JP2009066511A - Washing method of filtration apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filtration apparatus which is capable of effectively removing a solid matter clogged in a hollow fiber membrane by a detergent and which is capable of efficiently conducting the washing of a hollow fiber membrane. <P>SOLUTION: The filtration apparatus is provided with a membrane module 2 having a hollow fiber membrane 1 and a diffusion part 3 arranged at the lower side of the membrane module 2. The filtration apparatus conducts the filtration by immersing the membrane module 2 in a liquid to be treated to pass the liquid to be treated into the inside of the hollow part from the hollow fiber membrane 1 and washing the hollow fiber membrane 1 of the membrane module 2 by diffusing air jetted into the liquid to be treated from a diffusion part 3. The apparatus is further characterized by washing the hollow fiber membrane 1 with the detergent by supplying the detergent in the hollow fiber membrane 1 of the membrane module 2 to the opposite direction to the stream of the liquid to be treated while repeating the feed and feed back. Thus, it can strip the solid matter by the stream of reciprocation that the detergent moves back and forth and can remove the solid matter clogged in the hollow fiber membrane 1 effectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a filtration method for a filtration device in which a liquid to be treated is filtered through a hollow fiber membrane of a membrane module to perform a solid-liquid separation process and the hollow fiber membrane is washed by aeration from an aeration unit. is there.

  Conventionally, a membrane module formed by bundling a large number of hollow fiber membranes has been used as a membrane module when a liquid to be treated such as wastewater is filtered through a membrane module for solid-liquid separation treatment. Thus, in the membrane module formed with the hollow fiber membrane, the liquid to be treated can be filtered by passing the liquid to be treated from the outside to the inside of the hollow.

  And by filtering the liquid to be processed through the hollow fiber membrane in this way, when the liquid to be processed is subjected to a solid-liquid separation treatment, the filtered solid matter adheres to the surface of the hollow fiber membrane, and the hollow fiber membrane is clogged. May occur. For this reason, an air diffuser is disposed below the membrane module of the hollow fiber membrane, and gas such as air is diffused from the air diffuser, so that the effect of the diffused gas and the coverage generated by the air diffuser are reduced. The action of the upward flow of the treatment liquid will vibrate the hollow fiber membrane to prevent the solid content from adhering to the surface of the hollow fiber membrane, and to perform cleaning to peel off the adhering solid content from the surface of the hollow fiber membrane. I have to.

  As described above, while performing the operation of filtering the liquid to be treated by the hollow fiber membrane of the membrane module while cleaning the hollow fiber membrane of the membrane module with the air diffused from the air diffuser, the hollow fiber membrane is kept as the operation is continued. The hollow interior and micropores gradually become clogged, making it difficult for the liquid to pass through the hollow fiber membrane and reducing the filtration efficiency. Further, as the operation is continued in the air diffuser, the nozzle hole for ejecting the gas and the inside of the air diffuser may become clogged, and the hole diameter may be reduced or blocked, and the efficiency of the air diffuser will decrease.

  For this reason, for the hollow fiber membrane of the membrane module, a cleaning liquid such as hydrogen peroxide-containing water is supplied and passed through the hollow fiber membrane in the direction opposite to the flow of the liquid during filtration. Cleaning is performed to remove the solid content clogged in the hollow interior and the fine pores (see, for example, Patent Document 1).

For the air diffuser, the cleaning liquid is supplied to the air diffuser through the gas supply pipe that supplies the gas to the air diffuser, and the solids clogged in the air diffuser and the nozzle holes are removed with the cleaning liquid. (See, for example, Patent Document 2).
JP 2005-34694 A JP 2003-154236 A

  However, both of the above-mentioned Patent Document 1 and Patent Document 2 only supply the detergent to the hollow fiber membrane and the air diffuser and allow it to pass through, so that the hollow fiber membrane and the air diffuser are not clogged. As a result, the cleaning agent may be removed from the hollow fiber membrane or the diffuser, and the solid content clogged in the diffuser portion cannot be sufficiently obtained. It has a problem of needing. In particular, since the filtration operation is stopped while the hollow fiber membrane and the diffuser are being washed, if the washing takes a long time, the filtration device's filtration operation is stopped for a long time, and the liquid to be treated is processed. There was a problem in productivity.

