JP4513371B2 - Manufacturing method of separation membrane - Google Patents

Description

  The present invention relates to a separation membrane particularly suitable for purifying sewage (domestic wastewater generated from cooking, washing, baths, toilets, other living environments) and wastewater generated from production factories, restaurants, fishery processing factories, food processing plants, and the like.

  In recent years, separation membranes have been used to purify sewage and wastewater. There are various types and forms of such separation membranes, and an organic polymer solution containing a surfactant is applied to the surface of a porous substrate such as a woven fabric or a non-woven fabric. A so-called microfiltration membrane called a microfiltration membrane, in which an organic polymer is solidified after impregnation into a material and a porous organic polymer layer is formed on the surface of a porous substrate, has attracted attention. Although the porous organic polymer layer acts as a separation functional layer, it is difficult for such a flat membrane to have a larger effective membrane area per unit volume than other types of separation membranes, such as hollow fiber membranes. Therefore, it is required to increase the water permeation amount while maintaining the pore diameter according to the object to be filtered. However, if the porosity is increased to increase the water permeation amount, the pore size becomes too large or the surface cracks and the blocking rate decreases. On the other hand, if the pores are made small in order to increase the blocking rate, the water permeability will be lowered this time. In other words, the improvement in the rejection rate and the improvement in water permeability are in a contradictory relationship, and it is difficult to make a good balance between the two. In addition, in the separation membrane for sewage wastewater, by using an aeration operation to prevent minerals such as sand, sludge and other solids from colliding violently during use, or to supply oxygen to activated sludge and prevent clogging. Since the bubbles violently collide with the film surface, it is required to have strength enough to withstand such an impact. This strength is mainly borne by the porous base material, but when used in an environment where a significant impact is applied to the conventional separation membrane, the surface of the porous organic polymer may be scraped during the filtration operation. is there.

  In Patent Document 1, zeolite A-4 particles (made by Wako Pure Chemical Industries, 200 mesh) as inorganic particles and a crosslinking agent are added to an aqueous solution of polyvinyl alcohol OKS7158G (made by Nippon Synthetic Chemical Industry Co., Ltd.) as a binder polymer. A separation membrane has been proposed in which the solution is applied to a felted nonwoven fabric and dried and crosslinked to immobilize zeolite particles on the surface of the nonwoven fabric fibers and / or between the fibers. However, since the particle size of zeolite, which is an inorganic fine particle, is as large as 10 to 50 μm, the obtained separation membrane has a large pore size and poor dispersibility in the solution. As a result, the surface and the inside of the separation membrane are uniformly distributed. The inorganic fine particles cannot be dispersed until they become uneven, and there are problems that the film performance varies.

Patent Document 2 discloses stabilized anatase-type titanium oxide particles in which the surface of fine anatase-type titanium oxide particles having a particle size of about 30 to 40 nm that promotes decomposition of organic substances by light irradiation is coated with porous calcium phosphate. A hollow fiber separation membrane that holds the photocatalytic substance is disclosed. However, in this separation membrane, anatase-type titanium oxide particles having a bulk density of 0.55 g / ml, which are inorganic fine particles, are suspended in water or an appropriate solvent, and this suspension is passed from the outside to the inside of the hollow fiber membrane. Since it is only held on the outer surface and the hollow inner surface of the hollow fiber membrane by circulating toward the surface, there is a possibility that the anatase-type titanium oxide particles may be lost during use, and the separation that can suppress the scraping of the porous layer It is hard to call it a membrane.

  An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a separation membrane that can satisfy the blocking rate and the water permeability in a well-balanced manner and can suppress the scraping of the porous organic polymer. It is what.

The present invention for solving the above-described problems has the configurations described in the following (1) to (4) .
(1) 5-30% by weight of organic polymer, 0.1-30% by weight of inorganic fine particles having an average particle size in the range of 5-5000 nm and a bulk density of 0.05-0.5 g / ml, poly as a pore-opening agent A film-forming stock solution containing 0.1 to 15% by weight of oxyethylene sorbitan fatty acid ester or polyoxyethylene fatty acid ester, 40 to 95% by weight of solvent, and 0.1 to 10% by weight of non-solvent is applied on the substrate, A method for producing a separation membrane, which is brought into contact with a coagulation liquid containing at least 80% by weight of a non-solvent.
(2) The method for producing a separation membrane according to (1), wherein the inorganic fine particles are carbon-based fine particles or at least one kind of oxide fine particles selected from the group consisting of silicon, aluminum, magnesium and calcium .
(3) In the above (1) or (2), the organic polymer is at least one selected from the group consisting of a polyvinylidene fluoride resin, a polysulfone resin, a polyacrylonitrile resin, and a polyethersulfone resin. The manufacturing method of the separation membrane of description .
(4) Concerning the rejection rate of latex fine particles having an average particle size of 0.088 μm before and after the sandfall wear test, when the rejection rate before the test is A and the rejection rate after the test is B , the inequality AB−50 ≦ 50 The method for producing a separation membrane according to any one of (1) to (3) , wherein the relationship is satisfied .

Min separation membrane is according to the onset bright, with an organic polymer, in the range the average particle diameter of 5 to 5000 nm, and a bulk density of 0.05 to 0. Inorganic fine particles of 5 g / ml are included, so that the blocking rate and water permeability are well balanced, and the membrane surface is violently collided with inorganic substances such as sand, sludge, and other solid substances contained in the water to be treated. Even if air bubbles are violently collided by aeration operation to prevent oxygen clogging or supply of oxygen to activated sludge, the film surface is sufficiently durable. Therefore, the durability of the separation membrane is improved and long-term operation can be achieved.

The separation membrane according to the present invention has an organic polymer such as polyvinylidene fluoride resin, an average particle diameter in the range of 5 to 5000 nm, and a bulk density of 0.05 to 0.00. It is those containing an inorganic fine particle is 5 g / ml, for example, in the case of separation membranes with the base and the porous layer includes a surface or inside the inorganic fine particles of the porous layer. By including such specific inorganic fine particles, the surface of the separation membrane can be prevented from being scraped.

  The porous layer has a separation function. Among them, the organic polymer constituting the porous layer is a polyvinyl chloride type that is easy to form a film with a solution and has excellent physical durability and chemical resistance. Resin, polyvinylidene fluoride resin, polysulfone resin, polyacrylonitrile resin, polyethersulfone resin, or a main component thereof is preferable, and polyvinylidene fluoride or a main component thereof is most preferable. . In addition, a main component means containing 50 weight% or more.

