JPH08131783A - Membrane separation device - Google Patents

Abstract

PURPOSE: To provide a membrane separation device which can efficiently clean a membrane using an air scrapping method, regardless of the type of the device consisting of bag-like membrane members installed side by side. CONSTITUTION: This membrane separation device is composed of a bag-like membrane member 1 with an inner side acting as a filtrate side, and a flexible cleaning member 2 which is longer than the member 1 and is vertically arranged, alternating with the member 1, with the lower end part of the flexible cleaning member 2 being protruded downward past the lower end of the bag-like membrane member 1. In addition, both bag-like membrane member 1 and flexible cleaning member 2 are installed side by side in a tank 31 for a liquid to be treated across an untreated liquid flow path between the members. Further, the upper end parts of the bag-like membrane member and the flexible cleaning member are supported on the top of these parallel-installed members. On the lower end sides, only the lower end part of the flexible cleaning member is supported, and an air dispersion means 36 is installed on the lower end side of the parallel-installed members.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane separation device in which a plurality of bag-shaped membrane members are arranged side by side in a liquid tank to be treated.

[0002]

2. Description of the Related Art As a membrane separation device, a plurality of bag-shaped membrane members, the inner side of which is the filtered liquid side, are arranged side by side in an open type liquid tank to be treated. A membrane separation device with a simple configuration is known, in which the pressure inside is reduced by a vacuum pump to generate a transmembrane pressure difference necessary for filtration, and the stock solution is supplied and the stock solution is processed while the stock solution supply amount is balanced with the filtrate flow rate. There is.

As is well known, in a membrane separation device, a decrease in filtration flow rate with time due to adhesion of solids to the membrane surface is unavoidable.

Conventionally, as a membrane cleaning method for a hollow fiber membrane module, an air scrubbing method, that is, air is jetted into a stock solution from below a bundle of hollow fiber membranes, and the jetted air and the stock solution are combined with each other. There is a known method of separating and removing the deposits on the membrane surface with the rising mixed flow of the gas. Factors in which the gas-liquid mixed flow is brought into contact with the membrane surface in a turbulent state and the vibration of the hollow fiber membrane promotes the separation of the deposits. Has become.

[0005]

SUMMARY OF THE INVENTION However, the present inventors have found that the above-mentioned bag-shaped membrane member is installed in the membrane separation device in parallel with air.
When the scrubbing method was tried, it was difficult to obtain a satisfactory result because the bag-shaped membrane member vibrated less than the hollow fiber membrane. Therefore, a flexible cleaning member (for example, a plastic mesh) is provided in the gap between the juxtaposed bag-shaped membrane members.
Was also provided, and the flexible cleaning member was vibrated by air scrubbing, and an attempt was made to rub the surface of the bag-shaped membrane member with this flexible cleaning member.

However, even in this case, the high-concentration suspension such as river water, domestic wastewater, factory wastewater, etc., is air-cooled.
It is necessary to increase the air-flow rate of scrubbing, and under such high-speed air-scrubbing, it was often found that the bag-shaped membrane member was bent and damaged due to the high-speed gas-liquid mixed flow.

It is an object of the present invention to provide a membrane separation device which can efficiently perform membrane cleaning by the air-scrubbing method even though the bag-shaped membrane members are arranged side by side.

[0008]

As shown in FIG. 3, a membrane separation device according to the present invention has a bag-shaped membrane member 1 having an inner side as a filtrate side and a bag-shaped membrane member 1 longer than the bag-shaped membrane member 1. Flexible cleaning member 2
Alternately in the vertical direction, the lower end of the flexible cleaning member 2 is projected below the lower end of the bag-shaped membrane member 1, and the liquid to be treated is separated from each other with a stock solution flow path gap therebetween. The juxtaposed members are arranged side by side in the tank 31, and the upper end of the juxtaposed member supports both the upper end of the bag-shaped membrane member and the upper end of the flexible cleaning member, and the lower end of the juxtaposed film member supports the lower end of the flexible cleaning member. The horizontal bar 26 is provided on the lower end side of the juxtaposed member, and the air diffusion means 36 is provided on the lower end side of the juxtaposed member.
Is provided and the lower end of the flexible cleaning member 2 is supported by the horizontal bar 26, so that only the lower end of the flexible cleaning member is supported, or an air diffuser is used as an air diffuser,
By supporting the lower end of the flexible cleaning member on the air diffusing pipe, only the lower end of the flexible cleaning member can be supported. The transmembrane pressure difference required for filtration can be obtained, for example, by means 34, 35 for depressurizing the filtrate side of the bag-shaped membrane member.

