JP2002011469A - Immersed flat membrane separation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an immersed flat membrane separated device apparatus having accelerated flow velocity on the membrane surface by improving factors decelerating the flow velocity. SOLUTION: This immersed flat membrane separation device 10 has membrane modules 16 immersed in the water to be treated 14. Wedge-shaped distributing plates 26 are fit to the bottom of a membrane plate 46 of each module 16. Air diffusing pipes 24 are disposed below the modules 16 and diffused air guiding walls 18 are disposed around the modules 16. The top of each wall 18 is folded back to the outside and formed into almost a U shape. A partition plate 30 is hung between the adjacent walls 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submerged flat membrane separator, and more particularly to a submerged flat membrane separator used in the fields of industrial wastewater treatment and activated sludge treatment such as sewage.

[0002]

2. Description of the Related Art An immersion flat membrane separator is a type of membrane separator in which a flat membrane is immersed in a suspension, and is used for treating coagulated sludge of industrial wastewater and activated sludge such as sewage and human waste. ing. In this apparatus, as shown in FIG. 11, a membrane module 2 having a flat membrane 1 is immersed in a highly-concentrated treated water (suspension) 3, and the treated water 3 is introduced into the membrane module 2. By suction, treated water (filtrate) is obtained. An air diffuser 5 is provided below the membrane module 2, and the air is diffused by the air diffuser 5. Here, the purpose of the air diffusion by the air diffusing means 5 is to remove the sludge cake deposited on the flat membrane 1 to suppress the blockage of the flat membrane 1 (that is, to obtain a cleaning effect), This means that a swirling flow is caused to give a cross flow to the flat membrane 1 and the inside of the tank 4 is stirred, and when the liquid in the tank 4 is activated sludge or the like, oxygen is supplied for aerobic treatment.

[0003] Around the membrane module 2, a box-shaped air diffusion guide wall 6 which is opened vertically is usually installed. The air bubbles diffused from the air diffusing means 5 are guided to the membrane module 2 by the air diffusing guide wall 6, and enter the space between the flat membranes 1 and 1 of the membrane module 2 and rise. At this time, the to-be-processed water 3 rises together with the bubbles to give a cross flow to the flat membrane 1. When the to-be-treated water 3 rises to the liquid level, it turns and descends outside the diffusion guide wall 6, enters the diffusion guide wall 6 from the lower end of the diffusion guide wall 6, and rises again.

[0004]

However, in the conventional immersion flat membrane separation device, the upper end portion of
There is a drawback that the upward flow and the downward flow interfere with each other to generate a vortex. Particularly, in the case of a viscous liquid such as activated sludge, bubbles of about several millimeters are easily entrapped in the descending flow, and the bubbles are combined with each other, enlarged, and rise to generate a vortex. When the vortex is generated in this way, the vortex becomes a flow path resistance, and the membrane surface velocity (the velocity of the water 3 to be treated in the flat membrane 1) decreases. Therefore, the permeation flux (the amount of filtered water per 1 m ^{2 of} the membrane area per day) is also reduced. Therefore, the conventional immersion flat membrane separator has a large number of membrane modules 2 for the treatment scale, initial cost, and There was a disadvantage that running costs were high.

In the conventional immersion flat membrane separation apparatus, only a few millimeters of air bubbles diffused from the air diffusion means 5 are removed from the membrane module 2.
However, there is a drawback that bubbles do not enter between the flat membranes 1 and 1 and the air bubbles accumulate below the membrane module 2 because they are enlarged to 20 mm or more before reaching the temperature. For this reason,
The water to be treated 3 that cannot flow between the flat membranes 1 and 1
A downward flow is formed along the flow path, and the downward flow serves as a flow path resistance to reduce the film surface flow velocity. For example, immediately after air bubbles are diffused, the air pressure is reduced to 0.1.
Even if it rises at 8 m / s, it drops to 0.4 m / s when passing between the membranes 1 and 1. Therefore, the permeation flux also decreased, and the initial cost and running cost increased.

Further, the conventional device is provided below the air diffusing means 5.
There is a drawback that a stagnant area without flow is generated. Since there is no contact with the air, the stagnation area becomes anaerobic and the activated sludge rots.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an immersion flat membrane separation apparatus which improves a flow rate on a membrane surface by improving a factor of loss of the flow rate.