  Here, the polyvinylidene fluoride resin is an organic polymer containing a vinylidene fluoride homopolymer or a vinylidene fluoride copolymer. A plurality of types of vinylidene fluoride copolymers may be contained. Examples of the vinylidene fluoride copolymer include a copolymer of vinylidene fluoride and one or more selected from the group consisting of ethylene tetrafluoride, propylene hexafluoride, and ethylene trifluoride chloride.

  The weight average molecular weight of the polyvinylidene fluoride resin is preferably in the range of 50,000 to 1,000,000, more preferably 100,000 to 750,000, considering the processability to the separation membrane. When the weight average molecular weight is larger than this range, the viscosity of the organic polymer solution becomes too high. When the weight average molecular weight is smaller than this range, the viscosity of the organic polymer becomes too low, and it becomes difficult to form a separation membrane in either case. . If the average particle size of the inorganic fine particles contained in the separation membrane is too large, the pores on the membrane surface will be reduced, or the inorganic fine particles will not be uniformly dispersed during the preparation of the membrane-forming stock solution. Accordingly, in order to uniformly disperse the inorganic fine particles on the surface and inside of the separation membrane, those having an average particle diameter in the range of 5 nm to 5000 nm are preferable.

In addition, the inorganic fine particles contained in the separation membrane in the present invention, when the bulk density is too high, are difficult to disperse in the stock solution and settle and become hardened, making the pores uneven in the obtained membrane and easily missing. Therefore, 0.05-0. Need to be 5 g / ml .

  Examples of such inorganic fine particles include carbon fine particles, spherical carbon fine particle carbon beads, various carbon blacks, ketjen black (highly conductive carbon black), graphite, and the like. Examples thereof include oxides of single or plural metal elements such as silicon, aluminum, magnesium, calcium, barium, zinc, zirconium, manganese, and hafnium. Among them, at least one kind selected from carbon-based fine particles, silicon, aluminum, magnesium and calcium from the viewpoint of being familiar with the organic polymer and expected to improve durability and wear resistance by mixing with the organic polymer. The oxide is preferred. Among these, carbon fine particles and silicon oxide (silica) are particularly preferable from the viewpoint of suppressing the dispersibility in the membrane-forming stock solution and the weight of the separation membrane.

  In the present invention, the average particle size of the inorganic fine particles is sampled by the intercept method, and the inorganic fine particles of the sample are observed with a scanning electron microscope (Hitachi, Ltd., scanning electron microscope S-800, etc.). And by calculating the number average.

  The bulk density of the inorganic fine particle sample previously placed in the funnel was poured from a height of 5 cm into a 100 ml cylinder without spout having a diameter of 28 ± 2 mm and a height of 180 ± 5 mm. Are weighed and converted to g weight per ml.

  And when forming a porous layer on a base material, a base material supports a porous layer and gives intensity | strength to a separation membrane. Although it does not specifically limit as a material, such as an organic base material and an inorganic base material, From the point which is easy to reduce in weight, an organic base material is preferable. Examples of the organic substrate include 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, a nonwoven fabric whose density is relatively easy to control is particularly preferable.

  If the thickness of the substrate is too thin, it will be difficult to maintain the strength as a separation membrane, and if it is extremely thick, the water permeability will be reduced, so the range of 0.01 mm to 1 mm is preferable. Most preferably, the range is 0.05 mm to 0.5 mm.

The density of the substrate is 0.7 g / cm ³ or less, preferably 0.6 g / cm ³ or less. This density range is suitable for accepting a film-forming stock solution and forming a composite layer of a substrate and a porous layer in the production process described later. However, when the density is extremely low, the strength as a separation membrane is lowered, and thus it is preferably 0.3 g / cm ³ or more. The density here is the apparent density, and can be determined from the area, thickness and weight of the substrate by the equation density = weight / (area of substrate × thickness).

  On the other hand, if the thickness of the porous layer is too thin, defects such as cracks may occur, and the filtration performance may deteriorate. If the thickness is too thick, the water permeability may decrease. Is preferably selected in the range of 0.05 to 0.2 mm.

  Furthermore, when forming a porous layer on a base material, it is preferable that a part of organic polymer which comprises a porous layer enters a base material, and the composite layer is formed. By entering the organic polymer into the base material, the porous layer is firmly fixed to the base material by a so-called anchor effect, and the porous layer can be prevented from peeling off from the base material. The porous layer may exist on one side with respect to the base material, or may exist on both sides. The porous layer may have a symmetric structure or an asymmetric structure with respect to the substrate. Further, when the porous layer is present on both sides with respect to the base material, the porous layers on both sides may be continuous through the base material or may be discontinuous. .

  Next, the manufacturing method of the separation membrane of this invention is demonstrated. The separation membrane of the present invention can be obtained, for example, by coagulating a membrane-forming stock solution containing an organic polymer, inorganic fine particles and a pore-opening agent in a coagulating solution containing a non-solvent to form a porous layer. It can be obtained by including inorganic fine particles in the material layer.

  At this time, a film-forming stock solution may be applied to the surface of the substrate to form a porous layer, or the substrate may be immersed in the film-forming stock solution to form a porous layer. When applying the film-forming stock solution to the substrate, it may be applied on one side of the substrate or on both sides. Of course, you may form a porous layer, without using a base material.

  In coagulating the film-forming stock solution, only the porous layer formed on the substrate may be brought into contact with the coagulating solution, or the porous layer may be immersed in the coagulating solution together with the substrate. In order to bring only the porous layer into contact with the coagulation liquid, for example, a method of bringing the porous layer formed on the substrate into contact with the coagulation bath surface so that the porous layer is on the lower side, or a smooth surface such as a glass plate or a metal plate There is a method in which a base material is brought into contact with a plate and attached so that the coagulation bath does not wrap around the substrate side, and the base material having a porous layer is immersed in the coagulation bath together with the plate. In the latter method, the base material may be attached to the plate and then the film of the film-forming stock solution may be formed, or the stock solution film may be formed on the base material and then attached to the plate.

  Then, a solvent that dissolves an organic polymer, a pore opening agent, or the like may be added to the film forming stock solution.

  In the case of adding a pore-opening agent having an action of promoting porous formation to the film-forming stock solution, the pore-opening agent only needs to be extracted by the coagulating liquid, and is preferably highly soluble in the coagulating liquid. For example, polyoxyalkylenes such as polyethylene glycol and polypropylene glycol, aqueous polymer such as polyvinyl alcohol, polyvinyl butyral, and poracrylic acid, and glycerin can be used.

