JPH07299337A - Membrane module - Google Patents

Abstract

PURPOSE:To efficiently filter a liquid high in turbidity (especially turbidity of org. matter). CONSTITUTION:In a separation membrane module fixed in a rectangular form by a fixing member 2 while holding the end part of a separation membrane to an open state and performing membrane surface washing by an air scrubbing method, an air collecting plate 4 for certainly guiding rising air to a membrane from below is attached.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel 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, membrane modules have been used in many fields of so-called microfiltration such as aseptic water, drinking water, high-purity water production and air purification, but in recent years, secondary treatment in sewage treatment plants, Tertiary treatment, solid-liquid separation in septic tank, solid-liquid separation of ss (floating suspended solids) in industrial wastewater,
Various investigations have been conducted for use in highly polluted water treatment applications such as direct filtration of river water, filtration of industrial tap water, and filtration of pool water in water purification plants.

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

[0004]

Highly polluted water (for example, ss ≧ 50 pp) is obtained by using such a conventional membrane module.
m, TOC ≧ 100 ppm), the films should be adhered (bonded) and integrated with each other via 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 larger size.

The present inventors previously proposed a hollow fiber membrane module molded into a rectangular shape as shown in FIGS. 5 and 6 for the purpose of eliminating these drawbacks (Japanese Patent Laid-Open No. 5-261).
253, JP-A-6-342, JP-A-6-340, etc.). An example of the manufacturing method is to prepare a hollow fiber membrane knitted fabric, stack the fabrics, and fix them with resin. Further, the same idea can be applied to a flat membrane formed in a bag shape or a tubular ceramic membrane.

These modules have been very effective 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 used and the modules are supported and fixed with a space between them, Ss between membrane knitted fabrics and modules
Was observed, and the filtration efficiency was slightly lowered.

The object of the present invention is to prevent the separation membrane in the module from sticking and integrating even when used for filtering highly polluted water.
In addition, even if a plurality of modules are fixed at narrow intervals,
It is an object of the present invention to provide a module in which the hollow fiber membrane does not adhere and the filtration capacity does not decrease even if the membrane area per module increases.

[0009]

Means and Actions for Solving the Problems Such an object is achieved by the following inventions.

(1) In a separation membrane module in which the end portion of the separation membrane is fixed in a rectangular shape by a fixing member while keeping the opening state, and the membrane surface is cleaned by an air scrubbing cleaning method, rising air from below is used. Membrane module characterized in that an air concentrating plate is attached to securely guide air to the membrane surface.

(2) The membrane module according to (1) above, wherein the separation membrane is a hollow fiber membrane.

The present invention will be specifically described below. In the filtration of highly polluted water, many ss and organic substances are deposited on the membrane surface. 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 and the like deposited on the membrane surface 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 to flow parallel to the membrane surface, a method of causing a water flow in a membrane module immersion layer with a pump or a motor, an air scrubbing method utilizing an upward flow of air, Examples thereof include a method of vibrating the module itself and a method of vibrating the liquid to be treated with ultrasonic waves.

These washings may be carried out continuously or intermittently depending on the progress of the film surface blockage.

In the above cleaning methods, cleaning is performed by physical action. Therefore, when the hollow fiber membranes are excessively fixed and integrated with each other, the cleaning efficiency is extremely reduced. In particular, when the hollow fiber membranes stick to each other in a rod shape or when the flat membranes stick to each other completely,
Its cleaning is not easy.

The present invention proposes a module structure capable of effectively performing the air scrubbing method. In order to effectively carry out the air scrubbing method, it is necessary to reliably apply air to the film surfaces and between the films. Particularly in the case of a module in which hollow fiber membrane knitted fabrics or flat membranes are arranged in parallel, cleaning air must be surely applied between the knitted fabrics and the flat membranes.

For that purpose, the positional relationship between the air diffusing tube and the module, the pitch of the openings of the air diffusing tube, and the like are important factors, but it is very difficult to accurately match them.

The membrane module of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an example of a membrane module using a hollow fiber membrane among the membrane modules of the present invention,
FIG. 2 is a sectional view thereof. The hollow fiber membrane module of the present invention basically comprises a housing 1, a fixing member 2, a hollow fiber membrane 3, and an air concentration plate 4.

The housing 1 functions as a member for maintaining the entire hollow fiber membrane module and has an elongated, substantially rectangular opening. 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, and modified PPE resin.

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.

The opening of the housing 1 must be such that the fixing member, which is filled and fixed together with the hollow fiber membrane, has a cross section perpendicular to the hollow fiber membrane that is elongated and substantially rectangular. The length of the short side of this rectangle is preferably 30 mm or less, and particularly preferably 15 mm or less.

In this way, the hollow fiber membranes are arranged in the form of a flat sheet so that the entire hollow fiber membranes are fixedly integrated into a single rod, and the effective membrane area of the hollow fiber membranes is rapidly increased. It can be prevented from falling. Even if the hollow fiber membranes are fixed to each other, the fixing 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 by the above-mentioned method. be able to.

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, while if it is too long, the production is too long. It is difficult because it is difficult. Usually, the length of the long side is about 100 to 2000 mm.

The fixing member 2 is filled and fixed in the opening of the housing 1, and the ends of a large number of U-shaped hollow fiber membranes 3 are converged and fixed while keeping the open state. 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 2 is usually formed by curing a liquid resin such as epoxy resin, unsaturated polyester resin, polyurethane or the like.