  The present invention has been made in view of the above points, and a filtration device that can effectively remove solids clogged in a hollow fiber membrane or an air diffuser with a cleaning agent and can perform cleaning efficiently. An object of the present invention is to provide a cleaning method.

  The cleaning method for a filtration device according to claim 1 of the present invention includes a membrane module 2 formed with a hollow fiber membrane 1 and an air diffuser 3 disposed on the lower side of the membrane module 2. The module 2 is immersed in the liquid to be treated and filtered by passing the liquid to be treated from the outside of the hollow fiber membrane 1 to the inside of the hollow fiber, and is scattered by the gas ejected from the air diffuser 3 into the liquid to be treated. In a filtration device that is adapted to wash the hollow fiber membrane 1 of the membrane module 2, the cleaning liquid is supplied into the hollow fiber membrane 1 of the membrane module 2 in a direction opposite to the flow of the liquid to be treated while being repeatedly fed and withdrawn. Thus, the hollow fiber membrane 1 is washed with a detergent.

  According to the present invention, by supplying the cleaning liquid while repeating the feeding and pulling back into the hollow fiber membrane 1, the reciprocating flow in which the cleaning liquid advances and retreats while allowing the cleaning liquid to permeate the solid content clogged in the hollow fiber membrane 1. The solid content can be peeled off, the solid content clogged in the hollow fiber membrane 1 can be effectively removed, and the hollow fiber membrane 1 can be washed efficiently.

  Further, the invention of claim 2 is that in claim 1, after the hollow fiber membrane 1 is washed with the washing liquid, water is supplied into the hollow fiber membrane 1 of the membrane module 2 in the opposite direction to the flow of the liquid to be treated. The hollow fiber membrane 1 is rinsed and washed.

  According to this invention, the hollow fiber membrane 1 can be finished and washed by rinsing the hollow fiber membrane 1 with water, and the washing liquid can be washed away from the hollow fiber membrane 1 with water and discharged. It is possible to prevent the cleaning liquid from being mixed into the filtrate when the liquid to be treated is filtered with the hollow fiber membrane 1.

  In addition, the invention of claim 3 includes a plurality of membrane modules 2 according to claim 1 or 2, wherein the filtration operation is stopped while performing the operation of filtering with some of the membrane modules 2 among the plurality of membrane modules 2. The hollow fiber membranes 1 of some of the membrane modules 2 are washed with a detergent.

  According to the present invention, it is not necessary to stop the entire filtration operation of the filtration device, and it is possible to prevent the productivity for treating the liquid to be treated from being lowered.

  The cleaning method for a filtration device according to claim 4 of the present invention comprises a membrane module 2 formed with a hollow fiber membrane 1 and an air diffuser 3 disposed on the lower side of the membrane module 2. The module 2 is immersed in the liquid to be treated and filtered by passing the liquid to be treated from the outside of the hollow fiber membrane 1 to the inside of the hollow fiber, and is scattered by the gas ejected from the air diffuser 3 into the liquid to be treated. In the filtration device that is adapted to clean the hollow fiber membrane 1 of the membrane module 2, the air diffuser 3 is washed with a cleaning agent by supplying the cleaning liquid into the air diffuser 3 while repeatedly feeding and pulling back. It is characterized by doing.

  According to the present invention, by supplying the cleaning liquid while repeating the feeding and pulling back into the air diffuser 3, the cleaning liquid penetrates into the solid content clogged in the air diffuser 3 and the cleaning liquid moves forward and backward. The solid content can be peeled off, the solid content clogged in the diffuser 3 can be effectively removed, and the diffuser 3 can be cleaned efficiently.

  In addition, the invention of claim 5 comprises a plurality of membrane modules 2 and aeration units 3 according to claim 4, and filtration is performed with some of the membrane modules 2 out of the plurality of membrane modules 2 and aeration is performed with the diffusion unit 3. The air diffuser 3 disposed corresponding to the other part of the membrane module 2 that has stopped the filtration operation is washed with a cleaning agent while the operation is performed.

  According to the present invention, it is not necessary to stop the entire filtration operation of the filtration device, and it is possible to prevent the productivity for treating the liquid to be treated from being lowered.