Further, in the present invention, the apertures include polyoxyalkylene structure, a surfactant containing a fatty acid ester structure and water group Ru used. By the use of surfactants, distributed inorganic particles becomes good in film-forming solution in, it is easy to obtain a pore structure of interest.

  Examples of the polyoxyalkylene structure include-(CH2CH2O) n-,-(CH2CH2 (CH3) O) n-,-(CH2CH2CH2O) n-,-(CH2CH2CH2CH2O) n-, and the like. From the viewpoint,-(CH2CH2O) n-, so-called polyoxyethylene is preferable.

  Examples of the fatty acid ester structure include fatty acids having a long-chain aliphatic group. The long-chain aliphatic group may be linear or branched, and examples of the fatty acid include stearic acid, oleic acid, lauric acid, and palmitic acid. Moreover, fatty acid ester derived from fats and oils, such as beef tallow, palm oil, coconut oil, etc. are also mentioned.

  Examples of those having a hydroxyl group include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, glycerin, sorbitol, glucose, and sucrose.

  A surfactant containing all of a polyoxyalkylene structure, a fatty acid ester structure and a hydroxyl group is particularly preferably used. For example, polyoxyethylene sorbitan fatty acid ester includes polyoxyethylene sorbitan monostearate, polyoxyethylene palm Oil fatty acid sorbitan, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene fatty acid ester, polyethylene glycol monostearate, polyethylene glycol monooleate, polyethylene glycol monolaurate Can be mentioned. These surfactants are particularly preferable because they not only improve the dispersibility of the inorganic fine particles, but also have the characteristics that even if they remain in the porous layer and are dried, the water permeability and blocking properties are not lowered.

In addition, when using a solvent that dissolves a porous layer forming agent such as an organic polymer or a pore opening agent in the film forming stock solution,
As the solvent, N-methylpyrrolidone (NMP), N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetone, methyl ethyl ketone and the like can be used. Among them, NMP, DMAc, DMF and DMSO, which have high solubility of organic polymers, can be preferably used.

  In addition, a non-solvent can also be added to the film-forming stock solution. The non-solvent does not dissolve the organic polymer, and acts to control the size of the pores by controlling the solidification rate of the porous layer forming agent such as the organic polymer. As the non-solvent, water, alcohols such as methanol and ethanol can be used. Of these, water methanol is preferred from the viewpoint of ease of wastewater treatment and price. These may be mixed.

  In the film forming stock solution, the organic polymer is 5 wt% to 30 wt%, the inorganic fine particles are 0.1 wt% to 30 wt%, the pore-opening agent is 0.1 wt% to 15 wt%, and the solvent is 40 wt% to 95 wt%, non-solvent is preferably in the range of 0.1 wt% to 10 wt%. Among them, when the amount of the organic polymer is extremely small, the strength of the porous layer is lowered, and when the amount is too large, the water permeability may be lowered, so that the range of 8% by weight to 20% by weight is more preferable. If the amount of inorganic fine particles is too small, the effect of suppressing the surface of the separation membrane will be reduced, and if it is too large, the strength of the porous layer may be lowered. Therefore, the range of 0.5 wt% to 15 wt% is more preferable. If the amount of the pore-opening agent is too small, the water permeability may decrease, and if the amount is too large, the strength of the porous layer may decrease. On the other hand, if the amount is extremely large, it may remain excessively in the porous organic polymer and elute during use, and the quality of the permeated water may deteriorate or the water permeability may change. Therefore, a more preferable range is 0.5 wt% to 10 wt%. Furthermore, if the amount of the solvent is too small, the stock solution is likely to be gelled, and if the amount is too large, the strength of the porous layer is lowered, and therefore the range is preferably 60% to 90% by weight. If the amount of non-solvent is too large, gelation of the stock solution tends to occur, and if it is extremely small, control of the size of pores and macrovoids becomes difficult. Therefore, it is more preferably 0.5 to 15% by weight.

  On the other hand, as the coagulation bath, a non-solvent or a mixed solution containing a non-solvent and a solvent can be used. When a non-solvent is used for the film-forming stock solution, the non-solvent in the coagulation bath is preferably at least 80% by weight of the coagulation bath. If the amount is too small, the solidification rate of the organic polymer is slowed and the pore diameter is increased. More preferably, it is in the range of 85% by weight to 100% by weight. On the other hand, when a non-solvent is not used for the film-forming stock solution, it is preferable to reduce the content of the non-solvent in the coagulation bath, compared to the case where a non-solvent is also used for the film-forming stock solution. preferable. When the amount of non-solvent is large, the solidification rate of the organic polymer is increased, and the surface of the porous layer becomes dense and water permeability may be lowered. More preferably, the range is from 60% to 99% by weight. By adjusting the content of the non-solvent in the coagulation bath, the pore size on the surface of the porous layer and the size of the macrovoids can be controlled. If the temperature of the coagulation bath is too high, the coagulation rate will be too fast. Conversely, if the temperature is too low, the coagulation rate will be too slow, so it is usually selected in the range of 15 ° C to 80 ° C. preferable. More preferably, it is the range of 20 to 60 degreeC.

  According to the present invention as described above, the following separation membrane can be obtained. That is, regarding the rejection rate of latex fine particles having an average particle size of 0.088 μm, A−B ≦ 50, more preferably, where A is the rejection rate before the falling sand wear test and B is the rejection rate after the test. A separation membrane satisfying A−B ≦ 10 can be obtained. A small change in the blocking rate before and after the test means that it can sufficiently withstand a strong impact and suppress the abrasion of the film surface. Therefore, the water to be treated contains inorganic substances such as sand, sludge, and other solids, and they collide violently, and bubbles are formed by aeration operations to prevent oxygen supply to the activated sludge and clogging. Even in the treatment of sewage wastewater that collides violently with the surface, there are few leaks of bacterial cells and sludge, etc., membrane clogging by bacterial cells and sludge, etc., and prevention of increase in filtration differential pressure can be made, and the life of the membrane can be extended It is suitable. And the permeated water obtained by the wastewater treatment can also be used as reused water.

  Further, the separation membrane of the present invention may be any of a nanofiltration membrane, an ultrafiltration membrane, and a microfiltration membrane, and one or more appropriate membranes can be selected and combined depending on the size of the substance to be separated. However, ultrafiltration membranes and microfiltration membranes are particularly preferred for treating sewage wastewater. Further, it is more preferable that the rejection of fine particles having an average particle size of 0.088 μm is 90% or more. If this rejection rate is not satisfied, microbial cells and sludge may leak during clogging of sewage water, clogging may occur due to microbial cells and sludge, filtration differential pressure may increase, and the service life may become extremely short. To do.

