membrane. A large number of filtration units and a plurality of filtration units disposed below the large number of filtration units, the air is diffused into the water to be treated in the tank, and the filtration membrane is washed by introducing bubbles between the filtration units. Air diffusion means, and the plurality of filtration units are vertically displaced from each other such that the lower end positions thereof are uneven, and the air diffused from the air diffusion means accumulates in the concave portions. It is characterized by doing so.

According to the first aspect of the invention, the air diffused from the air diffusing means accumulates in the concave portion and forms an air reservoir divided into the convex portion. Since the air pockets thus divided are not affected by the adjacent air pockets, each air pocket grows to have substantially the same size. Therefore, the same pressure is applied to each air reservoir, so that the air bubbles that split from each air reservoir and rise to the liquid level are uniformly generated in each air reservoir. That is, since substantially the same number of bubbles rise between the filtration units, the filtration membrane can be uniformly washed with the bubbles. As a result, the filtration performance of the filtration membrane can be evenly restored, and high filtration performance can be maintained as a whole.

According to the second aspect of the present invention, the immersion flat membrane device is provided with means for adjusting the lower end position of each filtration unit. The lower end position can be adjusted, and the air pool can be reliably divided. Therefore, it is possible to quickly respond to a change in the viscosity of the water to be treated, which affects the state of formation of the air pool.

According to the third aspect of the present invention, since the lower end positions of the multiple filtration units are alternately arranged in a rugged manner, below the multiple filtration units,
The divided air pockets are formed evenly. Thereby, the filtration membranes of the large number of filtration units are uniformly washed, and the immersion flat membrane filtration device can maintain high filtration performance as a whole.

[0012]

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 front sectional view of the immersion flat membrane filtration device 10 according to the first embodiment, and FIG. 2 is a side view of the immersion flat membrane filtration device 10 shown in FIG.

As shown in these figures, the immersion flat membrane filtration device 10 mainly includes a flat membrane tank 12, a filtration unit 14, and an air diffuser 16. The flat membrane tank 12 has a supply pipe 2
2 is connected, and the water to be treated 20 is supplied from a reaction tank (not shown) via the supply pipe 22 and stored. A large number of filtration units 14, 1
4, ... are immersed. As shown in FIG. 3, the filtration unit 14 includes two perforated plates 24 facing each other at a predetermined interval.
To form a box body,
4 is formed by attaching filtration membranes 26, 26 to the surface. Each filtration unit 14 is connected via a pipe 28 to FIG.
The collecting pipe 30 is connected to a suction pump 32. Thereby, the suction pump 3
When 2 is driven, a suction force acts in the filtration unit 14,
The water to be treated 20 outside the filtration unit 14 is
6 and is sucked into the filtration unit 14. And
The water to be treated (permeated water) 20 that has passed through the filtration membrane 26 is
It is collected in the collecting pipe 30 via 8 and drained by the suction pump 32.

The filtration unit 14 includes the flat membrane tank 12.
3 erected above the opposing side walls 12A, 12A
6 is suspended via a support member 38. The support member 38 includes a rod 42, a rod 44, and a turnbuckle 4.
6, the rod 42 is erected on the upper surface of the filtration unit 14, and the rod 44 is erected on the lower surface of the beam 36. In the turnbuckle 46, a screw hole for a right-hand screw and a screw hole for a left-hand screw are formed coaxially from both directions. The upper end of the rod 42 and the lower end of the rod 44 are screwed into the screw holes of the turnbuckle 46, respectively. Therefore, when the turnbuckle 46 is rotated, the screwed amount changes, and the support member 38 expands and contracts. Thereby, the large number of filtration units 14,
By moving up and down 14, the lower end position can be easily adjusted.

By adjusting the lower end positions of the plurality of filtration units 14, 14,... As described above, the lower end positions are arranged unevenly as shown in FIG. That is, the large number of filtration units 14, 14,... Are a filtration unit 14A (a convex portion) disposed at a lower end thereof relatively lower and a filtration unit 14A having a lower end disposed relatively upward. 14B (concave portions) are alternately arranged. Filter unit 14A arranged below and filtration unit 14 arranged above
The difference h at the lower end in B is determined by conditions such as the viscosity of the water 20 to be treated, and ensures that an air reservoir 56 described later is surely divided by the filtration unit 14A disposed below.

Further, the plurality of filtration units 14, 1
Below the 4,..., An air diffuser cylinder 50 of the air diffuser 16 is provided. The diffuser cylinder 50 has a number of diffuser holes (not shown) on its surface.
Is formed and connected to the blower 52 of the air diffuser 16. Thereby, when the blower 52 is driven,
External air is supplied to the diffuser 50, and the supplied air is blown out of the diffuser 50 into the flat membrane tank 12.

Air collecting plates 54, 54 are provided on both sides of the lower end of the filtering unit 14, and the air blown out from the air diffuser cylinder 50 is used for the filtering units 14, 1.
4,... Are configured to gather downward. Next, the operation of the immersion flat membrane filtration device 10 configured as described above will be described. The suction pump 32 of the immersion flat membrane filtration device 10 is driven,
When the water to be treated 20 is continuously filtered by the filtration membrane 26, suspended matter in the water to be treated 20 is deposited on the filtration membrane 26. By driving the diffuser 16, the accumulated suspension is
Peel off from the filtration membrane 26. That is, when the air blowing device 52 of the air diffuser 16 is driven, air is blown from the outside to the air diffusion cylinder 50, and the blown air is blown out from the air diffusion holes of the air diffusion cylinder 50 to be below the filtration unit 14. Air pocket 56
To form At this time, the filtration unit 14 </ b> A
As shown in FIG. 4, the air reservoir 56 is formed by being divided into the lower filtration unit 14A and the lower filtration unit 14A, as shown in FIG. Is done. That is, the air pool 56 is formed in a concave portion at the lower end portion which is arranged unevenly. Therefore, if air is evenly diffused from the air diffuser cylinder 50, the divided air pools 56 also grow substantially evenly, so that air bubbles are evenly generated between any of the filtration units 14. Thereby, since the suspended matter is evenly separated from the filtration membrane 26 of each filtration unit 14, the recovery of the filtration performance of the filtration membrane 26 is not dispersed, and the immersion flat membrane filtration device 10 has a high filtration efficiency as a whole. Obtainable.

