JPS62114609A - Hollow yarn membrane filter - Google Patents

Abstract

PURPOSE:To effectively perform air scrubbing with a small quantity of air, by stretching a network which allows liquid to pass through it but does not allow bubbles of air to pass through, over a distributing plate excepting such part thereof located just and nearly under a hollow yarn membrane module, causing air bubbles of air scrubbing to be passed intensively only from just and nearly under said module. CONSTITUTION:A network such as a wire gauze 10, etc., having such meshes that allow liquid to pass through them but do not allow bubbles of air to pass through because of the action of surface tension is stretched over the upper surface of a distributing plate 6 located under hollow yarn membrane modules 5 disposed in a filter chamber 3. In this case, a part of the wire gauze 10 just and nearly under each module 5 is cut off so that bubbles of air are allowed to pass only through the cut off part. After continuous filtration of liquid to be treated fed through a feed pipe 7 for a predetermined period of time, back washing is carried out. Air scrubbing is conducted by blowing off air bubbles into water from an air blow-off pipe 9. The air bubbles pass only through the cut off part of the wire gauze, causing the hollow yarn membranes to vibrate, so that attached matters on the surfaces of the membranes are effectively separated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a hollow fiber membrane module consisting of a hollow fiber membrane that passes liquid from the outside to the inside for filtration. The present invention relates to a hollow fiber membrane filtration device for filtering substances.

[Conventional technology]

A hollow fiber membrane module consisting of a hollow fiber membrane that passes liquid from the outside to the inside for filtration is installed in the tank, a rectifying plate is provided at the bottom of the hollow fiber membrane module, and the material to be filtered is placed under the rectifying plate. In a hollow fiber membrane filtration device that introduces the treated liquid and air for air scrubbing during backwashing, the liquid to be treated is forced into the lower part of the tank at the appropriate time, and is rectified by the rectifying plate at the top of the tank. The liquid reaches the fiber membrane module, passes from the outside to the inside of each hollow fiber membrane, and is filtered.The filtrate flows out from the inside of the hollow fiber membrane, is collected, and taken out of the tank.

As this type of filtration continues, suspended substances in the liquid to be treated are captured on the surface of each hollow fiber membrane, gradually increasing resistance to liquid passage, so filtration is stopped after a predetermined period of time and backwashing is performed. In backwashing, pressurized water for backwashing is passed in the opposite direction from the inside to the outside of each hollow fiber membrane, contrary to the timely filtration, to make it easier to remove the deposits on the surface. Air scrubbing is performed by blowing air into the lower part of the tank and causing the rising bubbles to vibrate the hollow fiber membrane to remove deposits from the surface. Therefore, in order to enhance the air scrubbing effect, it is necessary to bring the hollow fiber membrane into contact with the bubbles sufficiently effectively.

[Problem that the invention seeks to solve]

However, in conventional air scrubbing, because the air bubbles pass from the bottom over almost the front surface of the current plate, many air bubbles do not come into contact with the hollow fiber membrane, and a large amount of air must be blown in order to make effective contact. There was a drawback that. In addition, in order to increase the effect of contact with air bubbles, there is a method of installing an air blow-off pipe with an air blow-off port directly below each hollow fiber membrane module, but this method has the disadvantage of complicating the structure and installation. .

It is an object of the present invention to provide a hollow fiber membrane filtration device that eliminates such conventional drawbacks, performs sufficient air scrubbing with an extremely simple structure, and can enhance the backwashing effect. .

[Means and effects for solving the problems] The present invention provides a hollow fiber membrane module consisting of a hollow fiber membrane that passes liquid from the outside to the inside for filtration in a tank. A hollow fiber membrane filtration device in which a rectifying plate is provided at the bottom, and the liquid to be treated and air are introduced into the lower part of the rectifying plate,
The baffle plate is characterized by being provided with a mesh that allows liquid to pass through but does not allow air bubbles to pass through the area other than the area directly below the hollow fiber membrane module; A solids outflow pipe is provided on the upper surface of the mesh body, the upper end of which is open, and the lower end of which extends below the air layer formed at the bottom of the mesh structure when air is introduced, or below the air blowing part in the tank. The present invention provides a hollow fiber membrane filtration device having the following characteristics.

