JP2011005361A - Membrane filtration apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filtration treatment method capable of reducing the twining of residue to a hollow yarn membrane and performing a stable filtration.SOLUTION: The method of filtering water to be treated is carried out using a hollow yarn membrane module having a plurality of the hollow yarn membranes having an upper part and a lower part respectively fixed to an upper part housing and a lower part housing having a diffusing gas introducing port with a potting agent, wherein the lower end part of the hollow yarn membrane is fixed around the diffusing gas introducing port in an inclination toward the outside from the diffusing gas introducing port. The upper end part of the hollow yarn membrane is exposed on the water surface of the water to be treated, bubbles are supplied from the diffusing gas introducing port into the bundle of the hollow yarn membrane, the water is collected from the upper part housing, and the upper end part of the hollow yarn membrane is coated at least in the area exposed on the water surface of the water to be treated.

Description

  The present invention relates to a filtration method.

  Conventionally, many membrane separation techniques have been used for producing aseptic water, drinking water, highly pure water, purifying air, and the like. In recent years, in addition to these applications, for the treatment of highly polluted water, such as secondary and tertiary treatment in sewage treatment plants, solid-liquid separation in septic tanks, and solid-liquid separation of suspended solids in industrial wastewater. It has come to be used.

  In particular, as a treatment for highly polluted water, a method in which a separation membrane is immersed in activated sludge and bubbling from below is performed, and aerobic treatment with microorganisms and cleaning of the separation membrane are simultaneously attracting attention. This method has an advantage that good separation is possible regardless of the sedimentation property of sludge, and the treatment efficiency per volume can be increased by increasing the MLSS concentration.

  As a problem when the hollow fiber membrane module is used for wastewater treatment such as actual human waste treatment, entanglement of very fine fibrous debris in the wastewater with the hollow fiber membrane can be mentioned. A large amount of this residue is removed by pretreatment or the like, but a very small residue that cannot be completely removed by pretreatment is entangled with the hollow fiber membrane, thereby coarsening the hollow fiber membrane. Once the scum is entangled, it is difficult to remove, and the stagnation of the scum gradually accumulates, and sludge adheres and accumulates at the core. The accumulated sludge becomes a lump and blocks between the hollow fiber membranes, resulting in an increase in the filtration differential pressure. Therefore, it may be difficult to use the hollow fiber membrane in waste water.

  Here, since the entangled residue can move along the hollow fiber membrane, the residue adhered to the hollow fiber membrane can be used as long as it has a structure capable of imparting a high water flow toward the unconstrained end portion of the hollow fiber membrane. It is possible to reduce the entanglement and return to a state where it can be operated again.

  Therefore, as disclosed in Patent Document 1 and Patent Document 2, a module has been developed that has a water collection structure in the lower part and a shape in which one end is a free end.

Japanese Patent No. 3918304 JP 2006-142303 A

  In modules such as those described in Patent Documents 1 and 2, when the flexibility of the membrane is increased to increase the oscillating property of the hollow fiber membrane, or the length of the hollow fiber membrane is increased to improve the degree of integration. In some cases, the self-supporting property of the membrane is impaired, and the membrane is warped in the module or in a unit in which they are assembled, causing problems such as entanglement with each other. In order to prevent entanglement between membranes, improvements such as arranging support members along the longitudinal direction of the membrane have been made, but if new problems arise, such as the need to prevent friction between the membrane and the support was there.

  Then, this invention is made | formed in view of the above situation, It aims at providing the filtration processing method which can reduce the entanglement of the residue to the hollow fiber membrane, and can perform the stable filtration process. To do.

Therefore, the first aspect of the present invention is
The upper end portion and the lower end portion of the plurality of hollow fiber membranes are respectively fixed to the upper housing and the lower housing having the diffuser introduction port with a potting agent, and the lower end portion of the hollow fiber membrane is around the diffuser introduction port. , A method of filtering water to be treated using a hollow fiber membrane module, which is inclined outwardly from the aeration inlet and fixed with a potting agent,
The upper end of the hollow fiber membrane is exposed on the water surface of the water to be treated, and water is collected from the upper housing while supplying air bubbles from the diffuser inlet into the bundle of hollow fiber membranes,
The upper end portion of the hollow fiber membrane is a filtration method in which at least a range exposed on the surface of the water to be treated is coated.

The second aspect of the present invention
The upper end portion and the lower end portion of the plurality of hollow fiber membranes are respectively fixed to the upper housing and the lower housing having the diffuser introduction port with a potting agent, and the lower end portion of the hollow fiber membrane is around the diffuser introduction port. , A method of filtering water to be treated using a hollow fiber membrane module, which is inclined outwardly from the aeration inlet and fixed with a potting agent,
A filtration method for collecting water from the lower housing while exposing an upper end portion of the hollow fiber membrane on the surface of the water to be treated, and supplying air bubbles from the diffuser inlet into the bundle of hollow fiber membranes. It is.

  By the filtration treatment method of the present invention, tangling of the residue to the hollow fiber membrane can be reduced, and stable filtration treatment can be performed.

In schematic sectional drawing ((a-1), (b-1)) and schematic external view ((a-2), (b-2)) for demonstrating the structural example of the hollow fiber membrane module used for this invention. is there. It is a schematic sectional drawing for demonstrating the structural example of the lower housing of the hollow fiber membrane module used for this invention. It is a schematic sectional drawing for demonstrating the structural example of the upper housing of the hollow fiber membrane module used for this invention. It is the schematic for demonstrating the concept of the angle of a hollow fiber membrane and the potting part surface. It is a figure for demonstrating the structural example of the hollow fiber membrane module used for this invention, (a) is a schematic sectional drawing of a transversal direction, (b) is a schematic external view of a longitudinal direction. It is a general | schematic process drawing for demonstrating the method to manufacture the hollow fiber membrane module used for this invention using a hollow bag. It is a figure which shows the structural example of a cylindrical lower housing. It is a figure which shows the structural example of a rectangular lower housing. It is a schematic sectional drawing for demonstrating embodiment of 1st this invention. It is a schematic sectional drawing for demonstrating embodiment of 2nd this invention. It is a schematic sectional drawing for demonstrating embodiment of 1st this invention. It is a figure for demonstrating embodiment of this invention.