  Here, the blocking rate is the temperature of 25 ° C. of raw water in which polystyrene latex fine particles (nominal particle size 0.088 μm, standard deviation 0.0062 μm) manufactured by Ceradyne are dispersed in reverse osmosis membrane permeated water to a concentration of 10 ppm. From the absorbance of ultraviolet light having a wavelength of 202 nm obtained by allowing the separation membrane to permeate under a pressure of 10 kPa and obtaining the raw water and the permeated water, respectively, the following equation is used.

Blocking rate (%) = [(absorbance of stock solution−absorbance of permeated water) / absorbance of raw water] × 100
When the separation membrane of the present invention is used, if the separation membrane is a flat membrane, an element having a separation membrane (or a separation membrane and a channel material) and a permeate collecting member is used. Alternatively, it is preferable that a plurality of these elements are housed in a housing to form a module. In the case where the separation membrane is in the form of a hollow fiber, the plurality of hollow fiber membranes are aligned in one direction and accommodated in a housing having a stock solution inlet and a permeate outlet, and at least one end thereof is an end surface. The module is preferably fixed to the case so as to be in an open state. The element or module is preferably used for the treatment of sewage wastewater as a liquid processing apparatus by providing a means for supplying the stock solution to the separation membrane and a liquid collecting means for collecting the permeated liquid that has passed through the separation membrane. it can.

  Although the form of an element is not specifically limited, One of the forms of the element which can be used suitably for a waste-water-treatment process is demonstrated using FIG.

  The elements shown in FIGS. 1 and 2 are formed by arranging the flow path material 2 and the separation membrane 3 of the present invention in this order on both sides of a rigid support plate 1. Since it is difficult to increase the membrane area of the element of this form, the separation membranes 3 are arranged on both surfaces of the support plate 1 in order to increase the water permeability. The support plate 1 has convex portions 4 and concave portions 5 on both sides. The separation membrane 3 filters impurities in the liquid. The flow path member 2 is for efficiently flowing the permeated water filtered by the separation membrane 3 to the support plate 1. The permeated water that has flowed to the support plate 1 is taken out through the recesses of the support plate 1.

  The support plate 1 is not particularly limited as long as it has a structure having a plurality of projections and depressions on both sides of the plate-like body. However, the distance to the permeate outlet and the flow path resistance are made uniform so that the water to be treated is a film. The recesses are preferably provided so as to form a plurality of grooves arranged in parallel at regular intervals so as to flow evenly with respect to the surface. At this time, the width of each recess 5 is within a range of 1 to 20 mm, and further 1.5 to 5 in order to prevent the passage material 2 and the separation membrane 3 from falling down under severe aeration conditions while keeping the permeated water amount high. It is preferable to be within a range of 5 mm. The depth of the recess 5 is preferably selected within a range of about 1 to 10 mm in order to secure the permeate 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 permeate flow path and suppress the flow resistance when the permeate flows, while maintaining the strength of the support plate. Is preferred. This indicates the volume ratio of the voids formed by the recesses when the solid rectangular parallelepiped support plate is 100%. When the porosity is below 15%, the flow resistance increases and the permeate is efficiently taken. If it exceeds 85%, the strength of the support plate is significantly reduced.

  The material of the support plate 1 is preferably a material having a rigidity with a tensile strength of about 15 MPa or more in accordance with ASTM test method D638. Metals such as stainless steel, acrylonitrile-butadiene-styrene copolymer (ABS resin), resins such as polyethylene, polypropylene and vinyl chloride, composite materials such as fiber reinforced resin (FRP), and other materials are preferably used. it can.

  In order to reduce the thickness of the element while securing the flow path, the thickness of the flow path material is preferably in the range of 0.1 to 5 mm. In order to reduce pressure loss, it is preferable to use a material having a high porosity such as a plastic net. A channel material having a porosity in the range of 40% to 96% is particularly preferable.

  Moreover, in the element of this invention, it is also preferable to install the frame 6 in the peripheral part of the support plate 1 as shown in FIG. In this case, the separation membrane 3 may be fitted between the support plate 1 and the frame body 6 or may be adhered to the outer surface of the frame body 6. Here, “adhesion” means to attach in a contact state, and may be adhered using a separate resin, the separation membrane itself may be welded, or may be adhered by various other methods. . Costs can be reduced by fitting the frame body 6 manufactured by injection molding, extrusion molding or the like into the peripheral edge portion of the support plate 1 manufactured by an inexpensive manufacturing method such as extrusion molding. In order to make it easy to fit the support plate 1, the frame body 6 is preferably formed so that the cross-section is a U-shape.

In the element configured as described above, the permeated water filtered by the separation membrane 3 flows to the flow path member 2 and the concave portion 5 of the support plate 1 and finally from the permeated water outlet 7 to the outside of the element. And discharged.

  Then, the module which accommodated the said element in multiple sheets housing, and its usage method are demonstrated based on FIGS. FIG. 3 shows a separation membrane module 10 in which a plurality of elements 9 are housed in a housing so that a space is formed in parallel with each other and between the membrane surfaces of the separation membrane 3. The separation membrane module 10 is used so as to be immersed in water to be treated such as organic waste water stored in the water tank 11 to be treated. Inside the separation membrane module 10 are provided a plurality of elements 9 loaded in the vertical direction, and an air diffuser 12 for supplying the gas from the blower 13 to the membrane surface of the separation membrane below it, and the separation membrane A pump 14 for sucking permeate is provided downstream of the module 10.

  In the sewage wastewater treatment apparatus configured as described above, water to be treated such as wastewater passes through the separation membrane 3 by the suction force of the pump 14. At this time, suspended substances such as microbial particles and inorganic particles contained in the water to be treated are filtered. Then, the permeated water that has passed through the separation membrane 3 passes through the water collecting section 8 formed in the frame body 6 from the concave portion 5 of the support plate 1 through the permeated water flow path formed by the flow path material 2 and permeated. The water is taken out from the water tank 11 through the water outlet 7. On the other hand, in parallel with the filtration, the air diffuser 12 generates bubbles, and the upward flow parallel to the membrane surface of the element 9 generated by the air lift action of the bubbles separates the filtrate deposited on the membrane surface.

  Of course, the liquid to be treated is not limited to sewage wastewater, but can be used for water purification, clean water treatment, wastewater treatment, industrial water production, etc. in the water treatment field. River water, lake water, groundwater, seawater In addition, sewage, drainage, etc. can be treated water.

  The water permeability and blocking rate of the separation membranes in the examples and comparative examples were measured as follows.

