JPH07178320A - Hollow-fiber membrane module - Google Patents

Abstract

PURPOSE:To allow a compact module unit to have a large membrane surface by limiting the area of the fixing member surface on the side where a hollow- fiber membrane is exposed from the fixing member and the area of the end face of the fixing member where the membrane is opened to conform to a specified relation. CONSTITUTION:When the area of a fixing member surface on the side where a hollow-fiber membrane 1 is exposed from the fixing member is denoted by A and the area of the end face of the fixing member where the membrane 1 is opened by B, 100>=A/B>=1.2 is fulfilled. The membrane 1 and the hollow- fiber membrane knitted or weaved fabric are preferably formed with a high- ductility material such as PE and PP. A housing 2 functions as a member to fix the end of the hollow-fiber membrane bundle fixed with resin. A filtrate is discharged from the open end face 3 of the membrane and sent to a water pipe, etc. A structure supporting material 4 is positioned at the center of the module and integrated with the housing 2 covering the resin-fixed part formed on both ends of the bundle membrane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow fiber membrane module, and more particularly to a hollow fiber membrane module suitable for filtering a highly polluted liquid (pollutable by an organic substance).

[0002]

2. Description of the Related Art Conventionally, hollow fiber membrane modules have been manufactured using sterile water,
It has been widely used in the field of so-called microfiltration, such as the production of drinking water and high-purity water, and the purification of air, but in recent years, it has been used for secondary and tertiary treatments at sewage treatment plants and for solidification in septic tanks. Various studies have been conducted for use in highly polluted water treatment applications such as liquid separation.

Since the hollow fiber membrane module used for such an application has a large clogging of the hollow fiber membrane during the filtration treatment, after the filtration treatment for a certain period of time, air is sent to vibrate the hollow fiber membrane to cause the membrane surface to be vibrated. The membrane surface is repeatedly washed, such as washing the membrane or passing treated water in the opposite direction to the filtration treatment.

Hollow fiber membrane modules used in these fields are of the cylindrical type in which hollow fiber membranes are concentrically arranged in a circular circle or concentricity, which has been used in the field of conventional microfiltration. Most were things. Further, even if improvements are made, most of them merely change the filling rate or filling form of the hollow fiber membrane.

[0005]

Highly polluted water (for example, ss ≧ 5) is obtained by using such a conventional hollow fiber membrane module.
When the filtration treatment (0 mg / L, TOC ≧ 100 mg / L) is performed, the hollow fiber membranes are fixed (adhered) to each other through the deposits such as organic substances attached to the surface of the hollow fiber membranes during use. Due to the integration, the effective membrane area of the hollow fiber membrane in the module was reduced, and the filtration flow rate was rapidly reduced. Further, even when the hollow fiber membrane module in which the hollow fiber membranes are fixed and integrated in this manner is subjected to regular membrane surface cleaning or backwashing, it is not easy to recover the function of the module once fixed and integrated. A decrease in cleaning efficiency was seen.

[0006] As a solution to this problem, instead of a concentrating and cylindrical hollow fiber membrane module, the hollow fiber membranes are arranged in a sheet form, and one end or both ends of the hollow fiber membrane are either one or A hollow fiber membrane module which is fixed by fixing materials in two different housings while respectively maintaining an open state, and the shape of a cross section of the fixing member perpendicular to the hollow fiber membranes is an elongated rectangular shape. Modules are proposed.

In such a sheet-shaped flat hollow fiber membrane module, it becomes possible to evenly arrange the hollow fiber membranes in the inner and outer layers with a space between layers, and the surface of the hollow fiber membranes is washed during the cleaning of the membrane surface. It is a module suitable for filtering highly polluted water because it makes it extremely easy to wash it evenly, and can prevent the deterioration of filtration efficiency as it has been so far.

When a large volume (for example, 1 m ³ / h) of water is treated using such a flat type hollow fiber membrane module, it is necessary to increase the membrane area. By increasing the membrane area of the module, it is difficult to handle, the treatment tank becomes unnecessarily large, and when performing scrubbing cleaning, etc., the hollow fiber membranes will be accumulated by increasing the membrane area. There is a problem that the entire membrane surface in the module cannot be efficiently cleaned with air or the like.

Further, in the use of the conventional flat type hollow fiber membrane module, there is a method of increasing the number of modules to form a unit in order to increase the membrane area. In this case, the module arrangement within the unit (that is, The distance between the modules when the modules are arranged in parallel so that the sheet-shaped hollow fiber membranes are superposed on each other is governed by the diameter of the water collecting pipe of each module, and there is a limit in narrowing the distance between the modules.

