JPH07275665A - Hollow yarn membrane module - Google Patents

Abstract

PURPOSE:To provide a hollow yarn membrane module made hard to generate the accumulation of suspended matter between hollow yarn membranes even when adapted to the filtering of highly turbid water and efficiently subjected to scrubbing by arranging film sheets so as to hold a sheet like aggregate of hollow yarn membranes therebetween. CONSTITUTION:In order to arrange hollow yarn membranes 4 in a sheet like form to fit them to the almost rectangular opening part of a structural material 2, a knitted fabric formed by using the hollow yarn membranes 4, for example, as warp yarns is used or several knitted fabrics are used in a laminated state. The film sheets 5 arranged to this hollow yarn membrane module 1 are provided for the purpose of guiding air bubbles supplied from an air diffusion pipe at the time of scrubbing along the sheet like aggregate of the hollow yarn membranes 4 and prevent air bubbles from scattering from the hollow yarn membrane module 1 even if air bubbles rise. The film sheets 5 are arranged so as to hold the sheet like aggregate of the hollow yarn membranes 4 and pref. have an area sufficient to cover the whole of the sheet like aggregate of the hollow yarn membranes 4.

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 liquid having a high pollutant (particularly a pollutant of organic matter).

[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 highly polluted by secondary and tertiary treatments at sewage treatment plants and solid-liquid separation in septic tanks. Various types of studies have been conducted for use in water treatment applications.

Most of the hollow fiber membrane modules used in these fields are of the cylindrical type in which the hollow fiber membranes are arranged concentrically in a circular shape or concentric circles which have been used in the field of conventional microfiltration. Met. Further, even if improvements are made, most of them merely change the filling rate or filling form of the hollow fiber membrane.

[0004]

Highly polluted water (for example, SS ≧ 5) is obtained by using such a conventional hollow fiber membrane module.
(0 ppm, TOC ≧ 100 ppm), the hollow fiber membranes are integrated (bonded) to each other through the deposits such as organic substances attached to the surface of the hollow fiber membranes due to use. As a result, the effective membrane area of the hollow fiber membrane in the module was reduced, and the filtration flow rate was rapidly reduced.
In particular, this phenomenon was remarkable in the hollow fiber membrane in the central portion of the cylindrical module, and was more remarkable in the large-sized one.

Further, even when the hollow fiber membrane module in which the hollow fiber membranes are fixed and integrated as described above is regularly subjected to membrane surface cleaning or backwashing, it is easy to recover the function of the module once fixed and integrated. However, there was a decrease in cleaning efficiency.

As a solution to this problem, in place of the concentrating and cylindrical hollow fiber membrane module, a large number of hollow fiber membranes are arranged in a sheet form and arranged so that one end or both ends of the hollow fiber membrane are A hollow fiber membrane module in which one or two different structural members are fixed by a fixing member while maintaining their respective open states, and the shape of the cross section perpendicular to the hollow fiber membrane of the fixing member is an elongated rectangular shape. A hollow fiber membrane module is proposed (Japanese Patent Laid-Open No. 5-220356, etc.).

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.

However, even in this type of hollow fiber membrane module, when filtering raw water having a high degree of pollution, if washing (scrubbing) by applying air bubbles to the hollow fiber membrane and vibrating is insufficient, While continuing the filtration, suspended matter gradually accumulated between the hollow fiber membranes. The accumulation of this turbidity causes a decrease in the effective film area, which causes a rise in differential pressure and a decrease in flow rate, which has a problem of shortening the life of the module.

The object of the present invention is to prevent turbidity from accumulating between hollow fiber membranes even when used for filtering highly polluted water, to efficiently perform scrubbing, and to increase differential pressure and decrease flow rate over a long period of time. Another object of the present invention is to provide a hollow fiber membrane module that does not cause

[0010]

Means for Solving the Problems That is, the present invention provides a hollow fiber membrane which is arranged in a sheet form and spread, and a fixing member which fixes the end portion of the hollow fiber membrane while keeping it open.
A hollow fiber membrane module comprising a structural member that supports and houses a fixing member, and has a cross section perpendicular to the hollow fiber membrane of the fixing member that is elongated and substantially rectangular, and sandwiches the sheet-shaped assembly of the hollow fiber membranes. It is a hollow fiber membrane module in which a film sheet is arranged as described above.

[0011]

The hollow fiber membrane module of the present invention will be described below in more detail with reference to the drawings.

FIG. 1 is a perspective view showing an example of the hollow fiber membrane module of the present invention, and FIG. 2 is a transverse sectional view thereof. The hollow fiber membrane module 1 of the present invention basically comprises a structural material 2
The fixing member 3, the hollow fiber membrane 4, and the film sheet 5 are included. In addition to these, various accessory members may be attached.