  To measure the water permeability of the separation membrane, cut the separation membrane into a circle with a diameter of 50 mm, set it in a cylindrical filter holder, and pre-permeate the reverse osmosis membrane permeate at 25 ° C. for 5 minutes at a head height of 1 m. Then, the permeated water was sampled for 5 minutes after permeation.

  For the rejection, a calibration curve of the concentration was obtained using latex particles (polystyrene latex fine particles manufactured by Ceradyne, nominal particle size 0.088 μm, standard deviation 0.0062 μm). That is, a separation membrane (diameter: 43 mm) was set in a holder for measuring a fine particle rejection rate (UHP-43K, manufactured by Advantech Toyo Co., Ltd.), raw water prepared to a latex particle concentration of about 10 ppm was added, and a nitrogen pressure with an evaluation pressure of 10 kPa was added. Then, 25 cc of permeated water was collected while stirring the raw water, and 25 cc of permeated water was collected, and the latex particle concentration of the raw water and the permeated water was measured with an ultraviolet ray having a wavelength of 202 nm using a spectrophotometer (manufactured by Hitachi, U-3200). The blocking rate was determined from the concentration ratio by the following formula.

Blocking rate (%) = [(absorbance of stock solution−absorbance of permeated water) / absorbance of raw water] × 100
In addition, the sand fall type abrasion test of the separation membrane was performed by using a sand fall type wear test apparatus (ASTM D673 # 80, manufactured by Toyo Seiki Seisakusho Co., Ltd.), separating the separation membrane sample cut into a circle with a diameter of 44 mm at an angle of 45 ° with the horizontal plane. Fix the both ends of the membrane with a holding plate so that the surface of the separation membrane sample appears on the surface of the pedestal held in place, and replenish it with a hole with a diameter of 2 mm in the center and six places around it. Put 400 g of SiC (45 #) into the tank and rotate the replenishing tank so that it falls to the center of the separation membrane where 400 g of SiC (45 #) is set from a height of 650 mm through a cylinder with a diameter (inner diameter) of 23 mm. There was Tsu line is dropped. Thereafter, the above-described blocking rate was measured except for the SiC adhering to the membrane surface of the separation membrane held at an angle of 45 ° with the horizontal plane.
<Example 1>
Polyvinylidene fluoride (PVDF) resin as an organic polymer , carbon black with an average particle size of 18 nm and a bulk density of 0.13 g / ml as inorganic fine particles (manufactured by Mitsubishi Chemical Industries, Ltd., carbon black # 650), as a pore-opening agent Using polyoxyethylene sorbitan monostearate, N, N-dimethylformamide (DMF) as a solvent, and H 2 O as a non-solvent, these were sufficiently stirred at a temperature of 95 ° C. to prepare a film-forming stock solution having the following composition: Obtained.

Polyvinylidene fluoride (PVDF): 13.0% by weight
Polyoxyethylene sorbitan monostearate: 6.5% by weight
N, N-dimethylformamide (DMF): 72.5% by weight
Carbon black: 5.0% by weight
H2O: 3.0% by weight
Next, after the film-forming stock solution is cooled to 30 ° C., it is applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm, and after application, immediately immersed in pure water at 20 ° C. for 5 minutes. It was immersed in hot water at 90 ° C. for 2 minutes to wash away N, N-dimethylformamide as a solvent and polyoxyethylene sorbitan monostearate as a pore opening agent to obtain a separation membrane.

Next, when the initial rejection of the latex fine particles having an average particle size of 0.088 μm was measured for the separation membrane, it was 98.5%. The initial water permeability was 70 × 10 ⁻⁹ m ³ / m ² · s · Pa. Next, a sandfall type abrasion test was performed on the separation membrane, and the rejection rate of latex fine particles having an average particle size of 0.088 μm was measured. As a result, it was 98.0% and the water permeability was 75 × 10 ⁻⁹ m ³ / m ² · s · Pa. That is, the performance of the separation membrane was not deteriorated by the sandfall wear test, and the average average particle size 0.088 μm before and after the sandfall wear test was inhibited by A (before the test) and B (after the test). A−B = 0.5, and A−B ≦ 10 was satisfied. The results are shown in Table 1.

Further, as shown in FIG. 4, no scratches were observed on the surface of the separation membrane after the sand-sand-type wear test even by observation with a scanning electron microscope.
<Example 2>
Polyvinylidene fluoride (PVDF) resin as the organic polymer , finely divided silica having an average particle diameter of 1300 nm and a bulk density of 0.08 g / ml as inorganic fine particles (manufactured by Tosoh Silica Co., Ltd., finely divided silica AZ-204), open Using polyoxyethylene sorbitan monostearate as a pore agent, N, N-dimethylformamide (DMF) as a solvent, and H 2 O as a non-solvent, these were sufficiently stirred at a temperature of 95 ° C., and had the following composition: A membrane stock solution was obtained.

Polyvinylidene fluoride (PVDF): 13.0% by weight
Polyoxyethylene sorbitan monostearate: 6.5% by weight
N, N-dimethylformamide (DMF): 72.5% by weight
Silica: 5.0% by weight
H2O: 3.0% by weight
Next, after cooling the film-forming stock solution to 30 ° C., it was applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm, and immediately after application, immersed in pure water at 20 ° C. for 5 minutes, Further, it was immersed in hot water at 90 ° C. for 2 minutes to wash away N, N-dimethylformamide and polyoxyethylene sorbitan monostearate to obtain a separation membrane.

Next, when the initial rejection of latex particles having an average average particle size of 0.088 μm was measured for the separation membrane, it was 98.4%. The initial water permeability was 68 × 10 ⁻⁹ m ³ / m ² · s · Pa. Next, a sandfall type abrasion test was performed on the separation membrane, and the blocking rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 97.8% and the water permeability was 74 × 10 ⁻⁹ m ^3. / M ² · s · Pa. That is, the performance of the separation membrane was not deteriorated by the sandfall wear test, and the average average particle size 0.088 μm before and after the sandfall wear test was inhibited by A (before the test) and B (after the test). A−B = 0.6 and A−B ≦ 10 was satisfied. The results are shown in Table 1.

Further, as shown in FIG. 5, no scratches were observed on the surface of the separation membrane after the sand-sand-type wear test even by observation with a scanning electron microscope.
<Example 3>
Polysulfone (PS) resin as the organic polymer, carbon black with an average particle size of 18 nm as inorganic fine particles (carbon black # 650, manufactured by Mitsubishi Kasei Kogyo Co., Ltd.), polyoxyethylene sorbitan monostearate as the pore-opening agent, and N as the solvent , N-dimethylformamide (DMF), and H2O as a non-solvent, respectively, were sufficiently stirred at a temperature of 95 ° C. to obtain a film-forming stock solution having the following composition.