Therefore, the air scrubbing air bubbles are concentrated only from directly below the hollow membrane module to perform effective air scrubbing, and the air bubbles do not pass from other areas, so the amount of air used is small. Furthermore, if there are any large solid impurities that remain on the network body peeled off from the surface of the hollow fiber membrane, they can be washed to the bottom of the tank through the solids outflow pipe and discharged out of the tank.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.
The figure is a schematic diagram of the whole, and the inside of the tank 1 is divided into a filtration chamber 3 and a filtrate chamber 4 by a partition plate 2, and inside the filtration chamber 3 there is a hollow fiber that passes liquid from the outside to the inside for filtration. A hollow fiber membrane module 5 consisting of a plurality of membranes is disposed and supported, and the end of each hollow membrane is opened into the filtrate chamber 4 . At the bottom of the hollow fiber membrane module 5 in the filtration chamber 3, a rectifying plate 6 through which the liquid and air bubbles pass is provided.
The air introduction pipe 8 is opened, and the air introduction pipe 8 is a single pipe or an air discharge pipe 9 provided with an air outlet, which is a single pipe or several branch pipes connected to the pipe provided at the lower part of the rectifying plate 6. It is connected to

Furthermore, the upper surface (or lower surface) of the rectifying plate 6 is made of gold with openings that allow liquid to pass through without any problem, but air bubbles cannot pass through due to surface tension. 410
, other net-like bodies (including perforated plates) are stretched, and as shown in FIG. is so that air bubbles cannot pass through. The mesh of the wire mesh 10 that prevents air bubbles from passing through is preferably 20 meshes or more, and the air pressure (
1 to 2 kg f/-), 25 to 40 mesh is optimal.

In FIG. 1, 11 is a filtrate outflow pipe, 12 is a pressurized air introduction pipe for backwashing, 13 is an air scrubbing air discharge pipe, 14 is a vent, and 15 is a drain.

Therefore, the liquid to be filtered is transferred from the introduction pipe 7 to the filtration chamber 3.
The current plate 6 and the wire mesh 10 are press-fitted into the lower part of the current plate 6 inside.
and is rectified to reach each hollow fiber membrane module 5,
The liquid is passed from the outside to the inside of each hollow fiber membrane and filtered. The filtrate that has entered the inside of the hollow fiber membrane is collected in the filtrate chamber 4 and taken out from the filtrate outflow pipe 11.

As this type of filtration continues, suspended substances in the liquid to be treated are captured on the surface of the hollow fiber membrane, and the resistance to liquid passage gradually increases.After a predetermined period of time, the filtration is stopped and reversed. When performing washing, that is, introducing backwash water into the filtrate chamber 4 from the filtrate outflow pipe 11 and applying pressure by introducing pressurized air from the pressurized air introduction pipe 12, the backwash water flows into each hollow space. After flowing into the inside of the fiber membrane, it flows out to the outside, making it easier to remove deposits on the surface of the hollow fiber membrane, and then performing air scrubbing with air.

Air scrubbing is performed using air pressure 1 to 2 from the air introduction pipe 8.
When air of about kg r/- is introduced and blown into the water from the air blowing pipe 9, the air bubbles rise, but the surface tension prevents the air bubbles from passing through the wire mesh IO, and the air flows under the gold mlO. A layer is formed, and air bubbles pass through only from the cutout portion of the wire mesh 10, that is, directly below each hollow fiber membrane module 5, and effectively contact the hollow fiber membrane, vibrating the hollow fiber membrane and removing deposits on the surface. Peel off. At this time, the bubbles rise only from the vicinity directly below the hollow fiber membrane module 5,
Since it is blocked from other parts, the air layer used is at least effectively air scrubbed and then discharged through the air scrubbing air discharge pipe 13.

After the backwashing operation including air scrubbing is completed, the water in the filtration chamber 3 is drained from the drain 15, and the detached deposits flow out together with the water from the cutout of the wire mesh 10.

Next, another aspect of the present invention will be explained in detail.

The main part is the same as the examples shown in FIGS. 1 and 2 described above, but large solid impurities in the deposits peeled off from the hollow fiber membrane during backwashing (including air scrubbing) are gold kI? In order to discharge this, the upper end is opened on the upper surface of the wire mesh 10 and the lower end is scrubbed at an appropriate location other than the vicinity directly below the hollow fiber membrane module 5, as shown in FIG. A solid matter outflow pipe 16 is provided which extends below the air layer where air flows to the lower surface of the wire mesh 10 or below the air outlet of the air blowout pipe 9.

Therefore, small solid impurities peeled off from the surface of the hollow fiber membrane will also pass through the wire mesh IO and be washed away when draining the water in the filtration chamber 3, but if the solid impurities are relatively large, they will remain on the wire mesh 10. do.