  According to the present invention, a reciprocating flow in which the cleaning liquid advances and retreats while allowing the cleaning liquid to permeate into the solid content clogged in the hollow fiber membrane 1 by supplying the cleaning liquid while repeatedly feeding and retracting into the hollow fiber membrane 1. The solid content can be peeled off, the solid content clogged in the hollow fiber membrane 1 can be effectively removed, and the hollow fiber membrane 1 can be washed efficiently.

  Further, according to the present invention, by supplying the cleaning liquid while repeating the feeding and pulling back into the aeration unit 3, the cleaning liquid penetrates the solid content clogged in the aeration unit 3, and the reciprocation of the cleaning liquid advances and retreats. The solid content can be peeled off by the flow, the solid content clogged in the diffuser 3 can be effectively removed, and the diffuser 3 can be cleaned efficiently.

  Hereinafter, the best mode for carrying out the present invention will be described.

  The hollow fiber membrane 1 is formed in a hollow fiber shape having fine pores, and the membrane module 2 is formed by bundling the hollow fiber membrane 1 with a liquid collection part 11. For example, the membrane module 2 can be formed by aligning and bundling a large number of hollow fiber membranes 1, bending them in a U-shape at the center, and fixing both ends with the liquid collection portion 11. The liquid collection part 11 is formed hollow by resin molding or the like, and both ends of each hollow fiber membrane 1 are opened in the liquid collection part 11. The liquid collection part 11 is provided with a filtrate outlet 12. It is.

  A plurality of the membrane modules 2 are arranged and provided in a treatment tank 13 to which a treatment liquid is supplied, while being immersed in the treatment liquid. In the embodiment of FIG. 1, three membrane modules 2 a, 2 b, 2 c are provided in the processing tank 13. In FIG. 1, reference numeral 14 denotes a liquid collection pump, and a liquid collection header pipe 15 is connected to the inlet of the liquid collection pump 14. A number of liquid collection pipes 16a, 16b, and 16c corresponding to the number of the membrane modules 2 are branched from the liquid collection header pipe 15. Each of the liquid collection pipes 16a, 16b, and 16c is divided into the membrane modules 2a, 2b, and 2c, respectively. Is connected to the filtrate outlet 12 of the liquid collecting part 11. Each liquid collecting pipe 16a, 16b, 16c is provided with a membrane switching valve 17a, 17b, 17c formed by an electromagnetic three-way valve or the like. The liquid collecting pipes 16a, 16b, 16c and the liquid collecting header pipe 15 are provided. Communication with can be opened and closed individually. These membrane switching valves 17a, 17b, and 17c are electrically connected to the control device 18, and are individually controlled to be opened and closed by a command from the control device 18.

  In addition, in the bottom of the treatment tank 13, the air diffuser 3 is disposed at a position directly below the membrane module 2. The air diffuser 3 is formed by a pipe or the like provided with nozzle holes. In the embodiment shown in FIG. 1, three air diffusers 3a, 3b, 3c corresponding to the membrane modules 2a, 2b, 2c are provided. 3c is provided. In FIG. 1, 19 is a blower to which an air supply header pipe 20 is connected. A number of air supply pipes 21a, 21b, and 21c corresponding to the number of the air diffusers 3 are branched to the air supply header pipe 20, and the air supply pipes 21a, 21b, and 21c are respectively provided with the air diffusers 3a and 3b. , 3c. Each of the air supply pipes 21a, 21b, 21c is provided with an air diffusion switching valve 22a, 22b, 22c formed by an electromagnetic three-way valve or the like. The air supply pipes 21a, 21b, 21c and the air supply header pipe are provided. Communication with 20 can be opened and closed individually. These air diffusion switching valves 22 a, 22 b, and 22 c are electrically connected to the control device 18, and are individually controlled to be opened and closed by a command from the control device 18.

  In FIG. 1, reference numeral 25 denotes a cleaning tank, and a cleaning liquid is supplied from a cleaning liquid supply pipe 26 and water is supplied from a water supply pipe 27. The cleaning liquid is not particularly limited, but sodium hypochlorite or the like can be used. The cleaning liquid supply pipe 26 is provided with a cleaning agent supply valve 28 formed of an electromagnetic valve or the like, and the water supply pipe 27 is provided with a water supply valve 29 formed of an electromagnetic valve or the like. Each of the water supply valves 29 is electrically connected to the control device 18 and is individually controlled to open and close by a command from the control device 18. A liquid level gauge 30 is provided in the cleaning tank 25 and is electrically connected to the control device 18.