[0009]

In the flexible cleaning member 2, the flexible cleaning members 2 are arranged vertically in parallel and supported at both upper and lower ends, and even if the flexible cleaning member 2 is agitated by air scrubbing by the air diffusing means.
The original narrow spacing between the two is well retained.

Since the lower end of the bag-shaped membrane member 1 is in a free state, the bag-like film member 1 tries to move for air scrubbing, but the spacing is kept sufficiently narrow. Since it is located between the second and second parts, it is not bent upward, and it is possible to prevent bending damage of the film. Further, since the bag-shaped membrane member 1 and the flexible cleaning member 2 are in contact with each other and the contact surface is in sliding contact due to the gas-liquid mixed flow due to the air-scrubbing, the solid matter is not attached to the film surface. Effectively prevented.

In particular, the flexible cleaning member is provided with an appropriate degree of slack, and the spacing between the flexible cleaning members is kept within a limit that can prevent the bending of the flexible cleaning member toward the bag-shaped membrane member. If the flexible cleaning member is shaken and vibrated by the gas-liquid mixed flow of the scrubbing, the flexible cleaning member and the bag-shaped membrane member can be made to slide more violently, and the solid matter does not adhere to the membrane surface. Even more effectively prevented.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1A is an explanatory view of the bag-shaped membrane member used in the present invention, and FIG. 1B is a cross-sectional view taken along the line RO in FIG. In (a) and (b) of FIG. 1, 1
Reference numeral 1 is a filtered liquid flow path holding member, for example, a net such as polyethylene or polyvinyl chloride, a porous plastic sheet.
Can be used. Reference numerals 12 and 12 denote semipermeable flat membranes attached to both sides of the filtered liquid flow path holding member, and a membrane material such as polysulfone, polyethylene sulfone, polyacrylonitrile, polyolefin, polyamide is formed on a polyester or polypropylene non-woven fabric. A membrane layer (microfiltration membrane layer or ultrafiltration membrane layer) formed, or a polyester layer or polypropylene woven fabric embedded in the membrane layer (microfiltration membrane layer or ultrafiltration membrane layer) can be used. . Reference numerals 13 and 13 denote sealing portions at the four edges of the membrane cell, which can be sealed by an adhesive or fusion. Reference numeral 14 is a filtrate extraction hole.

In the membrane separation apparatus according to the present invention, the bag-shaped membrane member is usually assembled together with the flexible cleaning member into a separation unit separate from the liquid tank to be treated, and this separation unit is placed in the liquid tank to be treated. It can be detachably installed. 2A is a side view showing an example of the separation unit A used in the present invention, and FIG. 2B is a cross-sectional view taken along line II-B of FIG. In FIGS. 2A and 2B, 1, ... Represents the above-mentioned bag-shaped membrane member, 2, ... Represents the flexible cleaning member, and the flexible cleaning member 2 is Is also long. Reference numerals 21 and 21 denote end plates having rigidity. Between these end plates, the bag-shaped membrane member 1 and the flexible cleaning member 2 are vertically oriented and alternately, and the lower ends of the flexible cleaning members 2 are arranged. The portions 20 are projected below the lower end 10 of the bag-shaped membrane member 1, and are arranged in parallel with each other with a stock solution flow passage gap a therebetween. B indicates a side-by-side member configured by this side-by-side arrangement.

