JPH08229360A - Membrane module - Google Patents

Abstract

PURPOSE: To provide a membrane module wherein the separation membranes are hardly stuck to one another or integrated even when used in a highly contaminated water and to conduct filtration with high efficiency for a long period by allowing an air diffuser pipe to function as a spacer between the separation membranes. CONSTITUTION: Plural membrane modules 2 each having a sheet-shaped separation membrane 1 are arranged in a filtration tank, and a diffuser pipe 3 is furnished between the membranes 1 almost parallel to each other. The membrane 1 is made movable to some extent and may be curved. The diffuser pipe 3 acts as a spacer between the almost parallel membranes. Consequently, cleaning air is surely blown against the membrane 1, the distance between the membranes 1 is forcedly controlled, the accumulation of org. matter between the membranes 1 is suppressed, and the membranes 1 are prevented from sticking to one another or being integrated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filtration device provided with a membrane module, and particularly to a filtration device suitable for treating a liquid having a high pollutant (particularly, a pollutant of organic matter) and a membrane used for the filter. It relates to a module assembly.

[0002]

2. Description of the Related Art Membrane modules have hitherto been used in many fields of so-called microfiltration such as production of sterile water, drinking water, high-purity water and purification of air.
Various studies have been conducted for secondary and tertiary treatments at sewage treatment plants and for highly polluted water treatment applications such as solid-liquid separation in septic tanks.

However, the membrane module used in these fields also has a circular shape or a concentric shape (flat membrane spiral, flat membrane pleats, hollow fiber membrane ditch, etc.) which has been used in the field of conventional microfiltration. Most of them were of the cylindrical type in which the separation membranes were converged and arranged. Even if improvements are made, most of them merely change the packing rate and packing form of the separation membrane.

[0004]

Highly polluted water (for example, SS ≧ 50 pp) is produced by using such a conventional membrane module.
(m, TOC ≧ 100 ppm), the films are fixed (adhered) to be integrated with each other through the deposits such as organic substances attached to the film surface or between the films due to use. As a result, the effective membrane area of the separation membrane in the module was reduced, and the filtration flow rate was rapidly reduced. In particular, this phenomenon was remarkable in the separation membrane in the central part of the cylindrical module, and was more remarkable in the large size.

As a solution to this problem, in place of a 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 membranes are arranged. Fixed hollow fiber membrane modules have been proposed (JP-A-5-261253, JP-A-6-340, JP-A-6-342, etc.). These modules are manufactured by, for example, a method of forming a knitted fabric of hollow fiber membranes, and by directly or laminating the knitted fabric and fixing the ends with a potting agent. Such a method can be applied to a flat membrane formed in a bag shape or a tubular ceramic membrane.

[0006] Such a hollow fiber membrane module exerted a great effect in filtering highly polluted water. In particular, a stable filtration capacity was obtained by additionally using air scrubbing cleaning for separating the deposits on the film surface by the rising air flow. However, when the number of hollow fiber membranes or the number of hollow fiber membrane knitted fabrics per module is large, or when a plurality of modules are installed with the spaces therebetween, the sss between the hollow fiber membrane knitted fabrics and the modules are separated. Was observed and the filtration efficiency was sometimes lowered.

The object of the present invention is to prevent the separation membranes in the module from sticking and integrating even when used for filtering highly polluted water, and to prevent the separation membranes from sticking even if the intervals between the modules are narrowed. It is an object of the present invention to provide a filtration device in which the filtration capacity per unit membrane area is less deteriorated even if the membrane area of the separation membrane per module is increased.

Another object of the present invention is to provide a membrane module assembly which can be easily installed in such a filtration device.

[0009]

That is, according to the present invention, in a filtration device in which a plurality of sheet-shaped separation membranes are arranged in a filtration tank so as to be substantially parallel to each other, an air diffuser is provided between the separation membranes. The filtration device is characterized in that it is arranged so as to function as a spacer for keeping the distance between the separation membranes.

