JP2009090223A - Manufacturing method of filter membrane element, filter membrane element and membrane filtration module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for firmly bonding a support plate of a filter membrane element to a separation membrane thereof with a physically and chemically stable adhesive power, for manufacturing the filter membrane element used for solid-liquid separation of liquid containing suspended matter like activated sludge. <P>SOLUTION: When manufacturing the filter membrane element 1 by sticking sheet-like separation membranes 2 formed by forming porous separation function layers on a base material on both faces of the resin support plate 3 having the front and rear faces in each of which a protruded part 3a is provided on the peripheral edge and a recessed part 3b is provided inside surrounded by the protruded part 3a, an adhesive bonding the base material of the separation membranes to the protruded parts 3a of the support plate 3 includes, as a bonding resin, polymerized resin including one kind of compound of monomer constituting the resin raw material of the support plate 3, and after applying the adhesive onto the base material and/or protruded parts 3a, the base material of the separation membrane is superposed and bonded to protruded parts 3a of the support plate with the adhesive interposed therebetween. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a filtration membrane element used as a filtration membrane for solid-liquid separation of a solid-containing liquid such as an activated sludge solution or a microorganism culture solution.

  The membrane separation method has features such as energy saving, space saving, labor saving, and product quality improvement, and is therefore widespread while expanding its application field. Membrane separation methods include methods such as reverse osmosis, ultrafiltration, and microfiltration, and filtration membranes in the form of hollow fiber membranes, flat membranes, tubular membranes, etc. are used. As an application field, it has been used for seawater desalination, water purification, gas separation, blood purification, etc., but recently, membrane separation has also been applied to wastewater treatment from the viewpoint of environmental conservation.

  When membrane separation technology is applied to wastewater treatment, treat the treated water by immersing the membrane filtration device in a biological treatment tank containing activated sludge and sucking the permeate side with a pump, or using a water level difference such as siphon. The method of obtaining is known. At this time, normally, in the biological treatment tank, since microorganisms require oxygen in order to oxidize organic substances in the wastewater, oxygen is supplied by aeration. By using this aeration and placing a filtration membrane element on the upper part of the aeration diffuser, membrane filtration (solid-liquid separation) can be performed while washing the membrane surface simultaneously with the purpose of supplying oxygen. Overall, very low cost operation is possible. In particular, when a flat membrane type filtration membrane element is used, the membrane surface is highly cleanable and it is easy to construct an efficient process.

  Such a flat membrane type filtration membrane element is usually produced by fixing a separation membrane to a flat support plate. For example, the filtration membrane element described in Patent Document 1 is a filtration membrane element that is fixed using a frame body that sandwiches a support plate and a separation membrane. Moreover, the filtration membrane element described in Patent Document 2 is a filtration membrane element in which a support plate and a separation membrane are bonded using a soft adhesive. In addition, the filtration membrane element described in Patent Document 3 is a filtration membrane element in which a separation membrane is welded to a support plate and then a peripheral portion is reinforced with a soft adhesive.

By using these filtration membrane elements, the activated sludge can be solid-liquid separated as described above, and the basic functions are exhibited.
JP 2003-190746 A JP 11-235519 A JP 2000-202253 A

  As described above, when solid-liquid separation is performed while immersing the filtration membrane element in activated sludge and aeration from the lower part to clean the membrane surface, the upward flow of gas-liquid mixing caused by aeration The film surface cleaning is performed by energy, but there is a risk that the bonded portion is fatigued and destroyed by this energy. Therefore, it is desired to further increase the adhesive strength between the support plate and the separation membrane in the filtration membrane element.

  In addition, when the membrane pores are blocked by continuous membrane filtration, the membrane is usually washed with a sodium hypochlorite aqueous solution or acid, but it is physically and chemically resistant to such chemical cleaning. There is a need for a membrane filtration element having the desired adhesive strength. In addition, since the amount of water that can be filtered by a filtration membrane element per sheet is limited, it is usually necessary to create a large number of filtration membrane elements, and the members and labor required for production are kept to a minimum. It is desirable.

