JP3615820B2 - Membrane module - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a membrane module, and more particularly to a hollow fiber membrane module suitable for filtering a liquid having high pollution (particularly, organic pollution).
Specifically, filtration by such a membrane module includes solid-liquid separation in sewage and wastewater treatment, industrial wastewater treatment (solid-liquid separation), river water filtration, industrial water filtration, pool water filtration, water for use in the food industry, etc. Filtration and clarification of products, filtration of liquor, beer, wine, etc. (especially raw products), separation of bacterial cells from fermenters in the pharmaceutical and food industries, filtration of water and dissolved dyes in the dyeing industry, seawater filtration, RO (Reverse Osmosis) Pretreatment filtration in pure water production processes (including seawater desalination) in membranes, pretreatment filtration in processes using ion exchange membranes, pretreatment filtration in pure water production processes using ion exchange membranes, etc. Can be mentioned.
[0002]
[Prior art]
Conventionally, membrane modules have been widely used in the field of so-called microfiltration, such as the production of sterile water, drinking water and high-purity water, and air purification. In recent years, secondary and tertiary treatment in sewage treatment plants, solid-liquid separation in septic tanks, solid-liquid separation of SS (floating suspended solids) in industrial wastewater, direct filtration of river water in water treatment plants, industrial use Studies for use in highly polluted water treatment applications such as tap water filtration and pool water filtration have been conducted in various forms.
[0003]
However, the membrane modules used in these fields also have separation membranes in a circular shape or concentric shape (flat membrane spiral, flat membrane pleat, hollow fiber membrane winding, etc.) that have been used in the field of conventional microfiltration. Most of the cylindrical types were converged and arranged. Even if improvements are made, there are many cases in which only the filling rate and packing form of the separation membrane are changed.
[0004]
[Problems to be solved by the invention]
For filtration of highly polluted water (for example, SS concentration ≧ 50 ppm, TOC (total organic matter concentration) ≧ 100 ppm), a lot of SS and organic matter are deposited with the surface of the membrane or between membranes. Thus, the filtration life is reduced. Therefore, it is necessary to peel the deposits between the membrane surfaces and between the membranes using water flow, air, vibration, ultrasonic waves, etc., and to wash them.
[0005]
Such a phenomenon that the filtration life is reduced is particularly remarkable in the separation membrane at the center of the cylindrical module, and is more remarkable as the size is larger.
Therefore, for the purpose of eliminating these drawbacks, we have made hollow fiber membrane modules molded into a rectangular shape, such as Japanese Patent Application No. 04-058344, Japanese Patent Application No. 04-161322, Japanese Patent Application No. 04-161323, etc. Proposed in As an example of the manufacturing method, a method of producing a hollow fiber membrane knitted fabric, laminating it, and fixing with a resin is proposed. The same idea can also be applied to a flat membrane molded into a bag or a tubular membrane.
[0006]
In particular, these modules can exert a very large effect on the filtration of highly polluted water by using in combination with air scrubbing cleaning in which deposits on the film surface are peeled off by an upward air flow. Such cleaning between the membrane surface and the membrane may be performed continuously or intermittently depending on the progress of the membrane surface blockage.
Hollow fibers found when the number of hollow fiber membranes per module and the number of hollow fiber membrane knitted fabrics increase, and when a plurality of modules are used and the intervals between the modules are held and fixed. For SS accumulation between membrane knitted fabrics and between modules and slight decrease in filtration efficiency, spacers are inserted between hollow fiber membrane knitted fabrics and between modules, and air is emitted from there. The scrubbing air can surely hit between the membranes to prevent the membranes from sticking to each other and to prevent the deposition of SS and the reduction of the filtration efficiency.
[0007]
However, in such a system, in order to reliably apply air to the entire hollow fiber knitted fabric or between the modules, a large number of spacers must be inserted, which increases the number of parts and makes the apparatus piping system complicated or large. Was inviting.
Accordingly, the object of the present invention is to provide a hollow fiber even when used for filtration of highly polluted water, even if the separation membrane in the module is difficult to be fixed and integrated, and even if a plurality of modules are narrowed and fixed. It is an object of the present invention to provide a compact module having an aeration function in which there is no adhesion of the membrane, and even when the membrane area per module increases, the filtration capacity does not decrease.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a membrane module in which one or both ends of a separation membrane are fixed in a rectangular shape by a fixing member while maintaining an open state, and at least a membrane surface is cleaned by an air scrubbing cleaning method. There is provided a membrane module characterized by having a water collecting function at at least one end portion and having an air diffusion function at at least one end portion.
[0009]
The membrane module of the present invention having such a configuration achieves a compact module structure in which the air scrubbing method can be effectively performed.