Another aspect of the present invention is a membrane module assembly obtained by integrally assembling a plurality of membrane modules having a sheet-shaped separation membrane and an air diffuser, wherein the separation membranes are substantially parallel to each other. A membrane module assembly in which the membrane modules are arranged so that the air diffuser tubes function as spacers for keeping the distance between the separation membranes between the separation membranes.

[0011]

[Function] When highly polluted water is filtered through a separation membrane, a large amount of SS and organic substances are deposited on the membrane surface. Therefore, it is necessary to remove the deposits on the film surface with water, air, vibration, ultrasonic waves, etc. If not washed, organic substances and the like deposited on the membrane surface may cause clogging of the membrane, leading to a reduction in filtration life.
Therefore, air is reliably scrubbed between the membrane surfaces to ensure efficient air scrubbing, and the separation membranes do not stick or adhere to each other, so that the separation membranes in the sheet form are approximately parallel to each other. In addition to the above, the air diffuser is also disposed between the separation membranes so as to also serve as a spacer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A filtration device of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a filtration device of the present invention, and FIG. 2 is a plan view thereof. A plurality of membrane modules 2 each having a sheet-shaped separation membrane 1 are arranged in a filtration tank, and an air diffusing tube 3 is arranged between the separation membranes that are positioned substantially parallel to each other. In the present invention, the separation membrane has a certain degree of freedom of movement, and the separation membrane is not only in the case of a completely flat state but also in the case of forming a curved surface in many cases. Therefore, as is clear from the figure, that the separation membranes in the present invention are substantially parallel does not mean a perfect parallel relationship between planes, but a straight line on the surface formed by at least one separation membrane. It suffices that and a certain straight line on the surface formed by another separation film have a substantially parallel relationship. In other words, when expressed roughly, it means a positional relationship in which the separation membranes are arranged close to each other, but do not intersect or contact. In the case of this example, the vertical lines on the surface formed by each separation membrane satisfy the above relationship.

The diffusing pipe 3 is arranged not only as a pipe having an original air discharge hole but also as a spacer for keeping a constant distance between separation membranes arranged substantially in parallel. It is set up. When the separation membrane is formed as a module supported by the structural members 4 at the left and right ends as shown in FIG. 1, it is appropriate to dispose the air diffusing pipes in the direction parallel to the structural members. Usually, a plurality of air diffusing tubes are slightly longer than the length of the separation membrane per one gap between the separation membranes (the upper end of the air diffusing tube is located above the upper end of the separation membrane). It is preferably provided. Further, when a plurality of separation membranes are arranged in one module, the separation membranes tend to have a narrow interval and are easily fixed and integrated. Therefore, it is necessary to arrange a sufficient number of air diffusers. preferable.

FIGS. 3 and 4 are perspective views showing an example of a membrane module used in the filtration device of the present invention, in which the hollow fiber membrane 6 is used as a separation membrane. As can be seen from these examples, the single sheet-shaped separation membrane referred to in the present invention does not mean only a flat membrane, but an aggregate in which a large number of hollow fiber membranes are arranged in a sheet form and expanded, for example, hollow fibers. It also means a membrane knitted fabric. These hollow fiber membrane modules are configured to have a structural material 4, a fixing member 5, and a hollow fiber membrane 6.

The structural member 4 functions as a member for supporting the entire hollow fiber membrane module, has an elongated and substantially rectangular opening, and has a filtrate chamber 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.

As shown in FIG. 4, 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.
As described above, in a module of the type in which the hollow fiber membrane is bent in a U shape and used, one structural material is used. A filtrate outlet 7 is provided at one end of the structural material 4.

The opening of the structural member 4 is such that the shape of the cross section perpendicular to the hollow fiber membrane of the fixing member 5 that is filled and fixed together with the hollow fiber membrane is an elongated rectangular shape. The short side has a length of preferably 30 mm or less, particularly preferably 15 mm or less. 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. Further, even if the hollow fiber membranes are fixed to each other, the fixed portion of the hollow fiber membranes is thin and the hollow fiber membranes are arranged in a sheet shape, so that the fixed state can be easily recovered. . 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, it is difficult to manufacture. Is not desirable. Usually, the length of the long side is 100 to 2000
It is about mm.