  In the hollow fiber membrane module used in the first aspect of the present invention, the upper end portion and the lower end portion of the plurality of hollow fiber membranes are respectively fixed to the upper housing and the lower housing having the aeration inlet with a potting agent. Further, at least the lower end portion of the hollow fiber membrane is fixed to the periphery of the air diffusion inlet with a potting agent inclined outward from the air diffusion inlet. The upper end of the hollow fiber membrane is coated with a coating agent.

  Further, according to the first aspect of the present invention, the upper end of the hollow fiber membrane is exposed on the surface of the water to be treated, and water is collected from the upper housing while air bubbles are supplied into the bundle of hollow fiber membranes from the air diffusion inlet. . Also, the coated portion of the hollow fiber membrane is exposed on the water surface.

  In the hollow fiber membrane module used in the present invention, at least the lower end portion of the hollow fiber membrane is arranged around the air diffusion inlet, and is inclined outward from the air diffusion inlet and fixed by a potting agent, A space can be provided in the bundle of hollow fiber membranes. This space is particularly easily formed during operation, and the presence of the space can improve the cleanability. More specifically, when air bubbles enter from the diffuser introduction port provided in the housing during cleaning or operation, the air bubbles rise in the space and pass through the hollow fiber membrane bundle, and the outside of the hollow fiber membrane module. Go out to. A large water flow is generated by the flow of bubbles, and deposits can be prevented from adhering to the hollow fiber membrane, or adhering deposits can be washed.

  Further, the hollow fiber membrane module used in the present invention is excellent in durability without tension being concentrated on a short hollow fiber membrane caused by length variation. Further, since the hollow fiber membrane is fixed with a potting agent with an inclination in advance, bending near the root of the hollow fiber membrane can be prevented, and membrane damage can be suppressed. In addition, since the hollow fiber membrane is disposed so as to be inclined outward in the vicinity of the air diffusion inlet, damage due to the spread of the hollow fiber membrane accompanying the diffusion of the air diffusion can be prevented.

  The hollow fiber membrane module used in the present invention can be provided with a space inside the hollow fiber membrane bundle as described above, and the hollow fiber can be provided by supplying bubbles from the air diffusion inlet provided in the lower housing into the space. The space between the membranes can be widened, and the internal space can be widened. The internal space becomes narrower as it approaches the surface of the upper potting portion, and the distance between the hollow fiber membranes becomes particularly narrow near the surface of the upper potting portion. For this reason, a residue or the like that is caused to flow by the water flow generated by bubbles may be easily entangled near the surface of the upper potting portion.

  Therefore, in the present invention, by providing a space between the surface of the upper potting portion and the water surface, the residue or the like is prevented from flowing to the vicinity of the surface of the upper potting portion where the distance between the hollow fiber membranes is narrow. As a result, the water to be treated flows through the portion where the interval between the hollow fiber membranes is widened, and the entanglement of the residue on the hollow fiber membrane can be reduced.

  In the first aspect of the present invention, water is collected from the upper housing, but the upper end portion of the hollow fiber membrane exposed on the water surface is coated, so that air is not sucked.

  In the second aspect of the present invention, water is collected from the lower housing. In this case, air is hardly sucked even if the exposed upper end is not coated. Therefore, in the second aspect of the present invention, the upper end portion of the hollow fiber membrane does not need to be coated.

  First, the structure of the hollow fiber membrane module used by this invention is demonstrated in detail.

(housing)
The housing functions as a member that supports the hollow fiber membrane and collects the filtrate filtrated by suction inside the hollow fiber membrane. The housing may be made of, for example, a metal such as stainless steel or steel, a resin such as a fluororesin, an ABS resin, a polyolefin resin, or a vinyl chloride resin.

  The lower housing is provided with an air diffusion inlet for introducing bubbles into the space in the hollow fiber membrane bundle. The shape, size, or number of the air introduction ports can be selected as appropriate.

  The diffuser inlet is preferably provided at the center or the center of the cross section of the lower housing. The shape of the housing is not particularly limited, and examples thereof include a rectangular shape, a cylindrical shape (columnar shape), a spherical shape, a conical shape, and a pyramid shape. For example, when the shape of the housing is a cylindrical shape, the air diffusion inlet can be provided in the central portion so as to penetrate the housing, and the hollow fiber membrane is disposed around the air diffusion inlet. For example, when the shape of the housing is rectangular, a plurality of air diffusion inlets may be provided at equal intervals in the longitudinal direction along the center line of the cross section in the short direction, or may be provided over the entire length in the longitudinal direction. Moreover, it is preferable that the air diffusion inlet is formed as a part of the housing.

  A potting recess for inserting a distal end portion of the hollow fiber membrane and fixing with a potting agent is provided in the lower housing provided with the air diffusion inlet. FIG. 7 shows a configuration example of a cylindrical lower housing. 7A is an upper view, and FIG. 7B is a cross-sectional view taken along the line AA ′ in FIG. 7A. As in the example shown in FIG. 7, the lower housing has a diffuser introduction port 8 in the center, and has a potting recess 11 around which a hollow fiber membrane is fixed. It is preferable that the housing having such a diffuser introduction port is integrally formed because it can be manufactured in large quantities at a low cost. An example of a rectangular lower housing is shown in FIG. 8A is an upper view, and FIG. 8B is a cross-sectional view taken along the line BB ′ in FIG. 8A. As a rectangular lower housing, as shown in FIG. 8, a structure having a diffuser introduction port 8 along the longitudinal direction at the center in the short direction is given as an example.