Reference numeral 22 denotes a filtered liquid collecting pipe (having a large number of holes in the wall of the filter) which can be inserted into the holes formed in the bag-shaped membrane member 1 and the flexible cleaning member 2 on the upper end side of the juxtaposed member B. , 23, ... are rubber spacers mounted between the bag-shaped membrane members 1 and 1 and between the bag-shaped membrane member 1 and the end plate 21 through the water collecting pipe 22 (flexible cleaning member). 2 is inserted through the rubber spacer at the hole), 24 is a stopper watertightly attached to one end of the water collecting pipe 22, and 25 is a nut screwed to the end of the water collecting pipe protruding from the end plate. The upper end of the bag-shaped membrane member 1 is supported by the water collecting pipe 22 between the end plates 21 and 21 by the compression of the rubber spacer 23 by tightening the nut 25, and the upper end of the flexible cleaning member 2 is collected. The filtration liquid flow path (the filtration liquid flow path storage) inside each bag-shaped membrane member 1 is inserted into and supported by the water pipe 22. Securing the member) through the hole (filtrate extraction hole 14 in FIG. 1) are communicated with the filtrate collecting the water tube 22.

Reference numerals 26 and 26 denote horizontal bars attached between the end plates 21 and 21 on the lower end side of the juxtaposed member B. A hole is formed in the lower end portion 20 of each flexible cleaning member 2, and a horizontal hole is provided in this hole. The lower end portion 20 of each flexible cleaning member 1 is supported by the end plates 21 and 21 through the horizontal rod 26 by inserting the rod 26.

FIG. 3 is an explanatory view showing an embodiment of the membrane separation device of the present invention. In FIG. 3, reference numeral 31 denotes an open type liquid tank to be treated (which is usually provided with a cover for preventing falling), which can be constructed by casting concrete, for example. Reference numeral 32 is a stock solution supply pipe, and 33 is a stock solution supply pump. A is the separation unit described above, and is the liquid tank 31 to be treated.
It is easily installed on the bottom of the. Reference numeral 34 is a filtered liquid extraction pipe communicating with the permeated liquid collecting pipe 22 of the separation unit A, and 35 is a decompression pump. The filtered liquid extraction pipe 34 and the decompression pump 35 allow the filtered liquid side of each bag-shaped membrane member 1 to be separated. The pressure reducing means is configured to generate a transmembrane pressure difference between the inside and the outside of each bag-shaped film member 1. Reference numeral 36 denotes an air diffuser arranged below the juxtaposed members of the separation unit A (air diffuser holes are formed at predetermined intervals), 37 denotes an air supply pipe to the air diffuser,
38 is a blower.

To process the stock solution with this membrane separator, the stock solution supply pump 33 is driven to supply the stock solution into the liquid tank 31 to be treated, the decompression pump 35 is driven, and the filtration side of each bag-shaped membrane member 1 is driven. The pressure is reduced to generate a transmembrane pressure difference necessary for filtration, the filtration is advanced under the transmembrane pressure difference, and the stock solution is continuously or intermittently supplied at a flow rate substantially equal to the filtration flow rate. The stock solution is processed while keeping the water level of the stock solution in the processing solution tank 31 substantially constant.

In parallel with this stock solution treatment, the blower 38 is driven intermittently or continuously to disperse air from the air diffuser 36 into the stock solution, and the gas-liquid mixed flow of the diffused air and the stock solution is formed into a bag. It is raised to the stock solution flow path gap between the membrane members 1, 1.

In this case, in the flexible cleaning member 2,
It is supported at both upper and lower ends, and the original narrow space between the flexible cleaning members 2 and 2 is sufficiently maintained even when being agitated by the air scrubbing by the air diffuser 36. On the other hand, since the lower end of the bag-shaped membrane member 1 is in a free state, the bag-shaped membrane member 1 tries to move vigorously for air scrubbing, but the space between the flexible cleaning members 2 and 2 is kept sufficiently narrow. Therefore, the bag-shaped membrane member 1 and the flexible cleaning member 2 are in sliding contact with each other without being bent upward, and the solid matter is effectively prevented from adhering to the membrane surface.