[0008]

Means for Solving the Problems In order to achieve the above object, the invention according to claim 1 has a membrane for filtering water to be treated,
A membrane module vertically immersed in the water to be treated, and a diffuser installed below the membrane module to diffuse air,
A diffusion guide wall provided around the membrane module and for guiding bubbles diffused from the diffusion means to the membrane module, wherein the upper end of the diffusion guide wall has an upper end. It is characterized in that it has a shape that is folded outward between the upper end of the membrane module and the liquid surface of the water to be treated.

According to the first aspect of the present invention, since the upper end of the diffusion guide wall is turned outward, the upward flow rising inside the diffusion guide wall and the downward flow descending outside the diffusion guide wall. Does not interfere with the upper end of the air diffusion guide wall, and the loss of the membrane surface flow velocity can be suppressed.

In order to achieve the above object, the invention according to claim 2 has a membrane plate member having a membrane for filtering the water to be treated attached to a support plate, and the membrane plate member is vertically attached to the water to be treated. A membrane module that is immersed, a diffuser installed below the membrane module to diffuse air, and a gas diffuser provided around the membrane module and guided by the diffuser to the membrane module. And a diffuser guiding wall, wherein the lower end of the membrane plate member is formed in a wedge shape.

According to the second aspect of the present invention, since the lower end of the membrane plate member is formed in a wedge shape, large bubbles are divided and flow quickly between the membrane plate members. Therefore, since air bubbles do not accumulate below the membrane plate member, the membrane surface flow velocity can be improved.

According to a third aspect of the present invention, in order to achieve the above object, a plurality of membrane modules having a membrane for filtering the water to be treated, and vertically immersed in the water to be treated, and the plurality of membrane modules are provided. And a plurality of diffusion guide walls provided around the membrane module and configured to guide bubbles diffused from the diffusion unit to the membrane module. In the provided immersion flat membrane separation apparatus, a partition plate is provided between the air diffusion guide walls.

According to the third aspect of the present invention, since the partition plate is provided, the flow of the water to be treated circulating inside and outside the diffusion guide wall is changed to the treated water circulating inside and outside the adjacent diffusion guide wall. Does not interfere with the flow of air. Therefore, the flow path resistance is reduced, and the membrane surface flow velocity can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an immersion flat membrane separation 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 separation apparatus, and FIG. 2 is a perspective view in which a part of the flat membrane tank is cut away to explain the internal structure of the flat membrane tank of FIG. . FIG.
FIG. 3 is a side view from the direction of arrow 3 in FIG. 2.

A to-be-processed water (suspension) 14 is stored in a flat membrane tank 12 of the immersion flat membrane separation apparatus 10, and a plurality of membrane modules 16, 16,. . The plurality of membrane modules 16, 16,... Are arranged vertically and vertically in two stages so as to be parallel to each other, and are provided with a large interval every two rows. The membrane module 16 is surrounded every two rows by an air diffusion guide wall 18 formed in a cylindrical shape. Also, the membrane module 16
Is connected to the pump 22, and by driving the pump 22, a suction force can be applied to the inside of the membrane module 16.

FIG. 4 is a perspective view showing the structure of the membrane module 16.

As shown in FIG. 1, the membrane module 16 comprises
A plurality of (for example, 10) membrane plates 46 (only one is shown);
A pair of film edge fixing members 4 supporting the left and right ends of the film plate 46
8, 48. The membrane plate 46 is configured by attaching an organic flat membrane 54 to both surfaces of a hollow support plate (plastic step) 50 via spacers 52. Binders 56 are attached to the upper and lower ends of each membrane plate 46, thereby reinforcing the ends of the membrane plates 46. Further, the membrane plate 46 is supported by a gap holding member 58 made of urethane rubber so as to have a constant interval, for example, 5 to 10 mm.

On the other hand, the film end fixing member 48 is made of a resin such as PVC, and the plurality of film plates 46 are embedded and fixed in the film end fixing member 48 in a state of being arranged in parallel. Further, a water collecting passage communicating with the inside of the support plate 50 is formed inside the membrane end fixing member 48, and the water collecting passage is connected to the pump 22 of FIG. Thereby, when the pump 22 is driven, each membrane plate 4
The suction force acts on the inside of the membrane 6, and the water to be treated 14 outside each membrane plate 46 is sucked into the membrane plate 46 via the organic flat membrane 54 and is filtered. The size of the membrane module 14 is
For example, width 1116 mm, thickness 124 mm, height 115
2 mm.