  The air diffuser for generating bubbles is generally provided below the hollow fiber membrane module.

(Hollow fiber membrane)
In the hollow fiber membrane module, at least the lower end portion of the hollow fiber membrane is fixed to a housing having an air diffusion inlet, and as shown in FIG. 2, the hollow fiber membrane is fixed while being inclined outward from the air diffusion inlet. As described above, the air diffusion inlet is preferably provided along the center line of the cross section of the housing. In this case, a hollow fiber membrane is disposed around the air diffusion inlet. With such a configuration, a space can be preferably created between the hollow fiber membranes.

  In addition, the hollow fiber membrane is preferably fixed to the upper housing so as to be inclined in the outer peripheral direction with respect to the surface of the upper potting portion. That is, as shown in FIG. 3, the hollow fiber membrane 2 is preferably fixed while being inclined outward from the center or cross-sectional center of the upper housing 3 (or the upper potting portion 5).

  The hollow fiber membrane of the present invention can be used without particular limitation as long as it can be used as a filtration membrane. For example, a porous membrane having a predetermined pore diameter can be used.

  As the hollow fiber membrane, for example, cellulose-based resin, polyolefin-based resin, polyvinyl alcohol-based resin, polysulfone-based resin, polyacrylonitrile-based resin, fluorine-based resin, or any other material that can be molded into the shape of a separation membrane. Can be formed from More specifically, for example, a polyethylene resin, a polypropylene resin, a polyvinylidene fluoride resin, a polytetrafluoroethylene resin, a polysulfone resin, or the like can be given. In particular, as the surface characteristics of the porous membrane, it is preferable to use a highly hydrophobic resin, more preferably a fluororesin. Among the fluororesins, it is more preferable to use vinylidene fluoride resin from the viewpoint of formability to the film and chemical resistance. Here, examples of the vinylidene fluoride resin include a homopolymer of vinylidene fluoride and a copolymer of vinylidene fluoride and a monomer copolymerizable with vinylidene fluoride. Examples of the copolymerizable monomer include vinyl fluoride, tetrafluoroethylene, ethylene trifluoride, and hexafluoropropylene.

  Moreover, as long as it can be used as a filtration membrane, the pore diameter, porosity, film thickness, outer diameter and the like are not particularly limited, but are appropriately selected depending on what is to be filtered. Specific types of pore diameters may be separation membranes such as microfiltration membranes (MF), ultrafiltration membranes (UF), and nanofiltration membranes (NF). Furthermore, in order to remove organic substances and viruses, an ultrafiltration membrane having a molecular weight cut off of tens of thousands to hundreds of thousands may be used.

  The porous membrane has a plurality of pores, and the pores are preferably continuous pores penetrating the front and back surfaces of the hydrophobic porous membrane. The pore diameter can be arbitrarily selected depending on the purpose, but for example, it is suitably 0.01 to 5 μm, preferably 0.1 to 1 μm. The porous membrane having hydrophobicity preferably has an asymmetric structure in which the pore diameter on one surface is small and the pore diameter on the other surface is large. In the case of an asymmetric structure, it is appropriate that the pore diameter of one surface is 1 to 100 times, preferably 2 to 10 times the pore diameter of the other surface.

The outer diameter of the hollow fiber membrane is, for example, 0.1 to 10 mm, preferably 0.5 to 5 mm. The hollow fiber membrane of the present invention has a pure water permeability coefficient indicating liquid permeation performance with respect to pure water of 10 to 250 m ³ / m ² / hr / MPa, preferably 20 to 150 m ³ / m ² / hr / MPa. Is appropriate. In addition, a pure water permeability coefficient can be calculated | required from the following formula | equation.

Pure water permeability coefficient = [pure water permeation amount (m ³ )] / [surface area of porous membrane (m ² )] / [permeation time (hr)] / [pure water pressure (MPa)]

As for the strength of the material, the strength against external force is preferably about 300 to 700 g / mm ² . Further, since it is difficult to use if it is brittle, it preferably has an elongation of about 30 to 90%. The hollow fiber membrane shape surface preferably has a film thickness of about 10 to 30% with respect to the outer diameter of the hollow fiber membrane. However, the strength, film thickness, and the like are not particularly limited as long as the swingability is not impaired.

  It is preferable that the hollow fiber membrane has sufficient strength and flexibility in order to swing smoothly. The hollow fiber membrane may be fixed as a knitted fabric.

  The hollow fiber membrane 2 is preferably fixed while being inclined in a symmetric direction with respect to the air inlet. Further, from the viewpoint of enhancing the washability of the hollow fiber membrane and improving the durability, the angle formed by the hollow fiber membrane and the surface of the potting part (a in FIG. 4) is preferably in the range of 45 to 85 °. More preferably, it is in the range of 55-80 °. If it is fixed at an angle of about 90 ° as in the past, suspended substances are likely to accumulate on the hollow fiber membrane near the potting surface, and the performance of the hollow fiber membrane module may be reduced by prolonged operation. There is. Moreover, by setting it as 45 degrees or more, it can prevent that a bubble hits the fixing part vicinity of the hollow fiber membrane 2 excessively, and it is easy to prevent the strength reduction of a hollow fiber membrane. By setting it to 85 ° or less, it is possible to more effectively provide a space inside the hollow fiber membrane bundle.