Particularly, the flexible cleaning member 2 is provided with an appropriate degree of slack so that the space between the flexible cleaning members 2 and 2 is set to the bag-shaped film member 1.
If the flexible cleaning member 2 is swung by air-scrubbing while vibrating the flexible cleaning member 2 to the extent that it can be prevented from bending upward, sliding between the flexible cleaning member 2 and the bag-shaped membrane member 1 Can be performed more violently, and the adhesion of solid matter to the film surface can be prevented even more effectively.

In FIG. 3, the horizontal bar 26 may be omitted, and the flexible cleaning member 2 may be supported by the air diffusing tube 36. In the above description, the flexible cleaning member 2 may be made of cloth or mesh made of synthetic fibers or natural fibers, or a plurality of strings arranged in parallel. In the above, the lower end of each flexible cleaning member 2 is supported via an elastic body such as rubber or a spring (supported by the horizontal rod or the air diffusing pipe), and the flexible cleaning member 2 is supported by the tensile stress of the elastic body. It is also possible to strain the flexible cleaning member 2 and prevent excessive tensile stress from being generated in the flexible cleaning member 2.
In the above, the number of filtrate collection pipes is plural (for example,
It is also possible to support the upper end of the bag-shaped membrane member and the upper end of the flexible cleaning member in each filtrate collecting pipe.

The membrane separation device according to the present invention can also be used for treating wastewater by the activated sludge method. In this sewage treatment, organic matter in sewage water is adsorbed and metabolized by aerobic suspended microorganisms under the aeration of air blown out from the air diffuser, and microorganisms are proliferated as the number of pathogenic bacteria is reduced. Under the transmembrane pressure difference of the member (for example, depressurization on the filtrate side by driving the decompression pump 35), the water in the wastewater is permeated through the membrane and discharged from the permeated liquid take-out pipe.

[0023]

The membrane separation device of the present invention is configured as described above, and the upper end is provided between the vertically oriented flexible cleaning members that support the upper and lower ends with respect to the gas-liquid mixed flow at the time of air scrubbing. Since the supporting vertical bag-shaped membrane member is sandwiched, it is possible to prevent the bag-shaped membrane member from bending and to bring the bag-shaped membrane member and the flexible cleaning member into sliding contact with each other. Even so, it is possible to effectively prevent the solid content from adhering to and depositing on the membrane surface, and ensure a high filtration flux.

[Brief description of drawings]

1 (a) is an explanatory view showing a bag-shaped membrane member used in the present invention, and FIG. 1 (b) is a cross-sectional view taken along the line lo-ro in FIG. 1 (a).

2 (A) is an explanatory view showing a separation unit used in the present invention, and FIG. 2 (B) is a sectional view taken along line II-B of FIG.

FIG. 3 is an explanatory diagram showing an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bag-shaped membrane member 2 Flexible cleaning member 22 Permeate collection pipe 26 Horizontal rod 31 Liquid tank 34 to be treated Permeate extraction pipe 35 Decompression pump 36 Aeration means

Claims (3)

[Claims] 1. A bag-shaped membrane member having an inner side as a filtrate side and a flexible cleaning member which is longer than the bag-shaped membrane member are vertically oriented and alternately, and a lower end of the flexible cleaning member. Of the bag-shaped membrane member are arranged below the lower end of the bag-shaped film member, and are arranged in parallel in the liquid tank to be treated with a raw liquid flow path gap therebetween. Both the upper end of the member and the upper end of the flexible cleaning member are supported, and only the lower end of the flexible cleaning member is supported at the lower end thereof, and the air diffuser is provided at the lower end of the juxtaposed member. Characteristic membrane separation device. 2. At least one horizontal bar is provided on the lower end side of the juxtaposed members, and the lower end of the flexible cleaning member is supported by this horizontal bar, so that only the lower end of the flexible cleaning member is supported. The membrane separation apparatus according to claim 1, which has been performed. 3. An air diffuser is used as an air diffuser, and the lower end of the flexible cleaning member is supported by the air diffuser to support only the lower end of the flexible cleaning member. Membrane separator.