As shown in FIG. 5, a dispersion plate 26 formed in a wedge shape is attached to the lower end of the film plate 46 via a binder 56. The dispersion plate 26 has a base end formed to have the same thickness (for example, about 5 to 6 mm) as the binder 56 and a lower end formed to be about 1 to 2 mm. Also,
The longer the length of the dispersion plate 26 is, the more gradual the flow path is reduced. However, considering the installation space and the like, about 30 mm is sufficient. Thereby, even large bubbles of 20 mm or more are dispersed by the dispersion plate 26 and quickly flow between the film plates 46. Although FIG. 5 shows an example in which the dispersion plate 26 is attached to the binder 56 that reinforces the membrane plate 46, the dispersion plate 26 may be attached directly to the membrane plate 46. Further, the binder 56 may be formed in a wedge shape. Further, the shape of the dispersion plate 26 is not limited to a wedge shape, and may be any shape as long as the interval between the dispersion plates 26 gradually decreases from below to above.

As shown in FIGS. 1 to 3, the membrane module 1
Below 6, an air diffuser 24 is provided. Diffuser 2
Numeral 4 has a large number of air diffusion holes (not shown) on the outer peripheral surface and is connected to the blower 20 shown in FIG.
By driving the air bubbles, fine bubbles are diffused into the water to be treated 14 from the air diffusion holes. The diffused air bubbles are guided by the diffusion guide wall 18 and rise inside the diffusion guide wall 18. The to-be-processed water 14 rises inside the diffusion guide wall 18 together with the bubbles, and the raised to-be-processed water 14 turns and descends outside the diffusion guide wall 18. That is, treated water 1
4 forms a circulating flow that circulates inside and outside the diffusion induction wall 18.

Further, as shown in FIG.
It is disposed with a slight gap e from the bottom surface 12A of the flat membrane tank 12. Here, the slight gap e is the minimum size that does not block the flow to the drain port (not shown) when the water to be treated 14 in the flat membrane tank 12 is drained. It is set to 5 to 20 mm. Thereby, generation of a stagnation area below the flat membrane tank 12 can be suppressed as much as possible. Further, since the water 14 is provided with a slight gap, the water to be treated 14 in the water tank can be smoothly discharged at the time of inspection or the like.

The air diffusion guide wall 18 is formed in a box shape opened in the vertical direction, and includes a plurality of membrane modules 16, 16,.
It is arranged so that it surrounds. The upper end of the diffusion guide wall 18
It is folded outward twice and is formed in a substantially U-shape.
Specifically, the upper end of the diffusion guide wall 18 installed vertically is bent outward by 100 to 110 ° at a position higher than the upper end of the membrane module 16 and lower than the liquid level, and further, 9
It is bent by 0 °. As a result, the angle θ1 formed between the upper surface portion 18A of the diffusion guide wall 18 and the horizontal line, and the diffusion guide wall 1
The angle θ2 formed between the side surface portion 18B of FIG.
It is set to 20 °. Therefore, a gap a between the upper surface portion 18A and the liquid surface is gradually increased toward the outside, and a gap between the side surface portion 18B and the wall surface 12B of the flat membrane tank 12 (or between the side surface portion 18B and the partition plate 30). The gap b is gradually increased downward. Thus, the flow of the water to be treated 14 circling from the inside to the outside around the upper end of the air diffusion guide wall 18 is set to gradually increase, and a smooth swirling flow is formed. As shown in FIG. 2, a small opening, for example, φ10
A plurality of holes 32 of about mm are formed. As a result, when bubbles trapped in the descending flow rise,
Only air bubbles can be slowly discharged to the outside. Note that the shape of the air diffusion guide wall 18 is not limited to the above-described embodiment. For example, as shown in FIG. 10A, the air diffusion guide wall 18 may be curved. Also in this case, it is preferable to set the angle θ1 between the upper surface 18A and the horizontal line and the angle θ2 between the side surface 18B and the vertical line to 10 to 20 °. Further, the shape may be as shown in FIG.

As shown in FIG. 7, a distance c between the lower end of the air diffusion guide wall 18 and the air diffusion tube 24 is substantially equal to one half of a distance d between the opposing surfaces of the air diffusion guide wall 18. Is set to Thus, the flow path of the water to be treated 14 entering from the outside to the inside of the diffusion guide wall 18 has a substantially same area as the flow path of the water to be treated 14 flowing inside the diffusion guide wall 18. Therefore, the water to be treated 1 that has fallen outside the diffusion induction wall 18
4 smoothly flows into the inside of the air diffusion guide wall 18 through the space between the lower end of the air diffusion guide wall 18 and the air diffusion tube 24.