In the immersion flat membrane filtration device 10 according to the first embodiment, the lower end position of the filtration unit 14 can be easily adjusted only by turning the turnbuckle 46. Therefore, it is possible to quickly respond to the formation state of the air pool 56 that varies depending on the viscosity of the water 20 to be treated. Further, the lower end position adjusting means of the filtration unit 14 provided on the support member 38 has a simple structure and is low in cost.

The means for adjusting the lower end of the filtration unit 14 is not limited to the above-described embodiment. For example, the filtration unit is supported by using a cylinder device and the filtration device is driven by driving the cylinder device. It may be moved up and down. Next, a second embodiment of the immersion flat membrane filtration device according to the present invention will be described. FIG. 5 is a front sectional view of the immersion flat membrane filtration device 60 according to the second embodiment.

As shown in FIG.
The left and right ends are fixed by the water collecting member 62. The water collecting member 62 is suspended from the collecting pipe 64 by the pipe 66 and communicates with the collecting pipe 64 via the pipe 66. Further, in the filtration unit 14, similarly to the first embodiment, the filtration units 14A arranged in the lower part and the filtration units 14B arranged in the upper part are alternately arranged. The difference h between the lower end positions of the lower filtration unit 14A and the upper filtration unit 14B is set in advance to a value that allows the air reservoir 56 to be reliably divided by experiments or the like. Note that the same or similar members as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

In the immersion flat membrane filtration device 60 of the second embodiment configured as described above, since the filtration unit 14 is supported by the pipe 66 that connects the collecting pipe 30 and the filtration unit 14, the structure is reduced. It is simple and costs can be reduced. Also, in the immersion flat membrane filtration device 60, as in the first embodiment, it is possible to eliminate the variation in the recovery of the filtration performance of the filtration membrane 26, and to obtain a high filtration efficiency as a whole.

In the above-described first and second embodiments, the filtration units 14A arranged in the lower part and the filtration units 14B arranged in the upper part are alternately arranged. However, the present invention is not limited to this. May be changed according to the processing conditions such as the viscosity. For example, as shown in FIG. 6, a plurality of filtration units 14B disposed above may be provided between the filtration units 14A disposed below and 14A.

[0023]

As described above, according to the immersion flat membrane filtration device according to the present invention, since a large number of filtration units are arranged so that their lower end positions are uneven, they are diffused by the air diffusion means. The evacuated air forms an air pocket in the concave portion. Therefore, the air bubbles that are separated from the air pool and rise between the filtration units are uniformly generated on the entire surface, and the cleaning of the filtration membrane by the air bubbles is performed uniformly in all the filtration membranes. As a result, it is possible to eliminate variations in the recovery of the filtration performance of the filtration membrane, and to obtain high filtration efficiency as a whole.

[Brief description of the drawings]

FIG. 1 is a front view of a first embodiment of an immersion flat membrane separation device according to the present invention.

FIG. 2 is a side view of the immersion flat membrane separation device shown in FIG.

FIG. 3 is a side sectional view of the filtration unit shown in FIG. 1;

FIG. 4 is an explanatory view for explaining the operation of the immersion flat membrane separation device according to the present invention.

FIG. 5 is a front view of a second embodiment of the immersion flat membrane separation device according to the present invention.

FIG. 6 shows another embodiment of the immersion flat membrane separation device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 ... Flat membrane tank 14 ... Filtration unit 16 ... Air diffuser 20 ... Water to be treated 26 ... Filtration membrane 38 ... Support member 42, 44 ... Rod 46 ... Turnbuckle 56 ... Air pool

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroki Ando 1-1-1 Uchikanda, Chiyoda-ku, Tokyo Inside Hitachi Plant Construction Co., Ltd. (72) Inventor Seiwa Takemura 1-1-1, Uchikanda, Chiyoda-ku, Tokyo No. 14 Hitachi Plant Construction Co., Ltd. F term (reference) 4D006 GA02 HA42 HA93 JA01A JA01B JA31A KA43 KE08P PB08 PC62

Claims (3)

[Claims] 1. A plurality of filtration units which are immersed vertically in a water to be treated in a tank at intervals, and wherein the water to be treated is sucked inside through a filtration membrane, and disposed below the plurality of filtration units. Air diffusion means for diffusing air into the water to be treated in the tank, and washing the filtration membrane by introducing air bubbles between the filtration units. An immersion flat membrane filtration device characterized in that the lower end positions are vertically shifted from each other so as to be uneven, and the air diffused from the air diffusing means accumulates in the concave portion. 2. The immersion flat membrane filtration device according to claim 1, wherein the immersion flat membrane filtration device is provided with lower end position adjusting means for individually adjusting the lower end position of each filtration unit. 3. The immersion flat membrane filtration device according to claim 1, wherein the plurality of filtration units are arranged so that lower end positions thereof are alternately uneven.