[0010] Therefore, an unnecessarily large module interval (an interval between the hollow fiber membrane knitted fabrics in the sheet-shaped flat hollow fiber membrane module) is opened, and accordingly, the volume of the processing tank is unnecessarily increased or scrubbing is performed. There is a problem that the amount of bubbling must be increased.

The present invention provides a hollow fiber membrane module which has a large membrane area in a compact module unit, but the space occupied by the water collecting portion is small, and the entire hollow fiber membrane in the module can be efficiently scrubbed and washed. The purpose is to do.

[0012]

The gist of the present invention is as follows. (1) A hollow fiber membrane module in which one end or both ends of a hollow fiber membrane are fixed by a fixing member inside a housing while maintaining an open state, and the fixing member on the side where the hollow fiber membrane is exposed from the fixing member A hollow fiber membrane module satisfying the following expression, where A is the area of the surface and B is the area of the end surface of the fixing member where the hollow fiber membrane is open. 100 ≧ A / B ≧ 1.2

(2) Using a sheet-shaped hollow fiber membrane knitted fabric,
A hollow fiber membrane module in which one end or both ends of the hollow fiber membrane are fixed by a fixing member in a structural material while maintaining an open state, and the shape of a cross section of the fixing member perpendicular to the hollow fiber membrane is an elongated rectangular shape. Where the area of the fixing member surface on the side where the hollow fiber membrane is exposed from the fixing member is A and the area of the end surface of the fixing member where the hollow fiber membrane is open is B, a hollow fiber membrane module satisfying the following equation: . 100 ≧ A / B ≧ 1.2

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view of a hollow fiber membrane module of the present invention in which both ends of a hollow fiber membrane are fixed by fixing members while maintaining openings and a cylindrical shape is formed. A / B of this module is 4.6
Is. FIG. 2 is a perspective view of a hollow fiber membrane module of the present invention in which eight hollow fiber membrane knitted fabrics are used and one end portion of each hollow fiber membrane is fixed by a fixing member while maintaining an open state. The A / B of this module is 1.7.

FIG. 3 shows the hollow fiber membrane knitted fabric as in FIG.
FIG. 3 is a perspective view of a hollow fiber membrane module of the present invention in which both ends of each hollow fiber membrane are fixed by a fixing member while maintaining the open state. FIG. 4 is a cross-sectional view of the hollow fiber fixing portion in a direction perpendicular to the longitudinal direction of the water collecting pipe of the module shown in FIGS. 2 and 3.

1 is a hollow fiber membrane, 2 is a housing (fixing member inside), 3 is a hollow fiber membrane open end surface, 4 is a structural support material, 5
Is a hollow fiber membrane knitted fabric, 6 is a housing and a water collecting pipe, 7 is a fixing member, 8 is a water guiding pipe, and 9 is a filtrate outlet.

The hollow fiber membrane 1 and the hollow fiber membrane knitted fabric 5 may be made of various materials such as cellulose-based, polyolefin-based, polyvinyl alcohol-based, polysulfone-based, etc., and particularly strong stretch such as polyethylene and polypropylene. It is preferable to use a material of high degree.

There are no particular restrictions on the pore diameter, porosity, film thickness, outer diameter, etc., so long as it can be used as a filtration membrane. Considering the strength of the membrane and the like, a preferable example is a pore size of 0.
01 to 1 μm, porosity 20 to 90%, film thickness 5 to 300 μ
m and an outer diameter of 20 to 2000 μm. In addition, it is essential that the pore size is 0.2 μm or less for the purpose of removing bacteria, and the ultrafiltration membrane having a molecular weight cut-off of tens of thousands to hundreds of thousands for the purpose of removing organic substances and viruses. May be used.

As a surface characteristic of the hollow fiber membrane, a so-called permanent hydrophilization membrane having a hydrophilic group on the surface is desirable. As a method for producing the permanently hydrophilic membrane, known methods such as a method for producing a hollow fiber membrane with a hydrophilic polymer such as polyvinyl alcohol or a method for hydrophilizing the surface of a hydrophobic polymer membrane can be used. For example, as an example of the hydrophilic polymer when the hydrophilic polymer is applied to the membrane surface to make the hydrophobic hollow fiber membrane hydrophilic,
Examples thereof include saponified ethylene-vinyl acetate copolymers and polyvinylpyrrolidone.