  A liquid feed pipe 33 is connected to the cleaning tank 25. The liquid feed pipe 33 is provided with a positive / negative pressure pump 34, a positive / negative pressure gauge 35, and a forward / reverse flow meter 36 in this order from the upstream side. The positive / negative pressure pump 34 is formed by a ceramic gear pump or the like, and performs a forward / reverse switching operation between a normal operation for sending out the liquid in the cleaning tank 25 and a reverse operation for drawing back the sent liquid to the cleaning tank 25 side. I can do it. The positive / negative pressure pump 34, the positive / negative pressure meter 35, and the forward / reverse flow meter 36 are electrically connected to the control device 18, and in response to a command from the control device 18, the positive / negative pressure pump 34 is activated / stopped and switched between forward and reverse. Is controlled, and data measured by the positive / negative pressure meter 35 and the forward / reverse flow meter 36 is input to the control device 18.

  The tip of the liquid feeding pipe 33 is connected to a cleaning switching valve 38 formed by an electromagnetic three-way valve or the like. A membrane cleaning header pipe 39 and a diffuser cleaning header pipe 40 are connected to the cleaning switching valve 38, and the liquid feed pipe 33 is connected to the membrane cleaning header pipe 39 and the diffuser cleaning header pipe 40. The communication can be individually opened and closed by the cleaning switching valve 38. The cleaning switching valve 38 is electrically connected to the control device 18 and is controlled to be opened and closed by a command from the control device 18.

  A number of membrane cleaning pipes 42a, 42b, 42c corresponding to the number of membrane modules 2 are branched from the membrane cleaning header pipe 39. The membrane cleaning pipes 42a, 42b, 42c are respectively connected to the membrane cleaning pipes 42a, 42b, 42c. It is connected to the switching valves 17a, 17b, 17c for use. Further, the number of diffuser cleaning pipes 43a, 43b, 43c corresponding to the number of the diffuser parts 3 branches off in the diffuser cleaning header pipe 40, and the diffuser cleaning pipes 43a, 43b, 43c are branched. Are respectively connected to the switching valves 22a, 22b, 22c.

  Next, the operation of the filtration device formed as described above will be described. 1, 2, and 4, among the piping systems, the liquid piping system is indicated by a solid line, the gas piping system is indicated by a broken line, and the piping system through which the liquid or gas passes is indicated by a thick line. The piping systems through which no liquid or gas passes are indicated by thin lines. The control system is indicated by a two-dot chain line. Further, regarding the valve, the closed state is displayed in black and the opened state is displayed in white.

  First, the normal filtration operation will be described with reference to FIG. At this time, each of these valves is controlled by the control device 18 so that the cleaning agent supply valve 28 and the water supply valve 29 are closed and the communication from the liquid supply pipe 33 to the cleaning switching valve 38 is closed. Therefore, the cleaning agent is not supplied to the hollow fiber membrane 1 or the air diffuser 3. Further, the membrane switching valves 17a, 17b, and 17c are controlled by the control device 18 so as to open the communication from the liquid collecting pipes 16a, 16b, and 16c to the liquid collecting header pipe 15, and the air supply header pipe 20 and each air supply The air diffusion switching valves 22a, 22b, and 22c are controlled by the control device 18 so as to open the communication with the pipes 21a, 21b, and 21c. At this time, the communication between each membrane cleaning pipe 42a, 42b, 42c and each liquid collection pipe 16a, 16b, 16c is closed, and each diffuser cleaning pipe 43, 43b, 43c and each air supply pipe 21a, 21b, 21c. The membrane switching valves 17a, 17b, and 17c and the air diffusion switching valves 22a, 22b, and 22c are controlled so as to close the communication with each other.