FIG. 7 shows that the air diffusion guide wall 18
Although this is an example in which the individual diffuser tubes 24 are provided, the present invention is not limited to this. For example, one diffuser 24 may be provided as shown in FIG. 8, and in this case, the distance c ′ between the lower end of the diffuser guide wall 18 and the diffuser 24 is equal to the distance d of the diffuser guide wall.
´ of ´.

As shown in FIG. 3, a partition plate 30 is provided between adjacent air guide walls 18. The lower end of the partition plate 30 is disposed below the upper end of the membrane module 16, for example, at a position 1000 mm from the liquid level. By providing the partition plate 30 in this manner, the circulating flow circulating inside and outside the diffusion guide wall 28 does not interfere with the circulating flow circulating inside and outside the adjacent diffusion guide wall 28.

Next, the operation of the immersion flat membrane separator 10 configured as described above will be described.

The immersion flat membrane separator 10 is a pump 2 of FIG.
By driving 2, the water to be treated 14 is sucked into the membrane modules 16, 16, and at that time, the water to be treated 14 is filtered. Further, by driving the blower 20, air is diffused from the air diffuser tube 24, oxygen is supplied to the water to be treated 14, and the diffused air bubbles pass between the membrane plates 46 to form a membrane surface. The sludge cake that accumulates on the soil is removed, and the clogging of the membrane is suppressed. Further, the diffused air bubbles rise to the liquid level, and as shown in FIG.
4 rises inside the diffusion guide wall 18 and descends outside the diffusion guide wall 18 to form a circulating flow of the water 14 to be treated.

By the way, several meters diffused from the diffuser 24
The m bubbles reach the lower end of the membrane module 16 by being guided by the air diffusion guide wall 18. At this time, the water to be treated 14
Is a viscous liquid, bubbles are combined with each other, and bubbles are 20m
m or more. However, the membrane plate 46
Since the wedge-shaped dispersion plate 26 is provided at the lower end of the bubble, the bubbles are smoothly dispersed and flow between the membrane plates 46.
Therefore, since no air bubbles accumulate below the membrane module 16, the flow velocity of the upward flow that rises inside the air diffusion guide wall 18 does not decrease, and the membrane surface velocity can be improved. Particularly, in the present embodiment, the lower membrane module 16
Is relatively low (for example, from the floor 12A to the floor 12A).
(At a position of 0 mm), it is possible to prevent the air bubbles from becoming too large, and to prevent the generation of air bubbles.

The to-be-processed water 14 that has risen inside the diffusion guide wall 18 turns outward beyond the upper end of the diffusion guide wall 18,
Form a downward flow. At this time, since the upper end of the diffusion guide wall 18 is turned outward, the upward flow and the downward flow do not interfere with each other, and no vortex is generated. Therefore, the velocity of the descending flow does not decrease due to the resistance of the eddy current. In particular, the immersion flat membrane separation device 10 is formed with the air diffusion guide wall 18 so that the flow path of the swirling flow gradually increases.
Low flow resistance. Furthermore, the adjacent air diffusion guide wall 18,
Since the partition plate 30 is provided between the 18, the flows of the water 14 to be swirled around the upper end of the air diffusion guide wall 18 do not interfere with each other.

The to-be-processed water 14 that has descended outside the diffusion guide wall 18 flows into the inside of the diffusion guide wall 18 from between the lower end of the diffusion guide wall 18 and the diffuser pipe 24, and is discharged from the diffusion guide wall 18. Rise inside again. At this time, since the flow path between the lower end of the diffusion guide wall 18 and the diffusion pipe 24 is secured to be substantially the same size as the internal flow path of the diffusion guide wall 18, the flow path of the water 14 to be treated is Very low resistance. Further, since the diffuser tube 24 is disposed with a slight gap from the flat membrane tank 12, it is possible to prevent the generation of a stagnation area.

As described above, the immersion flat membrane separation device 10 turns over the upper end portion of the diffusion induction wall 18 to prevent the generation of a vortex,
The dispersion plate 26 is attached to the lower end of the membrane plate 46 to prevent the formation of air bubbles, and the partition plate 30 is provided between the adjacent diffusion guide walls 18 to prevent interference between the circulating flows of the water 14 to be treated. Since this is prevented, it is possible to reduce the factor of losing the flow rate of the water to be treated as much as possible. Therefore, the membrane surface flow rate is improved, and the cross flow effect can be improved.

