TW200815296A - Membrane separation method, immersion type membrane separation device and membrane separation process - Google Patents

Abstract

The present invention provides a treatment method of wastewater such as the sewage such as drainage (wastewater) by membrane separation activated sludge procedure, wherein the washing efficiency of the membrane face will not be obstructed and the supply function of necessary oxygen to the activated sludge will also not be obstructed while the air diffused into the living thing processing tank. Besides, the said wastewater treatment method also has high air diffusion efficiency and could be achieved with lower cost and lower fouling. The present application relates to a membrane separation method which the microorganism-containing liquid with activated sludge is stored in the tank and then the separation treatment of membrane is taken place by the immersion type membrane separation device set up inside the said tank. The said immersion type membrane separation device at least comprises a separation membrane having 0.1 μm or less of the surface roughness and a micro-bubble diffusion pipe set up under the separation membrane to generate bubbles. The membrane separation process is taken place by way of micro-bubbles generated from micro-bubble diffusion device acted on the surface of separation membrane so as to wash the surface of separation membrane, at the same time; the membrane separation process of the microorganism-containing liquid in the tank is carried out.

Description

200815296 IX. Description of the invention: [Technical field of the invention] The wastewater separation method of the micro-separation channel, etc., is located in the Liquor product, and is therefore clarified for the internal use of the oxygen component. The present invention relates to a membrane separation method, an impregnated membrane separation apparatus, and a membrane method for solid-liquid separation of an activated sludge-containing liquid using a membrane. Specifically, the separation of the sewage water after the activated sludge treatment is carried out, that is, the treatment method using the membrane separation activated sludge method. [Prior Art] Nowadays, a membrane separation activated sludge process is generally developed as a waste water. The membrane separation activated sludge method uses a precision filtration membrane or an ultrafiltration membrane to replace the final sedimentation tank of the general activated sludge method to carry out a membrane treatment method, which has the advantage of maintaining high water in the biological reaction tank. Biomass (generally expressed as MLSS (= Mixed Suspended Solids)) can be used to reduce the set surface by using membrane filtration to separate sludge and treat water without SS (= Suspended Sol ids, The suspended matter) flows out, and the water can be treated. Among them, the membrane separation device is immersed in an aeration tank, and the membrane separation activated sludge method is used for both aeration energy supply and membrane surface cleaning, and the membrane separation device is disposed outside the aeration tank with a circulation pump. The membrane separation activated sludge method in the circulation mode requires less power and space, and is inexpensive and rapidly popularized. Membrane separation is carried out by a membrane separation activated sludge method of an immersion type, generally for washing the surface of the separation membrane, and is disposed under the separation membrane to generate coarse bubbles (aeration), so that the gas-liquid mixture generated by the bubbles is mixed up to 200815296 The upward flow acts on the surface of the film to perform film surface cleaning. The larger the bubble acting on the film surface, the higher the shearing force on the deposited sludge on the film surface, so that the cleaning efficiency of the surface of the separation membrane can be improved. Therefore, it is necessary to use coarse bubbles for the "cleaning time of the separation membrane". On the other hand, in order to supply oxygen to the active sludge of the biological treatment liquid, bubbles generated by the diffusing tubes provided in the tank are also required. However, the large bubbles suitable for washing the surface of the separation membrane are due to the large surface area in the water, so that the efficiency of dissolving oxygen in the water is lowered, and the amount of oxygen required to supply the activated sludge must be increased. Reduced air diffusion efficiency. In order to improve the efficiency of the gas diffusion, while maintaining the cleaning efficiency of the surface of the separation membrane due to coarse bubbles, and minimizing the amount of oxygen required to supply the oxygen required for biological treatment, it is proposed to simultaneously generate microbubbles and coarse bubbles. A gas method, or a method of diffusing air bubbles after generating microbubbles. For example, it is proposed to provide a processing apparatus for generating coarse bubbles and microbubbles while providing both a coarse bubble diffusing means and a microbubble diffusing means under the separation membrane (membrane apparatus) (refer to Patent Document 1). Further, it is proposed to provide a diffusing device for the upper and lower stages in the lower part of the separation membrane (membrane apparatus), a microbubble generated by the lower diffusing means, and a processing means for generating coarse bubbles by the upper diffusing means (refer to Patent Document 2). In addition, it is proposed to provide a micro-bubble diffusing device at a position lower than the separation membrane (membrane device), and a bubble-supplied device for coarsening the bubble at a position directly below the separation membrane (refer to Patent Document 3). In addition, it is proposed to separate the activated film method by arranging the flat films of a plurality of sheets and generating microbubbles thereunder (refer to Patent Document 4). However, in the techniques of Patent Document 1 and Patent Document 2, since the air bubbles and the microbubbles are used, it is necessary to use a diffusing tube for both large and small bubbles, and the technique of Patent Document 3 is based on The apparatus for the bubble unit which is coarsened in the bubble or the distance from the film for increasing the gas diffusion efficiency to the microbubble must be sufficiently long, so that the cost of the apparatus is easily increased, and the gas diffusion efficiency cannot be sufficiently improved by using the coarse air bubbles at the same time. Not conducive to industrial use. Further, the technique of Patent Document 4 requires a high-flow sludge feed pump due to external circulation, and the flow rate of the microbubbles staying in the sludge is short due to the flow velocity above the air lifter which must generate microbubbles. The oxygen supply efficiency cannot be sufficiently improved, and the overall device cost and running cost are improved, which is not conducive to industrial use. On the other hand, the membrane separation activated sludge method can be operated in a low sludge load state in which the amount of activated sludge in the biological treatment tank is increased as compared with the activated sludge method in which the solid-liquid separation is performed in the sedimentation tank. The amount of excess sludge generated simultaneously with the wastewater treatment can be reduced (refer to Non-Patent Documents 1 and 2). Further, at this time, the following formula 1 can be used. △ X=aS — bX.........Form 1 where ΛΧ: excess sludge production (kg/day) S : removal of BOD amount (kg/day) X : active fouling in aeration tank Mud amount (kg) a : Sludge conversion rate (kg/kg) for removing B〇D amount b: Self-oxidation rate based on endogenous respiration (1/day) Increased sludge retention time by the above formula 1 When the operation of increasing the amount of activated sludge held in the biological treatment tank is increased, the amount of excess sludge generated is further reduced. However, the longer the sludge retention time, the higher the risk of membrane blockage or insufficient oxygen supply due to the increase in viscosity. 'The operation without excess aeration is not easy to achieve. The utility facility controls the sludge retention time, periodically extracts the remaining sludge, and maintains the sludge concentration within the range of the management concentration of 8 to 12 g/L. However, a large amount of industrial waste, that is, excess sludge, is still generated. Therefore, from the viewpoint of reducing environmental load or wastewater treatment costs, it is desired to further reduce the amount of excess sludge generated. However, as described above, even if the microbubbles contribute to an increase in the oxygen supply amount, the film surface cleaning effect of the separation membrane is small, so that the microbubbles which generate the self-dispersing gas tube directly act on the membrane surface, even if the membrane separation active stains The standard sludge concentration in the mud method is also not easy to fully clean the membrane surface, and if it is a high sludge concentration, it is more difficult to wash. Further, in general, it is difficult to elongate the microbubble diffusing pipe, and in the case of a large-scale membrane separating device, a plurality of branching pipes are provided on one side of the gas supply pipe, and a microbubble diffusing pipe or the like is disposed (refer to the patent) Document 5). However, when the microbubble diffusing pipe of the arrangement method is applied to a diffusing pipe for a membrane separation device (refer to Fig. 13), the upper portion of the central gas supply pipe and the branch pipe where the microbubbles cannot be diffused cannot be fed into the membrane. Since the surface is cleaned with air bubbles, the surface of the film is insufficiently cleaned, and the filter function of the film is lowered. [Patent Document 1] Japanese Laid-Open Patent Publication No. JP-A No. Hei. No. Hei. [Patent Document 5] JP-A-2005-8 1 203 [Non-Patent Document 1] Chemical Engineering, Vol. 64, No. 8 (2000), 390 to 3 92, Yamamoto Kazuo 200815296 [Non Patent Document 2] Information Technology Center, "Comparison of Sludge Reduction System and Reduction of Cost by Sludge Measures" Workshop (2004.6.25) Textbook [Invention Contents; Γ Problem to Solve the Invention The present invention is intended to include the treatment of sewers or In the membrane separation method of the membrane separation activated sludge method for wastewater such as factory wastewater, the cleaning effect on the surface of the separation membrane is not hindered, that is, the membrane filtration flux is not lowered, and the oxygen supply efficiency is improved. Further, one of the purposes is to simultaneously improve the microbial concentration and biological reaction efficiency in the tank, and to provide an economical membrane separation method which can reduce the amount of excess sludge generated in the membrane separation activated sludge process. Further, another object is to provide an impregnated membrane separation device which efficiently supplies microbubbles to the membrane surface and has a sufficient membrane surface cleaning effect. Solution to Problem In order to solve the above problems, the membrane separation method of the present invention is specified as follows. The membrane separation method for performing membrane separation treatment by storing the microorganism-containing liquid containing the activated sludge in the microorganism-containing liquid storage tank and the membrane-separating membrane separation device provided in the microorganism-containing liquid storage tank, the impregnated membrane separation device The method further comprises a separation membrane having a membrane surface roughness of 〇. 1 # m or less and a microbubble diffusing tube for generating microbubbles under the separation membrane, so that microbubbles generated from the microbubble diffusing tube act on the surface of the separation membrane. A membrane separation method in which the surface of the separation membrane is washed while the microorganism-containing liquid is subjected to membrane separation treatment. Further, the impregnated membrane separation device of the present invention is specifically as follows. The impregnated membrane separation device is characterized in that the impregnated membrane separation device is disposed in a tank for storing the liquid to be treated, wherein the microbubble diffuser is disposed as follows: the surface roughness of the plurality of membranes is A separation membrane element in which a flat membrane of 0.1 // m or less is disposed as a separation membrane is disposed in parallel with the membrane surface, and a microbubble diffusing tube that generates microbubbles is disposed below the separation membrane element, and the pores are present in the adjacent The space formed between the membranes of the separation membrane element is vertically below. According to the present invention, the surface of the membrane is washed by the action of the gas-liquid mixed flow of the microbubbles which are ejected from the microbubble diffusing tubes, and the microbial content such as activated sludge can be stably maintained without reducing the amount of flow. Liquid membrane solid-liquid separation. That is, the present invention does not require a large bubble diffusing tube to be used for cleaning the membrane as in the prior art, and a bubble unit is provided to increase the liquid flow rate by the liquid feeding pump. Moreover, since the oxygen supply efficiency can be improved, it is economical in terms of device installation and operation, and the device composition is simple and easy to maintain. The present invention is only a membrane surface of microbubbles even under high microbial concentration operation. A high-flux filtration operation of a certain degree or more can be performed by washing. Therefore, by using the technique for treating wastewater with a high sludge concentration operation, it is possible to effectively reduce the amount of excess sludge generated by a small-sized apparatus. In particular, the amount of excess sludge generated can be suppressed by saving space and other additional equipment such as ozone oxidation associated with decomposing sludge. According to the present invention, when the operation for suppressing the amount of excess sludge generated (promoting the mineralization) is carried out under a high sludge concentration, although the aeration power is larger than that during the operation of the general low sludge concentration, the electric power fee is increased. The amount of mud generated is greatly reduced, because the treatment cost is reduced by -11-200815296, and the effect is less than the increase of electricity costs, so the operating cost during wastewater treatment can be reduced. In particular, in areas where the excess sludge treatment cost before and after the water content of 85% exceeds 10,000 yen/ton, the cost reduction effect is more remarkable. Further, the present invention provides a technique for improving the structure of a microbubble diffusing tube or an improved technique for the arrangement of a microbubble diffusing tube for a membrane element, by which microbubbles are efficiently supplied to the membrane surface, and it is easy to have a sufficient membrane surface washing. The net effect is achieved, and the contamination in the diffusing pipe provided in the tank can be alleviated. Thereby, the impregnated membrane separation device which can be stably operated is completed. [Embodiment] The present invention relates to a membrane separation method, an impregnation membrane separation apparatus, and a membrane separation treatment method for performing solid-liquid separation using a microorganism-containing liquid separation membrane containing activated sludge. For example, the sewage from a sewer or the like is subjected to activated sludge treatment in a biological treatment tank, and the membrane-separated active sewage is subjected to membrane separation treatment by an impregnated membrane separation device by subjecting the treatment mixture containing activated sludge to the biological treatment tank. A method of treating wastewater by mud. In the wastewater treatment method for performing the membrane separation activated sludge treatment, in order to improve the gas removal efficiency of the separation membrane surface and the oxygen supply function of the activated sludge, a specific separation membrane is used, and the dispersion membrane is produced. The gas bubbles are placed in the microbubbles, and the surface of the separation membrane is washed by the microbubbles. In other words, in order to improve the gas diffusion efficiency during wastewater treatment, the surface properties of the gas and the separation membrane used for membrane cleaning were comprehensively investigated. It was found that if a separation membrane having a surface property within a specific range is used, even microbubbles are used. The effect also has sufficient membrane cleaning efficiency to create the present invention. -12- 200815296 Fig. 1 shows an example of a membrane separation living water treatment apparatus to which the method of the present invention is applied. In the following, the waste apparatus of the first embodiment is used. The method for treating wastewater such as organic sewage according to the method of the present invention can be treated according to the wastewater treatment method of the present invention (sewage 7) wastewater or domestic wastewater, etc. Effective for industrial waste water rich in organic matter such as acupuncture factories or food factories: In the wastewater treatment plant shown in Fig. 1, a microbial containing liquid containing mud is stored and a raw aeration by activated sludge is required. The tank (microbial-containing liquid storage tank) 2, the raw water supply pump 3 for feeding the raw water (the water to be treated) to the aeration tank 2, and the raw water supply pipe 1 for the solid-liquid separation of the biologically treated activated sludge mixture a membrane extraction pump 6 that sucks the membrane separated by the membrane separation device and solid-liquid separation through the water to evacuate the excess sludge in the aeration tank. The membrane separation device 4 is provided by the membrane module 4 1 and disposed below it. The membrane separation device 4 is immersed in the aeration tank 2, and the air diffusing device 8 is connected to the supply device 7 by an air line (gas supply line) 81. That is, the air unit 8 is provided by the air supply unit 7, By making the microbubbles The aeration treatment of the activated sludge is carried out, and the size and material of the membrane aeration tank 2 are also not particularly limited, and the membrane separation device 4 can be immersed in the raw water and The activated sludge (microorganism-containing liquid) may be, for example, a concrete tank, a slime tank, etc., and the inside of the aeration tank may be divided into a plurality of tanks to immerse the membrane separation device 4 into a plurality of tanks. The neutral process wastewater treatment equipment [C), for example, is produced by self-chemical treatment. The waste of the chemical liquid treated with the active waste is passed through the air into the diffused air through the separation device ί, and the air is fed into the dispersed sludge. The active mixture is stored in a dimensionally reinforced plastic structure, also in the partial groove -13- 200815296. In addition, an anaerobic tank, an anaerobic tank, an aerobic tank, or the like may be additionally provided in the front section of the aeration tank to carry out removal procedures of nutrients such as nitrogen and phosphorus other than organic substances. The raw water supply pump 3 can transport the raw water (waste water) to the pump in the aeration tank 2 without any particular limitation, and for example, a vortex pump, a diffusing pump, a vortex oblique pump, a diagonal flow pump, a piston pump, or the like can be used. Piston pump, diaphragm pump, gear pump, screw pump, vane pump, step pump, jet pump, etc. The suction pump 5 is a pump that permeates the membrane through the membrane in the water conduit 42 to permeate the water, and the suction force required to perform the membrane filtration solid-liquid separation by the membrane separation device 4 is supplied by the suction force of the pump to generate a water flow. The shape and the like of the air suction pump 5 are not particularly limited, and are generally used in a pump that is operated under a reduced pressure state to 300 kPa or less. Further, instead of the air suction pump 5, the membrane filtration can be carried out by using the natural water level difference as the driving force. At this time, the membrane filtration stream (membrane filtration flux per unit membrane area) is an extremely important item for determining the efficiency of the water treatment method. The higher the membrane filtration stream, the larger the membrane area of the membrane separation device can process a certain amount of wastewater, affecting the installation area of the water treatment device and reducing the aeration energy required for the membrane surface. However, as the membrane filtration stream is increased, the membrane filtration resistance is increased, so that it is not easy to operate stably. According to the method of the present invention, even at a relatively high membrane filtration stream, i.e., 0·5 m/曰 or more, it can be operated stably. Further, a membrane separation stop rotation control device 43 that can switch the operation/stop of membrane filtration for a fixed period of time is provided in the membrane through the water line. The control device is not particularly limited. For example, as shown in Fig. 1, the control device 43 provided for supplying the driving force required for the solid-liquid separation of the air suction pump 5 is provided with a timer, which is based on a pre-recorded The program, by periodically switching the operation/stop of the air suction pump, the control device of the -14-200815296 electrical switch. Further, when the natural water level difference is used as the driving force, a solenoid valve is provided in the middle of the membrane-filtered water line, and the control valve of the same control as described above is provided by the opening and closing of the solenoid valve. According to the method of the present invention, the membrane separation operation/stop control unit 43 performs membrane filtration while repeating the operation and the stop of membrane filtration in a predetermined cycle. The ratio of the stop time of membrane separation is defined as in Formula 2. In the present invention, the ratio of the stop time of the membrane separation is preferably from 1 to 15%. (Proportion of the stop time of membrane separation) = (stop time) / ((operation time) + (stop time)) • • Equation 2 The previous method was performed to shorten the ratio of the stop time of membrane separation to less than 1 5%. Membrane filtration operation, membrane contaminants are not easily sufficiently peeled off from the membrane surface. However, a separation membrane having a surface roughness of 0.1/zm or less, particularly a separation membrane having a surface roughness of 0.1/m or less and an average pore diameter of 〇.2//m or less, is used to wash the membrane surface with microbubbles. In the method of the present invention, even if the ratio of the stop time of the membrane separation is 15% or less, the membrane fouling substance on the surface of the membrane can be sufficiently peeled off, and the membrane filtration safety can be improved in the opposite direction. Further, when the membrane separation duration (the above-described operation time per cycle) is 20 minutes or less, it is more appropriate to significantly improve the membrane filtration stability. The sludge pump 6 is a pump that periodically extracts sludge to maintain the concentration of the MLSS in the aeration tank. The pump is not particularly limited and can transport highly viscous sludge. In the membrane separation activated sludge process, the general MLS S concentration is about 3 to 20 g/L, but to maintain a more stable membrane filtration stream, the MLSS concentration should be about 5 to 15 g/L. In general, by increasing the concentration of organic matter per unit volume by increasing the concentration of MLSS, high-efficiency water treatment can be performed, but the membrane filtration system of -15-200815296 increases the membrane filtration resistance as the concentration of MLSS increases. filter. According to the present invention, even at a relatively high concentration, i.e., an MLSS concentration of 10 g/L or more, it is possible to operate stably. Further, the present invention is a flat membrane-shaped separation membrane having a smooth surface of the membrane having a surface roughness of 0.1 μm or less, and the membrane can be sufficiently washed by a single microbubble diffusing tube, even if it is described later. It can also be operated stably under the conditions of a certain amount of flow required for the actual membrane filtration operation. Further, even at a high sludge concentration of MLSS concentration of 15 g/L or more, membrane filtration can be carried out stably. Specifically, at a water temperature of 25 ° C, a membrane filtration stream of about 1.0 m/d at an MLSS concentration of 10 g/L, and a membrane filtration stream of about 0.7 m/d at 15 g/L, 20 g/L. The membrane filtration stream of about 4 m/d is about 0.2 m/d at 30 g/L, and each can be operated within 1 OkPa of the differential pressure between membranes for more than one month. The degree of effect of reducing the amount of excess sludge is different depending on the type of wastewater, activated sludge, operating conditions, etc., so it is not easy to discuss in detail, so that the BOD concentration is 200~l, 500ppm of wastewater in BOD volume load 0.5 ～2.0kg — B〇D/m3/day, and the MLSS concentration is 15g/L, and the treatment according to the method of the present invention has a high effect. If the sludge concentration is low, the sludge decomposition rate and the organic matter decomposition of endogenous respiration are not good. Therefore, the sludge concentration should be increased. The MLSS concentration should be 15g/L or more, especially 20g/L or more. However, if the sludge concentration is too high, the viscosity becomes high, the mixing of the activated sludge liquid in the aeration tank is poor, and the sludge properties are deteriorated, which increases the risk of operation. Therefore, even if the concentration of MLSS is high, it is suitable. It is 40 g/L· or less. Should manage the concentration of MLSS in the range of 15~40g/L -16- 200815296

