JPH0286893A - Activated sludge treating device - Google Patents

Abstract

PURPOSE:To prevent clogging of filter membranes by providing plural membrane modules to a filter membrane device perpendicularly at specified intervals, coating the surfaces of the membrane supports of the respective membrane modules with the filter membranes to internally form filtration-treated water passages and connecting the flow passages to a filtrationtreated water suction pipe. CONSTITUTION:The filter membrane device 22 is provided with the membrane modules perpendicularly at the specified intervals A and the surfaces of the membrane supports 36 are coated with the filter membranes 37. The filtration-treated water passages 45 are formed therein and are connected to the filtration-treated water suction pipes 44. Raw water 25 fed into an aeration chamber 21 is subjected to a cleaning treatment by a gas 31 for aeration and the cleaned water 28 is sucked into the filtration-treated water flow passages 45 of the membrane modules 30 and is subjected to a solid-liquid sepn. by the filter membranes 37. The treated water 35 formed by the sepn. is sucked from the flow passages 45 into the filtration-treated water suction pipe 44 and is sent to a filtration-treated water tank 34. On the other hand, the sludge sticking to the surfaces of the filter membranes 37 is desorbed from the membrane surfaces by the rising flow of the gas 31 for aeration and is returned into the cleaned water 28 so as to be reused as activated sludge.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an activated sludge treatment apparatus that performs digestion treatment of organic wastewater and solid-liquid separation using a filtration membrane in a single tank.

2. Description of the Related Art In general, in this type of activated sludge treatment equipment, the filter membranes become clogged with sludge during use, and various proposals have been made to prevent this clogging. For example, the apparatus shown in FIG. 1O is one in which a hollow fiber membrane 4 is suspended and immersed in purified water 3 of raw water 2 in an aeration tank 1, and an aeration pipe 5 is placed directly below the hollow fiber membrane 4. It is. Aeration air 6 necessary for purifying raw water 2 is supplied by a blower.
7 and is blown out into the purified water 3 via the aeration pipe 5.

The purified water 3 is separated into solid and liquid by being sucked into the hollow holes of the hollow fibers @4 by the suction pump 8, and the purified water 3 is separated into solid and liquid by the suction pump 8.
The clean filtered water 9 that has passed through is sent to the filtered water tank 10. On the other hand, excess sludge 11 accumulated in the aeration tank 1 is drawn out to the outside at a suitable time. If this hollow fiber membrane 4 is subjected to continuous suction, clogging will cause clogging, which will become unrecoverable in a short period of time, so rapid clogging can be prevented by performing intermittent suction and periodically releasing the pressure. , which enables stable operation over a long period of time. Furthermore, the apparatus disclosed in Japanese Patent Application Laid-Open No. 61-274799 is equipped with a filtration means within the processing tank. This filtration means consists of a plurality of filtration plates each having a hole in the center, which are arranged in parallel at regular intervals through a hollow rotating shaft with a pre-pierced hole, and are rotated together by the drive mechanism of the hollow rotating shaft. Aeration means for discharging gas is provided between the plates, and the filter plate is a membrane support having filtered water passages, with semipermeable membranes covering both sides. The raw water sent into the treatment tank is aerated and digested with gas from the aeration means. The digested water is filtered by the semipermeable membrane of the rotating filter plate, and the clean filtered water is taken out to the outside through the filtered water passage of the membrane support and the hollow part of the hollow rotating shaft. On the other hand, the sludge that has adhered to the membrane surface due to filtration is removed from the membrane surface by the agitation action of the aeration gas itself and the purified water of the gas. The membrane surface passes through the gas discharge pipe of the aeration means every time the filtration means rotates once, so
Since it is cleaned in extremely short cycles, it is always kept clean and can be used stably for a long period of time.

Excess sludge accumulated in the treatment tank is discharged outside in a timely manner.

Problem to be Solved by the Invention However, when raw water contains a large amount of fibrous impurities, in the former conventional device, the fibrous impurities are transferred to the hollow fiber membrane. There was a problem in that the hollow fiber membranes 4 became entangled with each other and eventually became like a stick of sludge, completely clogging the hollow fiber membranes 4. In addition, in the latter device, there was a problem in that fibrous impurities wrapped around the hollow rotating shaft and eventually blocked the space between the filter plates. Furthermore, in the latter device, since the gas-liquid multiphase flow is structured to cause uneven flow between the filter plates, the flow velocity on the membrane surface becomes non-uniform, and there is a possibility that a portion with low membrane permeation performance may occur. Therefore, in order to prevent this, the filtration means is rotated. Therefore.

There was a problem that the structure was not only complicated but also expensive.

The present invention aims to solve these problems by improving the conventional device.

Means for Solving the Problems In order to achieve the above object, the activated sludge treatment apparatus of the present invention has a filtration membrane device for solid-liquid separation of the purified water in the purified raw water in the aeration tank. The membrane is submerged in water, and an aeration pipe is placed directly below the filtration membrane device to supply aeration gas. Each membrane module has a membrane support whose surface is covered with a filtration membrane, and a filtration water flow path formed inside the membrane module. The outlet side of the channel is connected to the filtered water suction pipe.

