TWI373367B - Method of filtration and membrane filtration equipment - Google Patents

Description

1373367 VI. Description of the invention: [Technical field to which the invention pertains] The present invention relates to a pressure for treating tap water, industrial water, river water, lake water, ground water, water storage, sewage secondary treatment water, sewage, wastewater, etc. A filtration method and a membrane filtration device using a membrane module for driving force. [Prior Art] Membrane filtration using a pressure-driven liquid has two types of raw water side pressure filtration and transition water side pressure reduction filtration. The raw water side pressure filtration system pressurizes the raw water side of the membrane, and the filtered water side is normally opened to atmospheric pressure, thereby causing a pressure difference (membrane differential pressure) between the raw water side and the filtered water side of the membrane to be filtered. On the other hand, the filtered water side pressure filtration system is a method in which the raw water side of the membrane is normally opened to atmospheric pressure, and the filtered water side is decompressed to generate a membrane differential pressure. In the method as described above, if the raw water is filtered by the membrane, the suspended matter in the raw water or the substance having a pore size larger than the pore size of the membrane to be used is blocked by the membrane to form a concentration polarization or a cake layer, and the gap is The clogging increases the filtration resistance (hereinafter referred to as "membrane contamination", and the substance that causes membrane fouling is referred to as "membrane contamination causative substance"), so the membrane filtration flow (membrane filtration flux) is continuously fixed. During the process, the membrane differential pressure continues to rise. If the differential pressure of the membrane rises, it is necessary to carry out chemical cleaning, which is complicated by both cost and environmental load. * The number of chemical cleanings is preferably as small as possible. That is, it is preferable to suppress the increase in the film differential pressure in a state where the membrane filtration flux is in a fixed amount in the case where the film is continuously subjected to the operation. 140 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 The membrane was cleaned and the liquid was passed through a filter membrane using a suction pump to obtain filtered water. [Problems to be Solved by the Invention] However, in the prior film processing method disclosed in Japanese Laid-Open Patent Publication No. U-3〇〇168, the power to obtain the liquid is practically independent of the circulation pump. The pressure depends on the suction force of the suction pump. Therefore, when the membrane differential pressure is increased due to the fouling of the membrane, there is a possibility that the transition flux of the design cannot be ensured. SUMMARY OF THE INVENTION An object of the present invention is to provide an over-twisting method and a membrane filtering apparatus which are capable of suppressing a rise in membrane differential pressure and a long (four) continuous stable operation in a state T which ensures a designed membrane transition flux. [Technical means for solving the problem] In order to achieve the above object, the present invention is: (1) A method of over-twisting, which is characterized in that it is obtained by applying a pressure as a driving force to a membrane module (4) raw water. The water purifier'·the above filtration operation includes the raw water side pressurized over and over; the water side decompression filtration, the combination of the raw water side pressure filtration and the filtered water side pressure filtration combined filtration to determine the raw water At least one of the side water quality, the membrane filtration flux, and the membrane difference chamber is switched from the above three modes to another filtration according to the measured value. (2) The filtration method according to the above (1), wherein the measured value is a characteristic value X indicating a concentration of a membrane fouling substance calculated from the water quality of the original 140666.doc 1373367, wherein the characteristic value X is lower than the When the threshold value is set, the raw water side pressure filtration is performed, and when the characteristic value X is higher than the critical value, the pressure conversion from the raw water side is switched to the composite transition. (3) The filtration method according to (2) above, wherein the characteristic value X is calculated from at least one of a raw water side turbidity A (degree) and a raw water side total organic carbon amount (mg/L). (4) The above-mentioned characteristic value X is X=A when the turbidity of the raw water side is A (degree) and the total organic carbon amount of the raw water side is B (mg/L). Calculated by +B. (5) The filtration method according to (1) above, wherein the measured value is a membrane filtration flux 'in a constant flow filtration operation using a design flow rate of the filtered water side reduced pressure filtration', wherein the measured value is lower than a predetermined value In the case of the membrane filtration flux, the filtration from the filtered water side is switched to the above-mentioned raw water side pressurization or the above-mentioned compounding. (6) The filtration method according to (1) above, wherein the measured value corresponds to a suction lift force on the filtered water side of the membrane differential pressure, and in a constant flow filtration operation using a design flow rate of the filtered water side reduced pressure filtration When the suction lift force on the filtered water side reaches the effective NPSH (available net positive suction head), the filtered water side vacuum filtration is switched to the raw water side pressure filtration or the composite filtration. (7) The filtration method according to any one of (1) to (6), wherein the filtering operation and the backwashing operation are alternately repeated, wherein the backwashing operation is simultaneously performed from the filtered water side to the raw water side of the crucible unit Backwashing of the liquid feed, and gas cleaning of the membrane module described in 140666.doc 1373367. (8) The filtration method as described in the above (7), wherein the pressure backwashing is performed from the filtered water side when the backwashing operation is performed. (9) The filtration method according to (7) above, wherein in the case of performing the backwashing operation, the pressure-reducing backwashing of the raw water side decompression is performed. (10) The filtration method according to the above (7), wherein, in the case of performing the backwashing operation, the composite backwashing is carried out by combining the pressure backwashing combined with the water side pressure and the pressure backwashing of the raw water side pressure reducing side. . (11) The filtration method according to (7) above, wherein the pressure backwashing from the filtered water side pressurization, the pressure backwashing on the raw water side decompression, and the pressurization reaction in the combined transition from the transition water side are selected. Any one of the composite backwashing of the dewatering and backwashing of the raw water side decompression, and in the case of performing the backwashing operation, one of the pressure backwashing, the depressurization backwashing, and the composite backwashing is selected. By. (12) A membrane filtration device comprising: a membrane module having a pressure as a driving force; and a third pressure regulating mechanism that adjusts a pressure of a raw water side of the membrane module; and a second pressure regulation a mechanism for adjusting a filtered water side pressure of the membrane module; a measuring mechanism for measuring water quality of a raw water side of the membrane module; and a control mechanism for driving and controlling the third pressure regulating unit according to the measured value measured by the measuring mechanism At least one of the mechanism and the second pressure regulating mechanism; and the control mechanism is configured to perform pressure filtration on the raw water side, pressure filtration on the filtered water side, and composite filtration on the raw water side pressure filtration and the filtration water side pressure reduction filtration. Switch from 'one filter' to another. (13) The membrane filtration device according to (12) above, wherein the first pressure regulating mechanism 140666.doc 1373367 is a pressure reducing pump, and the measuring means is at least one of a turbidity meter and a total organic carbon amount measuring device. (14) The membrane filtration device of the above (12) or (13), wherein the control means drives and controls at least one of the first pressure regulating mechanism and the second pressure regulating mechanism to pressurize the filtered water side Backwashing, decompression backwashing of the raw water side decompression, and combined backwashing of the pressurized backwashing of the filtered water side and the depressurization backwashing of the raw water side decompression. [Effects of the Invention] According to the present invention, it is possible to suppress the increase in the differential pressure of the membrane while ensuring the filtration flux of the membrane to be designed, and to continuously perform a stable filtration operation for a long period of time. [Embodiment] An embodiment of a membrane filtration device of the present invention will be specifically described with reference to the drawings. As shown in Fig. 1, the membrane filtration device 5 of the present embodiment includes a membrane module 4 in which a solid-liquid separation membrane (hereinafter referred to as "membrane") is housed in a cartridge. The membrane transition device 50 is a device for obtaining filtered water by separating the suspended matter and the material having a pore size or larger from the raw water by the membrane module 4 using the pressure as a driving force. The film of the present embodiment has an inner diameter of 0.7 mm, an outer diameter of 丨2 mm+, and a hollow fiber-like microfiltration (PV' microfntration) film having an average pore diameter of (Μπη). The effective membrane area of the membrane module 4 having a surface area other than the hollow fiber is 7.4 m2. Further, the membrane module 4 is housed in a polyethylene (PVC) sleeve having a length of i-claw and a diameter of 84 mm. 140666.doc 1373367 Further, the raw material of the film is not particularly limited, and examples thereof include polyolefins such as polyethylene, propylene, and polybutylene; and vinyl fluoride/fluorine-based 4 (PFA) 'tetrafluoroethylene · hexafluoropropylene copolymer (FEp), tetrafluoroethylene _ hexafluoropropylene · all 1 thioethyl bond copolymer (EPE), ethylene glycol copolymer (ETFE), polychlorotrifluoroethylene (pCTFE) 'chlorotrifluoroethylene ethylene copolymer (ECTFE) 'polyfluoroethylene (PVDF) and other fluorine resin; polysulfone, polyethersulfone, polyetherketone, poly Super engineering plastics such as ether ether ketone and polyphenylene sulfide;

Cellulose such as acid-corrected cellulose or ethyl cellulose; polyacrylonitrile; a single component of a poly-l-alcohol and a mixture thereof. Further, as the shape of the film, any shape such as a hollow fiber shape, a flat film shape, a pleated shape, a spiral shape, or a tubular shape can be used. The hollow fiber shape is particularly good because of the high backwashing effect.