[0010]
[Action]
To perform air scrubbing method effectively, it is necessary to apply the reliable air between the film surface and membrane. In particular, in the case of a module in which hollow fiber membrane knitted fabrics or flat membranes are arranged in parallel, the membrane is fixed or bonded by applying cleaning air between the knitted fabrics or between the flat membranes. There must be no. However, it is very difficult to precisely match the important factors such as the positional relationship between the air diffuser and the module, the aperture pitch of the air diffuser and the like on site.
[0011]
Thus, in order to apply the scrubbing air easily and reliably between the membrane surface of the hollow fiber or the flat membrane and the membrane, it can be realized by providing the water collecting pipe itself of the module with an air diffusion structure.
[0012]
【Example】
Hereinafter, the membrane module of the present invention will be specifically described.
FIG. 1 is a perspective view showing an example of a membrane module using hollow fibers among the membrane modules of the present invention. FIG. 2 is a perspective view showing another example of such a membrane module of the present invention. However, in the present invention, the form of the module is not particularly limited to these.
[0013]
The membrane module of the present invention shown in FIG. 1 and FIG. 2 includes a water collecting end 1, a diffuser end 2, a water collecting diffuser integrated end 3, fixing members 4, 5, 6, a hollow fiber membrane 7 and a diffuser. Consists of air holes 8.
The water collection end 1, the air diffusion end 2, and the water collection / air diffusion integrated end 3 basically function as members that maintain the entire hollow fiber membrane module, and have an elongated, substantially rectangular opening. Any material may be used as long as it has mechanical strength and durability. 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-based resin that can be completely burned without emitting a toxic gas during combustion.
[0014]
In addition, the opening of each of the end portions 1, 2, and 3 is a fixing member that is filled and fixed with the hollow fiber membrane therein, and is perpendicular to the hollow fiber membrane and has a substantially rectangular shape in cross section. The length of the short side of this rectangle is preferably 30 mm or less, and particularly preferably 15 mm or less. Thus, by deploying the arrangement state of the hollow fiber membrane as a flat sheet, the entire hollow fiber membrane is fixed and integrated into a single rod shape, and the effective membrane area of the hollow fiber membrane is rapidly reduced. Can be prevented. Even if the hollow fiber membranes are fixed to each other, the thickness of the fixing portion of the hollow fiber membrane is thin and the hollow fiber membrane is arranged as a sheet, so that the fixed state can be easily recovered by the above-described method. can do. The length of the long side of the rectangle is not particularly limited. However, if the length is too short, the number of hollow fiber membranes that can be disposed in one hollow fiber membrane module is reduced. Since manufacture becomes difficult, it is not preferable. In general, the length of the long side is preferably about 100 to 2000 mm.
[0015]
The diffuser end 2 has a diffuser hole 8 for discharging scrubbing air around the long side of the elongated rectangular opening, and the fixing member 5 filled in the opening is connected to the end of the hollow fiber membrane 7. Since it is fixed with the part closed, it exists as an end exclusively for air diffusion, and it reliably and easily guides scrubbing air between the membranes and between the knitted fabrics, and suppresses contact between the membranes and between the knitted fabrics. Fulfills the function.
[0016]
Like the air diffusion end portion 2, the water collection air diffusion integrated end portion 3 has an air diffusion hole 8 for discharging scrubbing air, and has an air diffusion function, and at the same time, a fixing member 6 filled in the opening. However, since the end of the hollow fiber membrane 7 is fixed in an open state, it also has a water collecting function.
Therefore, the inside of this end portion has a double structure in which a diffuser channel and a water collecting channel independently exist separately.
[0017]
As for the pitch and the structure of the air diffuser holes 8 of the air diffuser end portion 2 and the water collecting air diffuser integrated end portion 3, there is no particular limitation as long as the air uniformly hits the hollow fiber and has a high cleaning effect. Absent. As an example, it is a structure in which air diffused holes having a diameter of about 0.5 to 3 mm are provided at a pitch of 30 to 50 mm in parallel to the hollow fiber membrane knitted fabric and air is sent to the entire knitted fabric. desirable.
[0018]
FIG. 3 shows sectional views a, b, and c of the end portions 1, 2, and 3, respectively.
The fixing member 4 in FIG. 3 (a) is filled and fixed in the opening of the water collection end 1, and converges and fixes one end of a number of U-shaped hollow fiber membranes 7 while maintaining the open state. In order to make the yarn membrane function as a filtration membrane, it functions as a member for partitioning water to be treated and treated water in a liquid-tight manner.
[0019]
The fixing member 5 in FIG. 3 (b) converges and fixes one end of the hollow fiber membrane 7 in a closed state, and is filled and fixed in the opening of the air diffusion end 2. Therefore, on this end portion side, it does not have a water collecting function, and exists as a flow path for scrubbing air that exits through the air diffusion holes 8 provided in the end portion itself.
The fixing member 6 in FIG. 3C, like the fixing member 4, converges and fixes the ends of a number of U-shaped hollow fiber membranes 7 while maintaining the open state. Filled and fixed in the opening. Therefore, in this edge part, it has the double structure which can perform both water collection and aeration simultaneously with one edge part. In FIG. 4, the end part of the donut structure in which the water collection part exists in the center and the air flow path exists around it is illustrated.