Effect: In the configuration of the present invention described above, the raw water sent into the aeration tank is aerated and purified by the aeration gas blown out between the membrane modules from the aeration tube. Purified water is
The inside of the filtered water flow path of the membrane support of the membrane module is sucked toward the filtered water suction pipe, where it is separated into solid and liquid by the filtration membrane, and the clean filtered water that has passed through the filtration membrane is transferred to the filtered water flow path. The filtered water is taken out to the outside through a suction pipe.

On the other hand, the sludge adhering to the membrane surface due to filtration is removed from the membrane surface and rises due to the upward flow generated by the air lift action of the aeration gas bubbles rising between the membrane modules.
It exits from the top of the filtration membrane device and returns to the purified water, where it is recycled and used as activated sludge. In addition, if the membrane module is installed so as to be inclined with respect to the vertical line, air bubbles collide with the downward facing membrane surface and disturb the membrane surface, making it easier for sludge to separate from the membrane surface. , the permeation resistance of the filtration membrane decreases.

The effect of the present invention is as described above, but if the spacing between the membrane modules is set appropriately, even if a large amount of fibrous foreign matter is contained in the raw water, the foreign matter will be removed from the membrane. There is no risk of it getting tangled with the module.

It is possible to prevent clogging of the filtration membrane due to adhesion of sludge. Furthermore, the air bubbles blown out from the diffuser tube rise between the membrane modules at a uniform density due to the rectification effect of the membrane modules, so there is no unbalanced flow in the liquid flow on the membrane surface. In other words, the entire membrane surface is uniformly disturbed by the bubble multiphase flow that rises at a uniform flow rate.6 Therefore, there is no need to rotate the membrane module as in conventional devices, which simplifies the structure and makes the device inexpensive. become.

Embodiments Hereinafter, embodiments of the present invention will be explained based on FIGS. 1 to 6.

First Embodiment In this embodiment, as shown in FIG. 1, a filtration membrane device 22 and an aeration pipe 23 are provided in an aeration tank 21. The aeration tank 21 is supplied with raw water 2 from a raw water supply pipe 24.
A sludge drawing pump 26 is connected to the bottom of the tank 5 through a sludge drawing pipe 27. The filtration membrane device 22 is a device that performs solid-liquid separation of digested water 28 produced by digesting raw water 25. A plurality of membrane modules 30 are arranged vertically in a rectangular box frame 29 that is open on both upper and lower sides. are arranged in parallel at a constant interval A, and are immersed with their tops submerged in the digested water 28. The aeration pipe 23 is a pipe that blows an aeration gas 31 containing oxygen such as air between the membrane modules 30,
It is arranged directly below the filtration membrane device 22 and connected to a blower 33 via an air supply pipe 32. 34 is the filtration membrane device 2
This is a filtered water tank that stores filtered water 35 from No. 2.

The membrane joule 30, as shown in FIGS. 2 to 4,
A filtration membrane 37 is attached to both surfaces of a membrane support 36 with an adhesive. The membrane support 36 is made of metal (for example, stainless steel, etc.), plastic, etc., and has a tubular member 4 attached to the upper edge of a rectangular support plate 39 having uneven parts 38 on both side edges.
0 and a reinforcing member 41 is fixed to the lower edge. The tubular member 40 is provided with a communication hole 42 at the position of the uneven portion 38, and is connected to a filtered water suction pipe 44 via a branch pipe 43 (see FIG. 1). The filtration membrane 37 is a macroporous flat membrane such as a precision filtration membrane or an ultrafiltration membrane. A filtered water flow path 45 (indicated by arrows in FIGS. 2 and 3) is formed between the filtration membrane 37 and the membrane support 36, and communicates with the communication hole 42, the inside of the tubular member 40, and the branch pipe 43. It communicates with the filtered water suction pipe 44 through the filter. The filtered water suction pipe 44 has a suction pump 46 connected therebetween and reaches the filtered water tank 34 .

Next, the operation of this embodiment will be explained.

The raw water 25 sent from the raw water supply pipe 24 into the aeration tank 21 is aerated and purified by the aeration gas 31 blown out between the membrane modules 30 from the blower 33 via the air supply pipe 32 and the aeration pipe 23. Ru. The purified water 28 is supplied to the filtered water flow path 45 of the membrane module 30 by the suction pump 4.
The clean filtered water 35 that has passed through the filter membrane 37 is filtered through the filter membrane 37 through the communication hole 42, the inside of the tubular member 40, and the branch pipe 43. The filtered water is then sucked into the filtered water suction pipe 44 and sent into the filtered water tank 34. On the other hand, the sludge that has adhered to the membrane surface of the filtration membrane 37 due to filtration is removed from the membrane module 3.
Due to the upward flow generated by the air lift action of the bubbles of the aeration gas 31 rising between
Returning inside, the purified water 28 generated in the aeration tank 21
It reaches below the filtration membrane device 22 along the circulation flow B (see Fig. 1), and is recycled and used again as activated sludge. In addition,
Excess sludge in the aeration tank 21 is extracted to the outside via a sludge extraction pipe 27 by a sludge extraction pump 26.