Further, as the membrane module of the present embodiment, it is preferable to use both of the both ends or one of the membrane bundles composed of a plurality of hollow fiber separation membranes to be fixed and to make either or both of them The hollow fiber membrane end of the end is open. The cross-sectional shape of the end portion to be fixed next may be a triangle, a quadrangle, a hexagon, an ellipse or the like in addition to the circular shape. Further, the film of the present embodiment and the film module 4 having the film are used to explain an example of the present invention. Further, the membrane filtration device 50 includes a raw water tank 2 for storing the raw water 1, a water filter 6 for storing the filtered water of the membrane module 4, a raw water inlet 4a of the membrane module 4, and a raw water introduction line 5 of the raw water tank 2. And a raw water circulation pipe 53 for returning the wastewater from the wastewater side outlet 4c of the membrane module 4 to the raw water tank 2. The raw water introduction line 51 is provided with a pressure regulating filter pump 3 that sends the raw water 1 pressure J40666.doc 1373367 accumulated in the raw water tank 2 to the membrane module 4, on the upstream side and the downstream side of the pressure regulating filter pump 3, Valves 14, 24 are provided, respectively. An air introduction pipe 5 la is connected between the valve 24 on the downstream side of the pressure regulating filter pump 3 and the membrane module 4. The air introduction pipe 5 la is connected to a compressor 10 that supplies air for cleaning the membrane of the membrane module 4, and a valve 22 is provided in the air introduction pipe 51a. Further, the waste water discharge line 52 is provided with a valve 23 for opening the line when the waste water is discharged. The pressure regulating pump 3 is equivalent to the ith pressure regulating mechanism that adjusts the pressure on the raw water side. Further, the first backwash water line 71 and the second backwash water line 72 which are connected to the raw water circulation pipe 53 and which the backwash water flows are connected to the raw water introduction line 51. The first backwashing water line 71 and the second backwashing water line 7.2 are used to introduce waste water from the waste water side outlet 4c of the membrane module 4 and to supply the liquid to the waste water discharge line 52 by the driving of the pressure regulating capsule 3. The conduits ' are respectively provided with valves 26 and 27 on the second backwash line 71 and the second backwash line 72. The raw water tank 2 is provided with a receiving port 2a of the raw water 1, and a raw water circulation pipe 53 connected to the waste water side outlet 4c of the membrane module 4 is connected. A valve 15 is provided on the raw water circulation pipe 53. Further, the raw water tank 2 is provided with a water quality measuring device 11 for measuring the water quality on the raw water side. The water quality measuring device 11 is at least one of a turbidity meter and a total organic carbon amount measuring device. The water quality measuring device 丨丨 corresponds to a measuring mechanism for measuring the water quality on the raw water side. Further, the membrane over/under device 50 is provided with a filtered water side outlet 4b of the membrane module 4 and a hydrophobic water line 55 of the weir. The water filtration pipe 55 is divided into two directions in the middle. One side is a pumping water that is sent to the water filter tank 6 in a state where it is not decompressed, and the other side is a water-repellent water by decompression. The membrane module 4 is sent to the second line 58 of the water filter tank 6. A valve 17 is provided at the inlet of the Jth line 57 with a valve 140666.doc 1373367 16 ' at the inlet of the second line 58. Further, the membrane filtration device 50 includes a raw water inlet pressure measuring device 12a disposed on the raw water introduction line 5, a filtered water side pressure measuring device 12b disposed on the water filtering line 55, and disposed on the raw water circulation pipe 53. Raw water outlet pressure measuring device i2c and membrane filtration flux measuring device 13. The raw water inlet pressure measuring device 12a, the raw water outlet pressure measuring device 12c, and the filtered water side pressure measuring device 121) are devices for measuring the pressure at each position. The membrane filtration flux measuring device 13 measures the flow through the first conduit 57. Water membrane filtration flux equipment. In addition, the pressure measured by the raw water outlet pressure measuring device 12c is pp when the pressure measured by the raw water inlet pressure measuring device 12 & and the pressure measured by the filtered water side pressure measuring device 12b is P? The membrane differential pressure pd is calculated by the following formula:

Pd=(Pi+p〇)/2-Pp · · · · (Formula). The second line 58 is divided into two directions in the middle, and one side is the filter side line 5 9, and the other side is the backwash side line 61. The filter side line 5 9 is provided with a pressure reducing filter pump 5, and valves 18 and 19 are provided on the upstream side and the downstream side, respectively, so as to sandwich the pressure reducing filter pump 5. Further, a backwashing pump 7 is provided in the backwashing side line 61, and a valve 21 is provided on the downstream side and the upstream side of the pressurized backwashing pump 7 based on the flow direction of the backwashing water, respectively. Valve 2〇. The depressurization bypass pump 5 corresponds to a second pressure regulating mechanism that adjusts the pressure on the filtered water side. In the present embodiment, the pressure regulating filter pump 3 is disposed on the raw water side of the membrane module 4, and the pressure reducing filter pump 5 is connected in series on the filtered water side, and the pressure regulating filter pump 3 and the pressure reducing filter pump 5 are connected in series. It is preferable to arrange the pressure-regulating filter pump 3 and the pressure-reducing filter pump 5 independently of opening and closing, and it is also possible to arrange the configuration of 140666.doc -11 - 1373367 other than the aspect. Further, the membrane filtration device 50 includes an oxidizing agent tank 8 for storing an oxidizing agent as a chemical, and a chemical supply line 63 for supplying the oxidizing agent accumulated in the oxidizing agent tank 8 to the membrane module 4. The oxidant liquid supply pump 9 is slid on the chemical supply line 〇, and further, the valve 25 is provided downstream of the oxidant delivery pump 9. The downstream end of the chemical supply line 63 is connected to the water filter line 55 at a position further upstream than the branch point of the second line 57 and the second line 58. . Further, the membrane filtration device 50 includes a control unit 40 that controls a filtration operation and a backwash operation, wherein the filtration operation uses the membrane module 4 to filter the raw water i, and the backwashing operation simultaneously performs backwashing of the filtered water through the membrane module 4. The rolling unit cleaning of the membrane module 4 is connected in such a manner that the control signals can be transmitted and received to the respective systems 3, 5, 7, 9 and the compressor 10. Further, the control unit 40 is connected to each of the valves 14, 15, 16, 17, 18, 19, 2, 21, 22, 24, 25, 26, 27 to transmit and receive control signals. Further, the control unit 40 is configured to receive the raw water measured by the water quality measuring device 11! The measurement data of the water quality-related measured value data is connected, and further, the measured value data relating to the membrane differential pressure measured by the raw water inlet pressure measuring device 12a, the filtered water side pressure measuring device 12b, and the raw water outlet pressure measuring device 12A can be received. The method is connected, and further connected so as to receive the measured value data related to the membrane filtration flux measured by the membrane filtration flux measuring device 13. The control unit 40 includes a central processing unit having a CPU (Central Processor Unit), a RAM (Rand〇m Access Mem〇ry, random access memory), and a R〇M (Read 〇niy I40666. Doc 12 1373367