The fixing member 5 is filled and fixed in the openings of the structural member 4, and the end portions of a large number of hollow fiber membranes 6 are converged and fixed while maintaining the open state, and these 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 5 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 6, 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. In consideration of ease of workability, a material having high strength and elongation such as polyethylene or polypropylene is preferable. The pore diameter, the porosity, the membrane thickness, the outer diameter, etc. are not particularly limited as long as they can be used as the filtration membrane.

In order to store the hollow fiber membranes 6 in a sheet shape in the elongated rectangular opening of the structural member 4, one hollow fabric or a knitted woven fabric using the hollow fiber membranes as a weft, or this knitted fabric is used. It is preferable to use a laminate in which several woven fabrics are laminated. The number of layers to be laminated varies depending on the thickness of the knitted fabric, that is, the thickness of the hollow fiber membranes and the number of yarns of the hollow fiber membranes at the time of knitting the knitted fabric. It is appropriate to meet the short side length limitation of the rectangular cross section of the member.

Although the above description has been made with reference to the example in which the hollow fiber membrane is used as the separation membrane, a separation membrane module using a flat membrane instead of the hollow fiber membrane can be similarly constructed and can be used in the present invention.

The air diffuser used in the present invention has a function of reliably feeding air between the separation membranes and at the same time providing a distance between the separation membranes to suppress contact between the separation membranes. If multiple separation membranes (or multiple hollow fiber membrane knitted fabrics if hollow fiber membranes are used) are installed in the same module, multiple air diffusers are installed between the separation membranes of the same module. Preferably. In FIG. 1, an example in which three air diffusing tubes are arranged between the hollow fiber membrane knitting fabrics of the same module, two between the hollow fiber membrane knitting fabrics of different modules, and two air diffusing tubes each outside the module are shown. Although shown, the number of air diffusers is not limited by this theory.

Since the air diffuser comes into contact with the separation membrane, the shape is preferably a circular tube without corners, and the outer diameter is preferably about 10 to 30 mm to prevent the separation membranes from sticking to each other. The structure of the holes arranged in the air diffuser is
There is no particular limitation as long as the air is uniformly applied to the separation membrane and the cleaning effect is high. As a preferable example, 0.5 to 3 m
With a diameter of about m, a diffuser hole is provided in the cross direction perpendicular to the pipe axis,
It is preferable that the air is uniformly discharged from four directions, and at least one set is located below the separation membrane so that the air diffusion holes can be applied to the entire separation membrane. Further, the air diffusing tube may be arranged outside the assembly of the separation membranes, and such an air diffusing tube is provided with diffusing holes at two positions by opening an angle of 30 to 90 ° toward the separation membrane. Is preferred.

The material of the air diffuser is polyvinyl chloride,
Examples include synthetic resins such as polycarbonate, polysulfone, polyethylene, polypropylene, acrylic resin, ABS resin, and modified PPE resin, metal, wood, etc. However, since they contact the hollow fiber, the contact part is hollow when rubbed with the hollow fiber. It is necessary to prevent the yarn from being scratched, and it is preferable to chamfer in the case of a shape with corners.
Considering the corrosion resistance and the ease of processing, synthetic resin is preferable.

The filtration apparatus of the present invention comprises a separation membrane and an air diffusing tube arranged in the filtration tank while maintaining the above-mentioned positional relationship. A plurality of membrane modules including the separation membrane and an air diffusing tube are provided. It is also possible to use a membrane module assembly in which the above are assembled to have the above-mentioned positional relationship and integrated. Conventionally, when installing a membrane module in a filtration device, it was necessary to finely align the air diffuser with the module, but when using this membrane module assembly, alignment is unnecessary, so installation in a filtration tank or the like is simple. Becomes Further, the installation of the membrane module assembly in the existing aeration tank or filtration tank can be carried out very easily.