  The filtration membrane element described in Patent Document 1 is not particularly problematic in terms of adhesive strength, but has a problem that the cost and labor required for production increase because it requires a frame. Since Patent Documents 2 and 3 use an adhesive different from the support plate, there is a problem in that the adhesive force is insufficient and a phenomenon in which the adhesive force gradually decreases is observed.

The present invention for solving this problem has the following configuration.
(1) Both sides of the front and back are formed with a porous separation functional layer on the base material on both sides of a resin support plate in which a convex portion is provided on the periphery and a concave portion is provided on the inner side surrounded by the convex portion. When manufacturing a filtration membrane element by laminating a sheet-like separation membrane, an adhesive that bonds the base material of the separation membrane and the convex portion of the support plate constitutes the resin material of the support plate as an adhesive resin Including a polymerized resin containing one kind of compound as a monomer, and after applying the adhesive to the base and / or the protrusion, the base of the separation membrane and the support plate A method of manufacturing a filtration membrane element, wherein the adhesive is overlapped and adhered to an adhesive surface with a convex portion of the material in a state where the adhesive is interposed.
(2) The adhesive is a liquid material in which an adhesive resin is dissolved or dispersed in an organic solvent at a concentration of 10 to 50% by weight, and after the adhesive is applied to the convex portions and / or the base material, The convex part and the base material are overlapped so as to be in contact with each other via the applied adhesive, and are adhered by evaporating at least a part of the solvent in the adhesive (1) A filtration membrane element according to 1.
(3) The method for producing a filtration membrane element according to (2), wherein the solubility of the adhesive resin in the organic solvent is higher than the solubility of the resin constituting the support plate in the organic solvent.
(4) The resin constituting the support plate is a copolymer polymerized from n types (n is an integer of 2 or more) of monomers, and the adhesive resin is any of the n types The method for producing a filtration membrane element according to any one of (1) to (3), which is a (co) polymer polymerized from (n-1) or less types of monomers including one or more types.

(5) The filter membrane element according to any one of (2) to (4), wherein the organic solvent is a ketone-based, ester-based, ether-based, or aromatic hydrocarbon-based organic solvent. Method.
(6) The method for producing a filtration membrane element according to any one of (1) to (5), wherein the base material is a nonwoven fabric composed of organic fibers.
(7) A filtration membrane element produced by the production method according to any one of (1) to (6), wherein the convex portion of the support plate and the base material of the separation membrane are interposed via an adhesive resin. The convex part of the support plate and the adhesive resin are fixed by welding, and the adhesive resin and the base material are fixed by impregnating the adhesive resin inside the base material. A filtration membrane element characterized by

  The filtration membrane element produced by the method of the present invention is easy to manufacture, and the adhesive strength is less likely to deteriorate even with aeration energy during membrane filtration and chemical washing of the membrane. High durability.

  As shown in FIGS. 1 and 2, the filtration membrane element 1 to be manufactured according to the present invention is a resin support having a shape in which both front and back surfaces are provided with a convex portion at the periphery and a concave portion is provided inside the convex portion. It comprises a plate 3 and a sheet-like separation membrane 2 formed by forming a porous separation functional layer on a base material bonded to both surfaces of the support plate 3, and the base material of the separation membrane is formed on the convex portion It is glued. In this element, the gap between the recess and the separation membrane functions as a flow path for the filtrate to move, and the filtrate is discharged from the filtrate outlet 4 to the outside of the filtration membrane element.

  The resin constituting the resin support plate 3 is preferably a polymer having a tensile strength of 15 MPa or more in D638 of the ASTM test method. For example, a copolymer represented by acrylonitrile butadiene styrene resin (ABS) And a general-purpose resin of a single polymer such as polyethylene and vinyl chloride, and a fiber reinforced resin as a composite material. In the present invention, the material of the convex portion that is a portion to be bonded to the separation membrane may be made of the resin as described above, and the other concave portion is a material (metal or the like) having other rigidity. It doesn't matter.