The memory 'read only memory' or the like is configured as a hardware, and has a control unit, a calculation unit, and a memory unit as functional components. Further, the control unit 4A includes a threshold value that is set in advance to obtain a predetermined set value, for example, a characteristic value 评价 indicating a concentration of a membrane fouling substance calculated from the raw water side water quality, and is used to evaluate the membrane filtration flux. An input device that filters information such as a predetermined amount, a filtered flux, or an effective NPSH (available net positive suction head), and an output device such as a monitor that outputs various kinds of information. The control unit 40 transmits a control signal to each of the pumps 3, 5, 7, and 9 and the compressor 10 to drive and stop driving, thereby performing drive control of each of the pumps 3, 5, 7, and 9 and the compressor 1A. Further, the control unit 40 transmits a control signal 'to each of the valves 14, 15, 16, 17, 18' 19 ' 20 ' 21, 22, 24, 25, 26, 27 to thereby perform the respective valves 14, 15, 16, 17 Opening and closing control of 18, 19, 20, 21, 22, 24, 25, 26, 27. Further, the control unit 4 detects the film difference between the raw water inlet pressure measuring device 12a, the filtered water side pressure measuring device 12b, and the raw water outlet pressure measuring device 12c with respect to the measured value of the raw water measured by the water quality measuring device 11. The pressure-related measured value and the measured value related to the membrane filtration flux measured by the membrane filtration detector 13 are monitored, and the suction force of the vacuum filtration pump 5 is monitored. The control unit 4 of the present embodiment of the membrane filter unit 50 performs a filtration operation of the membrane module 4 with a pressure as a driving force. Further, the control unit 4 performs a backwashing operation of simultaneously performing backwashing of the mixed liquid of the filtered water and the oxidant from the filtered water side of the membrane module 4 to the raw water side and gas cleaning of the membrane of the membrane module 4. . The control unit 4 performs the filtering operation by alternately repeating 140666. Doc •13· 1373367 Effectively suppress clogging of the membrane with backwashing. [Filtering Operation] First, the filtering operation performed by the control unit 40 will be described. Among the filtering operations performed by the control unit 40, there are three aspects of the raw water side pressurization filtration, the filtered water side decompression filtration, and the combination of the raw water side pressure filtration and the filtration water side decompression filtration. (Original water side pressure filtration) As shown in Fig. 2, when the raw water side pressure filtration is performed, the control unit 40 opens the first line of the valve Μ 24 and the water filtration line 55 provided in the raw water introduction line 51. The valve 1 6' provided on 57 closes the valve 22 for supplying air for gas cleaning, the valve 25 for supplying the oxidant, and the valve 17 provided on the second line 58 of the water filtering line 55. As a result, a fluid flow path for pressure filtration on the raw water side is formed. Then, the control unit 40 drives the pressure regulating filter pump 3. As shown in Fig. 2, the raw water 1 is pressure-fed to the membrane module 4 via the raw water tank 2 by driving the pressure regulating filter pump 3. The filtered water that has passed through the membrane module 4 is sent to the filter tank 6 through the i-th line 57 of the water filtration line 55. Further, when the valve 15 provided in the raw water circulation pipe 53 is closed and filtered, the end point filtration method is adopted, and when the opening degree of the regulating valve 15 is opened, the circulation filtering method is obtained. (Filtering water side pressure reduction filtration) As shown in FIG. 3, when the filtration water side pressure reduction filtration is performed, the control unit 40 opens the valves 14 and 24 provided in the raw water introduction line 51, and the filtration water line 55. 2 The valve 17 provided on the pipeline 58 and the cross-side pipe 140666 of the second pipeline 58. Doc -14- 1373367 Valves 18, 19 are provided on the road 59. Further, the valve 22 for supplying the air for cleaning the gas, the valve for supplying the oxidant, and the valve 16 provided on the i-th pipe 57 of the water filter line 55 are closed. As a result, a fluid flow path for filtration filtration on the filtered water side is formed. Further, the fluid flow path for filtering the water side of the filtered water is the same as the fluid flow path for the combined filtration. Then, the control unit 40 drives and controls the pressure regulating filter pump 3 and the pressure reducing filter pump 5. By the drive control of the control unit 40, the raw water i is sent to the membrane module 4 via the pressure regulating filter pump 3 via the raw water tank 2, and is depressurized by the pressure reducing filter pump 5 connected to the filtered water side of the membrane module 4. Thereby, filtered water is obtained. In the filtered water side pressure reduction filtration of the present embodiment, the control unit 4 drives and controls the pressure regulating pump 3 so as to apply a minimum pressure to supply the raw water 1 to the membrane module 4. The driving force of water is actually provided only by the vacuum filter pump 5. Further, the piping for bypassing the pressure regulating pump 3 may be provided without driving the pressure-regulating and extinguishing pump 3, and switching may be performed by a valve. (Composite transition) As shown in Fig. 3, in the case of performing composite filtration, the control unit 4A forms a fluid flow path which is the same as the fluid flow path for filtration water side pressure reduction filtration. Then, the control unit 40 drives the pressure regulating filter 3 and the pressure reducing filter pump 5 which have both the raw water supply function. As a result, the raw water 1 is pressure-fed to the membrane module 4' via the raw water tank 2 by the pressure-regulating filter 3, and the pressure-reducing pump 5 is used to depressurize the water-reducing side, thereby simultaneously performing pressurization and decompression. Both sides obtained filtered water by the above method. It has been paid > the water is stored in the filter tank 6 which is also used as a backwash sample. [Backwash operation] 140666. Doc • 15- 1373367 Further, in the case where the filtration operation is continuously performed and the membrane differential pressure is increased, it is preferred to perform physical cleaning such as backwashing and gas cleaning. The term "backwashing" refers to a method of removing the membrane fouling substance adhering to the inside of the pores and the raw water side by passing the filtered water from the filtered water side of the membrane of the membrane module 4 to the raw water side. Further, the term "gas cleaning" refers to a method of introducing a gas such as air into the raw water side of the film in the form of bubbles, thereby shaking the film to remove the film contamination causing substance deposited on the raw water side of the film. It is considered that when the pressure actually applied to the raw water side is low and the compression of the substance causing the membrane contamination is suppressed, the membrane contamination causing substance is easily removed by physical cleaning. The membrane filtration device 5 of the present embodiment is alternately and repeatedly subjected to the above-described filtration operation and backwashing operation. Here, the backwashing operation by the control unit 4A of the membrane filtration device 5A will be described. In the backwashing operation of the present embodiment, there are three modes of the reverse backwashing backwashing, the raw water side pressure reducing backwashing, and the combined filtering water side pressure backwashing and the raw water side pressure reducing backwashing. (Transitional water side pressure backwashing) As shown in Fig. 4, the backwashing step is applied to the filtered water side to perform a backwashing step and a draining step. First, the control unit 40 opens the valve 17 provided on the second line 58 of the water filtration line 5 5 and the valve 2 provided on the backwash side line 61, thereby opening the valve 23 provided in the waste water discharge line 52. On the other hand, the valve 18 provided on the filter side line 59 and the valve 24 provided in the raw water introduction line 51 are closed. As a result, a fluid flow path for forming a backwash is formed. In addition, the formation of the fluid flow path for backwashing is to supply the oxidizing agent to the membrane module 4 to open the valve 25 provided in the chemical supply line 63, and further to supply the air for cleaning the membrane to the membrane module. 