As an example of hydrophilization of the membrane surface by another method,
There is a film surface polymerization method for hydrophilic monomers, and examples of this monomer include diacetone acrylamide. As another method, a method of blending a hydrophobic polymer (for example, polyolefin) with a hydrophilic polymer to form a film by spinning can be cited, and examples of the hydrophilic polymer to be used include those mentioned above. To be

When the surface of the hollow fiber membrane is hydrophobic, hydrophobic interaction is caused between the organic matter in the water to be treated and the surface of the hollow fiber membrane to cause adsorption of the organic matter on the membrane surface, which is clogged. Leading to shorter filtration life. In addition, clogging caused by adsorption is generally difficult to recover filtration performance by washing the membrane surface.

When the permanent hydrophilic membrane is used, the hydrophobic interaction between the organic substance and the surface of the hollow fiber membrane can be reduced and the adsorption of the organic substance can be suppressed. Further, when scrubbing cleaning during use, a hydrophobic film may be dried and hydrophobized by the bubbling air, which may cause a decrease in flux. Never.

Regarding the fixing of the hollow fiber membrane, as shown in FIGS. 2 and 3, either one end or both ends of the hollow fiber membrane may be used. Either fixation can be selected according to the purpose and application. The hollow fiber membrane knitted fabric 5 is a product obtained by knitting a hollow fiber membrane in a sheet shape, and any method can be used as a method for producing the sheet-shaped hollow fiber membrane, for example, Japanese Patent Publication No. 26886/1992. It can be easily manufactured by using the apparatus and method described in JP-A-63-91673.

The housing 2 functions as a member for fixing the hollow fiber membrane focusing end portion which is fixed by resin. The hollow fiber membrane opening end face 3 takes out the filtrate from this end face and sends the filtrate to a water conduit or the like. The structure support member 4 is located at the center of the hollow fiber membrane module, and is integrally formed by being fixed to the housing 2 that covers the resin fixing portions formed at both ends of the bundled hollow fiber membranes. . In addition, this rod-shaped structural support 4
Can be used as a flow path for purified water. The cross-sectional shape may be circular, square, rectangular, or rod-like.

The housing and the water collection pipe 6 function as a member for supporting the entire hollow fiber membrane module shown in FIGS. 2 and 3, and have an elongated, substantially rectangular opening. The housing and the opening of the water collection pipe 6 have a substantially rectangular elongated shape in a cross section perpendicular to the hollow fiber membrane of the fixing member filled and fixed together with the hollow fiber membrane.

The fixing member 7 is filled and fixed in the openings of the housing and the water collecting pipe 6, and is formed to have a cross-sectional shape as shown in FIG. 3, but any shape may be used. Absent. This fixing member 7 is bundled and fixed while keeping each end of a large number of hollow fiber membranes in an open state, and in order to make this hollow fiber membrane function as a filtration membrane, the treated water and the treated water are treated. Functions as a liquid-tight partitioning member.

The fixing member 7 is usually formed by curing a liquid resin such as epoxy resin, unsaturated polyester resin, polyurethane or the like. The same applies to the fixing member inside the housing 2 in FIG. The water conduit 8 is a pipe through which the filtrate flows, and communicates with the filtrate outlet 9.

The material of the housing 2, the structural support member 4, the housing, the water collecting pipe 6 and the water guiding pipe 8 may be any as long as they have mechanical strength and durability, for example, hard polyvinyl chloride resin, polycarbonate, polysulfone. ,
Polypropylene, acrylic resin, ABS resin, modified PP
E resin and the like are exemplified. When incineration is required after use, it is preferable to use a hydrocarbon resin that can be completely burned without producing toxic gas by burning.

An arbitrary value can be selected for A / B, which is the ratio of the area A of the surface of the fixing member on the side where the hollow fiber membrane is exposed from the fixing member and the area B of the end surface of the fixing member where the hollow fiber membrane is open. The range of 1.2 to 100 is preferable in consideration of the processing capacity, the membrane area, the size of the can or the processing tank, and the handling property. In particular,
In the case of a flat type hollow fiber membrane module (using a hollow fiber membrane knitted fabric), the value of A / B is determined in consideration of the number of hollow fiber membrane knitted fabrics, the inner diameter and the outer diameter of the water collection pipe.