This embodiment works as described above, except that the membrane module 30
If the interval A is set appropriately, even if the raw water 25 contains a large amount of fibrous impurities.

There is no risk that the foreign matter will become entangled with the membrane module 30, and the filtration membrane 37 will not be clogged due to adhesion of sludge. Furthermore, the air bubbles blown out from the air diffuser 23 rise between the membrane modules 30 at a uniform density due to the rectification effect of the membrane modules 30, so that there is no unbalanced flow in the liquid flow on the membrane surface. That is, the entire membrane surface is uniformly disturbed by the bubble mixing flow that rises at a uniform flow rate.

Therefore, unlike conventional devices, there is no need to rotate the membrane module 30, so the structure is simple and the device is inexpensive.

Second Embodiment This embodiment has exactly the same structure as the first embodiment, except that the membrane module 30 is provided so as to be inclined with respect to the vertical line, as shown in FIG. be. Therefore, the operation and effect are almost the same as in the first embodiment, but the air bubbles collide with the downward facing membrane surface of the membrane module 30 and disturb the membrane surface, making it easier for sludge to separate from the membrane surface and filtration. The advantage is that the permeation resistance of membrane 37 is reduced.

Other Examples (1) The membrane support 36 may be a metal or plastic net-like material, a porous plate-like material, etc.
The uneven portion 38 may be formed by stacking two uneven plates in opposite directions, as shown in FIG.

(2) In the case of the second embodiment, the filtration membrane 37 may be attached only to one side of the membrane support 36. Further, as shown in FIG. 7, the filtration membrane 37 is formed into a bag shape and the membrane support 36 is
and the opening 47 is secured with a stopper band 48 to secure the tubular member 4.
It may be fixed at 0, making it easier to replace the filtration membrane 37.

Further, as shown in FIGS. 8 and 9, the membrane support 36 may be formed of a solid body.

(3) A plurality of filtered water suction pipes 44 may be connected not only to the upper edge of the membrane module 3° but also to both side edges and the lower edge.

As described in detail, according to the present invention, the spacing between membrane modules can be set appropriately.

Even if the raw water contains a large amount of fibrous impurities, there is no risk of the impurities getting entangled with the membrane module.
Therefore, clogging of the filtration membrane due to adhesion of sludge can be prevented. In addition, the air bubbles blown out from the air diffuser placed directly below the filtration membrane device rise between the membrane modules at a uniform density due to the rectification effect of the membrane modules.
There is no deviation in the membrane surface liquid flow, that is, the bubble mixing flow rises at a uniform flow rate, and the entire membrane surface is uniformly disturbed.

Therefore, unlike conventional devices, there is no need to rotate the membrane module, which simplifies the structure and reduces the cost of the device.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of the first embodiment of the present invention, FIG. 2 is a cross-sectional view of the membrane module of the present invention, FIG. 3 is a cross-sectional view taken along the line xx in FIG. 2, and FIG. Perspective view of the membrane module in Figure 5.
The figure is a circuit diagram of the second embodiment of the present invention, FIG. 6 is a partial sectional view of another embodiment of the membrane support of the present invention, and FIG. 7 is an explanatory diagram of another embodiment of the filtration membrane of the present invention. , FIG. 8 is a partial sectional view of another embodiment of the membrane support of the present invention, FIG. 9 is a sectional view taken along the Y-Y arrow in FIG. 8, and FIG. 10 is a circuit diagram showing an example of a conventional device. It is. 21... Aeration tank, 22... Filtration membrane device, 23...
Diffusion pipe, 25... Raw water, 28... Purified water, 30
...Membrane module, 31...Aeration gas, 36...
- Membrane support, 37...filtration membrane, 44...filtered water suction pipe, 45...filtered water channel, A...-regular interval. Agent Yoshi Morimoto Private 1 2/ -, 4'L-tank 22- Utsu repeating image ↑ 23, -, Touma Minami 25 - - Raw water 2i - Shishihi treatment Eiji 8θ 16. Yujin, Shinir 31...-III Qi Suikihon 41. -U@M Eiyobetsu Responsibility - 11 Sounbu Figure 2 Figure 30 - 11 Pus Moshi Ale 3A0 April East Support 4 Left Urinary Pus Filtration Processing Female Channel- Figure S Figure 1 ρ Figure 4 Figure/Goni: 7 Figure 7 Figure 1

Claims (1)

[Claims] 1. A filtration membrane device for solid-liquid separation of purified water is immersed in the purified water in the aeration tank with its top submerged, and aeration gas is placed directly below the filtration membrane device. A filtration membrane device has a plurality of membrane modules arranged vertically in parallel at regular intervals, and each membrane module has a membrane support whose surface is It is covered with a filtration membrane, and a filtered water flow path is formed inside.
An activated sludge treatment device characterized in that the outlet side of each filtered water flow path is connected to a filtered water suction pipe. 2. The activated sludge treatment apparatus according to claim 1, wherein the membrane module is provided so as to be inclined with respect to a vertical line.