4 and open the air inlet pipe 5 1 a set valve 140666. Doc -16 - 1373367 22 继 Next, the control unit 40 drives the pressurized backwash pump 7 to deliver the filtered water accumulated in the filter tank 6 serving as the backwash tank to the membrane module 4. Further, the control unit 40 drives the oxidizing liquid supply pump 9 to supply the oxidizing agent to the filtered water for backwashing through the chemical supply line 63 to generate a mixed liquid, and the mixed liquid is sent from the filtered water side of the membrane module 4 to the raw water side. Backwash. Further, the control unit 40 drives the compressor 10 to supply compressed air to the raw water 1 side of the membrane module 4 via the air introduction pipe 51a, and performs gas cleaning of the membrane. After the backwashing step, the control unit 40 performs a draining step. As shown in Fig. 6, the draining step is a step of discharging the object to be removed from the film in the backwashing step. In the draining step, the control unit 40 opens the valves 14 and 24 on the raw water introduction line 51 and the valve 23 on the waste water discharge line 52, and closes the other valves 16, 17, 22, 25, etc. to form a drain. Fluid flow path. On the other hand, the control unit 4 drives the pressure regulating filter 3 to supply the raw water 1 to the membrane module 4. Here, the material to be removed which has accumulated on the raw water 1 side of the membrane module 4 is discharged to the waste water discharge line 52 through the waste water side outlet 4c of the membrane module 4 together with the raw water 1. (Original water side pressure backwashing) As shown in Fig. 5, in the raw water side pressure backwashing, a backwashing step and a draining step are performed. In the backwashing step, the control unit 40 opens the valve 17 provided on the second line 58 of the water filtration line 55 and the valve 20, 2 1 ' provided on the backwash side line 61 to open the waste water discharge line 52. The valve 23 opens the first backwash water line 71 connected to the pressure regulating filter pump 3 and the valves 26 and 27 provided in the second backwash water line 72. On the other hand 'close the valve provided on the filter side line 59 140666. Doc 17 1373367 18 and the valves 14, 24β provided in the raw water introduction line 5, as a result, form a fluid flow path for backwashing. Further, a valve 22 for supplying air for cleaning the gas and a valve 25 for supplying the oxidant are opened. Then, the control unit 40 drives and controls the pressure reduction of the raw water side of the membrane module 4 by the pressure regulating filter pump 3, and further drives and controls the pressurized backwashing pump 7. By the drive control of the control unit 40, the filtered water accumulated in the filter tank 6 serving as the backwash tank is sent to the membrane module 4, and is depressurized by the pressure regulating filter pump 3 connected to the raw water side of the membrane module 4. This performs backwashing. In the raw water side decompression backwashing of the present embodiment, the control unit 4 drives and controls the pressurized backwashing pump 7 so as to apply a minimum pressure that can supply the water to the membrane module 4, thereby performing the reverse The driving force for washing is actually provided only by the pressure regulating filter pump 3. Further, the piping that bypasses the pressurized backwashing pump 7 may be provided without driving the pressure backwashing pump 7, and the valve may be switched. After the backwashing step, the control unit 4 performs the same liquid discharging step as that of the filtered water side pressure backwashing (see Fig. 6). (Composite backwashing) As shown in Fig. 5, in the composite backwashing, the backwashing step and the draining step are performed in the backwashing step, and the control unit 4〇 is used for backwashing in the same manner as the raw water side reduced pressure backwashing. The fluid flow path further opens a valve 22 for supplying air for gas cleaning and a valve 25 for supplying an oxidant. Then, the control unit 40 drives and controls the decompression of the raw water side of the membrane module 4 by the pressure regulating filter pump 3, and further drives and controls the pressurized backwashing pump 7° by the driving control of the control unit 40, and also serves as backwashing. The filtered water accumulated in the filter tank 6 of the tank is pumped to the membrane module 4 by the pressurized backwash pump 7, into 140666. Doc • 18 - The pressure-reducing filter 3 is used to depressurize the raw water side, thereby performing both the pressing and the depressurizing, and performing backwashing by the above method. After the backwashing step, the control unit 4 performs the same draining step as that of the filtered water side pressure backwashing (see Fig. 6). [Switching Control] The control unit 40 monitors the raw water side water quality measured by the water quality measuring device, the membrane differential pressure measured by the membrane pressure measuring device 12, and the membrane filtration flux measured by the membrane filtration flux measuring device 13 . Further, the control unit 4 performs control for switching from one of the above three types of filtering to another filter based on at least one of the measured values. The switching control by the control unit 4A will be described. As the switching control, for example, the control unit 4 can obtain the raw water side water quality as a measured value, and calculate the characteristic value X′ indicating the concentration of the membrane contamination causing substance from the obtained measured value, and the characteristic value X is lower than a predetermined threshold value. In the case of the case, the raw water side pressure filtration is performed, and when the characteristic value X is higher than the critical value, the pressure transition from the raw water side to the composite filtration β characteristic value X is calculated from the raw water side water quality. As a raw water side water quality item, turbidity (degree), TOC (total organic carbon amount) (mg/L), CODMn (chemical oxygen demand detection, high acid method) (mg/L), c 〇DCr (chemical oxygen demand test - potassium dichromate method) (mg / L), BOD (biochemical oxygen demand) (mg / L), or the concentration of the following metals, namely Fe (mg / L), Mn ( Mg/L), Al (mg/L), Si (mg/L), Ca (mg/L), and Mg (mg/L·), which can be used to determine the water quality measurement equipment. The characteristic value X indicating the substance causing the membrane contamination. The water quality measuring device of the present embodiment obtained turbidity 140666. Doc • At least one of 19- 1373367 (degrees) and TOC (mg/L), and the characteristic value X is calculated from each measured value. For example, the characteristic value X can be calculated only from turbidity (degrees) or only T〇c (mg/L). It can also be calculated from turbidity (degrees) and T〇C (mg/L). When the characteristic value X is calculated from turbidity (degrees) and TOC (mg/L), the turbidity can be set to a (degree), and the TOC can be set to B (mg/L) to χ=Α+Β. Calculated by the value. Furthermore, TOC (mg/L) is the total amount of organic carbon. Further, when the turbidity is used as the characteristic value X, it is preferable that the turbidity is 0. The threshold is set between 01 and 1000 degrees, and more preferably between 1 and 100 degrees. When using TOC as the characteristic value X, it is preferable to set a critical value between 0_〇1 mg/L and 1〇〇〇mg/L with respect to the critical value of 'the better value is 1 Set between mg/L and 100 mg/L. When turbidity and TOC (A + B) are used as the characteristic value X, it is preferable that the value of A+B is 〇 with respect to the critical value'. It is better to set the critical value between 〇1 and 1〇〇〇, and it is better to set the value of A+B between 1 and 1〇〇. Further, as another aspect of the switching control, for example, the control unit 4 may acquire the membrane filtration flux as a measured value, and perform the measurement in the constant flow filtration operation using the designed flow rate of the filtered water side decompression. When the value is lower than the preset membrane filtration flux, the 'self-filtering water side pressure filtration is switched to the raw water side pressure filtration or the composite filtration. Further, as another aspect of the switching control, for example, the control unit 4 may obtain the suction lift force on the filtered water side corresponding to the membrane pressure difference as a measured value, and the constant flow rate of the design flow rate by the filtered water side pressure reduction filter may be used. In the operation, when the suction lift force on the filtered water side reaches the effective NPSH, the pressure reduction filtration from the water passage side is switched to the raw water side pressure filtration or the composite enthalpy. •20-140666. Doc 1373367 Regarding the timing of switching and the aspect of switching control, various aspects can be considered in addition to the above. Next, the effect and effect of the switching control obtained by the control unit 40 will be described. The raw water of the water to be treated of the present embodiment is water, river water, lake water, ground water, water storage, sewage secondary treatment water, waste water or sewage. If the raw water raft is filtered by the membrane, membrane fouling occurs, that is, the filter cake layer is formed due to the membrane contamination in the raw water i, and the pores are blocked, resulting in an increase in filtration resistance, so that the continuous flow rate operation is performed continuously. During the process, the membrane differential pressure continues to rise. The present inventors have found that the raw water having a higher turbidity and at least one of the T 〇 C (total organic carbon amount) of the membrane contamination cause quantitative filtration of the membrane filtration flux having a membrane pressure difference of less than atmospheric pressure. In the case of operation, the raw water