  When the liquid collection pump 14 is operated in this state, the inside of the liquid collection part 11 of each membrane module 2a, 2b, 2c is sucked through the liquid collection header pipe 15 and each liquid collection pipe 16a, 16b, 16c. The liquid passes through the hollow fiber membrane 1 of each membrane module 2a, 2b, 2c from the outside to the inside of the hollow and is filtered. Further, by applying an external pressure such as a water pressure from the outside, the liquid to be treated can be filtered through the hollow fiber membrane 1 from the outside to the inside of the hollow. Thus, the liquid to be treated that has been separated into solid and liquid and filtered when passing through the hollow fiber membrane 1 from the outside to the inside of the hollow flows into the liquid collecting part 11 from the hollow fiber membrane 1. And the to-be-processed liquid which flowed in into the liquid collection part 11 comes out to each collection piping 16a, 16b, 16c from the filtrate outlet 12, and as shown by the arrow in FIG. 1, each membrane switching valve 17a, 17b, 17c is set. After passing, it flows to the liquid collection pump 14 through the liquid collection header pipe 15 and is discharged.

  At the same time, the blower 19 is operated and a gas such as air is supplied to the air supply header pipe 20. This gas passes through each aeration switching valve 22a, 22b, 22c as shown by an arrow in FIG. 1, and is then supplied to each aeration unit 3a, 3b, 3c through each aeration pipe 21a, 21b, 21c. The gas is blown out by ejecting gas from the nozzle holes of the air diffusers 3a, 3b, 3c into the liquid to be treated. Thus, when gas is diffused from each diffuser 3a, 3b, 3c, the diffused gas rises in the liquid to be treated by buoyancy, and is applied to the hollow fiber membrane 1 of each membrane module 2a, 2b, 2c. Works. Further, when the aeration gas rises in the liquid to be treated, an upward flow is generated in the liquid to be processed, and the upward flow of the liquid to be processed acts on the hollow fiber membranes 1 of the membrane modules 2a, 2b, and 2c. The hollow fiber membrane 1 is vibrated by the action of the aeration and the flow of the liquid to be treated, so that the solid matter is prevented from being deposited on the surface of the hollow fiber membrane 1, and the hollow fiber membrane 1 The hollow fiber membrane 1 can be washed by peeling off the solid matter adhering to the surface.

  Next, the cleaning of the hollow fiber membrane 1 using the cleaning liquid will be described with reference to FIG. FIG. 2 shows a method of cleaning the hollow fiber membrane 1 of the membrane module 2a among the membrane modules 2a, 2b, 2c. Among the membrane switching valves 17a, 17b, 17c, the membrane switching valves 17b, 17c are shown. Is controlled so as to maintain a state where communication between the liquid collection pipes 16b, 16c and the liquid collection header pipe 15 is opened and a state where communication between the membrane cleaning pipes 42b, 42c and the liquid collection pipes 16b, 16c is closed. Has been. The membrane switching valve 17a is controlled to switch between opening and closing so as to close the communication between the liquid collection pipe 16a and the liquid collection header pipe 15 and open the communication between the film cleaning pipe 42a and the liquid collection pipe 16a.

  Of the switching valves 22a, 22b and 22c for aeration, the switching valves 22b and 22c for aeration are in a state where the communication between the air supply pipes 21b and 21c and the air supply header pipe 20 is open, and The piping 43b, 43c and the air supply piping 21b, 21c are controlled so as to maintain a closed state. The air diffusion switching valve 22a performs control for switching between opening and closing so as to close communication between the air diffusion pipe 21a and the air diffusion header pipe 20 and open communication between the air diffusion cleaning pipe 43a and the air supply pipe 21a. It is.

  Further, the cleaning liquid supply valve 28 and the water supply valve 29 are controlled by the control device 18 so that the cleaning liquid and water are supplied from the cleaning liquid supply pipe 26 and the water supply pipe 27 to the cleaning tank 25. When adjusting the concentration of the cleaning liquid with water, both the cleaning liquid supply valve 28 and the water supply valve 29 are opened to supply both the cleaning liquid and water to the cleaning tank 25, but it is not necessary to adjust the concentration of the cleaning liquid. In some cases, only the cleaning liquid supply valve 28 may be opened to supply only the cleaning liquid. The concentration of the cleaning liquid can be adjusted by detecting the supply amount of the cleaning liquid and water with the liquid level gauge 30 and controlling the opening and closing of the cleaning liquid supply valve 28 and the water supply valve 29. The water supplied from the water supply pipe 27 may be water such as tap water. However, when the wastewater is filtered as the liquid to be treated as described above, the water after the filtration is used. It can also be used. When water filtered in this way is used, additional new water becomes unnecessary.