(Potting part)
The potting of the hollow fiber membrane is not particularly limited, but a stationary method can be used as in the production of a general hollow fiber membrane module. The fixing method is preferably a method that does not impair the oscillating property of the hollow fiber membrane.

  For example, in the potting part, the hollow fiber membranes are bonded and fixed using, for example, an epoxy resin or a urethane resin as a potting agent. It is preferable to use a urethane-based resin as the potting agent. A urethane-based resin is soft even after curing and can be easily cut, thereby facilitating subsequent operations. Further, the potting part may be formed by fixing the space between the hollow fiber membranes together with the potting agent in the mold, and removing the mold after curing. The hollow fiber membrane may be bonded and fixed in a fixing member prepared in advance. The presence or absence of the fixing member is not particularly limited.

(Coating agent)
As described above, in the hollow fiber membrane module used in the first aspect of the present invention, the upper end portion of the hollow fiber membrane is coated at least on the surface of the water to be treated. This coating prevents air from being sucked even when water is collected from the upper housing.

  The coating agent is not particularly limited as long as it forms an impermeable portion of the hollow fiber membrane and can prevent adhesion between the membranes. Among them, a silicon resin or a fluorine resin is preferable from the viewpoint of preventing dirt, and a silicon resin is more preferable.

  Moreover, since it is not preferable that the hollow fiber membranes are adhered to each other by the coating agent at the time of application of the coating agent, the coating agent is preferably dispersed in a solvent having high diffusibility. As the solvent, for example, aromatic hydrocarbon solvents such as toluene, ketone solvents such as acetone, ester solvents such as ethyl acetate, ether solvents such as cellosolve, nitrile solvents such as acetonitrile, and the like are known. .

  Examples of the type of coating agent include an ultraviolet curable type, a thermosetting type, and an aerosol type, and these may be used as a method for increasing the drying speed for forming the coating layer on the surface of the hollow fiber membrane.

(Embodiment 1)
Hereinafter, in Embodiment 1, the hollow fiber membrane module used for this invention is demonstrated with reference to FIG.

  FIG. 1 is a schematic cross-sectional view ((a-1), (b-1)) and schematic external views ((a-2), (b-) for explaining a configuration example of a hollow fiber membrane module used in the present invention. 2)). 1A shows a form in which the upper and lower housings are cylindrical, and FIG. 1B shows a form in which the upper and lower housings are rectangular. In the first aspect of the present invention, the upper end portion of the hollow fiber membrane needs to be coated, but the coating portion is not shown in the drawing.

  In the hollow fiber membrane module 1, for example, hundreds to tens of thousands of hollow fiber membranes 2 are fixed to the upper housing 3 and the lower housing 4.

  FIG. 2 shows an enlarged cross-sectional view near the lower housing 4. The lower housing 4 in FIG. 2 has a donut shape and has a diffuser introduction port 8 in the center. In the lower housing 4, the hollow fiber membrane is fixed by the lower potting portion 6 with its end face closed. The hollow fiber membranes 2 are arranged so as to face each other around a perpendicular passing through the center of the lower housing 4, and are fixed to the outer peripheral direction with respect to the potting surface of the lower housing 4. That is, the hollow fiber membrane 2 is arranged around the air diffusion inlet, and is fixed while being inclined outward from the air diffusion inlet 8 of the lower housing 4. Moreover, the hollow fiber membrane 2 is inclined and fixed in a symmetric direction with respect to the air diffusion inlet (see FIG. 2). The air diffusion inlet 8 is formed so as to penetrate the lower housing 4 and the lower potting portion 6. In FIG. 2, the hollow fiber membrane 2 is closed by the lower potting portion 6, but in the second aspect of the present invention, the hollow fiber membrane 2 is opened without being closed by the lower potting portion 6.

  Moreover, the formation method of the air diffusion inlet 8 is not particularly limited, and can be formed integrally with the constituent members of the lower housing as shown in the figure, for example. Moreover, after fixing a hollow fiber membrane to a lower housing, it can also form by making a through-hole in the center of a potting part and a lower housing.

  FIG. 3 shows an enlarged cross-sectional view near the upper housing 3. In the upper potting portion 5, the end surface of the hollow fiber membrane 2 is open and fixed in a liquid-tight manner in communication with the inside of the upper housing 3. The upper housing 3 in FIG. 3 has a cylindrical outer shape, has an upper potting portion 5 inside, and further has a water collection port 7 for collecting the filtrate filtered by the hollow fiber membrane 2. The hollow fiber membrane 2 is fixed while being inclined in the outer peripheral direction with respect to the potting surface of the upper housing 3. That is, the hollow fiber membrane 2 is fixed while being inclined outward from the center of the upper housing 3 (or the upper potting portion 5). Further, for example, in FIG. 3, the hollow fiber membranes 2 are disposed so as to face each other around a perpendicular passing through the center of the upper housing 8. The hollow fiber membrane 2 is fixed so as to be inclined in a symmetric direction with respect to a vertical line passing through the center of the upper housing.

  Note that the shape of the upper housing 3 or the lower housing 4 is not particularly limited, and may be any shape such as a rectangle, a cylinder (columnar), a sphere, a cone, or a pyramid. For example, when a cylindrical thing (horizontal direction is circular) is selected as a housing, the side view of the completed hollow fiber membrane module is as shown in FIG. Further, for example, when a rectangular or cylindrical shape is selected as the housing, the side view of the hollow fiber membrane module is as shown in FIG.

  In this hollow fiber membrane module, air bubbles enter the space provided in the bundle of hollow fiber membranes from the air diffusion inlet, and a large water flow can be generated by the flow of the air bubbles. The deposits can be prevented or adhered deposits can be cleaned.