side pressure filtration and the filtered water side pressure reduction filter have a faster rise in the membrane differential pressure. In addition, the raw water 1 generally changes in water quality, and the amount of substances in the membrane contamination also changes. The present inventors have found that if the cause of contamination in the raw leeches rises sharply, the membrane fouling increases sharply. In this case, in particular, the filtered water side vacuum filtration can suppress the increase of the membrane differential pressure as compared with the raw water side pressure filtration. . It is considered that the difference between the raw water side pressure filtration and the filtration water side pressure reduction filtration as described above is caused by the difference in pressure actually applied to the raw water side of the membrane in which the membrane contamination cause substance exists, that is, 'pressurized on the raw water side In the filtration, the pressure actually applied to the raw water side is the sum of the atmospheric pressure and the membrane differential pressure. On the other hand, in the filtered water side vacuum filtration, the pressure actually applied to the raw water side is the atmosphere 140666. Doc 1373367 Pressure 'For the pressure actually applied to the raw water side, the pressure on the raw water side is higher than the membrane pressure. In the case where the raw water side pressure filtration or the filtration water side pressure filtration is operated with an equal membrane filtration 'flux, the initial applied membrane differential pressure is equal' for the membrane contamination causative substance in the raw water 1 It is applied to the force in the direction perpendicular to the film. However, the actual pressure on the surface of the membrane on which the substance contaminated with the membrane is deposited is higher than the atmospheric pressure on the raw water side as compared with the filtration on the filtered water side. Therefore, it is considered that the particles of the membrane fouling substance are more compressed and deformed in the original water side pressure filtration, and the cake layer formed on the surface of the membrane becomes denser. It is considered that if backwashing and gas cleaning are simultaneously performed in this state, the effect of backwashing in the filtration of the filter cake layer becomes dense in the raw water side pressure filtration. Therefore, if the filtration operation is continued for a long period of time, the raw water side pressure filtration operated by the same membrane filtration flux is compared with the filtration water side pressure filtration, and the pressure rises faster. The membrane contamination cause in the β raw water is higher. The amount of the substance is small, and the difference is as small as possible, but if the amount of the substance causing the film contamination exceeds a certain fixed value, the difference becomes conspicuous. Therefore, it is generally considered that the filter water side pressure reduction enthalpy is more advantageous than the raw water side pressure filtration only when the effect of backwashing or the like is taken as a reference.乂::, in the filtered water side vacuum filtration, the resulting membrane differential pressure is maximum at atmospheric pressure. Under the condition that the membrane differential pressure is above atmospheric pressure, it cannot be used alone. (4) Water side ink reduction (4) operation, unable to read The design of the membrane is too much. That is to say, in the case of raw water with less membrane pollution causing substances, it is generally operated by high membrane filtration and flux, and the membrane difference (4) is higher when the operation is stable. Doc -22· 1373367 value, so it is not possible to use the filtered water side decompression filter for filtration. Therefore, raw water side pressure filtration or composite filtration must be performed. Here, in the case where the amount of the membrane-causing substance in the raw water is large, in order to reduce the pressure actually applied to the raw water side of the membrane, it is better to select the composite filtration as the driving force for obtaining the filtered water as much as possible. Increasing the effect of the filtered water side decompression transition' and supplementing the membrane filtration flux by the raw water side pressure filtration. On the other hand, when the amount of the membrane-causing substance in the raw water is small, 'in view of energy efficiency, it is advantageous to operate only by the raw water side pressure filtration' and by using the frequency of the over-water-side decompression pump And time suppression is minimal, which can make the life of the pump longer. That is, according to the membrane filtration device 50 and the filtration method performed by the membrane filtration device 50, the filtration state is switched in accordance with the change in the water quality of the raw water raft, the membrane filtration flux, and the membrane pressure difference to become an optimum filtration operation. Therefore, even when the quality of the raw water is changed, it is possible to suppress the increase in the differential pressure of the membrane under a high membrane filtration flux, and to reduce the number of chemical cleanings, and to minimize the energy consumption, thereby prolonging the pump life. As a result, it is possible to suppress the increase in the film differential pressure while ensuring the designed membrane filtration flux, and to continuously perform the filtration operation for a long period of time. Further, in the membrane filtration device 50 and the filtration method performed by the membrane filtration device 5, any backwashing of the filtered water side pressure backwashing, the raw water side pressure reducing back washing, and the composite back washing is selected and performed. This allows for effective backwashing. For example, the original water side depressurization backwash is compared with the filtered water side pressure backwashing, and the actual pressure of the membrane surface deposited by the membrane fouling substance is less than atmospheric pressure. Therefore, it is generally considered that the compression of the substance causing the film contamination on the surface of the film is 140666. Doc •23- 1373367 To ease, the backwashing effect is higher. On the other hand, it is generally considered that, similarly to the filtration method, there is a case where the backwashing flux of the design cannot be ensured only by the backwashing of the raw water side, and in this case, the composite backwashing is set as the backwashing water. The driving force increases the effect of the raw water side decompression backwash as much as possible, and supplements the insufficient portion by filtering the water side pressure backwashing, thereby performing better backwashing. Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the third and second pressure regulating mechanisms for performing raw water side pressure filtration, filtration water side pressure filtration, composite filtration, filtered water side pressure back washing, raw water side pressure reducing back washing, and composite back washing are used. Examples of the pressurizing mechanism include a pressurizing pump, a pressure regulating pump, a high-pressure gas, a head difference, and the like. Examples of the pressure reducing mechanism include a suction pump and a vacuum pump. [Examples] [Example 1] A river surface water having an average turbidity of 1 degree was used as raw water. The filtering operation and the backwashing operation are performed using the apparatus corresponding to the above membrane filtration device 50. This filtration operation is started by pressure filtration on the raw water side. From the water quality tester. The signal is sent to the control unit 4〇, and automatically switches to composite filtering by the control unit 4〇 from the time when the measured value reaches 5 degrees. The raw water side pressure filtration system is set to use a pressure regulating filter pump 3 at a fixed flow rate (membrane filtration pass is 2. 