It is best to determine the volumetric load and reduce the demand for sludge. There is no special restriction. The BOD sludge load can be MLSS concentration of 〇.lkg/MLSS/曰. In addition, when the sludge is to be reduced, the MLSS concentration of 0.05 kg/MLSS/day can be used. When the sludge is to be further reduced, the MLSS concentration of 〇.〇2kg/MLSS/day can be used. The sludge concentration may be 15 g/L or less during a part of the operation period due to the extraction of the sludge or the like. However, in order to suppress the amount of excess sludge generated, long-term operation at 15 g / L or more can suppress the amount of excess sludge generated in a certain period of time, for example, it should be maintained at more than 50% of the year, especially more than 70%. The concentration of MLSS is 15g/L or more. The air supply device 7 is a device that transports compressed air, and generally uses a blower, a compressor, and the like. The transported air is sent to the microbubbles in the tank by the diffuser 8, and the surface of the separation membrane of the membrane separation device is washed by the microbubbles, and the oxygen required for the biological treatment (aerobic treatment) is fed into the liquid. . At this time, the larger the aeration air volume, the easier it is to wash the surface of the separation membrane. However, when the aeration air volume is high, the cleaning effect is less due to the increase of the aeration air volume, so the right aeration air volume is too large. Reduce aeration efficiency. Further, if the amount of aeration air is too large, the oxygen dissolution efficiency per unit aeration air volume is lowered, and the energy efficiency is deteriorated. On the other hand, if the amount of aeration air is too small, not only the surface of the separation membrane cannot be sufficiently washed, but also the aeration efficiency per unit area is small, which is not economical. The aeration air volume is aerated air volume per unit area of the aeration air flow path, preferably 0.13~0.5L/min/cm2, especially 0.18~0.4L/min/cm2, and most preferably 0.18~0.25L/min/ Cm2. The membrane separation device 4 is composed of an upper membrane module 4 1 and a lower diffusing device -17-200815296 8 . It is preferable to form a frame using a material such as metal or resin to carry the film module 4 1 and the diffuser 8. The membrane module 41 has a structure in which a separation membrane for allowing solid-liquid separation of a substance-containing liquid containing activated sludge in a tank is provided. For this reason, the shape of the film may be a flat film or a hollow film, etc., and the shape of the flat film module is not particularly limited in the present invention, but it is preferable to increase the filter film (separation 丨 operability and physical durability, for example, for example) Fig. 3 (shown obliquely, the inner surface of the frame 45 formed of resin, metal, or the like is interposed, and a flat separation film (flat film) 46 penetrating the water flow path material is interposed to fix the periphery of the flat film. The flat membrane element 44 of the structure is configured such that the plurality of flat membrane elements 44 are arranged in parallel with the membrane surface. The flat membrane module is not limited to the above. The membrane module 41 having the flat membrane element is due to the membrane surface. Since the shearing force of the flow rate has a good effect of removing the dirt, the flat film (separation film) used in the present invention is required to have a smooth surface having a film surface degree of 0.1/zm or less as described later. As shown in Fig. 3, a film structure in which a plurality of flat sheets 44 of a plurality of sheets are vertically arranged at a constant interval and parallel to the film surface is shown. Fig. 3 is a schematic view showing two adjacent separation membrane elements 44. 'The provision between the film faces of the adjacent separation membrane elements 44 is vacant The interval, the upward flow of the liquid, in particular, the mixed flow of the bubbles and the liquid in the tank causes the gap between the membranes to rise. In order to clean the membrane surface of the separation membrane, it is possible to make the membrane surface space B unobstructed and good. The gas-liquid flow with micro-bubbles vertically downward flows upwards. In order to increase the filtration area per unit volume of the membrane module, it is preferable to reduce the micro-production, the film separation, and the structure of the film. The rough membrane element assembly has a B-line in the inclined groove, and the separation of the membrane surface of the membrane element 44 is arranged, and more separation membrane elements are disposed. However, if the membrane surface spacing is excessively narrow, the membrane surface of the separation membrane element cannot be It is fully in contact with air and the membrane surface is not completely cleaned, which in turn reduces the membrane filtration performance. In order to effectively carry out the membrane filtration, the interval between the membrane faces is preferably 15 mm, particularly preferably 5 to 10 mm. The air diffusing device 8 is a type of diffusing pipe that can generate microbubbles. There is no particular limitation. For example, the air discharging portion can be made of metal, ceramic, porous rubber or a film diffusing device, and can be used for oxygen dissolution. High efficiency diffuser. Further, if the pressure loss of the air diffusing device 8 is too high, the power consumption is increased, which is disadvantageous to energy saving and economy, so that it is a low-voltage loss. The microbubbles used in the present invention are preferably microbubbles which are generated by diffusing air from a pore having a pore diameter of from 1 to 500 /z m. When the portion where the air vent is provided is made of a non-stretch material such as a metal tube, the hole diameter of the air vent is directly determined by the hole diameter. In this case, when the air diffusion hole is circular, the diameter of the hole is the aperture. However, if it is not circular, the effective area of the hole is calculated from the photograph, and the diameter when converted into a circle is the aperture. That is, when the effective area of the hole is A, the aperture can be calculated from 2 χ(Α/ττ ) 1/2 . Further, when there are a plurality of pores having different pore diameters, the average enthalpy of each pore diameter is the pore diameter of the pores. Further, when a vent hole is provided in a portion made of a rubber-like porous film-like stretchable material, a predetermined pressure can be applied to the air vent tube, and the air vent hole can be photographed in an open state, and the aperture can be measured from a photograph. Further, the microbubbles are preferably 2 mm or less in diameter. The bubble diameter is a method in which aeration is carried out in a clean water environment, bubbles at a position corresponding to the photographic film surface, and an average enthalpy of the bubble diameter is evaluated from the photograph. This type of micro-19-200815296 bubble having a diameter of 2 mm or less is formed by the above-mentioned pores having a pore diameter of 1 to 500 // m. However, it is also possible to disperse and refine the bubble by generating a large bubble in the diffusing tube. The micro-refinement device is disposed in the middle of the diffuser device 8 and the membrane module 41 to thereby form microbubbles. Further, the microbubble diffusing means is preferably formed of an elastic sheet formed by a plurality of diffusing holes which are opened and closed by expansion and contraction, and the diffusing duct has a microbubble released by a switch of the diffusing hole thereof. structure. A diffusing hole, such as a micro slit, that is opened and closed by being stretched. Specifically, an ideal air diffusing device is provided with an elastic sheet forming a micro slit to cover the outer circumference of the cylindrical support tube, and when air is fed between the cylindrical support tube and the elastic sheet, the elastic sheet is expanded and formed on The micro-slit of the elastic sheet is opened to create a structure of micro-bubbles. Such a diffusing device is, for example, a rubber-made diffuser pipe sold by Meiling Industrial Co., Ltd. The structure and action of the above microbubble diffusing pipe will be described. Fig. 2 is a cross-sectional view showing the longitudinal center axis α of the micro-bubble diffuser. The microbubble diffusing duct has a support tube 20 at a central portion, and an elastic sheet 19 is provided to cover the entire outer periphery of the support tube 20, and the axial end portions of the elastic sheet 19 are fixed by an annular fixing tool 21. A plurality of air gaps (not shown) are formed on the elastic sheet 19. The length of the longitudinal direction of the air gap is 〇.1~i〇mm, and the slit of the length of 0.5~5mm is particularly suitable. One end of the support pipe 20 is connected to the branch pipe portion 16 and a communication hole 22 is provided in the vicinity of the connection end. The air supplied from the branch pipe 16 passes through the communication hole 22, enters between the support pipe 20 and the elastic sheet 19, and expands the elastic sheet bundle 9. The air gap is opened by the expansion of the elastic sheet 19, so that the fed air of -20-200815296 becomes a microbubble and is sprayed into the liquid in the aeration tank 2. When the supply of air is stopped, the pores are closed due to the shrinkage of the elastic sheet film 19, and the microbial liquid contained in the tank does not flow into the diffusing tube from the diffusing pores when the microbubbles are not released, thereby preventing microbial containment during the membrane filtration operation. The sludge in the liquid causes clogging of the diffusing holes or contamination in the diffusing pipe. The material of the branch pipe 16 and the support pipe 20 is a rigid material that is not damaged by a load such as vibration of a diffused air, and is not particularly limited. For example, a metal such as stainless steel, an acrylonitrile butadiene styrene resin (A B S resin), a resin such as polyethylene, polypropylene or polyvinyl chloride, or a fiber reinforced resin (FRP) or the like may be used. The material of the elastic sheet 19 is not particularly limited, and synthetic rubber such as ethylene propylene diene rubber (EPDM), enamel rubber, urethane rubber or the like, or other elastic material should be appropriately selected and used. Among them, ethylene propylene diene rubber is preferred because of its excellent chemical resistance. Further, in the inter-membrane space B of the separation membrane element 44 in the membrane module, in order to cause the microbubbles to rise from the lower side and the microbubbles to act on the membrane surface, it is preferable to provide the diffusing means 8 so that the space between the membrane spaces B is not vertically vertical. Full of stomata. Thereby, the microbubbles are uniformly applied to the film surface of the separation membrane element 44, and the surface of the separation membrane can be efficiently washed to obtain a high membrane filtration stream. The method of arranging the specific gas diffusion tube in the present invention is as follows. Fig. 4 is a schematic oblique view of an embodiment in which a membrane separation device is provided in a tank and membrane separation is carried out. A plurality of microbubble diffusing tubes 8a, 8b are disposed vertically below the separation membrane module 4 1. The plurality of microbubble diffusing tubes 8a, 8b are connected to the air supply tubes -21 - 200815296 15L, 15R via the branch tube portions 16L, 16R, respectively. The gas supply pipes 15L and 15R are disposed so as to be opposed to each other directly below the separation membrane. That is, the branch branches from the gas supply pipe 15R on the left side in Fig. 4, the gas supply pipe 15L on the right side of the branch pipe branches, and the diffusing pipes 8a, 8b of different lengths are connected to the branch pipes 16R, 16L. By arranging the long axis of the microtube in the film surface of the separation membrane element 44 as described above, the pores can be disposed in the vertical direction of the separation membrane module without any hindrance. Further, the longer the length of the microbubble diffusing tubes 8a, 8b, the more uniform the amount of gas is diffused. Therefore, when the separation membrane module is provided with a large component of the membrane element, it is difficult to produce a microbubble having a length of one end of the module and capable of diffusing in a uniform direction in a long direction. The invention preferably has a vertical configuration even when disposed in a large separation membrane module. A micro-structured diffuse tube that can generate microbubbles without hindrance and uniformity. As shown in Fig. 6, a plurality of gas diffusing ducts are arranged in a direction opposite to the portion directly below the separation membrane, and are connected thereto. The microbubble diffusing tube of the tube is configured to extend in a direction to the fork of the separation membrane element. That is, as shown in Fig. 4, the bubble diffusing ducts are arranged in the same manner in the same manner in the longitudinal direction central axis α. It is preferable to arrange the longitudinal end portions of the adjacent microbubble diffusing tubes to be different from each other. In the order of the microbubble diffusing pipe system, the bubble duct 8b, the short microbubble diffusing pipe 8a, and the long microbubble _ are sequentially arranged from the front side of the eye in the direction of the arrow, and are disposed on the right side by the branch pipe branch portion 16R. The gas component of the 16R series 16L system is not easy to extend from the long part of the front end to the other side of the bubble from the front end of the air bubble. When it is, it is still like the gas of the fourth component. The film supply surface shows the same, the micro-line is different, and the difference is based on the long micro gas, the tube 8b body supply tube-22-200815296 15R, and in the direction of the arrow A according to the short microbubble diffusing tube 8a The order of the bubble diffusing pipe 8b and the short microbubble diffusing pipe 8a is arranged in the gas supply pipe 15L on the left side by branching 16 6L, and the tip end position is irregularly arranged. Further, the embodiment of Fig. 4 is a gas dispersing device including a total of six diffusing tubes of three types of microbubble diffusing tubes 8a and 8b in the longitudinal direction, but the length and the number of the length of the diffusing duct are not Therefore, the volume of the aeration tank 2, the number of the membrane elements 44 of the separation membrane module 41, the degree of freedom of the piping, and the like can be appropriately selected. 