JP3290577B2 - Immersion type membrane separation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submerged membrane separation apparatus installed inside a processing tank.

[0002]

2. Description of the Related Art For example, in a water treatment facility for treating organic wastewater such as night soil, as shown in FIGS. 2 and 3, an immersion type for separating water to be treated 2 into a membrane in a treatment tank 1 is shown. A membrane separation device 3 is provided.

[0003] The membrane separation device 3 is configured such that flat membrane cartridges 5 arranged vertically in a box-shaped membrane case 4 having an open top and bottom are arranged in parallel at regular intervals, and a box-like membrane having an open top and bottom. A diffuser 8 communicating with an air supply source such as a blower 7 outside the tank is disposed inside the diffuser case 6, and the membrane case 4 and the diffuser case 6 are arranged above and below each other. . The size and the like of the membrane case 4, the membrane cartridge 5, and the air diffuser case 6 are determined in consideration of the properties and the inflow amount of the water to be treated and the installation space. The height of the case 6 is 1.5 m, and the distance between the membrane cartridges 5 is 5 to 10 mm.

[0004] In the membrane cartridge 5, an organic filtration membrane 10 is arranged on both surfaces of a filter plate 9, and a permeated water channel (not shown) communicating between the filter plate 9 and the filtration membrane 10 is formed in the filter plate 9. The suction tube 11 and the water collection tube 12 communicating with the permeated water flow path are provided. Then, suction means such as a permeated water pipe 13 and a suction pump 14 are provided so as to communicate with the water collection pipe 12.

In such a configuration, when the water to be treated 2 is subjected to membrane separation by the membrane separation device 3, the suction pump 14 passes through the permeated water pipe 13, the water collection pipe 12, and the suction tube 11 to the permeated water flow path of the membrane cartridge 5. By applying suction pressure or by setting the head of the water 2 to be treated above the membrane cartridge 5 to a filtration drive pressure, suspended substances such as activated sludge contained in the water to be treated 2 can be removed from the filtration membrane 10.
The permeated water permeated through the filtration membrane 10 and flowed into the permeated water flow path through the filtration membrane 10 is sucked by the suction tube 11, the water collection tube 12,
3 to the outside of the processing tank 1.

At this time, the air supplied from the blower 7 is diffused through the air diffusing holes 8a of the diffusing device 8, and the air bubbles of the diffused air and the rising water flow generated thereby are introduced into the gap between the membrane cartridges 5, 5. By inflowing, the entire membrane surface of the membrane cartridge 5 is uniformly washed by the bubbles and the rising water flow, and the rising water flow reduces the concentration polarization on the membrane surface to reduce the filtration resistance and stirs in the tank. To create a flow.

[0007]

When the cleaning of the membrane surface of the membrane cartridge 5 is performed by using air bubbles and a rising water flow as described above, it is necessary to increase the amount of diffused air in order to enhance the cleaning effect. It is conceivable that if the amount of bubbles flowing into the gap between the membrane cartridges 5 and 5 is too large, on the contrary, the flow rate of the liquid to be treated into this gap decreases, and the processing amount decreases.

Therefore, it is conceivable to increase the flow velocity of the rising water flow. However, in the above-described conventional apparatus, the rising water flow is generated only by air bubbles diffused in the diffusion case. The ascending flow velocity cannot be increased.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an immersion type membrane separation apparatus which can increase the flow velocity of the rising water flow even with a small amount of air and can efficiently clean the membrane surface. Things.

[0010]

Means for Solving the Problems To solve the above problems, the immersion type membrane separation apparatus of the present invention is provided with a box-shaped case which is immersed in water to be treated in a treatment tank and has an open top and bottom. In the upper part of the inside, membrane cartridges arranged vertically are provided in parallel at a fixed interval, and an air diffuser is provided below the membrane cartridge in the case, air bubbles diffused from the air diffuser and its air lift action In the immersion type membrane separation device configured to wash the membrane surface of the membrane cartridge with the rising water flow generated by the above, a box frame-shaped rectifier that guides upwardly the bubbles and the rising water flow that have escaped from the case to the upper part of the case. The case is provided separately from the inner wall of the processing tank .

Further, in the immersion type membrane separation device of the present invention, the rectifying case is provided such that the upper end thereof is located about 30 cm below the water surface. Further, in the immersion type membrane separation device of the present invention, at least one side surface of the rectifying case is detachably formed.

[0012] According to the above-described structure, an ascending water flow is generated in the lower portion of the case by the air-lifting action of the air bubbles diffused by the air diffuser, and the ascending water flow and the air bubbles are generated in the gap between the membrane cartridges. After passing through the case and exiting the case, it flows into the rectifying case and is guided upward without diffusing in the left-right direction. Then, also inside the rectifying case, a rising water flow is generated by the air lift action of the bubbles, and the flow velocity of the rising water flow flowing into the rectifying case is increased. In this way, as a result of the flow velocity of the rising water flowing out of the case being further increased in the rectifying case, the flow velocity of the rising water flowing in the case is also increased, and the membrane surface cleaning effect is increased.

The longer the flow straightening case is in the vertical direction, the greater the effect of increasing the flow velocity by the air lift action. However, if the flow straightening case is provided near the water surface, the water flow rising inside rises above the water surface, and a smooth swirling flow in the tank is generated. It becomes difficult.
However, according to the above-described configuration in which the upper end of the rectifying case is located at about 30 cm below the water surface, the rising water flow that has reached the upper end of the rectifying case quickly turns into a flow parallel to the water surface. A smooth swirling flow is formed.