  The shape of the resin support plate 3 is not particularly limited as long as the front and back surfaces of the plate-like body have a structure in which the peripheral edge is a convex portion and a concave portion is provided on the inside thereof. As shown in FIG. 1, the entire inner side surrounded by the convex portion may be a concave portion, but the concave portion is formed so that the distance to the filtrate water port and the flow path resistance are uniform and the membrane filtrate flows uniformly with respect to the membrane surface. Is preferably provided so as to form a plurality of grooves arranged in parallel at regular intervals. At this time, the width of each recess is preferably in the range of 1 to 20 mm in order to prevent the separation membrane 2 from dropping down under severe aeration conditions while keeping the amount of filtered water high. 5-5 mm. The depth of the recess is preferably selected within the range of 1 to 10 mm in order to secure the filtrate flow path while suppressing the thickness as the element. Furthermore, the porosity of the support plate due to the recesses is in the range of 15 to 85% in order to sufficiently secure the filtrate flow path and suppress the flow resistance when the filtrate flows, while maintaining the strength of the support plate. It is preferable. This indicates the volume ratio of the voids formed by the recesses when the solid cuboid support plate is 100%. When the porosity is less than 15%, the flow resistance increases and the filtered water is efficiently used. If the water cannot be taken and exceeds 85%, the strength of the support plate is significantly reduced.

  The resin support plate 3 having the shape as described above may be formed by bonding a convex portion to a flat plate or by forming a concave portion by cutting the flat plate, but by extrusion molding or injection molding. Manufacturing by integral molding is most preferable from the viewpoint of reducing manufacturing costs and improving structural accuracy.

  The separation membrane 2 is a sheet-like separation membrane manufactured by forming a porous separation functional layer 2a on the upper surface of the base material 2b.

  Here, the base material 2b is not particularly limited as long as it is a porous base material having voids inside, but it is preferably made of organic fibers from the viewpoint of easy weight reduction. . More preferred are woven and knitted fabrics and nonwoven fabrics made of organic fibers such as cellulose fibers, cellulose triacetate fibers, polyester fibers, polypropylene fibers, and polyethylene fibers. Among these, non-woven fabric is preferable because it is relatively easy to control the density and is easy to manufacture and inexpensive.

  The porous separation functional layer 2a is not particularly limited as long as the porous separation functional layer 2a is porous and has a membrane separation function, but particularly when solid-liquid separation of activated sludge is performed, the pore diameter of the membrane surface is 0.01. It is preferable to be within a range of about ˜20 μm. The material is not particularly limited, and polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinyl alcohol, cellulose acetate, polyacrylonitrile, chlorinated polyethylene, polyvinylidene fluoride, polyvinyl fluoride, and other materials are appropriately selected. Can be used. In particular, polyolefin and fluorine materials having high physical and chemical durability can be used particularly preferably.

  In the present invention, as an adhesive for adhering the base material 2b and the convex portion 3a, an adhesive resin is formed by polymerizing a resin containing one compound of monomers constituting the resin material of the support plate as a monomer. Use an adhesive. For example, when the resin material of the support plate is a copolymer polymerized from monomers A, B, and C, the adhesive resin contains one or more monomers of monomers A, B, and C. (Co) polymer polymerized by Thereby, the affinity between the adhesive resin and the resin support plate is increased, and a strong adhesion can be achieved.

  In the filtration membrane element manufactured by the method of the present invention, the resin support plate and the adhesive resin are fixed by welding, and the adhesive resin and the base material are impregnated in the base material with the adhesive resin. It is fixed by.

  Here, the welding means that the resin constituting the resin support plate is temporarily dissolved and then solidified after being mixed with the adhesive resin in an adhesive solvent, thereby solidifying the components in a mixed state. By doing, it refers to bonding. Therefore, the components of the resin support plate and the adhesive resin are both mixed at a ratio of 10% or more in the welded bonded portion. Such adhesion is very strong, and fatigue failure of the bonded portion due to aeration energy in the activated sludge hardly occurs.

