Description: 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 highly polluting liquids. 2. Description of the Related Art Conventionally, hollow fiber membrane modules have been constructed using sterile water,
It has been widely used in the field of so-called microfiltration such as production of drinking water and high-purity water, and purification of air. However, recently, high pollution such as secondary and tertiary treatment in sewage treatment plants and solid-liquid separation in septic tanks has been used. Various studies have been made for use in water treatment applications. Since the hollow fiber membrane module used for such an application has a large clogging of the hollow fiber membrane at the time of the filtration process, after the filtration process for a certain period of time, the air is sent to vibrate the hollow fiber membrane and the membrane surface is vibrated. Washing and membrane surface washing such as passing treated water in the opposite direction to the filtration process are repeatedly performed.
There are many methods of cleaning the membrane surface by sending air, by installing a diffuser tube or a diffuser plate in a can or tank equipped with the module and bubbling the water from there. Was.  Using such a conventional hollow fiber membrane module, highly polluting water (for example, ss ≧ 5)
(0 ppm, TOC ≧ 100 ppm), the hollow fiber membranes are fixedly adhered (adhered) to each other via deposits such as organic substances adhered to the surface of the hollow fiber membrane during use. As a result, the effective membrane area of the hollow fiber membrane in the module was reduced, and a sharp decrease in the filtration flow rate was observed. In addition, even when the hollow fiber membrane module in which the hollow fiber membranes are fixed and integrated as described above is periodically cleaned and backwashed, it is not easy to recover the function of the module once fixed and integrated. A decrease in cleaning efficiency was observed. As a solution to this problem, a hollow fiber membrane is arranged in a sheet shape instead of a bundled cylindrical hollow fiber membrane module, and one end or both ends of the hollow fiber membrane are one or different. A hollow fiber membrane module fixed to each of the fixing members in the two housings while maintaining an open state, wherein each of the fixing members has a substantially rectangular cross section perpendicular to the hollow fiber membrane. Has been proposed (Japanese Patent Application Laid-Open No. 5-220356).  In such a sheet-shaped flat hollow fiber membrane module, the hollow fiber membranes can be arranged evenly in the inner and outer layers with a space between the layers, and the surface of the hollow fiber membrane can be cleaned when the membrane surface is cleaned. Since it is extremely easy to wash evenly, the module is suitable for filtering highly polluted water, for example, it is possible to suppress a decrease in filtration efficiency as before.  Scrubbing cleaning with air is mainly used for cleaning the film surface of such a module. At this time,
In the above-mentioned flat hollow fiber membrane module and the conventional cylindrical module, a diffuser tube or a diffuser plate is installed in a can or a membrane immersion tank, and the air bubbling uniformly hits the entire module. As described above, a method of mounting and supporting a module in a can or a tank has been adopted. However, in the case of this method, when the module is supported and fixed, it is a complicated operation to arrange the module so that the air bubbles are evenly applied to the entire module. In particular, when a plurality of flat hollow fiber membrane modules are mounted, it is necessary to uniformly apply air to all the modules, which is a more difficult operation. Also, even if the modules are properly arranged at first, each module and air diffuser may move slightly during operation, or the air flow rate may differ depending on the location of the air diffuser, etc. There is a problem that scrubbing cleaning efficiency differs in each part of the module. Further, in a flat hollow fiber membrane module using a plurality of sheet-like hollow fiber membrane knitted fabrics, the module is fixed with the sheet surface vertical in the tank and the longitudinal direction of the hollow fiber horizontal. It is important that air bubbles pass between the knitted fabrics of the hollow fiber membranes to prevent sticking of the hollow fibers between the knitted fabrics and accumulation of turbidity. There is also a problem that it is extremely difficult to arrange the air diffuser and the module in the tank so that air bubbles pass between the knitted fabrics. An object of the present invention is to provide a hollow fiber membrane module that can easily and efficiently perform a recovery process of a filtration function reduced by use even when used for filtration of highly polluted water.  The gist of the present invention is that the hollow fiber membrane is constituted by a sheet-like hollow fiber membrane knitted fabric, and one end or both ends of the hollow fiber membrane is fixed by a fixing member while maintaining an open state. ,
A hollow fiber membrane module whose cross section perpendicular to the hollow fiber membrane of the fixing member is substantially rectangular, and which is fixed to a water collecting pipe or a hollow fiber collecting end so as to be parallel to the yarn length direction of the hollow fiber membrane. And two diffuser tubes integrated with each other, the length of each diffuser tube is approximately half of the effective hollow fiber length, the distal end of the diffuser tube is closed, and a fixing portion of the diffuser tube is provided. A hollow fiber membrane module , characterized in that an air diffuser tube is arranged obliquely outward from the module toward the tip.