According to the structure in which at least one side surface of the air lift case is detachably formed, the work can be easily performed by removing the detachable side surface when an inter-membrane blockage occurs.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, an immersion type membrane separation device 3 provided by being immersed in water to be treated 2 in a treatment tank 1 is configured substantially in the same manner as the conventional one described with reference to FIGS. A box-shaped membrane case 4 and an air diffuser case 6 each having an opening are arranged vertically above and below, and membrane cartridges 5 arranged vertically in the membrane case 4 are provided in parallel at appropriate intervals. An air diffuser 8 is provided inside.

Here, the immersion type membrane separation device 3 is different from the conventional one in that a box frame-shaped rectifying case 15 for guiding bubbles and rising water flowing out of the membrane case 4 to the upper portion of the membrane case 4 is provided. This is the point provided.

The rectifying case 15 has an upper end 15a formed at a height of about 30 cm below the water surface, and has adjoining side surfaces 15b and 15c detachably formed.
Hereinafter, the operation of the above configuration will be described.

By driving the suction pump 14, the membrane separation device 3
The water to be treated 2 is subjected to membrane separation by the membrane cartridge 5, and suspended substances such as activated sludge remain in the treatment tank 1, and the permeated water is passed through the suction tube 11, the water collecting pipe 12 and the permeated water pipe 13 to the outside of the treatment tank 1. To take out.

At the same time, air is supplied by the blower 7 and diffused through the diffuser 8, and the air bubbles of the diffused air and the rising water flow generated thereby are caused to flow into the gap between the membrane cartridges 5, 5. As a result, the membrane surface of the membrane cartridge 5 is washed with the bubbles and the rising water flow, and the concentration polarization on the membrane surface is reduced by the rising water flow to reduce the filtration resistance.

At this time, the rising water flow and the bubbles that have passed through the gap between the membrane cartridges 5 and 5 flow out of the membrane case 4 and flow into the rectification case 15.
The rising water flow is guided upward without being diffused by 5, and the rising water flow is subjected to the airlift effect of the bubbles, which expand and increase in speed as rising, inside the rectifying case 15, and the flow velocity increases. As a result, the flow rate of the rising water flow increases above the membrane case 4, so that the flow rate of the rising water flow inside the membrane case 4 also increases, and the membrane surface cleaning effect of the membrane cartridge 5 increases. This increases the amount of processing and
The frequency of back washing and chemical washing of the membrane cartridge 5 can be reduced.

The rising water flow that has reached the upper end of the rectifying case 15 is such that the upper end 15a of the rectifying case 15 is about 30 cm below the water surface.
, The flow quickly changes to a flow parallel to the water surface, and then changes to a downward flow along the outer peripheral surface of the rectifying case 15 toward the lower part of the air diffuser case 6. Therefore,
The agitated flow that smoothly swirls the entire inside of the tank is formed without generating the resistance that occurs when the rising water flow rises above the water surface.

When the gap between the membrane cartridges 5 and 5 is closed, the work is performed by removing the detachable side surfaces 15b and 15c.

[0023]

As described above, according to the present invention, a box frame-shaped rectifying case is provided above a case in which a plurality of membrane cartridges and an air diffuser are housed one above the other, and air bubbles that escape from the case are provided. In addition, since the rising water flow is guided upward without being diffused, the flow rate of the rising water flowing between the membrane cartridges can be increased with the same amount of air as in the related art. As a result, the contamination of the membrane surface of the membrane cartridge can be reduced, so that the operation cycle of the membrane cartridge can be lengthened, the processing amount can be increased, and the frequency of cleaning such as back washing and chemical washing can be reduced, so that maintenance is easy. become. Also, the flow rate of the rising water flow in the case can be made equal to or greater than that of the conventional case even with a smaller amount of air than in the conventional case, so that energy can be saved.

Further, the upper end of the rectifying case is set at about 30
cm, the rising water flow that has reached the upper end of the rectifying case can be quickly turned into a flow parallel to the water surface, and the inside of the tank smoothly swirls from near the water surface to the bottom. A flow can be formed.
Therefore, even in the case of water to be treated containing activated sludge, accumulation and decay of sludge or the like at a local portion in the tank can be prevented.

Further, since at least one side surface of the air lift case is formed so as to be detachable, maintenance can be easily performed in the case where an inter-membrane blockage occurs.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a processing tank provided with a submerged membrane separation device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an overall configuration of a processing tank provided with a conventional immersion type membrane separation device.

FIG. 3 is an explanatory diagram showing a configuration of the immersion type membrane separation device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Treatment tank 2 Treated water 3 Immersion type membrane separation device 4 Membrane case 5 Membrane cartridge 6 Air diffuser case 8 Air diffuser 15 Rectifier case 15a Upper end of rectifier case 15b, 15c Side of rectifier case

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-75938 (JP, A) JP-A-8-299979 (JP, A) JP-A-8-299984 (JP, A) JP-A-8-99984 332358 (JP, A) JP-A-7-39873 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 63/08 B01D 65/02 520 C02F 1/44 ZAB

Claims (3)

(57) [Claims] 1. A box-shaped case which is immersed in water to be treated in a treatment tank and has an open top and bottom is provided, and upper and lower membrane cartridges arranged in a vertical direction are provided in parallel at a predetermined interval.
A diffuser is provided below the membrane cartridge in the case ,
In the immersion type membrane separation device configured to wash the membrane surface of the membrane cartridge by air bubbles diffused by the air diffuser and the rising water flow generated by the air lift action, a case is provided above the case. A box-shaped rectifying case that guides the escaped air bubbles and rising water flow upwards inside the treatment tank
An immersion-type membrane separation device provided apart from a wall . 2. A rectifying case, the upper end of which is about 3 inches below the surface of the water.
2. The immersion type membrane separation device according to claim 1, wherein the immersion type membrane separation device is provided so as to be located at 0 cm. 3. The immersion type membrane separation device according to claim 1, wherein at least one side surface of the rectification case is detachably formed.