  In addition, the fact that the adhesive resin is fixed by impregnating the inside of the base material of the separation membrane means that the base material itself does not change chemically and the adhesive resin that has entered and hardened inside the base material. It refers to adhering when the substrate is intertwined. This is adhesion by a so-called anchor effect.

  In order to realize such adhesion, a liquid adhesive in which the adhesive resin is dissolved or dispersed in a solvent at a concentration of 10 to 50% by weight, a portion to which the convex portion of the support plate is bonded, and / or It is applied to the part of the separation membrane where the base material is adhered, and the convex portion and the base material are overlapped so as to be in contact with each other via the applied adhesive, and are adhered by maintaining a close contact state. . While maintaining this close contact state, at least a part of the solvent contained in the adhesive is evaporated.

  Here, the organic solvent is not particularly limited as long as both the adhesive resin and the resin of the resin support plate are soluble, but ketone type, ester type, ether type, aromatic hydrocarbon type, etc. preferable. As such an organic solvent, dimethyl ketone, methyl ethyl ketone, diethyl ketone, ethyl acetate, dimethyl ether, diethyl ether, styrene, benzene, toluene and the like can be preferably used.

  Moreover, it is preferable that the solubility with respect to the said organic solvent of the said adhesive resin is higher than the solubility with respect to the organic solvent of resin which comprises the said support plate. By selecting the material of such a combination, while suppressing the shape change of the resin support plate, the liquid adhesive in which the adhesive resin is dissolved is applied, and the applied liquid adhesive is impregnated inside the substrate. be able to.

  As a combination of such materials, when the resin support plate is composed of a copolymer polymerized from n types (n is an integer of 2 or more) of monomers, It is preferable that it is a (co) polymer polymerized from (n-1) or less monomers including any one or more of the above. For example, when the resin support plate is a copolymer polymerized from three types of monomers A, B, and C, as the adhesive resin, a copolymer composed of two types of monomers A and B; To do. Generally, the smaller the number of monomers in the polymer, the higher the solubility in the solvent, and the shape change of the resin support plate when applied can be suppressed.

Further, a liquid adhesive in which the adhesive resin is dissolved in an organic solvent at a concentration of 10 to 50% by weight is applied to the part to be bonded to the convex part and / or the part to be bonded to the base material. Although applied, the application amount of the adhesive resin per unit adhesion area is preferably in the range of 0.1 to 40 mg / cm ² , more preferably in the range of 1 to 15 mg / cm ² . If the amount of the adhesive resin applied is too large to exceed this range, no further improvement of the adhesive strength can be expected and the cost will only be high, and the adhesive resin will not be in the gap between the separation membrane and the resin support plate. Such a problem occurs that the filter membrane element protrudes and it becomes difficult to install the filter membrane element, and the flow path of the membrane filtrate (for example, activated sludge) between the filter membrane elements becomes narrow. In addition, if the amount of resin for adhesion is too small, adhesion is insufficient and sufficient sealing performance cannot be obtained, and the membrane filtrate can be mixed into the gap between the separation membrane and the recess, which is the flow path of the membrane permeate. Increases nature.

In addition, when the portion to be bonded of the convex portion and the portion to be bonded of the base material are overlapped and brought into close contact with each other with the applied adhesive interposed therebetween, adhesion should be performed. It is preferable to apply a pressure of 0.01 kg / cm ² or more, and more preferable to apply a pressure of 0.015 kg / cm ² or more per bonding area so that the parts to be pressed are pressed. Thereby, adhesion becomes strong. As a method of applying the pressure, it is preferable to apply the pressure evenly and vertically from the upper surface of the separation membrane to the resin support plate. As a means for that purpose, there is exemplified a method in which a plate-like member or the like is placed and the pressure is evenly distributed using its own weight. As the pressure, there are a method using the weight of the plate-shaped member described above and a method using air pressure, hydraulic pressure, and the like.