Polysulfone (PS): 13.0% by weight
Polyoxyethylene sorbitan monostearate: 6.5% by weight
N, N-dimethylformamide (DMF): 72.5% by weight
Carbon black: 5.0% by weight
H2O: 3.0% by weight
Next, after cooling the film-forming stock solution to 30 ° C., it was applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm, and immediately after application, immersed in pure water at 20 ° C. for 5 minutes, Further, it was immersed in hot water at 90 ° C. for 2 minutes to wash away N, N-dimethylformamide and polyoxyethylene sorbitan monostearate to obtain a separation membrane.

Next, with respect to the separation membrane, the initial blocking ratio of latex fine particles having an average average particle size of 0.088 μm was measured and found to be 98.9%. The initial water permeability was 48 × 10 ⁻⁹ m ³ / m ² · s · Pa. Next, a sandfall type abrasion test was performed on the separation membrane, and the blocking rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 97.6% and the water permeability was 56 × 10 ⁻⁹ m ^3. / M ² · s · Pa. That is, the performance of the separation membrane was not deteriorated by the sandfall wear test, and the average average particle size 0.088 μm before and after the sandfall wear test was inhibited by A (before the test) and B (after the test). A−B = 1.3 and A−B ≦ 10 was satisfied. The results are shown in Table 1.

Further, as shown in FIG. 6, no scratches were observed on the surface of the separation membrane after the sandfall type abrasion test even by observation with a scanning electron microscope .

< Example 4>
Polyvinylidene fluoride (PVDF) resin as the organic polymer, carbon black having an average particle size of 18 nm as inorganic fine particles (carbon black # 650, manufactured by Mitsubishi Chemical Industries, Ltd.), and N, N-dimethylformamide (DMF) as the solvent, respectively. These were sufficiently stirred at a temperature of 95 ° C. to obtain a film-forming stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 13.0% by weight
N, N-dimethylformamide (DMF): 82.0% by weight
Carbon black: 5.0% by weight
Next, after cooling the film-forming stock solution to 30 ° C., it was applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm, and immediately after application, immersed in pure water at 20 ° C. for 5 minutes, Furthermore, it was immersed in 90 degreeC hot water for 2 minutes, N, N- dimethylformamide was washed away, and the separation membrane was obtained.

Next, when the initial rejection of latex particles having an average average particle diameter of 0.088 μm was measured for the separation membrane, it was 99.0%. The initial water permeability was 5.0 × 10 −9 m 3 / m 2 · s · Pa. Next, a sandfall type abrasion test was conducted on the separation membrane, and the blocking rate of latex fine particles having an average average particle size of 0.088 .mu.m was measured. As a result, it was 99.0% and the water permeability was 4.8.times.10@-9 m @ 3. / M 2 · s · Pa. That is, the performance of the separation membrane was not deteriorated by the sandfall wear test, and the average average particle size before and after the sandfall wear test was 0.088 μm. Latex fine particles rejection rate A (before test) and B (after test) A−B = 0 and A−B ≦ 10 was satisfied. The results are shown in Table 1.
< Example 5>
Polyvinylidene fluoride (PVDF) resin as an organic polymer , artificial graphite having an average particle size of 4000 nm and a bulk density of 0.35 g / ml as inorganic fine particles (manufactured graphite SGB, manufactured by ESC Corporation), and monostearic acid as a pore-opening agent Using polyoxyethylene sorbitan, N, N-dimethylformamide (DMF) as a solvent, and H 2 O as a non-solvent, these were sufficiently stirred at a temperature of 95 ° C. to obtain a film-forming stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 13.0% by weight
Polyoxyethylene sorbitan monostearate: 6.5% by weight
N, N-dimethylformamide (DMF): 72.5% by weight
Artificial graphite: 5.0% by weight
H2O: 3.0% by weight
Next, after the film-forming stock solution is cooled to 30 ° C., it is applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm 3 and a thickness of 220 μm, and after application, immediately immersed in pure water at 20 ° C. for 5 minutes, It was immersed in hot water at 90 ° C. for 2 minutes to wash away N, N-dimethylformamide and polyoxyethylene sorbitan monostearate to obtain a separation membrane.

Next, with respect to the separation membrane, the initial average rejection of latex fine particles having an average average particle size of 0.088 μm was measured and found to be 92.8%. The initial water permeability was 69 × 10 −9 m 3 / m 2 · s · Pa. Next, a sandfall type abrasion test was performed on the separation membrane, and the blocking rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 90.6% and the water permeability was 76 × 10 −9 m 3 / m 2.・ It became s ・ Pa. That is, the performance of the separation membrane was not deteriorated by the sandfall wear test, and the average average particle size before and after the sandfall wear test was 0.088 μm. Latex fine particles rejection rate A (before test) and B (after test) A−B = 2.2 and A−B ≦ 10 was satisfied. The results are shown in Table 1.
< Example 6>
Polyvinylidene fluoride (PVDF) resin as an organic polymer , carbon black having an average particle diameter of 16 nm and a bulk density of 0.05 g / ml as inorganic fine particles (manufactured by Mitsubishi Chemical Industries, Ltd., carbon black # 3950), as a pore opening agent Using polyoxyethylene sorbitan monostearate, N, N-dimethylformamide (DMF) as a solvent, and H 2 O as a non-solvent, these were sufficiently stirred at a temperature of 95 ° C. to prepare a film-forming stock solution having the following composition: Obtained.

Polyvinylidene fluoride (PVDF): 13.0% by weight
Polyoxyethylene sorbitan monostearate: 6.5% by weight
N, N-dimethylformamide (DMF): 72.5% by weight
Carbon black: 5.0% by weight
H2O: 3.0% by weight
Next, after cooling the film-forming stock solution to 30 ° C., it was applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm, and immediately after application, immersed in pure water at 20 ° C. for 5 minutes, Further, it was immersed in hot water at 90 ° C. for 2 minutes to wash away N, N-dimethylformamide and polyoxyethylene sorbitan monostearate to obtain a separation membrane.