As the hollow fiber membrane 3, 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. However, considering the ease of processing into a knitted fabric, a material having a high strength and elongation such as polyethylene is preferable. The pore diameter, porosity, film thickness, outer diameter, etc. are not particularly limited as long as they can be used as a filtration membrane.

In order to store the hollow fiber membranes 3 in a U-shaped configuration in a long and narrow rectangular opening of the structural member 1, one piece of knitted woven fabric using the hollow fiber membranes as wefts, Alternatively, it is preferable to use a laminate in which several knitted fabrics are laminated. In the case of the conventional cylindrical module, there was no difficulty in accommodating the hollow fiber membranes that have been collected and converged in the cylindrical structural material.

On the other hand, it is difficult to store the hollow fiber membrane stripped in the elongated rectangular opening, but it can be easily stored if a knitted fabric is used. The layering of the knitted fabric referred to here includes a knitted fabric that is folded and stacked to an appropriate length without being cut. Lamination of knitted fabrics (folding)
The number of sheets varies depending on the thickness of the knitted fabric, that is, the thickness of the hollow fiber membrane and the number of yarns of the hollow fiber membrane when knitting the knitted fabric, but it is usually up to about 5 sheets, and It is preferable that the rectangular cross section is configured so as to satisfy the limitation of the length of the short side.

When a plurality of hollow fiber membrane knitted fabrics are used per module, the air concentrating plate 4 surely introduces air between the knitted fabrics and suppresses the contact between the knitted fabrics.
In FIG. 1, a corrugated plate-shaped air concentrating plate with slits is illustrated, but the shape of the air concentrating plate is not limited to this, and the funnel-shaped, perforated plate, grooved plate, etc. as shown in FIG. Various shapes can be used.

Examples of the material of the air concentrating plate include polyvinyl chloride, polycarbonate, polysulfone, polyethylene, polypropylene, acrylic resin, ABS resin, synthetic resin such as modified PPE resin, metal, wood, fiber and the like.

The air concentrating plate basically does not come into contact with the hollow fiber membranes, but in the case of contact with the hollow fiber membranes, it is necessary that the hollow fiber membranes are not scratched when they rub against the hollow fiber membranes. If there is a corner, it is necessary to chamfer. Considering the corrosion resistance and the ease of processing, it is desirable to use a synthetic resin.

When the hollow fiber membrane module of the present invention is used, a so-called pressure filtration method in which the module is placed in a closed container and the water to be treated is pressurized to permeate the hollow fiber membrane can be used, but FIG. It is desirable to arrange the hollow fiber membrane module in an activated sludge tank or a sedimentation tank as shown in (3) and use it in a suction filtration method in which the side for collecting the treated water that has permeated the hollow fiber filtration membrane is sucked.

In particular, the suction is periodically stopped for a predetermined time,
By adopting the so-called intermittent suction operation method, it is possible to efficiently prevent the film surface deposits from entering the internal pores.

The water to be treated outside the module may be stopped when performing suction filtration, but the agitating or the water to be treated is caused to flow substantially perpendicularly to the direction in which the hollow fiber membrane is arranged, and the hollow fiber It is preferable to carry out the cleaning while improving the cleaning efficiency of the film surface of the film.

[0035]

EFFECTS OF THE INVENTION In the hollow fiber membrane module of the present invention, by effectively using the air concentration plate, more hollow fiber membranes come into direct contact with the cleaning air, so that the accumulation of organic substances between the hollow fiber membranes is suppressed. It is possible to prevent the hollow fiber membranes from being fixedly integrated with each other, and particularly in the filtration of highly polluted water, it is possible to maintain a high filtration efficiency for a long time. Further, since fine alignment between the air diffuser and the module is not required, the module can be installed easily, and the module can be installed in an existing aeration tank or the like very easily.

The membrane module of the present invention is used for 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 the food industry and the like. Clarification filtration of products, filtration of liquor, beer, wine, etc. (particularly raw products), separation of bacterial cells from fermenters in pharmaceuticals, foods, etc., filtration of water and dissolved dyes in the dyeing industry, seawater filtration, pure water in RO membranes It is effectively used for pretreatment filtration in a production process (including seawater desalination), pretreatment filtration in a process using an ion exchange membrane, pretreatment filtration in a pure water production process using an ion exchange resin, and the like.

[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 module of FIG.

FIG. 3 is a perspective view showing a shape example of an air concentration plate.

FIG. 4 is a cross-sectional view showing an example of the installation form of the hollow fiber membrane module with an air concentrating plate of the present invention.

FIG. 5 is a perspective view showing an embodiment of a hollow fiber membrane module molded into a rectangle.

FIG. 6 is a perspective view showing another mode of the hollow fiber membrane module molded into a rectangle.

[Explanation of sign]

 1 Housing 2 Fixing Member 3 Hollow Fiber Membrane 4 Air Concentration Plate 5 Outlet

Claims (2)

[Claims] 1. A separation membrane module in which a separation member is fixed in a rectangular shape while keeping an end portion of the separation membrane open and a membrane surface is cleaned by an air scrubbing cleaning method. Membrane module characterized in that an air concentration plate for surely guiding it to the membrane surface is attached. 2. The membrane module according to claim 1, wherein the separation membrane is a hollow fiber membrane.