2 and the third embodiment of the microbubble diffuser (Fig. 5, Fig. 6). When the membrane filtration operation is performed in Fig. 4, the air fed from the blower 7 of the on-off valve 14 flows into the air. Supply the main pipe 8.1, the flow supply pipes 15R, 15L, and the air bubble diffusing pipes 8a, 8b through the branch pipes 16R, 16L. The air is ejected from the micro-bubble diffusing pipes 8a, 8b, and is ejected in the aeration tank ( The microbubbles are generated in the treatment tank). The gas-liquid mixture rising bubbles generated by the air-lifting action of the micro-bubbles act on the membrane surface of the separation membrane as a sweep, thereby preventing the membrane from adhering and depositing on the membrane surface. Next, Fig. 5 (above the diffuse tube portion) shows other embodiments of the micro air tube, wherein the length of the adjacent microbubble diffuser is different every two. Thus, The longitudinal lengths of the adjacent micro-pipes 8 are different and are not uniform, and may be irregularly arranged to be irregular. The composition of the different micro-tubular portions is limited and separated. The second (II) mentioned later is also turned on, and the micro-injection of gas into the micro-surface is by jet or Long bubbles bubble diffusing filter 8 when the complex roots -23-200815296 dispersion and, FIG. 6 (diffusion pipe portion (a) of FIG above, (b) side view) as shown in other embodiments the microbubbles like state based diffusing tubes. a branching pipe portion 6L connected to the left side of the gas supply pipe 5L and a front end portion of the extended microbubble diffusing pipe, and a branching pipe portion 6R connected to the right side of the gas supply pipe 5R and an extended front end portion of the microbubble diffusing pipe The parts are partially stacked. That is, the branching tube portion 6R connected to the right side and the extended microbubble diffusing tube system is located on a plane C whose horizontal direction central axis α is horizontal, and is connected to the branching tube portion 6L on the left side and the elongated microbubble diffusing tube It is disposed on a horizontal plane D whose central axis α in the longitudinal direction is lower than the horizontal plane C. At this time, it is preferable to shift the longitudinal center axis of the upper microbubble diffusing pipe and the long central axis of the lower microbubble diffusing pipe so as not to impede the upward flow of the microbubbles released from the lower microbubble diffusing pipe. Thus, the longitudinal center axis α of the microbubble diffusing tube 8 does not need to be on the same plane, or a part of the microbubble diffusing gas 'the front end of the tube 8 overlaps vertically. Fig. 7 is not a specific apparatus for setting a membrane separation device for a microbubble diffusing tube which is the same as that of Fig. 4. Fig. 7 (a), (b), and (c) are a front view, a side view, and an A-A cutaway view, respectively, of the membrane separation apparatus. This figure omits the gas supply pipe and its upstream side. The apparatus of Fig. 7 is provided with a parallel-arranged 1-diaphragm separation membrane element in the separation membrane module 4 1. A microbubble diffusing pipe extending from the branch pipe portion 16 R of the right side of the gas supply pipe (not shown) in the horizontal direction and a gas supply pipe from the left side are provided vertically below the separation membrane module 4 1 (not shown) The branched tube portion 16 6L is a microbubble diffusing tube extending in the horizontal direction. These microbubble diffusing ducts are arranged in such a manner that the long central axes are arranged in four rows on the substantially straight line -24 - 200815296 of the same horizontal plane, so that the front ends of the opposed microbubble diffusing tubes are positioned adjacent to each other. It is also configured such that its front end portions are different from each other. By forming the microbubble diffusing tube structure, microbubbles can be uniformly scattered on the film faces of the respective elements in the separation membrane module 41. Fig. 8 is a view showing a specific apparatus for providing a membrane separation device for a microbubble diffusing tube which is the same as that of Fig. 6. Fig. 8 (a), (b), and (c) are a front view, a side view, and an A-A cutaway view, respectively, of the membrane separation apparatus. This figure omits the gas supply pipe and its upstream side. In the apparatus of Fig. 8, the structure of the separation membrane module 4 1 is the same as that shown in Fig. 7, and the diffuser structure provided below the separation membrane module 4 1 is different from that shown in Fig. 7. A microbubble diffusing pipe extending in the horizontal direction from the branch pipe portion 16R of the gas supply pipe (not shown) on the right side and a gas supply pipe on the left side (not shown) are disposed vertically below the separation membrane module 4 1 . A microbubble diffusing tube extending in the horizontal direction by a branch portion of 16L. These microbubble diffusing ducts are arranged such that the longitudinal center axis is shifted in the upper and lower horizontal planes and the longitudinal central axis is shifted, and the front end portions are partially overlapped. By forming the microbubble diffusing tube structure, microbubbles can be uniformly scattered on the film surface of each element in the separation membrane module 4 1 . In general, when the coarse air bubbles are used for the film surface cleaning of the separation membrane, as described above, the washing and removing effect of the sludge adhering to the surface of the membrane is improved, but the contact area between the bubbles and the water is reduced, so that it is lowered. The efficiency with which oxygen dissolves in the liquid and reduces the efficiency of the gas. However, in the present invention, since the surface roughness of the film used in the membrane separation device 4 is 0.1/m or less, it is particularly preferable that the surface roughness of the film is 〇·1 #m or less and the average pore diameter of the film surface is 〇.2 /zm or less. The specific separation membrane of the traits -25 to 200815296, even if the microbubbles with low cleaning effect are used, can have a sufficient membrane surface cleaning effect, and can stably operate under the conditions of the general ventilation required for the membrane separation activated sludge method. under. In the present invention, the separation membrane flat membrane used in the membrane separation device 4 is a separation membrane which has a certain particle diameter or more in the filtrate to be collected by applying pressure on the filtered side or by suction on the permeate side. The function is classified into a dynamic filter membrane, a precision filtration membrane and an ultrafiltration membrane according to the difference in the diameter of the collected particles, and is preferably a precision filtration membrane. The surface portion of the film which is used as a flat film of the separation membrane is as shown in Fig. 9. In the membrane separation activated sludge method, the activated sludge is subjected to solid-liquid separation at the film surface layer portion 9, and the separated water is passed through the membrane as permeated water (treated water). The surface roughness of the surface of the separation membrane system used in the present invention is 0.1/zm or less, preferably less than the surface roughness of the membrane and the average pore diameter of the membrane surface is 0.2 μm or less, and the surface roughness of the membrane surface is particularly suitable. 1~〇. 〇7 // m, and the average pore diameter of the film surface is 0.01~〇.l/zm. The surface roughness of the film surface refers to the average height of the film in the vertical direction with respect to the surface of the film which is in contact with the liquid to be filtered, and the pattern of Fig. 9 is a graph in which the symbol 10 represents the height. The surface roughness of the film surface can be measured by the following apparatus and method. In the measurement apparatus, an atomic force microscope apparatus (Nanoscope Ilia, manufactured by Digital Instruments Co., Ltd.) was used, and a SiN cantilever (manufactured by Digital Instruments Co., Ltd.) was used as a probe. The scanning mode was a contact mode, and the scanning range was 1 〇// m X 2 5 // m. The scanning dissociation degree is obtained by measuring the height (Zi) of the Z-axis (in the vertical direction with respect to the film surface) of each point by 5 1 2 x 5 1 2 . Before the measurement, the film test product was immersed in ethanol at a temperature of -26 to 200815296 for 15 minutes, and then immersed in the reverse osmosis membrane filtered water for 24 hours, and then subjected to air drying pretreatment. Thereafter, the base line of the measurement number 値 was subjected to a horizontal treatment to obtain a square roughness RMS (/z m) calculated according to the following formula 3 as the surface roughness of the film surface portion. Π5 Z Σ(Ζι-Ζ)2 RMS=-\"- ^ N ...... Equation 3 The average pore size on the surface of the membrane refers to the average pore diameter of the surface of the separation membrane φ 値, the pattern diagram of Figure 9 A diagram represented by the symbol 1 1 representing the width. In order to measure the average pore diameter of the surface of the film, for example, a film surface of a film is photographed at a magnification of 10,000 by a scanning electron microscope, and the diameter of any 10 or more pores of 20 or more is measured, and the average number of pores is determined. When the pores are not round, a circle having an area equal to the area containing the pores (equivalent circle) is obtained by a video processing apparatus or the like, and the diameter of the equivalent circle is determined as the diameter of the pores. If the standard deviation σ of the pore diameter is too large, the ratio of the pores having poor filter pore properties is high, so the standard deviation σ is preferably 0.1 // m or less. Further, the porous film used in the present invention is preferably a film excellent in water permeability from the viewpoint of high water permeability and operational safety. The pure water permeability coefficient of the porous film before use can be used as an index of permeability. The pure water permeability coefficient of the porous film is calculated by using 25 ° C purified water of the reverse osmosis membrane and measuring the water permeability at the indenter height lm, preferably 2 x 1 (T9 m 3 / m 2 /s / pa or more, particularly 40 x l (T9m3/m2/s/pa or more, a substantially sufficient amount of permeate water can be obtained in this range. When a membrane separation device having a flat membrane-like separation membrane having such surface properties is used, 'by allowing microbubbles to act on the membrane surface The reason for the good cleaning of the film surface is -27-200815296 as described below. The smaller the surface roughness of the film, the higher the film surface peeling coefficient ratio (refer to Figure 14 for the permeation coefficient of the material) The ratio of the ease of peeling of the non-membrane-permeable substance attached to the separation membrane from the separation membrane to the peeling coefficient of the standard membrane indicates the ratio of the non-membrane-permeable material peeling coefficient, that is, the higher the ratio, the adhesion to the separation The non-membrane of the membrane is separated by the substance, and it is difficult to form a thin film of a non-membrane-permeable substance on the surface of the film. Further, the standard film refers to a VVLP02500 manufactured by Milly Boer Co., Ltd. (hydrophilic PVDF system, the pore diameter is 0.10a, and the average pore diameter is higher. Small separation membrane, The filtration is small (refer to Figure 15). The filtration resistance coefficient ratio is the ratio of the filtration resistance coefficient to indicate the filtration resistance of the amount of resistance per unit mass attached to the film surface, that is, the smaller the filtration resistance coefficient ratio, even if The membrane filtration resistance is also less likely to occur on the surface of the membrane, and the bubble generated by the self-dispersing gas tube and acting on the surface of the membrane is not coarse, and the surface is roughened by the gas-liquid mixing. However, the surface roughness of the membrane is The ratio of the membrane permeation material peeling coefficient is 0.1/zm or less, and the membrane permeation material from the membrane surface is easily peeled off from the surface of the separation membrane, and the membrane is not easily permeated through the thin layer of the material. Therefore, even if the microbubbles have sufficient membrane filtration performance, the membrane is not sufficient. Permeation material. The coefficient of the liquid stripping on the non-membrane surface of the membrane surface, the peeling coefficient of the membrane, the peeling coefficient ratio is easy to peel off from the separation membrane, and the membrane filtration is increased by the membrane filtration [m). The coefficient ratio is more relative to the non-membrane permeability coefficient of the surface of the standard film. The substance is also attached to the high water permeability. The separation membrane of the cleaning stress is a non-cleaned film surface which is not formed on the surface of the separation film, and the above-mentioned matter is also shown in Fig. -28-200815296, Fig. 14 and Fig. 5 The results of the following experiments and analysis were clearly observed for the four commercially available separation membranes having different average pore diameters. First, the four separation membranes shown in Table 2 were placed at a temperature of 30 ° C or higher (separation membranes A to D). The solution was immersed in a 2% aqueous ethanol solution for 2 hours or more, and then taken out and placed in a membrane filtration test apparatus using the apparatus shown in Fig. 16 (a schematic diagram of the membrane filtration test apparatus). The membrane filtration test apparatus was pressurized with nitrogen gas to house a pure water container 410 in pure water or a pressure agitating tube 401 (manufactured by Millipore Co., Ltd., Amicon 8050). The pressurization pressure was measured by a pressure gauge 4 1 1 . The filtered liquid was filtered by a separation membrane 402 provided on the membrane holding holder 406 by pressurization with nitrogen. Further, at the time of membrane filtration, the agitator 404 is rotated by the magnetic stirrer 403, and the filtrate liquid in the agitating tube 401 can be stirred. Further, the membrane permeation liquid that has passed through the separation membrane 402 can be placed in a beaker 407 on the electronic scale 408, and the amount of the membrane permeate can be measured by the electronic scale 408, and the measurement cartridge can be stored in the computer 409. Further, the pressure of each portion of the membrane filtration test apparatus is adjusted by the switches of the valve 4 1 2, the valve 4 13 and the valve 4 1 4 . Using the membrane filtration test apparatus described above, pure water in the pure water container 410 was pressurized with nitrogen gas 405, and pure water was fed into the agitating tube 40 1 to carry out membrane filtration with pure water. The number 表示 indicating the relationship between the measured time and the amount of the membrane permeated liquid was subjected to the following treatment. First, the membrane filtration stream of any filtration time is calculated using the differential coefficient of the membrane permeation amount of any filtration time. Next, the membrane filtration flux of any of the above filtration times was used, and the membrane filtration pressure was used to calculate the membrane filtration resistance at any filtration time according to the following formula. -29- 200815296 Membrane filtration resistance is calculated by the following formula.