The structural material 2 functions as a member for supporting the entire hollow fiber membrane module, has an elongated substantially rectangular opening, and has a filtrate chamber 6 inside thereof. Any material may be used as long as it has mechanical strength and durability, and examples thereof include polycarbonate, polysulfone, polypropylene, acrylic resin, ABS resin, modified PPE resin, vinyl chloride resin and the like. 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.

As shown in FIG. 1, in a hollow fiber membrane module of a type in which linearly arranged hollow fiber membranes have openings at both ends, two structural materials are used per module. One type of structural material is used in a module that is used by being folded in a letter shape. The filtrate outlet 7 is provided at one end or both ends of the structural material 2.

The opening of the structural member 2 must be such that the shape of the cross section of the fixing member, which is filled and fixed together with the hollow fiber membrane, in the section perpendicular to the hollow fiber membrane is an elongated rectangular shape. The length of the short side of this rectangle is preferably 30 mm or less, and particularly preferably 15 mm or less. That is, since the hollow fiber membranes are fixed to the string-shaped band of the fixing member, the entire hollow fiber membranes in the module are arranged in a flat sheet shape and spread. In this way, by arranging and expanding a large number of hollow fiber membranes in a sheet shape while aligning them in substantially parallel, it is possible to prevent the hollow fiber membrane bundle from being fixedly integrated into a single rod shape. On the other hand, the length of the long side of the rectangle is not particularly limited, but if it is too short, it is not preferable because the number of hollow fiber membranes that can be arranged in one hollow fiber membrane module decreases, and if it is too long, manufacturing is difficult. Is not desirable. Usually, the length of the long side is about 100 to 2000 mm.

The fixing member 3 is filled and fixed in the openings of the structural material 2, and the end portions of a large number of hollow fiber membranes 3 are converged and fixed while maintaining the open state, and the hollow fiber membranes are also fixed. In order to function as a filtration membrane, it functions as a member that liquid-tightly separates the water to be treated from the treated water. The fixing member 3 is
It is usually formed by curing a liquid resin such as an epoxy resin, an unsaturated polyester resin or polyurethane.

As the hollow fiber membrane 4, various types can be used, for example, various types of materials such as cellulose type, polyolefin type, polyvinyl alcohol type, PMMA type and polysulfone type can be used, but polyethylene, polypropylene and the like can be used. A material having a high strength and elongation is preferable. There are no particular restrictions on the pore size, porosity, film thickness, outer diameter, etc., as long as it can be used as a filtration membrane, but it is necessary to secure the membrane area per removal object or volume and the strength of the hollow fiber membrane. Considering the above, as a preferable example, the pore diameter is 0.01 to 1 μm,
Porosity 20-90%, film thickness 5-300 μm, outer diameter 20-
A range of 2000 μm can be mentioned. 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 property 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 film, a known method 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, saponified ethylene-vinyl acetate copolymer, polyvinylpyrrolidone and the like can be mentioned. . An example of hydrophilization of the film surface by another method is a film surface polymerization method of a hydrophilic monomer, and examples of this monomer include diacetone acrylate. Further, 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. Examples of the hydrophilic polymer to be used include those mentioned above. To be If the surface is a hydrophobic hollow fiber membrane, hydrophobic interaction between organic matter in the water to be treated and the surface of the hollow fiber membrane causes adsorption of organic matter on the membrane surface, which leads to blockage of the membrane surface and filtration. The life is shortened. In addition, clogging caused by adsorption is generally difficult to recover filtration performance by washing the membrane surface.
By using the permanent hydrophilization membrane, the hydrophobic interaction between the organic matter and the hollow fiber membrane surface can be reduced, and the adsorption of the organic matter can be suppressed. In addition, when scrubbing, the surface of a hydrophobic film may become dry due to bubbles, which may increase the hydrophobicity and cause a decrease in flux. Does not occur.

In order to store the hollow fiber membranes 4 in the form of a sheet in the elongated rectangular opening of the structural member 2, for example, one hollow fiber membrane is used as a knitted fabric, or one knitted fabric is used. It is preferable to use a laminate in which several sheets of ground are laminated.

The hollow fiber membrane module of the present invention is further provided with a film sheet 5, which is a sheet-shaped assembly of hollow fiber membranes containing bubbles supplied from an air diffusing tube or the like during scrubbing. The main purpose is to guide the air bubbles along the path, and even if the bubbles rise, the film sheet prevents them from separating from the hollow fiber membrane module, and the supplied bubbles can be reliably and effectively supplied. Can be applied to the membrane.

The film sheet 5 is not limited in thickness, material and the like as long as it has a strength sufficient to perform the function of inducing bubbles, and may have a thickness which can be called a plate. It is preferable that the surface is smooth.