However, the solid impurities remaining on the wire mesh 10 are washed away to the bottom of the tank 1 through the solid matter outflow pipe 16 during draining.
It will be discharged outside the tank.

Since the lower end of this solid matter outflow pipe 16 is located below the air outlet, air bubbles will not flow into this solid matter outflow pipe 16 during air scrubbing.

In any of the embodiments described above, if there is a gap between the wall of the tank 1 and the rectifying plate 6, air bubbles will flow out from this gap and rise as it is, reducing the air scrubbing effect. In order to prevent this, as shown in FIG.
A skirt 17 for preventing air bubbles from flowing out is installed on the lower surface of the current plate 6 between the outer periphery of the membrane module 5' and the hollow fiber membrane module 5' near the tank wall.
It is preferable that the air scrubber be installed vertically to prevent air bubbles from flowing out, thereby preventing deterioration of the air scrubbing effect.

〔Effect of the invention〕

As explained above, according to the present invention, by using an extremely simple structure in which a part of the net-like body that does not allow air bubbles to pass through is cut out and stretched over the rectifying plate, the air bubbles can be removed directly below the hollow fiber membrane module during air scrubbing. Since the air bubbles are concentrated and guided only in the air, effective air scrubbing can be performed with a small amount of air, and the structure of the air blowing part is simplified, making installation easier. If a solid matter outflow pipe is further provided as in the second invention, in addition to the above effects, solid impurities that are peeled off and remain on the way can be smoothly discharged.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic diagram of the whole, FIG. 2 is a cross-sectional explanatory diagram showing a part of the inside of the tank, and FIG. 3 shows another example of a part of the inside of the tank. FIG. 4 is a cross-sectional explanatory view of a part of the inside of the tank showing one embodiment of the present invention. 1...tank, 2...partition plate, 3...filtration chamber, 4...
・Filtrate chamber, 5.5'...Hollow fiber membrane module, 6...
・Brightening plate, 7...Introduction pipe, 8...Air introduction pipe, 9.
... Air blow-off pipe, lO ... Wire mesh, 11 ... Filtrate outflow pipe, 12 ... Pressurized air introduction pipe, 13 ... Air scrubbing air discharge pipe, 14 ... Vent, 15 ...・Drain, 16...Solid matter outflow pipe, 17...Skirt.

Claims (1)

[Claims] 1. A hollow fiber membrane module consisting of a hollow fiber membrane that passes liquid from outside to inside for filtration is disposed in a tank, a rectifying plate is provided at the bottom of the hollow fiber membrane module, and a rectifying plate is provided at the bottom of the hollow fiber membrane module. In a hollow fiber membrane filtration device in which a liquid to be treated and air are introduced into a lower part of a rectifying plate, a net-like body that allows liquid to pass through but does not allow air bubbles to pass through a portion of the current plate other than a portion directly below the hollow fiber membrane module. A hollow fiber membrane filtration device characterized by being stretched with. 2. The hollow fiber membrane filtration device according to claim 1, wherein the mesh size of the net-like body is 20 mesh or more, preferably 25 to 40 mesh. 3. Claim 1 or 2, wherein the current plate has a skirt for preventing air bubbles flowing out between the outer periphery of the current plate and the hollow fiber membrane module near the tank wall. The hollow fiber membrane filtration device described. 4. A hollow fiber membrane module consisting of a hollow fiber membrane that passes liquid from the outside to the inside for filtration is disposed in the tank, a rectifying plate is provided at the bottom of the hollow fiber membrane module, and a rectifying plate is provided at the bottom of the rectifying plate. In a hollow fiber membrane filtration device configured to introduce a treatment liquid and air, a net-like body that allows liquid to pass through but does not allow air bubbles to pass through is provided in a portion of the current plate other than the area directly below the hollow fiber membrane module, and The upper end opens on the upper surface of the net at a location other than directly above the air outlet in the tank, and the lower end extends below the air layer formed at the bottom of the net when air is introduced, or below the air outlet in the tank. A hollow fiber membrane filtration device characterized by being equipped with a tube. 5. The hollow fiber membrane filtration device according to claim 4, wherein the mesh size of the net-like body is 20 mesh or more, preferably 25 to 40 mesh. 6. Claim 4 or 5, wherein the current plate has a skirt for preventing air bubbles flowing out between the outer periphery of the current plate and the hollow fiber membrane module near the tank wall. The hollow fiber membrane filtration device described.