5 m3/m2/day, a flow rate of 2.5 m filtered water per i m2 membrane area per i day) The constant flow filtration of the raw water raft to the membrane module 4 is carried out by means of end point filtration. The composite filtration system was set to use a pressure-regulating filter pump 3 at a fixed flow rate (貘 filtration 140666. Doc _ 24 · 1373367 The flux is 2·5 mW/day, and the flow rate of 25 claws and 3 filtered water per membrane area per 丨 可获得 can be supplied to the membrane module 4 while using the constant flow rate for decompression. According to the endpoint filter side, the rotation speed of the filtration pump 5 is the maximum rotation speed of the pump, that is, 5 Hz. In this embodiment, the raw water side pressure transition or the composite filtration and cleaning operation are alternately repeated as The operating conditions were followed by a filtration operation for 29 minutes. The backwashing was carried out as a backwashing operation and the gas was purged for 1 minute and discharged for 3 seconds. The backwashing operation was carried out simultaneously with 爻〇m3/m2/day. The liquid supply pump 9 supplies the sodium hypogasate in the oxidant tank 8, so that the residual gas concentration of the backwash water reaches 3 mg/liter. The gas system for gas cleaning uses air compressed by the compressor, and the air flow rate is It is set to 15 Nm3/hr. Under the above operating conditions, continuous operation is started from the raw water side pressure filtration method. As a result, the turbidity exceeds 5 degrees and reaches 17 degrees after about 1000 hours (refer to Fig. 8), so it is automatically switched to composite filtration. The membrane differential pressure rises to i63 Kpa, after 3,000 hours, it becomes 145 kPa (refer to Figure 7). Within 3000 hours, it can maintain the predetermined membrane filtration flux. Continuous operation in the state of 5 m3/m2/day (refer to Figure 9). [Comparative Example 1] A river surface water having an average turbidity of 1 degree was used as raw water. The apparatus having the same configuration as that of the first embodiment except for the control unit 40 was used to carry out the enthalpy operation and the backwashing operation, and the filtration operation was carried out simultaneously with the first embodiment by the raw water side pressure filtration. It is set to use a pressure regulating filter pump 3 to fix the flow (the membrane filtration flux is 2. 5 m3/m2/day, the membrane area per i m2 per day can be 140666. Doc •25- 2·5 Flow of filtered water) The membrane module* is supplied with a predetermined flow rate, which is carried out by means of end point filtration. ~ As the operating conditions of Comparative Example 1, the anti-money laundering center, the anti-money laundering minute, and the #心〇秒, which are performed in the backwashing operation (4) for 29 minutes, are reversed to the lamp backwashing operation by 3 〇m3/m2/day. For the simultaneous use of the oxidant, please supply the sodium hypochlorite in the oxidizer tank 8 so that the residual chlorine concentration in the backwash water reaches 3 mg/liter. The gas system for gas cleaning uses a shrinkage machine 10, and the x-part (upper milk' air flow rate is set to 1. 5 NmVhr 连续 Continuous operation under the above operating conditions. As a result, after (1) (four) hours, the film differential pressure becomes 2 kPa which must be chemically cleaned, so the apparatus is stopped (refer to Fig. 7). [Comparative Example 2] A river surface water having an average turbidity of 丨 was used as raw water. The filtration operation and the backwashing operation were carried out using a device having the same configuration as in Comparative Example 1, and the filtration operation was carried out simultaneously with the Example 利用 by filtration water side pressure reduction filtration. It is set to use the pressure regulating filter pump 3 to fix the flow rate (the membrane filtration flux is 2. 5 m3/m2/day, every i day! The m2 membrane area can obtain a flow rate of 25 5 filtered water. The constant flow filtration of the raw water 1 to the membrane module 4 is carried out by means of an end point filtration method. The operation conditions of Comparative Example 2 were carried out by a filtration operation for 29 minutes, a backwashing as a backwashing operation, a gas washing for 1 minute, and a discharge for 30 seconds. The backwashing operation was carried out at 3 · 〇 rn3 / m 2 / day, while the oxidizing agent feed pump 9 was used to supply the sub-gas sulphur in the oxidizing agent tank 8, so that the residual chlorine concentration in the backwash water was 3 mg / liter. The gas system for gas cleaning uses air compressed by the compressor 10, and the air flow rate is set to 丨5 Nm3/hr. At 140666. Doc •26· 1373367 Continuous operation under the above operating conditions' results are less than the designed membrane transition flux after 1000 hours. 5m3/m2/曰, the minimum is 1. 5m3/m2/曰 (refer to Figure 9). [Example 2] A river surface water having an average turbidity of 0.1 degree was used as raw water. The filtration operation and the backwashing operation were carried out using a device having the same configuration as that of Example 1, and the transient operation was started with the transition water side decompression, and the time from the measurement of the membrane differential pressure measuring device 12 to 80 kPa was automatically performed. Switching to a combination of raw water side pressurization transition and filtration water side decompression filtration. The number of revolutions of the decompression transition fruit 5 of the combination of the raw water side pressurization and the filtration water side decompression filtration is a value at which the filtered water side decompression filtration is continued and the membrane differential pressure reaches 8 kPa. The composite filtration system was set to use a pressure-regulating filter pump 3 for a fixed flow rate (membrane filtration flux was 5. 0 m3/m2/day, a flow rate of 5·0 m3 of filtered water per 1 m2 of membrane area is obtained.) The raw water is supplied to the membrane module 4, and the constant-flow filtration is performed by using the vacuum filter pump 5 for decompression. Performed by endpoint filtering. As the operating conditions of Example 2, the filtration operation was carried out for 29 minutes, the backwashing as the backwashing operation, the gas washing for 1 minute, and the discharge for 3 seconds were repeated. The backwashing operation is performed by 3. 8 m3/m2/day was carried out while the oxidizing agent feed pump 9 was used to supply the sodium sulfoxide in the oxidizer tank 8, so that the residual gas concentration of the backwash water was 3 mg/liter. The gas system for gas cleaning uses air compressed by the compressor 10, and the air flow rate is set to 丨5 Nm3/hr. Under the above operating conditions, the continuous operation was started from the filtered water side vacuum filtration method. As a result, the membrane differential pressure reached 8 〇 kpa after about 400 hours, so that the composite transition was switched. Stable filtration continued for about 2,000 hours, about 25 inches and 140666. Doc •27· 1373367 After the time, the membrane pressure becomes 200 kPa (see Figure 10) where chemical cleaning is necessary. [Comparative Example 3] The average turbidity was 0. The 1 degree river surface water was used as the raw water. The filtration operation and the backwashing operation were carried out using the apparatus having the same configuration as that of Comparative Example 1. The "over-drying operation" was carried out by pressurizing the raw water side. It is set to use a pressure regulating filter pump 3 at a fixed flow rate (membrane filtration flux is 5. 0 m3/m2/曰, 5_0 m3 of filtered water flow per 1 m2 of membrane area per day). The flow rate of raw material 1 supplied to membrane module 4 is filtered by endpoint filtration. As the operating conditions of Comparative Example 3, the filtration operation was carried out for 29 minutes, and the backwashing and the gas washing were performed as the backwashing operation for 1 minute, and the discharge was repeated for 3 seconds. The backwashing operation is performed by 3. 8 m3/m2/day was carried out while the oxidizing agent feed pump 9 was used to supply the sodium hypochlorite in the oxidizer tank 8, so that the residual gas concentration of the backwash water was 3 mg/liter. The gas system for gas cleaning uses the air "air flow" compressed by the compressor 10 to be set to 丨5 Nm3/hr. Continuous operation under the above operating conditions resulted in a stable operation time, and after about 1900 hours, the differential pressure of the membrane became 2 〇〇 kpa (see Fig. 10) which required chemical cleaning. [Example 3] A backwashing wastewater of a river water sand filter having an average turbidity of 1 Torr was used as raw water. The filtration operation and the backwashing operation were carried out using a device having the same configuration as that of Example ,, and the filtration operation was started by filtering the water enthalpy under reduced pressure, and the measured value of the membrane filtration flux measuring device 13 was lower than that of the designed membrane filtration flux. 1 When 〇mVm2/曰, it automatically switches to composite filtering. Combined filtration decompression 140666. Doc •28· 1373367 The speed of record 5 is 50 Hz for maximum speed. The composite filtration system is set to use a pressure-regulating filter pump 3 at a fixed flow rate (membrane filtration flux is 〇 m3/m2/ 曰' per 1 m2 per 1 m2 membrane area. The flow rate of 0 m3 of filtered water is supplied to the membrane module 4 by means of the end point filtration method by supplying the raw water crucible to the membrane module 4 and performing the constant-flow filtration using the decompression filter pump $. As the operating conditions of Example 3, the filtration operation was carried out for 29 minutes, the backwashing as a backwashing operation, the gas washing for 1 minute, and the discharge for 3 seconds were repeated. The backwashing operation was carried out with 丨· 〇 mVm2/day, and the oxidizing agent was used to supply the sodium sulphate in the oxidizing agent tank 8 to make the residual chlorine concentration of the backwash water 3 mg/liter. The gas system for gas cleaning uses air compressed by the compressor 10, and the air flow rate is set to 丨. 5 Nm3/hr. Under the above operating conditions, the continuous operation was started from the filtered water side vacuum filtration method. The results of the membrane filtration flux analyzer 13 were lower than the designed membrane filtration flux after about 2250 hours. 