AP μ-J Formula 4 where R is the membrane filtration resistance (Ι/m), Δ P is the inter-membrane pressure difference (Pa), # is the permeated water viscosity (Pa-s), and the J-series membrane is filtered (m) /s). Among them, the system is obtained by temperature conversion according to the following formula. // xlO3 二F· exp[(l + BT)/(CT + DT2)]... where 5 is F = 0.0 1 257 1 87, B = — 0.005 806436, C = 0.00 1 1 309 1 1 , D = — 0.000 005 723952, T is the absolute temperature [K]. That is, the temperature in Celsius is σ [°C ], Τ = σ + 273.1 5 . From the results calculated above, the relationship between the total amount of the filtrate per unit membrane area and the membrane filtration resistance was determined, and the membrane filtration resistance was fixed as the initial membrane filtration resistance. Next, in order to obtain the filtration resistance coefficient, the membrane filtration test apparatus of Fig. 16 was used, and the activated sludge liquid (activated sludge liquid of the membrane separation type activated sludge apparatus for treating agricultural colony wastewater) was subjected to a membrane using a separation membrane. filter. In the membrane filtration system, the pure water container 410 of the membrane filtration test apparatus was placed outside, and the connection pipe 4 1 5 shown by the broken line in Fig. 6 was connected, and the filtrate and nitrogen gas were directly introduced into the agitating tube 401. The separation membrane to be evaluated is placed in the membrane fixing holder 406, and while the filtrate is fed into the agitating tube 401, the pressure is applied by nitrogen gas. At this time, membrane filtration was carried out without performing agitation of the magnetic agitator 403. The relationship between the time and the membrane filtration 'the relationship between the liquid amount and the amount of the liquid amount calculated by the membrane filtration was the same as the above, and the relationship between the total filtrate amount per unit membrane area and the membrane filtration resistance was obtained. Among the relationships between the total amount of filtrate per unit membrane surface -30-200815296 and the membrane filtration resistance, the inclination of the straight line is Κο. Further, the mass to be filtered and the mass of the liquid (dry weight) were measured, and the enthalpy was X (mg/L), and the filtration resistance was determined by the following formula. Ko a = - X Equation 6 According to the above method, the standard film and the evaluation membrane force coefficient were respectively measured, and the filtration resistance coefficient ratio a r was calculated from the following formula. • a ~ ... Equation 7 evaluates the membrane's filtration resistance coefficient to the 5 series standard membrane force factor. Next, in order to obtain the non-membrane-permeable substance peeling coefficient, the same membrane filtration test was carried out in the case of the filtration resistance coefficient. However, the system was subjected to membrane filtration while stirring. At this time, membrane filtration was temporarily terminated by membrane filtration. The time and the membrane filtration amount of the membrane were filtered by the membrane, and the relationship between the total membrane filtration resistance per unit membrane area was made in the same manner as described above. The relationship between the total filtrate amount per unit and the membrane filtration resistance was reproduced in accordance with the membrane filtration resistance prediction method described below. The membrane test method uses the following formula.