You. The present invention will be described below in detail with reference to the drawings.
You. Figure 1 is a flat hollow fiber membrane module using a sheet-like hollow fiber membrane knitted fabric, and the vertical sheet surface, and the hollow fiber
The horizontal direction is fixed horizontally, and a diffuser tube is provided directly below the hollow fiber membrane knitted fabric.However, two diffuser tubes with closed ends are used, and each diffuser tube is fixed by a water collecting tube, In addition, the module has an air diffuser in which the tip of the air diffuser is inclined downward. The sheet-like hollow fiber membrane 6 can be made of various materials such as cellulose, polyolefin, polyvinyl alcohol, and polysulfone, and particularly, it has a high elongation such as polyethylene and polypropylene. Higher materials are preferred. The pore diameter, porosity, film thickness, outer diameter, etc. are not particularly limited as long as they can be used as a filtration membrane. Considering the above, as a preferable example,
Pore diameter 0.01-1 μm, porosity 20-90%, film thickness 5-5
A range of 300 μm and an outer diameter of 20 to 2000 μm can be mentioned. When removing bacteria, the pore size must be 0.2 μm or less. When removing organic substances and viruses, the ultrafiltration membrane having a molecular weight cutoff of tens of thousands to hundreds of thousands is required. May be used. As the surface characteristics of the hollow fiber membrane, a so-called permanent hydrophilized membrane having a hydrophilic group or the like on its surface is desirable. As a method for producing a permanent hydrophilic membrane, a method for producing a hollow fiber membrane with a hydrophilic polymer such as a polyvinyl alcohol-based membrane,
Alternatively, a known method such as a method of hydrophilizing the surface of a hydrophobic polymer film can be used. For example, examples of the hydrophilic polymer for imparting a hydrophilic polymer to the membrane surface to hydrophilize the hydrophobic hollow fiber membrane include saponified ethylene-vinyl acetate copolymers and polyvinylpyrrolidone. . Examples of the hydrophilization of the membrane surface by another method include:
There is a film surface polymerization method of a hydrophilic monomer, and examples of this monomer include diacetone acrylamide. Further, as another method, a method of spin-forming a film by blending a hydrophilic polymer with a hydrophobic polymer (for example, polyolefin) can be mentioned, and examples of the hydrophilic polymer to be used include those described above. Can be If the surface of the hollow fiber membrane is hydrophobic, hydrophobic interaction between the organic matter in the water to be treated and the surface of the hollow fiber membrane will occur, causing organic matter to be adsorbed on the membrane surface. And the filtration life is shortened. In addition, clogging due to adsorption is generally difficult to recover filtration performance by washing the membrane surface. The use of the permanent hydrophilized membrane can reduce the hydrophobic interaction between the organic substance and the surface of the hollow fiber membrane, and can suppress the adsorption of the organic substance. Furthermore, in the scrubbing cleaning during use, the hydrophobic air causes drying and hydrophobicization due to the bubbling air, which may cause a decrease in the flux. Absent. The housing 2 functions as a member for fixing the resin-fixed hollow fiber membrane converging end, and is also a member for fixing and supporting the diffuser tube. The filtrate obtained from the end face of the hollow fiber bundle is collected and passed to the water pipe 3. Water pipe 3
Is a pipe through which the filtrate flows. The air diffuser 4 is for performing air bubbling in water in order to clean the membrane surface of the hollow fiber, and uses a pipe with a hole.