0 m3/m2/day, so it automatically switches to composite over. After about 3000 hours, the film differential pressure becomes 2 kPa (see Fig. 11) which must be chemically cleaned. The membrane filtration flux operation can be designed for 10 m3/m2/day. • About 3000 hours (refer to Fig. 12). [Comparative Example 4] A backwashing wastewater of a river water sand filter having an average turbidity of 100 degrees was used.  Raw water. The filtration operation and the backwashing operation were carried out using a device having the same configuration as in Comparative Example 1. The filtration operation was carried out by filtration under reduced pressure on the filtered water side. It is set to use a pressure-regulating filter pump 3 at a fixed flow rate (membrane filtration flux is i 〇m3/m2/曰' per 1 m2 of membrane area per day (〇m3 flow rate of turbulent water) to membrane module 4 Supply raw water 1, and use the vacuum filter pump 5 to reduce the pressure of 140666. Doc -29- 1373367 The flow is too high and is done by endpoint filtering. As the operating condition of Comparative Example 4, backwashing and gas cleaning were carried out while performing a filtration operation for 29 minutes as a backwashing operation! Minutes, #出^秒 and repeat. The backwashing operation is carried out simultaneously with i 〇 m3/m2/day using the oxidizing agent feed pump 9 to supply the sub-gas sulphate in the oxidizing agent tank 8, so that the residual milk concentration of the backwashing water reaches 3 mg/liter. The gas system for gas cleaning uses air compressed by the compressor 10, and the air flow rate is set to 15 Nm3/hr. After continuous operation under the above operating conditions, the membrane filtration flux was lower than the designed membrane filtration flux 丨〇m3/m2/day after about 23 hrs, and became 0.45 m3/m2 after about 3 hrs. /曰 (Figure 12). [Comparative Example 5] The backwashing wastewater of a river water sand filter having an average turbidity of 100 ° was used as raw water. The filtration operation and the backwashing operation were carried out using a device having the same configuration as that of Comparative Example 1. The filtration operation was carried out by pressure filtration on the raw water side. It is set to use a pressure-regulating filter pump 3 at a fixed flow rate (membrane filtration flux is 1 〇m3/m2/day, and the flow rate of i 〇m3 filtered water per 1 m2 of membrane area per day) is supplied to the membrane module 4 The flow rate of the raw water 1 is too high, and it is carried out by the end point. As the operating conditions of Comparative Example 5, the filtration operation was carried out for 29 minutes, and the backwashing and the gas washing were performed as the backwashing operation for 1 minute, and the discharge was repeated for 3 seconds. Backwashing operation is 1. At 0 m3/m2/day, the oxidizing agent feed system 9 was used to supply the sodium hypochlorite in the oxidizer tank 8, so that the residual gas concentration of the backwash water was 3 mg/liter. The gas system for gas cleaning uses air compressed by the compressor 10, and the air flow rate is set to 1. 5 Nm3/hr. 140666. Doc •30· 1373367 Continuous operation under the above operating conditions showed that the film differential pressure became 2 kPa (see Fig. 11) which had to be chemically cleaned after about 950 hours. [Example 4] A river surface water having an average turbidity of 2 degrees was used as raw water. The filtration operation and the backwashing operation were carried out using a device having the same configuration as that of Example 1, and the filtration operation was started by filtration under reduced pressure on the filtered water side, from the time when the measured value of the membrane differential pressure measuring device 12 reached 8 kPa. , automatically switch to composite filtering. The rotational speed of the pressure-reducing filter pump 5 after the completion of the filtration is continued until the filtered water side is depressurized and the membrane differential pressure reaches a value of 80 kPa. The composite filtration system is set to use a pressure-regulating transition pump 3 to supply a membrane module 4 at a fixed flow rate (membrane filtration flux is 丨7 m3/m2/day, and a flow rate of 17 m3 of filtered water per 1 m2 membrane area per 1 2) The raw water 1 is simultaneously subjected to a constant flow rate filtration by decompression using a vacuum filter pump 5, and is carried out by an end point method. As the operating conditions of Example 4, the filtration operation was carried out for 29 minutes, and the backwashing and the gas washing were performed as the backwashing operation for 1 minute, and the discharge was repeated for 3 seconds. The backwashing operation was carried out at i 7 m3/m2/day while the oxidizing agent feed pump 9 was used to supply the sodium sulfoxide in the oxidizing agent tank 8, so that the residual chlorine concentration in the backwash water was 3 mg/liter. The gas system for gas cleaning uses air compressed by the compressor 10, and the air flow rate is set to 5 Nm3/hr. Under the above operating conditions, continuous operation was started from the filtered water side vacuum filtration method. As a result, the film differential pressure became 43 kPa after 100 hours. After 1 hour, the turbidity was added to bring the turbidity to about 1 Torr, and as a result, the membrane differential pressure was increased to a maximum of 73 kPa, and then decreased. After 250 hours, the turbidity was again added to make the turbidity 1 degree, and after about 260 hours (after about 10 hours from the addition of turbidity), the membrane differential pressure reached 80]40666. Doc -31 - 1373367 kPa' automatically switches to composite filtration. The membrane differential pressure was increased to a maximum of M kPa and then decreased by 63 kPa after 500 hours (see Fig. 13). Can be 1. The membrane filtration flux of 7 m / m / day is designed to operate for 5 hours (see Figure 14). [Example 6] A river surface water having an average turbidity of 2 degrees was used as raw water. The filtration operation and the backwashing operation were carried out using a device having the same configuration as in Example 1, and the filtration operation was carried out by filtration under reduced pressure on the filtered water side. It is set to use the pressure regulating filter pump 3 to fix the flow rate (the membrane filtration flux is 丨7 m3/m2/day, and the flow rate of 1 〇m3 of filtered water per 1 m2 of membrane area per 1 )) is supplied to the membrane module 4. The raw water 1 and the constant flow rate filtration under reduced pressure by the vacuum filter pump 5 are performed by the end point method. As the operating conditions of Example 6, the filtration operation was carried out for 29 minutes, and the backwashing and gas washing were performed as a backwashing operation for 1 minute, and the discharge was repeated for 3 seconds. The backwashing operation is carried out at 1 7 m3/m2/day, and the oxidizing agent feed pump 9 is used to supply the sodium hypochlorite in the oxidizing agent tank 8, so that the residual chlorine concentration of the backwashing water reaches 3 mg/liter. Using air compressed by the compressor 10, the air flow rate was set to 丨5 Nm3/hr. Continuous operation under the above operating conditions resulted in a film differential pressure of 45 kPa after 1 hour. The turbidity was added after 100 hours, and the turbidity was about 1 Torr. The film differential pressure was increased to a maximum of 69 kPa, and then decreased (see Fig. u). After 25 hours, the turbidity was added again to make the turbidity 1 degree. After about 26 hours (after about 10 hours from the addition of turbidity), the membrane filtration flux was lower than the designed membrane filtration flux of 1 7 m / m. /曰, the minimum is 〇82 m3/m2/曰 (refer to Figure 14). [Comparative Example 7] 140666. Doc •32- 1373367 The raw water of the river surface water with an average turbidity of 2 degrees is used. Use with and compare examples! In the same configuration, the (four) operation and the backwashing operation are performed, and the filtering operation is performed by adding the raw water side. It is set to use the pressure-regulating filter pump 3 to fix the flow rate (the membrane filtration flux is 丨7(7)3"2/day, and the flow rate of h7 m3 perhydromethane per 1 m2 of membrane area per day) is supplied to the membrane module 4 The flow filtration of 1 is carried out by the end point filtration method. As the operation condition of Comparative Example 7, the filtration operation was carried out for 29 minutes, and the backwashing and gas cleaning were performed as the backwashing operation, and the gas was purged for 3 minutes and discharged for 3 seconds. The backwashing operation is performed at 7 m3/m2/day, and the oxidizing agent feed pump 9 is used to supply the sodium hypochlorite in the oxidizing agent tank 8, so that the residual gas concentration of the backwashing water becomes 3 mg/liter. The gas system uses air compressed by the compressor 10, and the air flow rate is set to 1. 