  The relaxation rate of the hollow fiber membrane is, for example, [(LD) / D] × 100 (where L: length of the hollow fiber membrane between the upper potting portion 5 and the lower potting portion 6, D: upper potting) The distance between the portion 5 and the lower potting portion 6). For example, in the case of a membrane module that is used under conditions where the turbidity of raw water is high, the relaxation rate is set to a large value, and the vibration of the hollow fiber membrane during air scrubbing is increased to adhere to the surface of the hollow fiber membrane. It is preferable to make the suspended substance easy to peel off.

  In the present embodiment, the relaxation rate is preferably in the range of 5% to 20% from the viewpoint of preventing clogging starting from the residue in wastewater treatment including fibrous matter such as residue. More preferably, it is about 10%. As the shape of the hollow fiber membrane bundle, a bundle shape in which the ends are opened by cutting the frame, or as disclosed in, for example, Japanese Patent Laid-Open Nos. 62-57965 and 1-266258, is disclosed. Examples thereof include knitted fabrics.

(Embodiment 2)
In the present embodiment, a hollow fiber membrane module used in the second invention will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view ((a-1), (b-1)) and a schematic external view ((a-2), for explaining a configuration example of a hollow fiber membrane module used in the second present invention. (B-2)). 5A shows a form in which the upper and lower housings are cylindrical, and FIG. 5B shows a form in which the upper and lower housings are rectangular. 1 is different from the hollow fiber membrane module shown in FIG. 1 in that the water collecting port 7 is provided in the lower housing 4 and the lower end portion of the hollow fiber membrane is opened.

  In the hollow fiber membrane used in the second aspect of the present invention, water is collected from the lower housing 4 so that the lower end portion of the hollow fiber membrane 2 is opened and fixed to the lower potting portion 6.

  When collecting water from the lower housing, it is not necessary to coat the portion of the hollow fiber membrane that comes out on the water surface.

(Embodiment 3)
In this embodiment, an immobilization method using a hollow bag in the hollow fiber membrane module used in the present invention will be described with reference to FIG. By using the hollow bag, the hollow fiber membrane module of the present invention can be easily produced.

  FIG. 6 is a process diagram for producing the hollow fiber membrane module described in Embodiment 1 using a hollow bag.

  First, the hollow fiber membrane is disposed around the diffuser inlet 8 at the lower housing 4 at the lower end of the hollow fiber membrane. Further, the upper end portion of the hollow fiber membrane is disposed in the upper housing 3. In addition, a hollow bag in a deflated state is loaded in the space formed between the hollow fiber membranes 2 and above the diffuser introduction port 8 (FIG. 6A).

  Next, the hollow bag is inflated, the hollow fiber membrane 2 is pushed outward with the hollow bag, and the outer side is inclined. Further, in this state, the hollow fiber membrane and the housing are fixed with a potting agent.

  As shown in FIG. 6 (a), the potting agent is preferably injected when the hollow fiber membrane is disposed. However, the potting agent is injected after the hollow bag 9 is inflated to incline the hollow fiber membrane. May be. The potting agent is cured with the hollow fiber membrane tilted outward.

  The hollow bag preferably has a relatively small thickness when contracted. This is because the potting agent is used after being expanded but must be removed after the potting agent is solidified.

  By using the hollow bag, the hollow fiber membrane can be easily inclined at a constant angle with respect to the potting surface, and the relaxation rate can be made uniform.

  The hollow bag can be appropriately selected depending on the gap shape to be formed inside the hollow fiber membrane bundle 2. For example, a suitable shape such as a sheet shape or a columnar shape may be used at the time of expansion.

  Further, the material is not particularly limited, but generally nylon, fluororubber, natural rubber, latex and the like can be mentioned. Further, the means for expanding is not particularly limited, but it is necessary to contract at the time of removal, and examples thereof include air, liquids such as nitrogen, inert gases, and water.

  In particular, if it is an air-injection type, 3M Co., Ltd. air-injection cushioning material Air cushion bag (ACP) “trade name” or Kawakami Sangyo Co., Ltd. It is done.

  The hollow bag has only to be of a size that can be inflated so that at least the hollow fiber membrane fixed end portion on the lower housing side where the air diffusion inlet 8 is formed is inclined outward, and the hollow fiber membrane fixed By inflating to the maximum width near the center of both end portions, both end portions of the upper and lower housings can be tilted outward and fixed. The size of the hollow bag is preferably about 80% of the total length of the hollow fiber membrane when expanded, for example.

  When the hollow bag is installed, in order to maintain the dispersibility of the hollow fiber membrane, a guide or a non-adhesive tape may be provided on the hollow bag, thereby constraining the outer peripheral portion of the hollow fiber membrane bundle.

  The angle of the surface of the hollow fiber membrane and the potting part (a in FIG. 4) can be adjusted by adjusting the shape of the hollow bag and the degree of swelling, for example.

(Embodiment 4)
In the present embodiment, the first aspect of the present invention will be described with reference to FIG.

  In FIG. 9, the plurality of hollow fiber membrane modules 1 are connected to a water collection header pipe 13, and a filtration pump or the like is connected to the water collection header pipe 13. The treated water filtered through the hollow fiber membrane is collected and collected in the water collection header pipe 13 via the upper housing 3. The hollow fiber membrane module 1 is connected to the water collection header pipe 13 through the water collection port 7 in the upper housing 3. By setting it as such a structure, it is easy to pull up the hollow fiber membrane module 1 by maintenance etc.

  When the hollow fiber membrane module 1 is arranged in the membrane immersion water tank, the upper end portion of the hollow fiber membrane 2 is exposed above the surface of the water to be treated. When aeration is performed, the water surface rises due to the aeration. In this case, the hollow fiber membrane module 1 is arranged so that the upper end of the hollow fiber membrane bundle 2 is exposed above the raised water surface. The length of the hollow fiber membrane bundle exposed on the water surface (distance from the surface of the potting portion of the upper housing to the water surface) is not particularly limited, but the tangling of the residue to the hollow fiber membrane is reduced and stable. From the viewpoint of performing the filtration treatment, 8 mm to 300 mm is preferable and 20 mm to 100 mm is more preferable when the aeration is stopped.