The diameter and pitch of the holes are not particularly limited, but in consideration of the module size and bubbling efficiency, the pipe diameter is 8 to
30mm, hole diameter 2-5mm, pitch 30-200
The range of mm is preferred. The housing 2, the water pipe 3, and the air diffuser 4
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 PPO resin, and polyvinyl chloride resin. In addition, a metal which does not easily corrode, such as stainless steel, can be used. The attachment jigs 5 and 5 'for fixing the diffuser tube may be any members as long as they can fix the diffuser tube, and may be stainless steel, resin, or any other material that does not easily corrode. The sheet-like hollow fiber membrane 6 is formed by knitting a hollow fiber membrane into a sheet shape, and any method can be used for producing the sheet-like hollow fiber membrane, for example, Japanese Patent Publication No. 4-26886.
It is easy to use the devices and methods described in Japanese Patent Application Laid-Open No. 63-91673 and Japanese Patent Application Laid-Open No. 63-91673. The water collecting pipe 7 functions as a member for supporting the entire flat hollow fiber membrane module, and has an elongated, substantially rectangular opening. The opening of the water collecting pipe 7 has a substantially rectangular shape in cross section perpendicular to the hollow fiber membrane of the fixing member filled and fixed with the hollow fiber membrane therein. An opening on one side of the water collecting pipe communicates with the outlet for taking out the filtrate, and the other side is closed, and the air diffuser is fixed by the air diffuser fixing part 9. In FIG . 1 , the lower end of the water collecting pipe 7 is closed and does not communicate with the air diffusing pipe 4. Although the air diffuser 4 in FIG. 1 is inclined so as to draw a curve in the drawing, the air diffuser 4 may be inclined linearly. In the module shown in FIG. 1 , when a plurality of modules are used, it is preferable to use them in parallel so that the sheet surfaces are overlapped. When using the hollow fiber membrane module of the present invention, the module is sealed. A so-called pressure filtration method in which the water to be treated is pressurized and permeated through the hollow fiber membrane can also be adopted, but a hollow fiber membrane module is disposed in an activated sludge tank or a sedimentation tank, and the hollow fiber filtration is performed. It is preferable to use the suction filtration method in which the side for collecting the treated water that has passed through the membrane is suctioned.
In particular, by adopting a so-called intermittent suction operation method in which suction is periodically stopped for a predetermined time, it is possible to efficiently prevent the membrane surface deposits from entering the internal pores. Function recovery processing frequency can be reduced. Since the air diffuser is integrated with the hollow fiber membrane module, air scrubbing is performed evenly on the entire module, and the cleaning efficiency is increased. Since the diffuser tube and the module are integrated at the time of attachment to the can body or the treatment tank, the work of arrangement and attachment becomes extremely easy, and it is not necessary to set a fine positional relationship between the diffuser tube and the module. Also,
Air scrubbing is performed properly even if the position of the module shifts from the initial position during operation. In the case of a diffuser tube having a downward slope at the center of the flat module, air scrubbing is mainly performed near the potting having the highest permeation flux in the whole module, and clogging is prevented. By suppressing clogging of this portion, a high filtration flow rate can be maintained for a long time. The one in which a diffuser tube is arranged in a plurality of flat modules is very easy to install, and air scrubbing during operation is efficiently performed on the entire module, so it can be applied to a processing tank requiring a large membrane area. . The hollow fiber membrane module of the present invention has a diffuser tube and a module integrated with each other. It is easy to attach to the processing tank, and the module and the diffuser are properly arranged. Therefore, uniform air scrubbing is performed on the entire module, and the cleaning efficiency is increased, so that clogging of the membrane surface is suppressed, and a high filtration flow rate is maintained for a long time.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing an example of the hollow fiber membrane module of the present invention. [Description of Signs] 3 water guide tube 4 diffuser tube 6 sheet-like hollow fiber membrane 7 water collector tube 9 diffuser tube fixing section 10 filtrate take-out port 11 air inlet
──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-221198 (JP, A) JP-A-5-261253 (JP, A) JP-A-63-119804 (JP, A) JP-A-4- 40221 (JP, A) JP-A-62-57965 (JP, A) JP-A-4-290529 (JP, A) JP-A-3-4983 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) C02F 1/44 B01D 61/00-65/10