[0020]
Each of these fixing members 4, 5 and 6 is usually formed by curing a liquid resin such as an epoxy resin, an unsaturated polyester resin, or polyurethane.
As the hollow fiber membrane 3, various materials can be used. For example, materials made of various materials such as cellulose, polyolefin, polyvinyl alcohol, PMMA, and polysulfone can be used. However, considering the ease of processing into a knitted fabric, a material having high elongation such as polyethylene is preferable. In addition, if a hollow fiber membrane can be used as a filtration membrane, there will be no restriction | limiting in particular in a hole diameter, a porosity, a film thickness, an outer diameter, etc.
[0021]
In order to store the hollow fiber membrane 3 in a substantially rectangular opening at each end 1, 2, 3 so as to converge in a U-shape, the hollow fiber membrane 3 is a knitted fabric using, for example, a weft as a knitted fabric. It is preferable to use a laminate obtained by laminating several sheets or knitted fabrics. In the case of the conventional cylindrical module, there was no difficulty in converging the hollow fiber membrane that has been scraped and converged into the cylindrical structural material. On the other hand, it is difficult to store a hollow fiber membrane that has been trimmed into an elongated rectangular opening, but can be easily stored using a knitted fabric. In addition, the lamination | stacking of the knitted fabric here includes what folded and piled up the appropriate length without cut | disconnecting a knitted fabric. The number of laminated (or folded) knitted fabrics varies depending on the thickness of the knitted fabric, that is, the thickness of the hollow fiber membrane and the number of combined yarns of the hollow fiber membrane when the knitted fabric is knitted. It is preferable that it is configured so as to satisfy the limitation of the length of the short side of the rectangular cross section of the fixing member described above.
[0022]
As described above, in using the hollow fiber membrane module of the present invention, a so-called pressure filtration method in which the module is disposed in a sealed container, pressurizes water to be treated, and permeates the hollow fiber membrane can be employed. It is desirable to use a suction filtration method in which a hollow fiber membrane module is disposed in an activated sludge tank, a sedimentation tank or the like as shown in FIG. 5 and the side for collecting treated water that has permeated through the hollow fiber filtration membrane is sucked. As a suction method, a method using a general self-contained suction pump, a method using a vacuum pump, a siphon method using a head difference, and the like are mainly listed. 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 film surface deposits from entering the internal pores.
[0023]
In the suction filtration method, the water to be treated outside the module may be stopped, but stirring or the water to be treated is allowed to flow substantially perpendicularly to the direction in which the hollow fiber membrane is disposed. It is preferable to carry out while increasing the cleaning efficiency of the film surface.
In the above description, the hollow fiber membrane is mainly described. However, it is obvious that the membrane module of the present invention can be similarly produced even when a flat membrane, a tubular membrane or the like is used instead of the hollow fiber.
[0024]
【The invention's effect】
The membrane module of the present invention has a water collecting function and a diffuser function at the end of the module, so that scrubbing air can be easily and reliably applied to more membranes, and organic matter is deposited between the membranes. Is suppressed, and the membranes are prevented from being fixed and integrated, and it is possible to maintain high filtration efficiency over a long period of time, particularly in the filtration of highly polluted water. In addition, since the fine alignment between the diffuser tube and the module as in the related art is unnecessary, the installation of the module is simple, and the diffuser tube having a different structure is unnecessary, so that a very compact module can be provided. Moreover, the installation of the module in an existing aeration tank or the like can be performed very simply.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a membrane module using a hollow fiber in the membrane module of the present invention.
FIG. 2 is a perspective view showing another example of a membrane module using a hollow fiber in the membrane module of the present invention.
FIG. 3 is a perspective view showing a cross-sectional view of each end of the membrane module of the present invention.
FIG. 4 is a cross-sectional view showing an example of an end portion integrated with a water collection diffuser.
FIG. 5 is a cross-sectional view showing an example of an installation form of a membrane module using a hollow fiber in the membrane module of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Water collecting end part 2 ... Air diffused end part 3 ... Water collecting air diffused integrated type end part 4 ... Water collecting end fixed member 5 ... Air diffused end fixed member 6 ... Water collecting diffused integrated type end fixed member 7 ... Hollow fiber membrane 8 ... Aeration hole

Claims (2)

Water collecting function and air diffusion function so that one end or both ends of the separation membrane are open and the shape of the cross section perpendicular to the separation membrane is substantially rectangular and the length of the long side is 100 to 2000 mm A membrane module that is fixed to an opening of a cylindrical water collection diffuser integrated end portion having a fixing member and performs membrane cleaning at least by an air scrubbing cleaning method. 2. The membrane module according to claim 1, wherein the end portion integrated with the water collection diffuser has a double-pipe structure in which flow channels for air diffusion and water collection exist independently separately.

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