  Bubbles released from the air diffuser flow along the hollow fiber membrane bundle 2 outside the hollow fiber membrane module, and part of the air bubbles are introduced into the hollow fiber membrane module from the air inlet 8 in the lower part 4 of the lower housing. Enter and rise toward the surface of the water. In the present invention, by exposing the upper end portion of the hollow fiber membrane bundle on the water surface, residue or the like can be prevented from being entangled near the surface of the upper potting portion 4 where the distance between the hollow fiber membranes is the smallest.

  Moreover, the air bubbles that have entered the hollow fiber membrane module push the hollow fiber membrane bundle 2 outward and rise while diffusing the voids inside the hollow fiber membrane bundle 2. Bubbles pass through the hollow fiber membrane bundle 2 from the lower side and are gradually discharged to the outside of the hollow fiber membrane module. Many of the bubbles are between the hollow fiber membrane bundles 2 near the upper end of the hollow fiber membrane module. And escapes from the water surface and is discharged outside the module. At this time, the space between the hollow fiber membrane bundles 2 of the hollow fiber membrane bundle 2 in the vicinity of the upper end portion of the hollow fiber membrane module is pushed and expanded by the air bubbles, and the residue and the like entering the inside are easily discharged from the gap.

  In addition, in the vicinity of the upper end portion of the hollow fiber membrane module, a large flow from the gap inside the hollow fiber membrane bundle 2 to the outside of the module occurs. Accordingly, the gap between the hollow fiber membrane bundles 2 near the upper end of the hollow fiber membrane module is expanded and the flow as described above is generated, so that a residue is left between the hollow fiber membranes near the upper end of the hollow fiber membrane module. It is possible to prevent tangling.

  As described above, in the upper end portion of the hollow fiber membrane 2, at least a portion that appears on the water surface is formed with the coating portion 12 using the coating agent.

  Moreover, it is preferable to adjust a water surface so that it may become the middle vicinity of the coating part 12 (length direction of a hollow fiber membrane bundle).

  The method for adjusting the water level of the membrane immersion water tank is not particularly limited, and examples thereof include a method of adjusting using a water surface position sensor and a pump, and a method of adjusting by providing a drain outlet for overflow. From the standpoint of simplifying the device configuration, a method of adjusting by providing a draining port for overflow in the membrane immersion water tank is preferable. As a method of adjusting by providing a drain outlet for overflow, for example, when an approximately L-shaped overflow pipe is connected to the side wall of the membrane immersion water tank and the water level of the film immersion water tank rises, the water to be treated is placed at the upper end of the overflow pipe. There is a method of discharging from the drainage port which is an open port. The water level can be adjusted by changing the length and height of the overflow pipe. Examples of the method of changing the length include a method of attaching and detaching another tube to the overflow tube and a method of expanding and contracting the overflow tube having a stretchable structure such as a bellows. The structure of the overflow pipe is such that when the water surface rises above the upper end opening of the overflow pipe, the water to be treated flows into the overflow pipe from the upper end opening and is discharged out of the membrane immersion water tank from the drain outlet. it can.

(Embodiment 5)
In the present embodiment, the second invention will be described with reference to FIG.

  In the second aspect of the present invention, water is collected from the lower housing 4. When taking the form of the lower water collection system, air is not often sucked from the hollow fiber membrane 2 that is on the water surface. There is no need to form. In the lower water collection system, air is hardly sucked from the hollow fiber membrane area that is exposed from the water surface and not coated with the coating agent, so that bubbles are mixed in the treated water and a load is applied to the suction filtration pump. Can be prevented.

  The upper end of the hollow fiber membrane may be coated as shown in FIG. By applying the coating, it is possible to prevent the potting agent from rising onto the hollow fiber membrane in the vicinity of the potting surface. Moreover, it is preferable at the point which can raise the intensity | strength of a hollow fiber membrane, can make the hollow fiber membrane 2 easy to shake independently, and can make it easy to peel the residue and suspended substance adhering to the surface of the hollow fiber membrane.

  Further, as shown in FIG. 11, rectangular upper and lower housings are used.

(Embodiment 6)
FIG. 12 is a schematic view showing an example of a water treatment system provided with a membrane filtration apparatus for performing the filtration treatment method of the present invention. The water treatment system is an example of a water treatment system based on a membrane separation activated sludge process (MBR), a screen 16 for removing a relatively large solid content in the raw water; and a flow rate of the raw water flowing downstream from the screen 16 A denitrification water tank equipped with a stirring motor 19 and a stirring blade 20 connected to the stirring motor 19 for denitrifying raw water supplied from the flow control tank 17 by the supply pump 18 in an anaerobic state. 21; a membrane immersion water tank 23 that brings raw water supplied from the denitrification water tank 21 into contact with air and decomposes organic matter and the like by aerobic organisms; A drain port 24 of the overflow pipe 25 to be maintained; a hollow fiber membrane module 29 installed in the membrane immersion water tank 23; and disposed in the membrane immersion water tank 23 and below the hollow fiber membrane module 29 A diffuser pipe 26 (aeration means) for diffusing the air supplied from the blower 28; and filtered from the raw water side to the permeate side of the hollow fiber membrane module 29 by the pressure difference by the filtration pump 32, and the hollow fiber membrane module A permeated water tank 34 for storing the permeated water discharged from 29; a backwash pump 30 for supplying permeated water for backwashing from the permeated water tank 34 to the hollow fiber membrane module 29; and a blower provided downstream of the blower 28 Supply valve 37 and air flow meter 27; Filtration valve 38 and pressure gauge 31 provided upstream of filtration pump 32; Permeate flow meter 33 provided downstream of filtration pump 32; Provided in denitrification water tank 21 A denitrification water tank drain 35; a film immersion water tank drain 36 provided in the film immersion water tank 23; and a backwash water valve 39 provided on the downstream side of the backwash pump 30.