AP J(t) =- ••式8 "•m

Xm(t +1) = Xm{t) + (X(t) · J(t) - / · (r ~ Λ · ΔΡ) · {ηΧπι{ί)) · Xm{t)) · At with straight line The solid-state coefficient α is the filter resistance of the filter resistance and the above-mentioned membrane filtration test, the liquid amount of the filter liquid level membrane area filter resistance pre-type 9 • 31- 200815296 R(t) - Rm-l · a · Xm{t) ••式l 0 Χ(0)Ύ(0) = Χ(ί)Ύ(ί)^Χηι(ί)^Α ••式li = F (9)-(1)汾·•1 2 where 'J (t) is the membrane filtration stream (m / s) at time t, R (t) is the membrane filtration resistance (1/m) at time t, and Xm(t) is attached to time The solid component mass per unit membrane area (g/m2), X(1) is the solid component mass (g/m3) in the filtered liquid at time t, and the r-type non-membrane permeability material peeling coefficient (1/m/s) , r film detergency (1), λ system friction coefficient (1/Pa), .7? system density reciprocal (m3/g), Δ t system time t scale width (s), Rm membrane filtration Initial resistance 値(1/m), V(1) is the volume of the filtered liquid at time t (m3), and A is the effective membrane area (m2). Also, r = 1,? ? = 1 X 1 (Γ 6, the filtration resistance coefficient α is determined by the above-determined α, and Rm is the filtration resistance of the pure water film determined as described above. By repeating the calculation time, the calculation of the above formula 8-1 2 is repeated. After the membrane filtration flow rate and membrane filtration resistance at each time, the relationship between the total filtrate amount per unit membrane area and the membrane filtration resistance was determined. The peeling coefficient and friction coefficient of each non-membrane permeate were calculated. Prediction of the relationship between the total filtrate amount per unit membrane area and the membrane filtration resistance 値, the non-membrane permeation material peeling coefficient and the friction coefficient of the separation membrane are the non-membrane permeability material peeling coefficient which is the smallest difference from the above-mentioned measured enthalpy And the coefficient of friction. Among them, the difference between the predicted enthalpy of the measured enthalpy at each time should be based on the following formula: -32- 200815296 Ε ηΣ(

Rmsr,i- Real· RmsrJ Ν~~ ...Formula 1 3 Ε 値 値 値 - - - - - - , , , - - - R R R R R R R - - - - - - - - - - - - - - - - - - - - - - - The calculation of the filtration resistance 値 (l/m), the total number of N-points (1). According to the above, the non-membrane transmissive material peeling coefficient of the standard film and the evaluation film was calculated, and the non-membrane transmissive material peeling coefficient ratio r r was calculated according to the following formula.