The filtration apparatus of the present invention can be used in a pressure filtration method using a closed vessel as a filtration tank. However, a hollow fiber membrane module is installed in an activated sludge tank or a sedimentation tank to allow the hollow fiber membrane to permeate. It is preferably used in a suction filtration method in which the side for collecting the treated water is suctioned. In particular, by adopting a so-called intermittent suction operation method in which temporary suction is periodically stopped, it is possible to effectively prevent the film surface deposit from entering the inside of the film surface.

FIG. 5 is a schematic view showing an example in which the filtration device of the present invention is used as an aeration tank. The hollow fiber membrane module immersed in the liquid to be treated is sucked by the vacuum pump 10, and the treated water 13 separated and filtered by the hollow fiber membrane is collected. The membrane cleaning air is supplied from the blower 3 to the air diffusing tube 3 and is discharged from the hollow fiber membrane tube to the membrane surface, so that the membrane surface can be efficiently cleaned.

In the suction filtration method, the water to be treated outside the module may be stopped, but the water to be treated may be agitated, or the water to be treated may be flown substantially perpendicularly to the direction in which the hollow fiber membranes are arranged, thereby making It is preferable to carry out the cleaning while improving the cleaning efficiency of the membrane surface of the thread membrane.

The filtration device of the present invention is particularly suitable for the treatment of highly polluted water. Specific fields of application include solid-liquid separation in wastewater treatment, industrial wastewater treatment (solid-liquid separation), river water filtration. , Industrial tap water filtration, pool water filtration, water filtration in food industry and clarification of products, filtration of liquor, beer, wine, etc. (especially raw products), separation of cells from fermenter in pharmaceutical food, dyeing industry Of water and dissolved dyes in seawater, seawater filtration, pretreatment filtration in pure water production process (including desalination of seawater) in RO membrane, pretreatment filtration in process using ion exchange membrane, pure water using ion exchange resin Examples include pretreatment filtration in the manufacturing process.

[0030]

In the filtration apparatus of the present invention, the cleaning air is reliably applied to the separation membranes and the distance between the separation membranes is forcibly regulated, so that the accumulation of organic substances between the separation membranes is suppressed, The separation membrane is prevented from being fixedly integrated. by this,
In particular, it is possible to maintain high filtration efficiency for a long period of time in filtering highly polluted water.

When the membrane module assembly of the present invention is used, in addition to the above-mentioned effects, fine alignment between the air diffusing tube and the module as in the conventional case is unnecessary, and the installation in a filtration tank or the like is simplified.

[Brief description of drawings]

FIG. 1 is a perspective view of a filtration device of the present invention.

2 is a plan view of the filtration device of FIG. 1. FIG.

FIG. 3 is a perspective view of an example of a hollow fiber membrane module used in the filtration device of the present invention.

FIG. 4 is a perspective view of another example of the hollow fiber membrane module used in the filtration device of the present invention.

FIG. 5 is a schematic view showing an example in which the filtration device of the present invention is used as an aeration tank.

[Explanation of symbols]

 1 Separation Membrane 2 Membrane Module 3 Air Diffuser 4 Structural Material 5 Fixing Member 6 Hollow Fiber Membrane 7 Filtrate Outlet 8 Aeration Tank 9 Blower 10 Suction Pump 11 Vacuum Gauge 12 Suction Pressure Control Valve 13 Treated Water

Claims (3)

[Claims] 1. In a filtration device in which a plurality of sheet-shaped separation membranes are arranged in a filtration tank so as to be substantially parallel to each other, a diffusing tube functions as a spacer for keeping a distance between the separation membranes between the separation membranes. A filtration device characterized by being arranged so as to allow 2. The filtration device according to claim 1, wherein one sheet-shaped separation membrane comprises an assembly in which a large number of hollow fiber membranes are arranged in a sheet form and expanded. 3. A membrane module assembly in which a plurality of membrane modules having sheet-shaped separation membranes and an air diffuser are integrally assembled, and the membrane modules are arranged such that the separation membranes are substantially parallel to each other. In addition, the membrane module assembly in which the air diffuser is arranged between the separation membranes so as to function as a spacer for keeping the distance between the separation membranes.