Next, when the initial rejection of the latex fine particles having an average average particle size of 0.088 μm was measured for the separation membrane, it was 93.1%. The initial water permeability was 63 × 10 ⁻⁹ m ³ / m ² · s · Pa. Next, a sandfall type abrasion test was performed on the separation membrane, and the blocking rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 90.1% and the water permeability was 65 × 10 ⁻⁹ m ^3. / M ² · s · Pa. That is, the performance of the separation membrane was not deteriorated by the sandfall wear test, and the average average particle size before and after the sandfall wear test was 0.088 μm. Latex fine particles rejection rate A (before test) and B (after test) A−B = 2 and A−B ≦ 10 was satisfied. The results are shown in Table 1.
<Comparative Example 1>
A separation membrane obtained in the same manner as in Example 1 was evaluated except that carbon black or silica, which is an inorganic fine particle, was not used, and a membrane was formed with a stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 13.0% by weight
Polyoxyethylene sorbitan monostearate: 6.5% by weight
N, N-dimethylformamide (DMF): 77.5% by weight
H2O: 3.0% by weight
With respect to the obtained separation membrane, the initial blocking rate of latex fine particles having an average average particle size of 0.088 μm was measured and found to be 98.0%. The initial water permeability was 85 × 10 ⁻⁹ m ³ / m ² · s · Pa. Next, a falling sand abrasion test was performed on the separation membrane, and the rejection rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 47.2% and the water permeability was 103 × 10 ⁻⁹ m ^3. / M ² · s · Pa. That is, the performance of the separation membrane was lowered by the falling sand type abrasion test, and the rejection rate was 90% or less. Further, the blocking ratios A (before the test) and B (after the test) of the latex fine particles having an average average particle size of 0.088 μm before and after the falling sand wear test are AB = 50.8 and AB ≦ 50. It was not satisfactory. The results are shown in Table 1.

Further, as shown in FIG. 7, scratches were observed on the surface of the separation membrane after the falling sand type abrasion test by observation with a scanning electron microscope.
<Comparative Example 2>
A separation membrane obtained in the same manner as in Example 3 was evaluated except that carbon black, which is an inorganic fine particle, was not used, and a membrane was formed with a stock solution having the following composition.

Polysulfone (PS): 13.0% by weight
Polyoxyethylene sorbitan monostearate: 6.5% by weight
N, N-dimethylformamide (DMF): 77.5% by weight
H2O: 3.0% by weight
With respect to the obtained separation membrane, the initial average rejection of latex fine particles having an average average particle diameter of 0.088 μm was measured and found to be 97.8%. The initial water permeability was 56 × 10 ⁻⁹ m ³ / m ² · s · Pa. Next, a sandfall type abrasion test was performed on the separation membrane, and the blocking rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 46.5% and the water permeability was 120 × 10 ⁻⁹ m ^3. / M ² · s · Pa. That is, the performance of the separation membrane was lowered by the sand-drop type abrasion test. Further, the blocking ratios A (before the test) and B (after the test) of the latex fine particles having an average average particle size of 0.088 μm before and after the sandfall wear test are AB−51.3 and AB ≦ 50. It was not satisfactory. The results are shown in Table 1.

Further, as shown in FIG. 8, scratches were observed on the surface of the separation membrane after the falling sand type abrasion test by observation with a scanning electron microscope.
<Comparative Example 3>
As inorganic fine particles, a particle diameter of 20000 nm, a bulk density of 0. A separation membrane obtained in the same manner as in Example 1 was evaluated except that 1 g / ml of graphite (manufactured by SCI Co., Ltd., artificial graphite SGL) was used to form a membrane with a stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 13.0% by weight
Polyoxyethylene sorbitan monostearate: 6.5% by weight
N, N-dimethylformamide (DMF): 72.5% by weight
Graphite: 5.0% by weight
H2O: 3.0% by weight
With respect to the obtained separation membrane, the initial blocking rate of latex fine particles having an average average particle diameter of 0.088 μm was measured and found to be 96.8%. The initial water permeability was 46 × 10 ⁻⁹ m ³ / m ² · s · Pa. Next, a sandfall type abrasion test was performed on the separation membrane, and the blocking rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 26.5% and the water permeability was 68 × 10 ⁻⁹ m ^3. / M ² · s · Pa. That is, the performance of the separation membrane was lowered by the sand-drop type abrasion test. In addition, regarding the blocking rate A (before the test) and B (after the test) of the latex fine particles having an average average particle size of 0.088 μm before and after the sandfall type abrasion test, AB = 70.3 and AB ≦ 50 is satisfied. It was not satisfactory. The results are shown in Table 1.

Further, as shown in FIG. 9, scratches were observed on the surface of the separation membrane after the falling sand type abrasion test by observation with a scanning electron microscope.
<Comparative example 4>
A separation membrane obtained in the same manner as in Example 4 was evaluated except that carbon black, which is an inorganic fine particle, was not used and a membrane was formed with a stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 13.0% by weight
Polyethylene glycol (PEG 20,000): 6.5% by weight
N, N-dimethylformamide (DMF): 77.5% by weight
H2O: 3.0% by weight
With respect to the obtained separation membrane, the initial blocking ratio of latex fine particles having an average average particle diameter of 0.088 μm was measured and found to be 98.3%. The initial water permeability was 44 × 10 ⁻⁹ m ³ / m ² · s · Pa. Next, a sandfall type abrasion test was performed on the separation membrane, and the blocking rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 30.4% and the water permeability was 73 × 10 ⁻⁹ m ^3. / M ² · s · Pa. That is, the performance of the separation membrane was lowered by the sand-drop type abrasion test. Further, the blocking ratios A (before the test) and B (after the test) of the latex fine particles having an average average particle diameter of 0.088 μm before and after the sandfall wear test are AB−67.9 and AB ≦ 50. It was not satisfactory. The results are shown in Table 1.
<Comparative Example 5>
A separation membrane obtained in the same manner as in Example 5 was evaluated except that carbon black, which is an inorganic fine particle, was not used, and a membrane was formed with a stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 13.0% by weight
N, N-dimethylformamide (DMF): 87.0% by weight
With respect to the obtained separation membrane, the initial blocking rate of latex fine particles having an average average particle diameter of 0.088 μm was measured and found to be 99.2%. The initial water permeability was 3 × 10 −9 m 3 / m 2 · s · Pa. Next, a falling sand type abrasion test was performed on the separation membrane, and the rejection rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 46.3% and the water permeability was 20 × 10 −9 m 3 / m 2.・ It became s ・ Pa. That is, the performance of the separation membrane was lowered by the sand-drop type abrasion test. Further, the blocking ratios A (before the test) and B (after the test) of the latex fine particles having an average average particle size of 0.088 μm before and after the sandfall wear test are AB−52.9 and AB ≦ 50. It was not satisfactory. The results are shown in Table 1.
<Comparative Example 6>
In place of carbon black, which is an inorganic fine particle, zeolite particles having a particle diameter of 50 μm and a bulk density of 0.55 g / ml (manufactured by Wako Pure Chemical Industries, zeolite A-4, 200 mesh) are used. A separation membrane obtained in the same manner as in Example 1 was evaluated except that the membrane was formed.