γ z =:ll! L , wherein, r m is a non-membrane transmissive material peeling coefficient of the film, and a non-membrane transmissive material peeling coefficient of the r s standard film. The flat membrane-like separation membrane having a smooth surface property specified in the present invention can be produced in accordance with the production method described below. For example, a film forming stock solution containing a polyvinylidene fluoride-based resin, a pore former, or the like is applied onto a substrate formed of a nonwoven fabric, and then solidified in a non-solvent-containing coagulating liquid to form a porous separating functional layer. A separation membrane used in the present invention can be produced. At this time, the substrate may be immersed in the film forming stock solution to form a porous separating function layer, instead of coating the film forming stock solution on the surface of the substrate. When the film forming stock solution is applied to the substrate, it may be applied to one side of the substrate or may be applied to both sides. It is also possible to form a porous separation functional layer other than the substrate and laminate it with the substrate. When the film forming solution is solidified, only the porous separating functional layer formed on the substrate is brought into contact with the coagulating liquid, and the porous separating functional layer is immersed in the coagulating liquid together with the substrate. A method in which only the porous separation functional layer is brought into contact with the coagulating liquid, for example, a method in which the porous separation functional layer formed on the substrate is placed below the coagulation bath surface, or the substrate is brought into contact with the glass On a smooth plate such as a plate or a metal plate, a method in which the coagulation bath is not transferred back to the substrate side and adhered, and the substrate and the plate having the porous separation functional layer are immersed in the coagulation bath. In the latter method, the substrate can be attached to the sheet to form a film for forming the film stock solution, and the film of the stock solution can be formed on the substrate and then attached to the sheet. In the film forming stock solution, in addition to the above polyvinylidene chloride-based resin, a solvent for dissolving the pore former or the above may be added as needed. When a cell opener having a function of promoting the formation of a porous material is added to the film forming solution, the cell opener may be extracted by a coagulating liquid, and it is preferably one which has high solubility to the coagulating liquid. For example, a polyalkylene oxide such as polyethylene glycol or polypropylene glycol, an aqueous solution polymer such as polyvinyl alcohol, polyvinyl butyral or polyacrylic acid or glycidol can be used. Further, as the cell opener, a surfactant containing a polyalkylene oxide structure, a fatty acid ester structure or a hydroxyl group can be used. It is easier to have the desired pore structure by using such an interfacial activator. The polyalkylene oxide alkane structure is, for example, [Chemical Formula 1] - (CH2CH2〇)n - (CH2CH2(CH3)0)n--(CH2CH2CH2〇)n--(CH2CH2CH2CH2〇)n-. Particularly from the viewpoint of hydrophilicity, it is particularly preferable that -(CH2CH2〇)n-, that is, a polyethylene oxide structure. -34- 200815296 Fatty acid ester structure, for example, a fatty acid containing a long-chain aliphatic group. The long-chain aliphatic group may be any of a chain, a branched form, and a fatty acid such as stearic acid, oleic acid, lauric acid, palmitic acid or the like. Further, a fatty acid ester derived from oleic acid such as cow's ester, palm oil, coconut oil or the like. The hydroxyl group-containing surfactants are, for example, ethylene glycol, propylene glycol, 1,3, propylene glycol, 1,4-butanediol, glycidol, sorbitol, glucose, sucrose, and the like. When the separation membrane is produced, a surfactant which is a cell opener is used, and it is preferred to contain two or more selected from the group consisting of a polyalkylene oxide structure, a fatty acid ester structure, and a hydroxyl group. Among them, it is particularly preferable to contain a total of a polyalkylene oxide alkane structure, a fatty acid ester structure and a hydroxyl group surfactant, such as a polyethylene oxide sorbitan fatty acid ester such as monostearate polyethylene oxide sorbose Alcohol anhydride, polyethylene oxide coconut oil fatty acid sorbitan, monooleic acid polyethylene oxide sorbitan, monolaurate polyethylene oxide sorbitan, monopalmitic acid polyethylene oxide Sorbitol anhydride, polyethylene oxide fatty acid esters such as polyethylene glycol monostearate, polyethylene glycol monooleate, polyethylene glycol monolaurate, and the like. Such a surfactant is not only excellent in dispersibility of inorganic fine particles, but also is particularly suitable even if it remains in the porous layer and is dried without deteriorating its water permeability and inhibiting properties. Further, when a solvent for dissolving a polyvinylidene fluoride-based resin, another organic resin, or a pore former is used in the film forming stock solution, for example, N-methylpyrrolidone (NMP), N, N can be used as the solvent. - dimethylacetamide (DMAC), 1^,1 dimethylformamide (〇"?), dimethyl hydrazine (〇^8〇), acetone, methyl ethyl ketone, etc. NMP, DMAc, DMF, and DMSO having high solubility to polyvinylidene fluoride-based resin are used. -35- 200815296 Other non-solvent may be added to the film-forming stock solution. Non-solvent does not dissolve polyvinylidene fluoride-based resin and Other organic resins are used to control the solidification rate of polyvinylidene fluoride-based resins and other organic resins, and to control the size of pores. Non-solvent systems can use alcohols such as water, methanol, and ethanol. Convenience and price, preferably water, methanol, may also be mixed. The composition of the film forming solution is preferably 5% by weight to 30% by weight of the polyvinylidene fluoride resin, and the opening agent is 〇.1 weight. %~15% by weight, solvent is 45% by weight to 94.8% by weight, non-solvent is 0.1% When the amount of the polyvinylidene fluoride-based resin is extremely small, the strength of the porous layer is lowered, and if the amount is too large, the water permeability is lowered, so it is particularly preferably in the range of 8 wt% to 20 wt%. When the amount of the pore-forming agent is too small, the water permeability is lowered, and if the amount is too large, the strength of the porous layer is lowered, and if it is extremely large, it remains excessively in the polyvinylidene fluoride-based resin, and is eluted during use to allow permeation. The water quality deteriorates and the water permeability changes. Therefore, the preferred range of the pore former is 5·5 wt% to 10 wt%. Further, if the solvent is too small, the stock solution is liable to gel, and if too much Since the strength of the porous layer is lowered, it is particularly preferably in the range of 60% by weight to 90% by weight. Further, if the amount of the non-solvent is large, the stock solution is liable to gel, and if it is extremely small, it is difficult to control the size of pores and voids. 0.5% by weight to 5% by weight. The non-solvent-containing coagulation bath may be a liquid formed of a non-solvent or a mixed solution of a non-solvent and a solvent. When the non-solvent is also contained in the film-forming stock solution, the non-solvent in the coagulation bath The ratio should be at least 80% by weight of the coagulation bath. If too small, the solidification speed of the polyvinylidene fluoride resin is too slow, the surface roughness is -36 - 200815296, the roughness is too large, and the pore diameter is too large, especially for the separation function layer. The surface roughness is 0 · 1 / m or less, and water is preferably used as the non-solvent, and the proportion of water is preferably in the range of 85% by weight to 100% by weight. On the other hand, when the film forming stock solution contains no non-solvent, the ratio is When the non-solvent is contained in the film forming solution, the content of the non-solvent in the coagulation bath is preferably less than the above, and is, for example, preferably 60% by weight to 99% by weight. If the amount of the non-solvent is large, the solidification rate of the polyvinylidene fluoride-based resin is high. Too fast, the surface of the porous layer is tight and the water permeability is too low. By adjusting the non-solvent content in the coagulation bath, the surface roughness or pore size and void size of the surface of the porous layer can be controlled. Further, if the temperature of the coagulation bath is high, the solidification rate is too fast. Conversely, if the coagulation rate is too low, the solidification rate is too slow. Therefore, it is generally selected from the range of 15 ° C to 80 ° C. It should be in the range of 20 °C to 60 °C. According to the production method of the separation membrane, the separation membrane obtained is a separation membrane of a porous resin layer formed of a polyvinylidene fluoride-based resin on the surface of a porous substrate, and is formed on the outer surface side of the porous resin layer. A separator having an average pore diameter (0.01 to 0.2/zm) required for membrane filtration and having a smooth surface (surface roughness of 0.1 μm or less) forms a layer having voids on the inner side. That is, a layer having a void near the inside of the porous substrate in the porous resin layer and a separating functional layer having a smooth surface having a predetermined pore diameter are present on the outer surface. [Examples] Hereinafter, the wastewater treatment method of the present invention will be more specifically described using examples. Further, the present invention is not limited to the form described in the embodiments. -37-200815296 (Example 1) Under the conditions shown in Table 1, the treatment of domestic wastewater was carried out by the water treatment method shown in Fig. 10. For example, the 10th raw water (domestic wastewater) is mixed with the activated sludge introduced into the denitrification tank 1 through the raw water supply pipe 1 and the raw water supply I. Thereafter, the living solution is introduced into the aeration tank 2. The biological treatment engineering is to remove nitrogen nitration engineering (aerobic) and nitrogen removal engineering (oxygen free). The nitrification of ammonia nitrogen (ΝΗ4-Ν) is carried out in the latter stage tank 2 (aerobic tank), and the nitrifying liquid is circulated from the membrane separation activated sludge tank to the previous stage by the sewage 13 to remove nitrogen in the nitrogen removal tank. In the aeration tank 2, aeration is performed by the air diffusing device 8 which is blown by the air supply device 7. The aerobic state is activated by the aeration to carry out the nitration reaction and the BOD oxidation. Further, it is washed and adhered to the film surface of the membrane separation device 4 by means of gas, and the sludge is extracted by the sludge pump 6 in order to maintain the MLSS concentration in the aeration tank 2 and the nitrogen removal tank 12. The membrane filtration system according to the membrane separation device 4 is carried out by passing the water suction side through the suction pump. In addition, in order to prevent the sludge from adhering to the separation membrane, a timer is provided, and a relay switch (membrane separation operation stop 43) for periodically activating/stopping the pump according to a pre-recorded program is used, and the operation is repeated for 8 minutes. The membrane filtration was intermittently operated for 2 minutes to fix the membrane filtration stream to 1·0 m /day (average flow: rpm. In the present embodiment, the diffuser is shown in a treatment package for generating coarse bubbles, I 3 First, the sludge is mixed with the air, and the air in the denitrification tank of the aeration mud circulation pump is maintained in the air-exposed sludge. The surface of the membrane is periodically attracted to the surface, and the ground control device is switched. The amount of the air is loaded with a gas-filling device-38-200815296 (a diffusing air hole of 6 mm) and a diffusing device for generating micro-bubbles (a fine slit length of 2 mm), and evaluation is performed separately. The separation membrane system is a flat membrane having a surface average pore diameter of 〇.〇8/zm and a surface roughness of 0.062 #m (film area: 1.4 m2 x 20 sheets) (produced by Toray Co., Ltd., used in MBR). A flat film of a membrane element TSP50 1 50 was used, and a flat membrane having a surface average pore diameter of 0.4 // m and a surface roughness of 0.18 /zm (membrane area: 0.8 m2 x 5 sheets) was used as a control (Kubada Membrane (manufactured by Membrane) used in the film of Carderly Gold H3-510). Two types of separation devices using the separation membranes (separation membranes A and B of Table 2) were placed in the same aeration tank.

-39- 200815296 (Table 1) Practice raw water type domestic wastewater. Raw water quality (average 値) BOD (biological oxygen demand): 200mg/L TN (total nitrogen): 45mg/L TP (total phosphorus): 8mg/L Treatment water volume 18m3/day Biological treatment tank volume denitrification tank: 2.25m3 Membrane separation Activated sludge tank: 2.25m3 4.5m3 Hydrological retention time (HRT) 6 hours Nitrogen removal tank: 3 hours Membrane separation Activated sludge tank: 3-hour activated sludge condition membrane separation activated sludge tank MLSS: 8,000mg/L~15,000mg/L membrane separation activated sludge tank dissolved oxygen (DO): 0.5~2.Omg/L sludge circulation amount treated water 3 times 54m3/day The temperature of the treated liquid is 13〇C-28〇C The fine gas of the diffusing device”^The rubber-type cylindrical diffusing tube made of Meiling Industrial Co., Ltd. MT-70-600S(25A)x3 || For the φ25ιϊπη chloroethylene suspicion pipeline, the Φ6γπγπ hole is opened at equal intervals, and the air volume is 20L/min-ELx25EL=500L/min (equivalent to 47.47L/min/cm2)~---

(Table 2)

Membrane surface § degree film g material film niobium; UUT tenth film area (example 0.062 β m