  Further, when evaporating at least a part of the solvent during the adhesion, it is preferably dried and evaporated in an environment of 10 to 30 ° C. for 1 hour or longer, more preferably 24 hours or longer. Thereby, adhesion becomes strong.

  In the filtration membrane element manufactured as described above, the permeated water filtered by the separation membrane 2 flows into the recess 3b of the resin support plate 3, and finally from the filtrate outlet 4 to the outside of the filtration membrane element. Is discharged. As a membrane filtration apparatus for realizing such a function, for example, there is an immersion type membrane filtration apparatus as shown in FIG.

  In this membrane filtration device 6, a plurality of filtration membrane elements 1 are installed in a housing 7 so that the distance A between the membrane surfaces of the filtration membrane elements is within a range of 4 to 10 mm. preferable. When the distance A between the membrane surfaces is larger than this range, the membrane area per installation area is reduced, resulting in an inefficient membrane filtration device. When the membrane surface distance A is smaller than this range, it becomes difficult to clean the membrane surface and it is difficult to perform stable operation. It becomes a filtration device. It is preferable that an air diffuser 8 is installed below the filtration membrane element 1.

  For example, as shown in FIG. 4, such a membrane filtration device is used by being immersed in the membrane filtrate 11 in the membrane filtrate reservoir 10. The membrane filtrate is a liquid containing a suspended substance, and examples thereof include a liquid containing activated sludge used for wastewater treatment. Inside the membrane filtration device, there are provided a plurality of filtration membrane elements 1 loaded in the vertical direction, and a diffuser device 8 for supplying the gas from the gas supply device 9 to the membrane surface at the vertically lower part thereof, Further, a suction pump 12 for sucking permeate is provided downstream from the filtration membrane element 1.

  Here, the membrane filtrate 11 such as activated sludge is filtered through the separation membrane by the suction force of the suction pump 12. At this time, suspended substances such as microorganisms and inorganic particles contained in the membrane filtrate 11 cannot pass through the separation membrane, and only the dissolved components pass through. So-called solid-liquid separation is performed. Then, the permeated water that has passed through the separation membrane is taken out from the recessed portion 3b of the resin support plate 3 through the filtrate outlet 4 to the outside of the membrane filtrate storage tank 10. On the other hand, the air diffuser 8 generates bubbles in parallel with the filtration, and the gas-liquid mixed upward flow generated by the air lift action of the bubbles separates the suspended substances deposited on the surface of the separation membrane from the surface of the separation membrane. Let Thereby, it becomes possible to continuously express the predetermined function of the membrane filtration device while ensuring high water permeability.

A filtration membrane element was produced by the following procedure.
First, a resin support plate was produced by injection molding with ABS (acrylonitrile butadiene styrene) resin. The shape of both front and back surfaces of the resin support plate was as follows.

  It is a plate-shaped rectangular parallelepiped having a height of 1000 mm, a width of 500 mm, and a thickness of 7 mm, and recessed grooves having a depth of 2 mm and a width of 2 mm are provided at a pitch of 5 mm on both sides so that the porosity is 70% in the inner part of the surface The convex portion has a shape provided with a width of 20 mm and a height of 1 mm so as to surround the periphery of the concave portion.

  As the separation membrane, a flat membrane-like separation membrane was used in which a porous separation functional layer having an average pore size of 0.08 μm made of polyvinylidene fluoride was formed on a polyester nonwoven fabric substrate. Further, AS (acrylonitrile styrene) resin was used as the adhesive resin, and this AS resin was stirred and dissolved in MEK (methyl ethyl ketone) as a solvent at a concentration of 30% by weight to prepare a liquid adhesive.

  First, 10 g of the adhesive was applied evenly over the entire convex portion. Immediately after that, the separation membrane is placed on a resin support plate so that the base material (nonwoven fabric) and the applied adhesive come into contact with each other, and a 10 kg weight (gravity is evenly applied to the adhesive surface). The plate material was used) and dried at room temperature (28 ° C.) for 2 hours. Similarly, after the separation membrane was adhered to the opposite surface, it was dried for 48 hours while generating a flow of air around the filtration membrane element by a blower.