  In FIG. 12, the overflow pipe 25 is erected in an L shape with the end communicating with the drain port 24. The water level of the water to be treated can be adjusted by the height of the upper end opening of the overflow pipe 25. That is, by installing the upper end opening of the overflow pipe 25 at a height corresponding to the vicinity of the upper end of the hollow fiber membrane, the upper end of the hollow fiber membrane can be exposed on the surface of the water to be treated. The water treatment system is preferably operated in an overflow state in which the overflow pipe 25 is installed as described above and the upper end portion of the hollow fiber membrane is exposed on the surface of the water to be treated.

(Air diffuser)
For example, a predetermined number of aeration means can be installed below the immersed hollow fiber membrane module. Further, in order to increase the cleaning efficiency, it is preferable that the air diffuser is installed so that the gas jet port is disposed immediately below the air diffuser inlet provided in the lower housing of the hollow fiber membrane module, for example.

  The ejected bubbles have a large energy, and the rising water flow created thereby becomes a high-speed turbulent flow, which acts not only as a shearing force but also as an impact force on the membrane surface, and vibrates the membrane. Therefore, the deposit on the surface of the hollow fiber membrane can be well peeled off, and deposits can be prevented from adhering to the hollow fiber membrane.

  The air bubbles that have entered the void generated inside the hollow fiber membrane bundle from the air inlet port tend to spread as they rise to the upper side of the hollow fiber membrane. Then, the bubbles rise while pushing the hollow fiber membrane outward and expanding the voids generated inside the hollow fiber membrane bundle.

  A normal apparatus is not particularly limited as long as it is used in a water tank, a hollow fiber membrane module can be disposed, and the water tank is suitable for the amount of wastewater to be treated. It is preferable to immerse directly in the activated sludge treatment tank, or it is preferable to operate a hollow fiber membrane module by providing a separate membrane separation tank.

  The air diffuser is preferably a compressor or a blower, but the means is not particularly limited as long as gas can be supplied at low cost.

(Raw water to be treated)
The raw water to be treated is not particularly limited, and examples thereof include sewage, human waste, agricultural settlement drainage, domestic wastewater, and coagulated wastewater. It is also preferable to use it for filtering clear water.

(how to drive)
The filtered water acquisition means is not particularly limited as long as the permeated water acquisition position is set to a negative pressure when the pressure at the water level of the immersed water tank is set to 0, and a pump or the like is also preferable. An ejector or the like is more preferable because it saves energy.

  For the operation of the apparatus, it is preferable to perform filtration or stop periodically or periodically to keep the amount of dirt attached to the membrane surface low. Moreover, since it is a hollow fiber membrane, it is also preferable to carry out the operation of recovering the filtration pressure by flowing the permeated water in the reverse direction, performing the reverse pressure cleaning to blow out the permeated water from the membrane surface and removing the dirt. Back pressure cleaning is preferably carried out periodically, and it is preferable to push back water at a pressure higher than the filtration differential pressure. More preferably, the inside of the water tank is periodically replaced with water to perform rinsing and cleaning, which effectively removes most of the substances adhering to the film surface. Although it is preferable that the apparatus configuration is such that these operation methods can be implemented, it is preferable to select which operation method is to be performed appropriately depending on the state of raw water. There is no particular limitation.

  Further, it is preferable that the apparatus has a structure that stops when the water level falls below a predetermined position.

Example 1
As the hollow fiber membrane, a PVDF membrane (Mitsubishi Rayon Engineering Co., Ltd., pore diameter 0.4 μm, outer diameter 2.8 mm) using a polyester braid as a support was used.

  A hollow fiber membrane module as shown in FIG. 1 (a) was produced as follows.

  First, in the hollow fiber membrane module, support rods (not shown) were provided between a pair of housing upper portions 8 and housing lower portions 9 on both sides of the hollow fiber membrane to maintain a distance between the pair of housings.

  As the lower housing, a housing having a donut-shaped horizontal cross-sectional shape and having a diffuser inlet at the center is used. In the potting part, the hollow fiber membrane is arranged so that the hollow fiber membrane faces the aeration inlet with the end face of the hollow fiber membrane closed, and the angle of the surface of the hollow fiber membrane and the potting part is 70 °. Potting was performed using a urethane resin. The hollow fiber membrane was fixed so as to be inclined in a symmetric direction with respect to the air inlet.

  As the upper housing, a housing having a horizontal cross-sectional shape and having a water collection port 7 for taking out filtrated water from the inside of the housing was used. The potting part was arranged in a donut shape so that the hollow fiber membranes were opposed to each other, and the angle between the hollow fiber membrane and the surface of the potting part was 80 °. The hollow fiber membrane was fixed with a potting agent in a liquid-tight manner so as to communicate with the inside of the housing in an open state.

  In addition, a coating agent (manufactured by Shin-Etsu Silicone Co., Ltd., trade name: KS707) was applied over 100 mm from the interface with the upper potting part to prevent water from permeating. In addition to preventing the potting agent from rising near the interface with the upper potting portion, it is possible to prevent the hollow fiber membranes from adhering to each other while forming the membrane-impermeable portion. I can move.