1.4m3 0.8m3

Separation film D O.lO^m 0.417/zm PVDF flat film 20 pieces (Examples 1 to 3) -40- 200815296 Fig. 11 shows the results of the discussion on the use of a diffuser for microbubbles (representing a film) Fig. 12 is a view showing the results of a discussion on the use of a diffusing device for coarse air bubbles (a graph showing temporal changes in film differential pressure). Among them, the change in the membrane differential pressure was used as an index of the running performance. If membrane fouling occurs, the membrane differential pressure rises, indicating that it is unable to operate stably. When 90 曰 is operated in the case of using a diffusing device for microbubbles (Fig. 11), the rise of the separation membrane A in a specific range in the present invention is +6 kPa, and the operation can be continuously stabilized. However, when the separation membrane B' which is used outside the specific range of the present invention is operated for about 20 days, the membrane differential pressure is greatly increased, and the chemical washing is performed because it is difficult to operate stably. After that, the medicine must be cleaned every 13 to 18 days, and it is not easy to operate continuously. When the separation membrane surface is washed with fine bubbles, if the surface of the present invention is smooth and the surface pores are small, the membrane surface can be sufficiently washed, and the membrane surface can be continuously dried without being washed with chemicals. Running. However, in the case of a separation membrane having surface properties other than the characteristics of the present invention, as described in the prior art, the membrane surface cleaning effect of the microbubbles is not good. On the other hand, when the diffuser for coarse air bubbles is used (Fig. 1), when the separation membrane A and the separation membrane B are operated for 90 days, the membrane pressure of the separation membrane A is +3 kPa, and the separation membrane B is +7 kPa. , can run stably. When the separation membrane surface is washed with coarse bubbles, even if the general-purpose separation membrane of the present invention is used, the surface of the membrane can be sufficiently washed, and the membrane can be continuously operated for a long period of time without chemical cleaning. In the wastewater treatment method for performing membrane separation activated sludge treatment of sewage (waste water) such as sewers, when the separation membrane is used in the specific surface-41-200815296-like separation membrane of the present invention, microbubbles can be used in industrial operation. The conditions under which the diffuse gas is used to clean the surface of the film with microbubbles. (Example 2) 1. The actual wastewater test of the model field was carried out so that the actual wastewater of the chemical plant was 〇.4 m/d (running for 8 minutes, intermittent operation for 2 minutes), volumetric load 〇8~1.2kg B〇D/ Under the conditions of m3/曰, a membrane filtration treatment was carried out in a tank having a volume of 2.3 m3 and a water depth of 2.3 m, which was immersed in a flat membrane module (containing 20 sheets of 1.5 mxO. 5 m flat membrane elements). The air-distributing pipe system is such that a micro-bubble of a rubber sheet of a micro-slit having a length of 2 mm is disposed at a periphery of the cylinder to generate a diffusing pipe (air pipe A) (Shan Loyt Bending Air T series, 45 cm, 2 pieces) and A large air bubble tube (distribution pipe B) with a hole diameter of 4 mm (made of stainless steel, length 45 cm, number of holes per hole, 10 pieces, 4 pieces) is placed on the same plane and 20 cm below the membrane module, so that They are independent and can control the air volume, and can be used as a system for controlling the use of the air pipe and air volume according to the purpose. However, only the air pipe A is used mainly at 200 L/min (=0.24 L/min/cm2). The pH of the liquid to be treated in the tank was controlled to be around 7 with alkaline soda. The water temperature is controlled at around 20 °C. For the separation membrane, a PVDF flat membrane (separation membrane A) having an average pore diameter of 0.08 // m and a surface roughness of 0.062 // m (using a film of a membrane element TSP50 1 50 for MBR manufactured by Toray Industries, Inc.) was used. The test results are shown in Tables 1 to 3 of Table 3. When the concentration of MLSS is 8g/L, the amount of sludge generated is 〇6kg MLSS/kg BOD, but MLkg concentration of 17g/L is 0.25kg MLSS/kg B〇D, and the amount of sludge is reduced by about 60%. Next, when the sludge concentration is 17 g/L, when the air diffusing pipe is switched from the air diffusing pipe A to the air diffusing pipe B only by the same air volume, D〇 is rapidly reduced from 2 ppm to nearly 〇ρριη. When the diffuser tube is switched from the diffuser tube B to the diffuser tube A again, the DO is returned to about 2 ppm after a slight delay. 2. Experimental synthetic wastewater test The 30L experimental membrane separation activated sludge device was used to simulate the wastewater in the food factory with a B〇D concentration of l,000 ppm in water retention time! Membrane filtration treatment was carried out under the conditions of the day. As the separation membrane, a membrane module capable of accommodating six sheets of a membrane element (effective membrane area of 12 cm square x2) which was deposited on both surfaces of the frame was used. The separation system A is used in general operation (refer to Table 2). The air-distributing pipe system is such that the diffusing pipe A (a micro-bubble generating air-spraying pipe (Shan Leyte Bending Air T series) of a rubber sheet having a micro-slit having a length of 2 mm at a certain interval is formed at an outer circumference of the cylinder, and is processed into an experimental test size, Approximately 15 cm below the flat membrane module was placed at an air volume of 20 L/min and aeration was performed. The temperature is maintained at 20 to 25 °C. The membrane filtration treatment was carried out under the conditions of a flow rate of 〇4 m/d (intermittent operation for 8 minutes and 2 minutes of shutdown), and the inflowing simulated wastewater and the same amount of membrane permeate were discharged to control the liquid surface. The pump returned the remaining 30 L of the experimental membrane separation activated sludge unit. At a concentration of about 8 g/L of MLSS, the sludge was put into operation. The subsequent test results are shown in Table 3. The amount of sludge generated when the concentration of MLSS reached about I2g/L was 0.41kg MLSS/kg BOD (Example 5), but the amount of sludge generated when the concentration of MLSS was 25g/L was 0.17kg MLSS/kg B〇D (Example 4) ), a reduction of 58%. Next, the sludge was periodically discharged, and the MLSS concentration was maintained at 25 g/L to operate. Three of the six-piece elements are used as the film-43-200815296 element using the separation membrane A, and the remaining ones are used as the membrane elements using the separation membrane B (refer to Table 2), and these membrane elements are alternately accommodated in the assembly. During the operation, when the separation membrane B was operated for 25 days, the differential pressure was 20 kPa or more (Example 6). In the meantime, the separation membrane migrated stably at a differential pressure of 3 kPa or less. (Table 3) Separation membrane Diffusion tube MLSS (g/L) Result Example 1 Separation membrane A Dispersion tube A (fine bubble) 17 Good treatment at a differential pressure between membranes of 3 kPa or less. The amount of residual sludge generated was 0.25 kg MLSS/kg B 〇 D. Example 2 Separation membrane A The diffuser A (fine bubble) 8 was treated well at a differential pressure of 3 kPa between membranes. The amount of residual sludge generated was 0.6 kg MLSS/kg B 〇 D. Example 3 Separation membrane A The diffuser tube B (coarse bubble) 17 is not easy to handle when DO is insufficient. Example 4 Separation membrane A The air diffusing tube A (fine air bubbles) 25 was favorably treated at a differential pressure of 3 kPa or less between the membranes. The amount of residual sludge generated was 0.17 kg MLSS/kg B 〇 D. Example 5 Separation membrane A The diffuser tube A (fine bubble) 12 was treated well at a differential pressure between the membranes of 3 kPa or less. The amount of residual sludge generated was 0.41 kg MLSS/kg B 〇 D. Example 6 Separation membrane B Dispersing pipe A "Microbubbles" 25 The differential pressure between membranes was increased to 20 kPa or more on the 25th day of operation. (Example 3) Using the wastewater treatment apparatus (refer to Fig. 10) used in Example 1, the operation was carried out under the same conditions as in Table 1. However, in the present embodiment, a microbubble diffusing device is used instead of a coarse bubble diffusing device. In this test, the average membrane filtration pressure per hour was calculated, and the rate of rise of the membrane filtration pressure was increased at the rate of rise. The membrane filtration rate is as small as -44-200815296, which is the condition for stable operation. Table 4 shows the rate of increase in membrane filtration pressure for each filtration condition. When the separation membrane A having a membrane surface roughness of 0.062 /zm was used, the membrane filtration pressure rise rate of the same average membrane filtration stream was the same. When the average membrane filtration flow rate was 0.5 m/day (No. 2, 7), the membrane filtration pressure increase rate was lowered by making the ratio of the stop time 10% or less. Further, when the average membrane filtration flow rate was 0.6 m/day (No. 1, 3, 5), the membrane filtration pressure increase rate was lowered by setting the ratio of the stop time to 10% or less. In particular, when the continuous operation time is 20 minutes or less (No. 1 to 3), the effect is remarkable. On the other hand, when the separation membrane B having a membrane surface roughness of 0.180 // m is used (Νο·6, 8, 10, 1 1), the membrane filtration pressure rises when the ratio of the stop time is 20%, which is 10%. smaller. -45- 200815296 (Table 4) Example Continuous operation time of separation membrane (minutes) Stop time (minutes) Proportion of stop time (%) Average membrane filtration stream (m/day) Average sludge concentration (g/L) Membrane filtration pressure rise rate _曰) Νο·1 A 9 1 10 0.6 9.0 0.12 Νο.2 A 9 1 10 0.5 10.8 0.00 Νο·3 A 9.5 0·5 5 0.6 9.0 0.05 Νο.4 A 28 2 6.7 0.5 10.8 0.17 Comparative example Continuous operation time of separation membrane (minutes) Stop time (minutes) Proportion of stop time (%) Average membrane filtration stream (m/day) Sludge concentration (g/L) Membrane filtration pressure increase rate (kPa/曰No.5 A 8 2 20 0.6 9.0 0.45 No.6 B 8 2 20 0.6 10.8 1.16 No.7 A 8 2 20 0.5 10.8 0.10 No.8 B 8 2 20 0.5 10.8 0.56 No.9 A 8 2 20 0.4 8.9 0.00 No.10 B 9 1 10 0.5 9.5 0.89 No. 11 B 9 1 10 0.6 9.5 1.54 (Example 4) First, the composition of the coagulation bath was different when the film was formed under the conditions shown in Table 5 by the following method. A type of separation membrane (separation membrane F~J). Polyvinylidene fluoride (PVDF) resin was used as a pore-opening agent, polyethylene glycol (PEG) having a molecular weight of about 20,000, and N,N-dimethylacetamide (DM Ac) as a solvent, as a non-solvent. In pure water, these components were thoroughly stirred at a temperature of 90 ° C to prepare a film-forming stock solution having the following composition. PVDF : 1 3.0% by weight -46- 200815296 PEG : 5.5% by weight DMAc : 78.0% by weight Pure water: 3.5% by weight Next, after the film forming stock solution was cooled to 25 ° C, it was applied to a density of 0.48 g/cm 3 and a thickness. On a polyester fabric non-woven fabric (substrate) of 220 // m, it was immersed in a coagulation bath at 25 °C for 5 minutes, and then immersed 3 times in hot water at 80 °C to wash out DMAc and PEG. A separation membrane is produced. The composition of the coagulation bath separating the films F, G, Η, I is composed only of pure water, or pure water and DM Ac, and the weight ratio of individual pure water is 100%, 85%, 75%, 50%. Further, the composition of the coagulation bath of the separation membrane J was 25% in pure water and 75% in methanol. These separation membranes are composed of a composite layer (base material layer) impregnated with a resin in a substrate and a porous resin layer thereon. The outer surface of the porous resin layer was observed using a scanning electron microscope, and the pore diameter was measured. The observation photographs are shown in Fig. 17a, Fig. 17b, Fig. 17c, Fig. 17d, and Fig. 17e. The average pore diameters of the separation membranes F to J were 0,067, 0.104, 0.169, 1.19, 1.58/zm, respectively. Further, when a cross section perpendicular to the surface of the separation membrane was observed by a scanning electron microscope, a cavity having a short diameter of about 30 // m was distributed inside the porous resin layer. Further, the surface roughness on the side of the separation functional layer was measured by the above-described method using an atomic force microscope. The surface roughness of the separation membrane F~: [ was 0.062, 0.094, 0.15, 0.37, 0.63/zm, respectively (refer to Table 5). Further, the thickness of the porous resin layer of the separation membrane F to ho is about ho# m, and the thickness of the composite layer is almost equal to the thickness of the porous substrate of about 220 // m. Next, the obtained separation layer was measured for the exclusion rate and water permeability of the fine particles having an average particle diameter of 9. 9 # m. The water permeability was measured using the purified water of -47-200815296 251 obtained by using a reverse osmosis membrane under the condition of a drop height of 1 metre. The results are shown in Table 5. When the ratio of pure water in the coagulation bath in the film manufacturing process is lowered, the surface roughness and the average pore diameter of the film become large, and the water permeability becomes high, but on the contrary, the microparticle removal rate is deteriorated. The removal rate of the fine particles of the separation membranes I and J is 5 4 % and 24 %, respectively. When a separation membrane for solid-liquid separation of an activated sludge-like microorganism-containing liquid is used, a large amount of solids (microorganisms) are mixed in the permeate. Therefore, it is not suitable for membrane separation of microorganism-containing liquid. The separation membranes F, G, and Η were welded to both sides of the frame to prepare a flat membrane element, and the obtained membrane element was placed in a test apparatus for experimental synthetic wastewater of Example 2, and operated under the same operating conditions. However, membrane filtration was carried out by intermittent filtration for 9 minutes and 1 minute of shutdown, and the average membrane turbulent flow was 0.6 m/d. The sludge concentration at this time was 10 g/L. The results of measuring the membrane filtration pressure increase rate of this operation are shown in Table 5. That is, the separation membranes F and G were stably operated at 0.12 and 0.1 5 kPa/d, respectively, however, the membrane filtration rate of the separation membrane was higher at 0.98 kPa/d. As a result, it was found that the separation membrane F having a small surface roughness and a smooth surface can be cleaned by the microbubbles, but the separation membrane having a rough surface roughness cannot sufficiently clean the membrane surface by the microbubbles. -48- 200815296 (Table 5) Separation membrane F Separation membrane G Separation membrane 分离 Separation membrane I Separation membrane J Membrane solution composition (weight ratio) PVDF : 13.0% PEG : 5.5% DMAc : 78.0% Pure water: 3.5% Coagulating liquid composition (weight ratio) Pure water: 100% pure water: 85% DMAc: 15% pure water: 75% DMAc: 25% pure water: 50% DMAc: 50% pure water: 25% methanol: 75% average pore diameter (β m) 0.067 0.104 0.169 1.19 1.58 Surface roughness (β m) 0.062 0.094 0.15 0.37 0.63 Microparticle removal rate (average pore size 0.9 // m) 98% 91% 80% 54% 24% Water permeability (xlO'9m/ s/Pa) 37 45 51 67 78 Membrane filtration pressure rise rate (kPa/d) 0.12 0.15 0.98 — —