  A membrane filtration device similar to that shown in FIG. 3 was produced using the 20 membrane membrane elements thus produced. At this time, the distance between the film surfaces was 7.5 mm. This membrane filtration device was immersed in an activated sludge tank, and membrane filtration of activated sludge was conducted for 2 weeks with an aeration air volume of 500 L / min and a membrane surface filtration flux of 0.6 m / d. The turbidity of the permeated water was 0.1 NTU or less. Further, there was no particular problem with the adhesion of the separation membrane and the shape of the element.

It is an assembly figure about one embodiment of a filtration membrane element by the present invention method. It is a fragmentary sectional view which shows the part which the filtration membrane element by this invention adhere | attached. It is a schematic perspective view which shows one embodiment of the immersion type membrane filtration apparatus using the filtration membrane element by this invention method. It is the schematic which shows one embodiment of the system which performs membrane filtration with an immersion type membrane filtration apparatus.

Explanation of symbols

1: Filtration membrane element 2: Separation membrane 2a: Porous separation functional layer 2b: Base material 3: Resin support plate 3a: Convex part 3b: Concave part 4: Filtration water outlet 5: Adhesive resin 6: Membrane filtration device 7: Housing 8: Air diffuser 9: Gas supply device 10: Film filtrate storage tank 11: Film filtrate 12: Suction pump

Claims (8)

Sheet-like separation formed by forming a porous separation functional layer on a base material on both sides of a resin support plate in which both front and back surfaces are provided with convex portions on the periphery and provided with concave portions on the inside surrounded by the convex portions. When a membrane element is manufactured by laminating a membrane, an adhesive that bonds the base material of the separation membrane and the convex portion of the support plate is used as an adhesive resin for the monomer constituting the resin material of the support plate. A resin containing a polymer containing one kind of compound as a monomer is included, and after the adhesive is applied to the base material and / or the convex portion, the base material of the separation membrane and the convex portion of the support plate A method of manufacturing a filtration membrane element, wherein the adhesive surface is superposed and adhered with an adhesive interposed therebetween. The adhesive is a liquid in which an adhesive resin is dissolved or dispersed in an organic solvent at a concentration of 10 to 50% by weight, and after the adhesive is applied to the convex part and / or the base material, 2. The substrate according to claim 1, wherein the base material and the base material are superposed so as to come into contact with each other through the applied adhesive, and are adhered by evaporating at least a part of the solvent in the adhesive. A method for producing a filtration membrane element. The method for producing a filtration membrane element according to claim 2, wherein the solubility of the adhesive resin in the organic solvent is higher than the solubility of the resin constituting the support plate in the organic solvent. The resin constituting the support plate is a copolymer polymerized from n types (n is an integer of 2 or more) of monomers, and the adhesive resin is any one or more of the n types The method for producing a filtration membrane element according to any one of claims 1 to 3, wherein the filtration membrane element is a (co) polymer polymerized from (n-1) or less types of monomers including: The method for producing a filtration membrane element according to any one of claims 2 to 4, wherein the organic solvent is a ketone-based, ester-based, ether-based, or aromatic hydrocarbon-based organic solvent. The method for producing a filtration membrane element according to any one of claims 1 to 5, wherein the substrate is a nonwoven fabric composed of organic fibers. The filtration membrane element manufactured by the manufacturing method according to claim 1, wherein the convex portion of the support plate and the base material of the separation membrane are bonded via an adhesive resin, and the support The convex portion of the plate and the adhesive resin are fixed by welding, and the adhesive resin and the base material are fixed by impregnating the adhesive resin inside the base material. Filter membrane element. A membrane filtration module comprising a plurality of filtration membrane elements according to claim 7 arranged in parallel in the vertical direction with an interval of 4 to 10 mm as a distance between membrane surfaces.

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