FIG. 9 is an explanatory diagram showing the operation of the present embodiment, and compares the film surface flow rates of the present embodiment and the conventional example. As shown in the figure, the immersion flat membrane separation device 1 of the present embodiment
In the case of 0, the film surface flow velocity is significantly increased as compared with the conventional example.
In the present embodiment, a plurality of improvements such as a change in the shape of the upper end of the diffusion guide wall 18, a change in the arrangement of the diffuser tubes 24, an installation of the dispersion plate 26, and a change in the height of the membrane plate 46 were performed. Was also carried out individually, the effect of increasing the membrane surface flow velocity was obtained. In addition,
The diffuser superficial velocity is the cross-sectional area passing through the diffused air volume (the value obtained by subtracting the projected area of the membrane module from the cross-sectional area surrounded by the guide wall).
Divided by

When the membrane surface flow rate increases in this way, the permeation flux (the amount of filtered water per 1 m ^{2 of} membrane area per day) improves. For example, increasing the membrane surface velocity from 0.1 m / s to 0.2 m / s improves the permeation flux by 15%. When the permeation flux is improved, the number of membrane modules 16 can be reduced with respect to the processing scale, so that initial costs and running costs such as chemical cleaning costs and membrane replacement costs can be reduced.

[0035]

As described above, according to the immersion flat membrane separation apparatus of the present invention, since the resistance of the circulating flow of the water to be treated is reduced, the membrane surface flow rate can be increased without increasing the power. Can be. Therefore, it is possible to provide a submerged flat membrane separation apparatus in which the permeation flux is improved and the initial cost and running cost are low.

[Brief description of the drawings]

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

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

FIG. 3 is a view taken in the direction of arrow 3 in FIG. 2;

FIG. 4 is a perspective view showing the structure of a membrane module.

FIG. 5 is a side view showing a dispersion plate.

FIG. 6 is a side cross-sectional view showing the upper end of the air diffusion guide wall.

FIG. 7 is a side sectional view showing a lower end of the air diffusion guide wall.

FIG. 8 is a side sectional view showing an air diffuser arranged differently from FIG. 7;

FIG. 9 is an explanatory view showing the operation of the immersion flat membrane separation device according to the present embodiment.

FIG. 10 is a side sectional view showing an air diffusion guide wall having a shape different from that of FIG. 6;

FIG. 11 is a side view showing a conventional apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Immersion flat membrane separation apparatus, 12 ... Flat membrane tank, 14 ... Water to be treated, 16 ... Membrane module, 18 ... Aeration guide wall, 26 ... Dispersion plate, 30 ... Partition plate, 46 ... Membrane plate

Continued on the front page F term (reference) 4D006 GA02 HA42 HA93 JA03B JA03Z JA04Z JA10A JA23C JA31A JA52A JA70A KA01 KA13 KA43 KB22 KE05Q MA03 PA01 PB08 PC62 4D028 BC17 BD17

Claims (3)

[Claims] 1. A membrane module having a membrane for filtering water to be treated, vertically immersed in the water to be treated, a diffuser installed below the membrane module to diffuse air, and the membrane A diffuser guide wall provided around a module and guiding bubbles diffused from the diffuser to the membrane module, wherein the upper end of the diffuser guide wall is An immersion flat membrane separator characterized in that it has a shape that is folded outward between the upper end of the membrane module and the liquid surface of the water to be treated. 2. A membrane module having a membrane for filtering water to be treated attached to a support plate, wherein the membrane plate member is vertically immersed in the water to be treated; An immersion flat membrane, comprising: an air diffusion unit that is installed and diffuses air; and an air diffusion guide wall that is provided around the membrane module and guides air bubbles diffused from the air diffusion unit to the membrane module. A immersion flat membrane separator, wherein a lower end of the membrane plate member is formed in a wedge shape. 3. A plurality of membrane modules having a membrane for filtering the water to be treated and vertically immersed in the water to be treated, and an air diffuser installed below the plurality of membrane modules and performing air diffusion. And a plurality of diffusion guide walls provided around the membrane module and for guiding bubbles diffused from the diffusion means to the membrane module, wherein: An immersion flat membrane separation device, wherein a partition plate is provided between walls.