The hollow fiber membrane module of the present invention has the following features. A cylindrical type module in which hollow fiber membranes are bundled and arranged in a circular shape or a concentric shape has excellent handleability, particularly workability when mounting the module. Since the hollow fiber membranes are evenly arranged on the entire surface of the fixing member represented by the area A, the accumulation of suspended matter between the hollow fiber membranes and the accumulation of turbidity between the hollow fiber membranes are larger than those of the module having the same area B and A / B of 1. Adhesion between the hollow fiber membranes is less likely to occur, and effective use of the membrane surface and scrubbing cleaning are efficiently performed.

Further, even if the number of hollow fiber membranes is the same, a module having A / B> 1 can produce a smaller amount of resin to be used as a fixing member than A / B = 1. Therefore, in the case of a resin that generates heat during curing, the smaller the amount of resin is, the less heat is generated, the smaller the curing shrinkage, and the easier the molding.

A hollow fiber membrane module using a hollow fiber membrane knitted fabric as shown in FIGS. 2 and 3 is superior in handleability to a module having a similar membrane area, and the hollow fiber membrane knitted fabric has layer intervals. Since they are evenly arranged in the inner and outer layers, it becomes extremely easy to uniformly wash the hollow fiber membrane surface when washing the membrane surface. The effect is further improved by making the intervals of the respective hollow fiber membrane knitted fabrics equal.

When a plurality of modules are arranged in a treatment tank or the like, particularly in a case where the hollow fiber membrane knitted fabrics are arranged in parallel or stacked so as to be superposed, in the conventional module, the outer diameter of the water collection pipe or the water collection pipe The module spacing is governed by the size of the filtrate outlet connection.

In the module of the present invention, the width of the fixing member is larger than the outer diameter of the water collecting pipe or the connecting portion, and the modules are arranged in parallel so that the side surfaces of the fixing member are in contact with each other, so that all the modules are provided. Since all the hollow fiber membrane knitted fabrics are fixed at equal intervals, uniform scrubbing cleaning can be performed on the entire hollow fiber membrane, and partial reduction in filtration efficiency does not occur.

The intervals between the hollow fiber membrane knitted fabrics in the module are preferably equal intervals in consideration of applying the air bubbling evenly to the entire membrane surface at the time of scrubbing cleaning. Any distance is selected.

The distance between the sheets can be selected in consideration of the efficiency of scrubbing cleaning in air bubbling and the like, the prevention of adhesion of adjacent hollow fiber membrane knitted fabrics, the membrane area per module, etc., but it is preferable. , 5-100m
A range of m is suitable. Furthermore, by fixing the hollow fiber membrane knitted fabrics one by one at a predetermined interval, it becomes possible to further prevent the hollow fiber membranes from being fixedly integrated with each other.

In the module using the hollow fiber membrane knitted fabric, the hollow fiber membranes are converged toward the open end face as shown in FIG. 4, but the hollow fiber membranes are completely embedded in the fixing member. Is desirable.

In particular, in the case of using a flat type hollow fiber membrane module using a hollow fiber membrane knitted fabric, the module is placed in a closed container and the water to be treated is pressurized to permeate the hollow fiber membrane. A pressure filtration method can also be adopted, but it is preferable to use a suction filtration method in which a hollow fiber membrane module is provided in an activated sludge tank or a sedimentation tank and the side for collecting treated water that has permeated the hollow fiber membrane is sucked. .

Particularly, by adopting a so-called intermittent suction operation method in which the temporary suction is periodically stopped, it is possible to effectively prevent the film surface deposit from entering the inside of the film surface. It is possible to reduce the frequency of function recovery processing of the hollow fiber membrane module.

The optimum range of the intermittent suction is not defined because the optimum range varies depending on the contamination degree of the water to be treated, but as an example for the case of MLSS 5000 mg / L activated sludge, Suction time 1 to 30 minutes,
A desirable example is a stop time of 2 seconds to 15 minutes.

By adopting the suction filtration method,
It becomes easy to circulate the treated water in the tank at the time of filtration or to wash the membrane surface by performing air bubbling. In particular, the cleaning method by air bubbling has a further cleaning effect by being combined with the intermittent suction operation method capable of effectively preventing the film surface deposits from entering the inside of the film surface as described above. Demonstrate. It is preferable that the flow of the water to be treated in the suction filtration method is made to flow substantially perpendicularly to the arrangement direction of the hollow fiber membranes to enhance the cleaning effect on the membrane surface of the hollow fiber membranes.