[Possibility of Application to the Industry] The method of the present invention utilizes a membrane separation activated sludge method to treat sewage (waste water) such as sewers, and is applicable to wastewater treatment for purifying water. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing an example of a wastewater treatment apparatus according to a membrane separation activated sludge method in which the method of the present invention can be used. Fig. 2 is a longitudinal sectional view showing the longitudinal center axis of the microbubble diffusing pipe used in the present invention. Figure 3 is a schematic oblique view showing the separation of two adjacent elements in the separation membrane module of the present invention -49-200815296. Fig. 4 is a schematic oblique view showing an embodiment of a membrane separation apparatus used in the present invention. Fig. 5 is a plan view showing one of other embodiments of the microbubble diffusing tube used in the present invention. Fig. 6 is a plan view and a side view showing one of other embodiments of the microbubble diffusing tube used in the present invention. Fig. 7 is a front view, a side view and an A-A cutaway view showing a specific embodiment of the membrane separation device. Fig. 8 is a front view, a side view and an A-A cutaway view showing a specific other embodiment of the membrane separation device. Fig. 9 is a schematic sectional view showing a mode of a surface portion of a separation membrane to explain the surface properties of the separation membrane. Fig. 10 is a schematic view showing the apparatus of the wastewater treatment apparatus for membrane separation activated sludge method used in the examples. Fig. 1 is a graph showing changes with time of film differential pressure when microbubbles are applied in the examples. Fig. 1 is a graph showing the time-dependent change of the film differential pressure when the coarse bubbles are applied. Fig. 13 is a schematic oblique view showing an embodiment of a conventional membrane separation device. Fig. 14 is a graph showing the relationship between the surface roughness (RMS) of the film and the ratio of the peeling coefficient of the non-membrane-permeable substance. Fig. 15 is a graph showing the relationship between the average pore diameter and the filtration resistance ratio. -50- 200815296 Figure 16 shows a schematic diagram of the membrane filtration test apparatus. Fig. 17a is a scanning microscopic observation photograph showing the outer surface of the separation functional layer of the separation membrane F. Fig. 17b is a scanning microscopic observation photograph showing the outer surface of the separation functional layer of the separation membrane G. Fig. 17c is a scanning microscopic observation photograph showing the outer surface of the separation functional layer of the separation membrane. Fig. 17d is a view showing a scanning microscope observation of the outer surface of the separation functional layer of the separation membrane I. Fig. 7e is a scanning microscopic observation photograph showing the outer surface of the separation functional layer of the separation membrane. [Main component symbol description] 1 Raw water (waste water) supply pipe 2 Aeration tank (microbial containing liquid storage tank) 3 Raw water supply pump 4 Membrane separation device 5 Air suction pump 6 Sludge extraction pump 7 Air supply device 8 Air diffusing device ( Microbubble diffuser) 9 Membrane surface (film surface) 10 Height equivalent to surface roughness 11 Width equivalent to average pore size 12 Denitrification tank -51- 200815296 13 Sewage 14 Open 15 Empty 16 Minute 19 Bouncing 20 Support 21 Solid 22 with 41 membrane 42 membrane 43 membrane 44 flat 45 frame 46 flat 81 empty 401 stir 402 minutes 403 magnetic 404 stir 405 nitrogen 406 membrane 407 burn 408 electric 409 electricity

Mud circulation pump shut-off valve gas supply pipe branch tube-shaped sheet holding pipe set through-hole assembly through water pipe separation operation stop control device membrane element (separation membrane element) plate-like separation membrane (flat membrane) gas pipeline (gas supply pipe) Road) Mixing tube off-membrane stirrer mix · Gas fixed holder cup scale brain -52- 200815296 410 Pure water container 4 11 Pressure gauge 412, 413, 414 valve

-53-

Claims (1)

200815296 X. Patent Application Range: 1 · A membrane separation method characterized in that a liquid containing activated sludge is stored in a microbial-containing liquid storage tank, and is implemented by an impregnated membrane separation device in a liquid storage tank. In the film separation method of the membrane, the immersion membrane separation apparatus is a separation membrane having a surface roughness of at least 0.1 m or less, and a microbubble diffusing tube for separating microbubbles of the membrane, so that microbubbles generated from the microbubbles act on the separation membrane. The surface of the surface is washed and separated, and the microorganism-containing liquid is subjected to membrane separation treatment. 2. The membrane separation method according to claim 1, wherein the pore diameter of the diffusing surface of the microbubble diffusing tube is 1.0 μ it 3 · The membrane separation method according to claim 1 of the patent scope, wherein the separation is performed The microbubble on the surface of the membrane is a micro gas having a diameter of 2 mm or less. 4. The membrane separation method according to claim 1, wherein the gas diffusion surface of the bubble diffusion tube is formed by the formation of a plurality of elastic pores formed by expansion and contraction. The structure of the sheet is formed, and the diffuser tube is provided with a switch of the pores to release the microbubbles. 5. The membrane separation method according to claim 4, wherein the diffusing hole of the switch is used to expand the microslit switch by expansion and contraction; 6. The membrane separation method according to claim 5, wherein the microtubule system At least a cylindrical support tube and a micro-slit-forming elastic sheet are provided to cover the outer peripheral elastic sheet of the support tube and the support tube, and the gas is fed by the micro-slit of the elastic sheet. The pores release microbubbles. The microorganism is contained in the surface of the membrane having the diffusing tube formed below the membrane surface, and is used for the above-mentioned bubble of ~500 // mol. The above-mentioned separation membrane is attached to the membrane separation method according to the above-mentioned first-54-200815296. A flat film made of a porous separation functional layer made of polyvinylidene fluoride is formed on the base material layer which is not woven, and the average pore diameter of the porous separation functional layer is 0.2 /zm or less. 8. The membrane separation method according to the first aspect of the invention, wherein the membrane separation treatment is carried out by stopping the membrane separation for a certain period of time and then stopping the intermittent operation for a certain period of time, so that the membrane separation stop time in the intermittent operation is occupied. The ratio of the membrane separation is 20 minutes or less, and the dry weight of the microorganism-containing liquid in the microorganism-containing liquid storage tank is 10 g/L or more, and/or the average membrane of the separation membrane. The filtered stream is above 0.5 m / d. 9. The membrane separation method according to claim 1, wherein the microorganism-containing liquid has a dry weight of 15 g/l or more. 10. The membrane separation method according to claim 1, wherein the aeration air volume per microchannel has an aeration air volume of 0 · 1 3 to 0.5 L / min / c m2. 11. An impregnated membrane seeding device characterized by immersing an impregnated membrane separation device disposed in a tank for storing a liquid to be treated, wherein the microbubble diffuser is disposed as follows: the surface roughness of the plurality of membranes is A separation membrane element in which a flat membrane of 0.1/zm or less is disposed as a separation membrane is disposed in parallel with the membrane surface, and a microbubble diffusing tube that generates microbubbles is disposed below the separation membrane element, and the pores are present adjacent to each other. The space formed between the membranes of the separation membrane element is vertically below. 12. The impregnated membrane separation device according to claim 11, wherein the pores of the microbubble diffusing tube have a pore diameter of from 1 m to 500 // m. The impregnated membrane separation device of claim 1, wherein the gas diffusion surface of the microbubble diffusing tube is formed by forming a plurality of micro slits which are opened and closed by expansion and contraction. The air diffusing pipe has a structure in which the microbubbles are released by the opening and closing of the air holes. 14. The impregnated membrane separation device according to claim 13, wherein the microbubble diffuser has at least a tubular support tube and an elastic sheet forming a micro slit, the elastic sheet being disposed to cover the periphery of the support tube. When a gas is fed between the elastic sheet and the support tube, a microbubble diffusing tube of a structure in which microbubbles are released by the air diffusion hole by opening the micro slit of the elastic sheet. The impregnated membrane separator according to the first aspect of the invention, wherein the microbubble diffuser is disposed such that a longitudinal axis of the microbubble diffuser intersects a membrane surface of the separation membrane element. 16. The impregnated membrane separation device of claim 15, wherein the plurality of gas supply conduits for feeding gas into the microbubble diffuser are disposed in a direction opposite to a vertically lower portion of the separation membrane element. The microbubble diffusing pipe is connected by a branching manner from each of the opposing gas supply pipes, and the longitudinal axis of the microbubble diffusing pipe is extended to intersect the film surface of the separation membrane element. 17. The impregnated membrane separation device of claim 16, wherein the plurality of microbubble diffusing tubes connected to the respective opposite gas supply tubes are longitudinally located on a substantially straight line in a vertically lower portion of the separation membrane element. Arranged in a side-by-side manner such that the front ends of the opposing plurality of microbubble diffusing tubes are positioned adjacent to each other, and the positions of the front ends of the microbubble diffusing tubes of the plurality of microbubble diffusing tubes arranged in the range of -56-200815296 are inconsistent In a way, a combination of microbubble diffusing tubes of different lengths is used. 1 8 - The impregnated membrane separation device of claim 16 wherein the plurality of microbubble diffusing tubes connected to the respective gas supply tubes are extended to a level substantially perpendicular to the lower portion of the separation membrane module. The direction and the front end portions of the opposing microbubble diffusing tubes partially overlap. The impregnated membrane separation device according to the first aspect of the invention, wherein the separation membrane is a flat membrane formed by forming a porous separation functional layer made of polyvinylidene fluoride on a base material layer formed of non-woven fabric. And the average pore diameter of the porous separation functional layer is 0.2 /zm or less. 20. A membrane separation treatment method characterized in that a membrane separation device according to the first aspect of the patent application is installed in a microorganism-containing liquid storage tank, and a membrane-separating treatment is performed on the microorganism-containing liquid in the storage tank to obtain a membrane permeation. The membrane separation treatment method for water is a membrane separation treatment while generating microbubbles composed of an oxygen-containing gas from a microbubble diffusing tube. -57-