Polyvinylidene fluoride (PVDF): 13.0% by weight
Polyoxyethylene sorbitan monostearate: 6.5% by weight
N, N-dimethylformamide (DMF): 72.5% by weight
Zeolite: 5.0% by weight
H2O: 3.0% by weight
With respect to the obtained separation membrane, the initial average rejection of latex fine particles having an average average particle diameter of 0.088 μm was measured and found to be 93.0%. The initial water permeability was 52 × 10 −9 m 3 / m 2 · s · Pa. Next, a sandfall type abrasion test was performed on the separation membrane, and the blocking rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 40.0% and the water permeability was 70 × 10 −9 m 3 / m 2.・ It became s ・ Pa. That is, the performance of the separation membrane was lowered by the sand-drop type abrasion test. Further, the blocking ratios A (before the test) and B (after the test) of the latex fine particles having an average average particle size of 0.088 μm before and after the sandfall type abrasion test are AB = 53 and AB ≦ 50 cannot be satisfied. It was a thing. The results are shown in Table 1.
<Comparative Example 7>
As inorganic fine particles, the particle diameter is 6000 nm, the bulk density is 0. Separation obtained in the same manner as in Example 1 except that 6 g / ml mesocarbon microbeads (manufactured by Osaka Gas Co., Ltd., mesocarbon microbeads 6-28) were used to form a film with a stock solution having the following composition: The membrane was evaluated.

Polyvinylidene fluoride (PVDF): 13.0% by weight
Polyoxyethylene sorbitan monostearate: 6.5% by weight
N, N-dimethylformamide (DMF): 72.5% by weight
Mesocarbon microbeads: 5.0% by weight
H2O: 3.0% by weight
With respect to the obtained separation membrane, the initial blocking rate of latex fine particles having an average average particle diameter of 0.088 μm was measured and found to be 28.0%. The initial water permeability was 77 × 10 −9 m 3 / m 2 · s · Pa. Next, a sandfall type abrasion test was performed on the separation membrane, and the blocking rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 26.0% and the water permeability was 79 × 10 −9 m 3 / m 2.・ It became s ・ Pa. Although the change in the performance of the separation membrane by the falling sand type abrasion test was not as large as AB = 2, the latex rejection rate itself of the separation membrane before the test was low. The results are shown in Table 1.
<Comparative Example 8>
As Inorganic Fine Particles, natural graphite having a particle diameter of 1500 nm and a bulk density of 0.04 g / ml (SS Co., Ltd., natural graphite SNO) was used, and film formation was performed using a stock solution having the following composition. The separation membrane thus obtained was evaluated.

Polyvinylidene fluoride (PVDF): 13.0% by weight
Polyoxyethylene sorbitan monostearate: 6.5% by weight
N, N-dimethylformamide (DMF): 72.5% by weight
Natural graphite: 5.0% by weight
H2O: 3.0% by weight
With respect to the obtained separation membrane, the initial average rejection of latex fine particles having an average average particle diameter of 0.088 μm was measured and found to be 98.7%. The initial water permeability was 61 × 10 ⁻⁹ m ³ / m ² · s · Pa. Next, a sandfall type abrasion test was performed on the separation membrane, and the rejection rate of latex fine particles having an average average particle size of 0.088 μm was measured. As a result, it was 48.5% and the water permeability was 73 × 10 ⁻⁹ m ^3. / M ² · s · Pa. That is, the performance of the separation membrane was lowered by the sand-drop type abrasion test. Further, the blocking ratios A (before the test) and B (after the test) of the latex fine particles having an average average particle diameter of 0.088 μm before and after the sandfall wear test are AB = 50.2 and AB ≦ 50. It was not satisfactory. The results are shown in Table 1.

It is a general | schematic cross-sectional drawing of the element using the separation membrane which concerns on this invention (AA cross section of the element of FIG. 2). It is a general | schematic expansion | deployment perspective view of the element using the separation membrane which concerns on this invention. It is a schematic flowchart of the liquid processing method using the separation membrane module which concerns on this invention. 2 is a scanning electron micrograph of the surface of the separation membrane of the present invention according to Example 1 after a wear test. 6 is a scanning electron micrograph of the surface of the separation membrane of the present invention according to Example 2 after a wear test. It is a scanning electron micrograph of the surface after the abrasion test of the separation membrane of the present invention concerning Example 3. 4 is a scanning electron micrograph of the surface of the separation membrane of the present invention according to Comparative Example 1 after a wear test. It is a scanning electron micrograph of the surface after the abrasion test of the separation membrane of the present invention concerning comparative example 2. It is a scanning electron micrograph of the surface after the abrasion test of the separation membrane of the present invention concerning comparative example 3.

Explanation of symbols

1: Support plate 2: Channel material 3: Separation membrane 4: Convex part 5: Concave part (groove)
6: Frame 7: Filtrate outlet 8: Liquid collecting part 9: Element 10: Separation membrane module 11: Non-treatment water tank 12: Air diffuser 13: Blower 14: Pump

Claims (4)

5-30% by weight of organic polymer, 0.1-30% by weight of inorganic fine particles having an average particle size in the range of 5-5000 nm and a bulk density of 0.05-0.5 g / ml, polyoxyethylene sorbitan as a pore-opening agent A film-forming stock solution containing 0.1 to 15% by weight of a fatty acid ester or polyoxyethylene fatty acid ester, a solvent of 40 to 95% by weight, and a non-solvent of 0.1 to 10% by weight is applied onto the substrate, and at least 80% by weight. The manufacturing method of the separation membrane made to contact the coagulation liquid containing a non-solvent%. The method for producing a separation membrane according to claim 1, wherein the inorganic fine particles are carbon-based fine particles or at least one kind of oxide fine particles selected from the group consisting of silicon, aluminum, magnesium and calcium . The method for producing a separation membrane according to claim 1 or 2, wherein the organic polymer is at least one selected from the group consisting of a polyvinylidene fluoride resin, a polysulfone resin, a polyacrylonitrile resin, and a polyethersulfone resin. . Concerning the rejection rate of latex fine particles having an average particle size of 0.088 μm before and after the falling sand wear test, the relationship of inequality A−B ≦ 50 is satisfied, where A is the rejection rate before the test and B is the rejection rate after the test. The method for producing a separation membrane according to any one of claims 1 to 3 .

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