If the film sheet 5 is arranged so as to sandwich the sheet-shaped assembly of the hollow fiber membranes 4, the sheet-shaped assembly of the hollow fiber membranes is housed in a tubular film sheet, for example. However, a sheet-shaped aggregate of hollow fiber membranes may be sandwiched between two film sheets. However, it is preferable to have an area enough to cover the entire sheet-shaped aggregate of hollow fiber membranes.

The film sheet 5 in the hollow fiber membrane module may be fixed by burying it in the fixing member 3 similarly to the hollow fiber membrane, fixing it to the structural member 2, or fixing the film sheet. For fixing, a supporting member may be additionally provided and fixed to this. Further, it is also effective to spread both lower ends of the film sheet in a trumpet shape toward the air bubble supply source such as an air diffuser so that the air bubbles do not leak to the outside.

In the case where the sheet-shaped aggregate of hollow fiber membranes is formed of a laminated body in which several hollow fiber membrane knitted fabrics are stacked, A film sheet may be provided. By thus arranging the film sheet and partitioning the space containing the hollow fiber membranes arranged in a sheet shape, the supplied bubbles can be more uniformly and reliably applied to the hollow fiber membranes in the module. .

Since the space sandwiched by the film sheets containing the hollow fiber membranes serves to prevent air bubbles from moving away from the hollow fiber membranes, the space (w) between the film sheets is too wide. Is not preferable. The distance (w) between the film sheets is preferably 50 mm or less, 20
mm or less is more preferable.

The hollow fiber membrane module of the present invention can be used in a so-called pressure filtration method in which a hollow fiber membrane is placed in a closed container to pressurize the water to be treated to permeate the hollow fiber membrane. It is preferably used in a suction filtration method in which the side for collecting the treated water that has permeated the hollow fiber membrane is suctioned. In particular, by adopting the suction filtration method, it becomes easy to circulate the water to be treated in the tank at the time of filtration or to clean the membrane surface by scrubbing while performing filtration. Also,
By adopting the so-called intermittent suction operation method, in which temporary suction is periodically stopped, it is possible to efficiently prevent the membrane surface deposits from entering the inside of the membrane surface, and to perform the function recovery process of the hollow fiber membrane module. It can be less frequent.

Further, since scrubbing is carried out by supplying air bubbles from below, it is preferable that the film sheets are arranged so that they are oriented substantially vertically and the hollow fiber membranes are oriented horizontally as shown in FIG. It is also possible to arrange and use the film sheet so that it has a slight angle like an inclined plate.

The hollow fiber membrane module of the present invention is particularly suitable for filtering highly polluted water. Specific fields of application include filtration of river water, industrial water filtration, solid-liquid separation of sewage, and wastewater treatment ( For example, treatment in a combined septic tank) and the like.

[0029]

In the hollow fiber membrane module of the present invention, since a large number of hollow fiber membranes are arranged and expanded in a sheet form, it is difficult for organic substances to accumulate between the hollow fiber membranes and the hollow fiber membranes are fixed to each other. Integration is prevented. Further, since the air bubbles supplied to the module during scrubbing are prevented from being dispersed from the hollow fiber membrane by the provision of the film sheet,
Membrane surface cleaning can be performed efficiently, and in particular, in filtration of highly polluted water, increase in differential pressure and decrease in flow rate can be prevented over a long period of time.

Further, since the film sheet physically regulates the movement of the hollow fiber membrane, it can also exert a function of preventing the stress due to the movement of the hollow fiber membrane from concentrating on the rising portion of the hollow fiber membrane from the fixing member. The damage probability of the hollow fiber membrane in the module can be reduced.

[Brief description of drawings]

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

2 is a cross-sectional view of the hollow fiber membrane module of FIG.

[Explanation of symbols]

 1 Hollow Fiber Membrane Module 2 Structural Material 3 Fixing Member 4 Hollow Fiber Membrane 5 Film Sheet 6 Filtrate Chamber 7 Filtrate Extraction Port W Interval Between Film Sheets

Claims (2)

[Claims] 1. A hollow fiber membrane, which is arranged in a sheet form and arranged so as to be spread, a fixing member for fixing the hollow fiber membrane while keeping an end portion of the hollow fiber membrane open, and a structural material for supporting and housing the fixing member. A hollow fiber membrane module having a substantially rectangular elongated cross section perpendicular to the hollow fiber membrane of the fixing member, in which film sheets are arranged so as to sandwich the sheet-shaped aggregate of the hollow fiber membranes. Hollow fiber membrane module. 2. A hollow fiber membrane which is arranged and expanded in a sheet shape is formed by a laminate of hollow fiber membrane knitted fabrics, and a film sheet is also disposed between the hollow fiber membrane knitted fabrics and the hollow fiber membrane knitted fabrics. The hollow fiber membrane module according to claim 1, wherein