In filtering highly polluted water, a large amount of ss
And organic matter is deposited. For this reason, it is necessary to clean the film surface by using water flow, air, vibration, ultrasonic waves or the like to remove the deposits. When the washing is not performed, the organic substances deposited on the surface of the membrane cause the clogging of the membrane, leading to a reduction in filtration life. Specific cleaning methods include so-called cross-flow filtration in which a water flow is made parallel to the membrane surface, a method of causing a water flow with a pump or a motor in the membrane module dipping tank, a bubbling method using an upward flow of air, and vibration of the module itself Examples of the method include a method of vibrating, and a method of vibrating the liquid to be treated with ultrasonic waves.
These washings may be performed continuously or intermittently depending on the degree of progress of the membrane surface blockage.

When operating while scrubbing and cleaning by air bubbling, an air diffuser for bubbling is required. The positional relationship between the air diffusing tube and the module is important for proper air bubbling, but fixing the module and the air diffusing tube separately is a complicated task, and the module may move during operation. In that case, there is a problem that proper scrubbing cleaning cannot be performed during operation. As a measure against this, by fixing and integrating an air diffuser in the module of the present invention, it becomes easy to mount it on a can body or a treatment layer, and appropriate scrubbing cleaning can be continued during operation.

The hollow fiber membrane module of the present invention is particularly suitable for filtering highly polluted water.
River water filtration, industrial tap water filtration, solid-liquid separation of drainage,
Wastewater treatment (for example, treatment in a combined septic tank) can be mentioned.

[0045]

The hollow fiber membrane module of the present invention has a compact structure with a large membrane area, and more hollow fiber membranes come into direct contact with the water to be treated.
It is possible to prevent the hollow fiber membranes from being fixedly integrated with each other, and it is possible to maintain a high filtration efficiency for a long period of time, particularly in filtering highly polluted water.

Particularly when the hollow fiber membrane module using the hollow fiber membrane knitted fabric is immersed in the treatment tank for filtration, all the hollow fiber membrane knitted fabrics can be arranged at equal intervals, and a plurality of modules can be arranged. A uniform and efficient scrubbing cleaning can be carried out. In addition, it is easy to attach to and detach from the can body or the processing tank, and is easy to handle.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a hollow fiber membrane module of the present invention.

FIG. 2 is a perspective view showing an example of a hollow fiber membrane module of the present invention.

FIG. 3 is a perspective view showing an example of a hollow fiber membrane module of the present invention.

FIG. 4 is a cross-sectional view of a hollow fiber membrane fixing portion in an example (FIGS. 2 and 3) of the hollow fiber membrane module of the present invention.

[Explanation of symbols]

 1 Hollow Fiber Membrane 2 Housing 3 Hollow Fiber Membrane Opening End Surface 4 Structural Support 5 Hollow Fiber Membrane Knitted Fabric 6 Housing and Water Collection Tube 7 Fixing Member 8 Water Transfer Tube 9 Filtrate Outlet Port

Front page continuation (72) Inventor Naoya Tanakamaru 2-33-1 Kyobashi, Chuo-ku, Tokyo Within Mitsubishi Rayon Co., Ltd. Product Development Laboratory Co., Ltd. (72) Inventor Tatsuharu Okada 2-8-3 Kiba, Koto-ku, Tokyo Inside Mitsubishi Rayon Engineering Co., Ltd.

Claims (2)

[Claims] 1. A hollow fiber membrane module in which one end or both ends of a hollow fiber membrane are fixed by a fixing member in a housing while maintaining an open state, and the hollow fiber membrane on the side exposed from the fixing member. A hollow fiber membrane module satisfying the following expression, where A is the area of the surface of the fixing member and B is the area of the end surface of the fixing member where the hollow fiber membrane is open. 100 ≧ A / B ≧ 1.2 2. A sheet-shaped hollow fiber membrane knitted fabric is used, wherein one end or both ends of the hollow fiber membrane are fixed by a fixing member in a structural member while maintaining an open state, and the hollow fiber membrane of the fixing member is used. In a hollow fiber membrane module whose vertical cross-sectional shape is elongated and substantially rectangular, the area of the fixing member surface on the side where the hollow fiber membrane is exposed from the fixing member is A, and the area of the fixing member end surface where the hollow fiber membrane is open. A hollow fiber membrane module satisfying the following expression, where B is the area. 100 ≧ A / B ≧ 1.2