5 NmVhr. The operation was continued under the above operating conditions, and as a result, the film differential pressure became 45 kPa after 丨〇〇 hours. The turbidity was added after 1 hour, and the turbidity was about ι 〇〇. The film differential pressure was raised to 113 kPa at the maximum and then decreased (see Fig. 13). After 250 hours, the turbidity was again added to make the turbidity 1 degree, and after about 265 hours (about 15 hours after the addition of the turbidity), the membrane pressure became 200 kPa which required chemical cleaning (refer to the figure). 3). [Industrial Applicability] The present invention can be preferably used for tap water, industrial water, river water, lake water, ground water, water storage, sewage secondary treatment water, waste water, sewage, etc. as raw water for membrane filtration or The field of membrane filtration is applied to separate or concentrate valuables. [Simple description of the chart] 140666. Doc -33 - 1373367 Fig. 1 is an explanatory view showing a schematic configuration of a membrane filtration device capable of switching between a raw water side pressurized ruthenium, a filtered water side pressure reduction filtration, and a composite filtration according to an embodiment of the present invention; FIG. 3 is a view showing the flow path of the fluid in the filtration step of the membrane filtration device in the form; FIG. 3 is a view showing the flow of the fluid in the filtration step of the filtration water side decompression filtration or the filtration step of the composite filtration. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 4 is an explanatory view showing the flow of a fluid in a washing step of performing backwashing and gas washing while filtering water side backwashing; Fig. 5 is a view showing simultaneous pressure side backwashing or compound backwashing of raw water side Description of the flow of the fluid in the washing step of the backwashing and the gas cleaning: Fig. 6 is an explanatory view showing the flow of the fluid in the step of discharging the material to be removed which is peeled off from the membrane module; Fig. 7 is a view showing the embodiment 1. Comparative Example 1 and Comparative Example 2: FIG. 8 is a view showing turbidity change characteristics of Example i, Comparative Example 1, and Comparative Example 2. FIG. 9 is a view showing Examples 丨 and ratio. Fig. 1 is a view showing a film differential pressure change characteristic of Example 2 and Comparative Example 3; Fig. 11 is a view showing Example 3 and Comparative Example 4; Fig. 12 is a graph showing the membrane filtration flux change characteristics of Example 3, Comparative Example 4, and Comparative Example 5; 140666. Doc 1373367 Fig. 13 is a view showing the film differential pressure change characteristics of Example *, Comparative Example 6, and Comparative Example 7; and Fig. 14 is a graph showing the membrane filtration flux change characteristics of Example 4, Comparative Example 6, and Comparative Example 7. Figure. [Description of main component symbols] I Raw water 3 Pressure regulating filter pump (2nd adjustment mechanism) 4 Membrane module 5 Vacuum filter pump (1st adjustment mechanism) II Water quality measuring device (measurement mechanism) 40 Control unit (control mechanism) 50 Membrane Filter device 140666. Doc -35.

Claims (1)

1373367 Patent Application No. 098,122,132 Patent Application Serial No. (September 101)/< VII VII. Patent Application Range: 1. A filtering method characterized in that it is implemented by pressure on a membrane module The filtering operation of the driving force is to filter the raw water to obtain the filtered water; and the filtering operation includes the raw water side pressure filtration, the excessive water side decompression, and the combination of the raw water side pressure filtration and the filtered water side pressure reduction. The filtered composite filtration is used to filter at least one of the raw water side water quality and the membrane differential pressure, and is switched from the above three modes to another filtration according to the measured value. 2. The filtering method according to claim 1, wherein the measured value is a characteristic value X′ indicating a concentration of the membrane contamination causing substance calculated from the raw water side water quality, when the characteristic value X is lower than a predetermined threshold value. The raw water side pressure filtration is performed, and when the characteristic value X is higher than the critical value, the raw water side pressure filtration is switched to the composite filtration. 3. The filtration method according to claim 2, wherein the characteristic value X is calculated from at least one of a raw water side turbidity A (degree) and a raw water side total organic carbon amount (mg/L). 4. The filtration method according to claim 3, wherein the above-mentioned characteristic value X is X= when the turbidity of the raw water side is A (degree) and the total organic carbon amount of the raw water side is B (mg/L). Calculated by A+B. 5. The filtration method according to claim 1, wherein the measured value corresponds to a suction lift force of the filtered water side of the membrane differential pressure, and a constant flow filtration operation using a designed flow rate of the filtered water side vacuum filtration, When the suction lift force on the filtered water side reaches the effective NPSH I40666-1010716.doc, the filtered water side vacuum filtration is switched to the raw water side pressure filtration or the above composite filtration. 6. The filtration method according to any one of items 1 to 5, wherein the filtering operation and the backwashing operation are alternately repeated, wherein the backwashing operation is simultaneously performed from the filtered water side of the membrane module to the raw water side. Backwashing, and gas cleaning of the above membrane module. 7' The filtration method of claim 6, wherein the pressure backwashing is performed from the filtered water side press when the backwashing operation is performed. 8. The filtration method according to claim 6, wherein the pressure-reducing backwashing of the raw water side is performed when the backwashing operation is performed. 9. The filtration method according to claim 6, wherein in the case of performing the backwashing operation, a combined backwash which combines the pressure backwashing with the water side pressure and the pressure backwashing of the raw water side pressure is performed. 1〇_ The filtration method of claim 6, wherein the pressure backwashing from the filtered water side pressure, the pressure backwashing on the raw water side pressure reduction, and the pressure backwashing combined with the water side pressure And in the case of performing the backwashing operation in any of the backwashing operations of the reduced pressure backwashing of the raw water side decompression, selecting the above-described pressure backwashing, the above-described pressure backwashing, and the above composite backwashing Either. η. A membrane filtration device comprising: a membrane module having a pressure as a driving force; and comprising: a first pressure regulating mechanism that adjusts a pressure of a raw water side of the membrane module; and a second pressure regulating mechanism Adjusting the pressure of the water-repellent side of the membrane module; measuring means for determining the water quality of the raw water side of the membrane module; and 140666-1010716.doc -2- 1373367 July/3/4 曰 repair (more) a j control mechanism that drives and controls at least one of the first pressure regulating mechanism and the second pressure regulating mechanism based on a measured value measured by the measuring means; and the control mechanism pressurizes and filters water on the raw water side. In the three aspects of the side decompression and the above-mentioned raw water side dust filtration and the composite filtration according to the water side decompression filtration, 'from one type of filtration to another type of filtration. 12. The membrane filtration device according to claim 11, wherein the second pressure regulating mechanism is a pressure reducing pump. The measuring means is at least one of a turbidity meter and a total organic carbon amount measuring device. 13. The membrane filtration device according to claim 11 or 12, wherein the control means drives and controls at least one of the first pressure regulating mechanism and the second pressure regulating mechanism to perform pressure backwashing on the filtered water side, Decompression backwashing of raw water side decompression, and combined backwashing of pressurized backwashing with filtered water side and decompression backwashing of raw water side decompression" 140666-1010716.doc