  Potting was performed by placing a hollow bag inside the bundle of hollow fiber membranes at the center in the length direction and inflating it, and then injecting a potting agent and curing it. At that time, a cylindrical air cushioning material was used for the hollow bag. With the hollow bag 9 inflated with air, the membrane was fixed so that the relaxation rate of the membrane was 10%. After the resin was cured, the air in the hollow bag was extracted, the hollow bag was removed, and a hollow fiber membrane module was produced. And the some hollow fiber membrane module was connected to the water collection header pipe | tube 13 connected to the filtration pump (refer FIG. 9).

  The hollow fiber membrane module was placed in a membrane immersion water tank provided with a substantially L-shaped overflow pipe on the side wall so that the upper end of the hollow fiber membrane was exposed 80 mm above the water surface.

  Permeated water was obtained by repeating filtration, backwashing and drainage operations while performing aeration by the upper water collecting system from the upper water collecting header pipe. As a result, the increase in the fluidity in the vicinity of the hollow fiber membrane and the upper housing suppresses the entanglement of the residue, the accumulation of suspended solids and the uneven distribution of air, and about 120 times until the filtration differential pressure increases to 20 kPa. It took a day.

  In addition, the hollow fiber membrane bundles are distributed almost uniformly in the outer circumferential direction even during filtration by tilting the hollow fiber membrane end in the outer circumferential direction without variation in the length of the hollow fiber membrane. Improved cleaning performance.

(Example 2)
Except that the water collecting method in the hollow fiber membrane module was collected from the lower housing, it was the same as in Example 1.

  While performing aeration, permeated water was obtained while repeating filtration, backwashing and draining operations. As a result, the increase in the fluidity in the vicinity of the hollow fiber membrane 3 and the upper part of the housing suppresses the entanglement of the residue, the accumulation of suspended solids and the uneven distribution of the air, and the filtration differential pressure rises to 20 kPa. It took 120 days.

DESCRIPTION OF SYMBOLS 1 Hollow fiber membrane module 2 Hollow fiber membrane 3 Upper housing 4 Lower housing 5 Upper potting part 6 Lower potting part 7 Water collecting port 8 Air diffuser introduction port 9 Hollow bag 10 Potting part 11 Potting recessed part 12 Coating part 13 Water collecting header pipe 16 Screen 17 Flow Control Tank 18 Supply Pump 19 Stirring Motor 20 Stirring Blade 21 Denitrification Water Tank 23 Membrane Immersion Water Tank 24 Overflow Pipe Drainage Port 25 Overflow Pipe 26 Aeration Pipe (Aeration Unit)
27 Air flow meter 28 Blower 29 Hollow fiber membrane module 30 Backwash pump 31 Pressure gauge 32 Filtration pump 33 Permeate flow meter 34 Permeate tank 35 Denitrification water tank drain 36 Membrane immersion water tank drain 37 Blower supply valve 38 Filtration valve 39 Backwash water valve

Claims (11)

The upper end portion and the lower end portion of the plurality of hollow fiber membranes are respectively fixed to the upper housing and the lower housing having the diffuser introduction port with a potting agent, and the lower end portion of the hollow fiber membrane is around the diffuser introduction port. , A method of filtering water to be treated using a hollow fiber membrane module, which is inclined outwardly from the aeration inlet and fixed with a potting agent,
The upper end of the hollow fiber membrane is exposed on the water surface of the water to be treated, and water is collected from the upper housing while supplying air bubbles from the diffuser inlet into the bundle of hollow fiber membranes,
The filtration treatment method, wherein the upper end portion of the hollow fiber membrane is coated at least in a range exposed on the surface of the water to be treated. The upper end portion and the lower end portion of the plurality of hollow fiber membranes are respectively fixed to the upper housing and the lower housing having the diffuser introduction port with a potting agent, and the lower end portion of the hollow fiber membrane is around the diffuser introduction port. , A method of filtering water to be treated using a hollow fiber membrane module, which is inclined outwardly from the aeration inlet and fixed with a potting agent,
A filtration method for collecting water from the lower housing while exposing an upper end portion of the hollow fiber membrane on the surface of the water to be treated, and supplying air bubbles from the diffuser inlet into the bundle of hollow fiber membranes. .   The filtration processing method according to claim 2, wherein the upper end portion of the hollow fiber membrane is coated at least in a range exposed on the water surface of the water to be treated.   4. The filtration according to claim 1, wherein in the upper housing, an upper end portion of the hollow fiber membrane is inclined outward from a center or a cross-sectional center of the lower housing and fixed with a potting agent. Processing method.   The filtration method according to any one of claims 1 to 4, wherein the air diffusion inlet is arranged at a center or a cross-sectional center of the lower housing.   The said upper housing and the said lower housing are cylindrical, The said hollow fiber membrane is inclined and fixed toward the outward from the center of the said upper housing and the said lower housing, The fixing device in any one of Claims 1 thru | or 5. Filtration treatment method.   The said upper housing and a lower housing are rectangular shapes, The said hollow fiber membrane is inclined and fixed toward the outward from the cross direction center of the said upper housing and the said lower housing, The any one of Claim 1 thru | or 5 The filtration method of crab.   The filtration processing method according to claim 1, wherein a lower end portion of the hollow fiber membrane is fixed in a symmetric direction with respect to the aeration inlet.   The filtration method according to any one of claims 1 to 8, wherein an inclination angle of the hollow fiber membrane with respect to a surface of a potting portion made of the potting agent is an angle of 45 to 85 °.   The filtration processing method according to any one of claims 1 to 9, wherein a surface of the water to be treated is 20 mm to 100 mm from a surface of an upper potting portion of the upper housing.   The filtration processing method according to claim 10, wherein an overflow pipe is installed in a membrane immersion water tank in which the hollow fiber membrane module is immersed, and the height of the water surface is adjusted.

Images