  The control device 18 controls the cleaning switching valve 38 to close the communication between the liquid feeding pipe 33 and the diffuser cleaning header pipe 40 and open the communication between the liquid feeding pipe 33 and the membrane cleaning header pipe 39. Thus, the opening and closing of the cleaning liquid switching valve 38 is switched.

  In this state, the control device 18 controls the positive / negative pressure pump 34 to operate. The operation of the positive / negative pressure pump 34 is first performed in a positive operation in which the cleaning liquid in the cleaning tank 25 is sent out. When the cleaning liquid in the cleaning tank 25 is sent out through the liquid supply pipe 33 in this way, the cleaning liquid is supplied from the liquid supply pipe 33 to the membrane cleaning header pipe 39 through the cleaning switching valve 38 as indicated by the arrow in FIG. Since the communication between the membrane cleaning pipes 42b and 42c and the liquid collection pipes 16b and 16c is closed as described above, the cleaning liquid supplied to the membrane cleaning header pipe 39 is used for the membrane as indicated by the arrow in FIG. After passing through the switching valve 17a, the membrane cleaning pipe 42a is supplied to the liquid collection pipe 16a, and the cleaning liquid is sent through the liquid collection pipe 16a in the direction opposite to the flow of the liquid to be cleaned during the filtration operation. It flows into the liquid part 11. The cleaning liquid that has flowed into the liquid collecting section 11 of the membrane module 2a is supplied into the hollow interior of each hollow fiber membrane 1 of the membrane module 2a from the opening at the end, and the hollow fiber is opposite to the flow of the liquid to be cleaned during the filtration operation. It is injected into the membrane 1 and further passes out from the inside of the hollow fiber membrane 1 to be discharged.

  This injection of the cleaning liquid is performed by the positive / negative pressure pump 34 so that the cleaning liquid having a volume 1.5 to 3 times the internal volume of the entire hollow fiber membrane 1 of the membrane module 2a is supplied to the hollow fiber membrane 1 of the membrane module 2a. The operation is controlled. FIG. 3 shows a graph of the relationship between the amount of cleaning liquid supplied by the positive / negative pressure pump 34 and time. In the graph of FIG. 3, this injection step of the cleaning liquid is shown in the range of A. Thus, the hollow fiber membrane 1 can be back-washed by injecting and pushing the cleaning liquid into the hollow fiber membrane 1 of the membrane module 2a.

  Next, the operation of the positive / negative pressure pump 34 is stopped, and the positive and negative pressure pumps 34 are allowed to stand in a state where the cleaning liquid is injected into the hollow fiber membrane 1 of the membrane module 2a. By allowing the hollow fiber membrane 1 to stand while being injected with the cleaning liquid in this way, the cleaning liquid penetrates into the solid content adhering to the hollow interior of the hollow fiber membrane 1 and the micropores, and the solid content is easily swollen and peeled easily. It is a state. The standing time is not particularly limited, but is preferably about 30 to 120 minutes. The step of allowing the hollow fiber membrane 1 to stand while injecting the cleaning liquid is shown in the range of B in the graph of FIG.

  After this, the positive / negative pressure pump 34 is operated again. At this time, the positive / negative pressure pump 34 is switched between forward and reverse, and control is performed so as to repeat the forward operation for sending the cleaning liquid in the cleaning tank 25 to the membrane module 2a and the reverse operation for returning the sent cleaning liquid to the cleaning tank 25 side. Control is performed by the device 18. The amount of cleaning liquid fed and the amount of withdrawal is such that the amount of feeding is greater than the amount of withdrawal, and the number of repetitions of feeding and withdrawal of this cleaning liquid is not particularly limited, About 30 times is preferable. As for the amount and pressure of the cleaning liquid being fed and withdrawn, the flow rate and pressure of the cleaning liquid in the liquid feeding pipe 33 are measured by the forward / reverse flow meter 36 and the positive / negative pressure meter 35, and the operation of the positive / negative pressure pump 34 is controlled based on this measurement result. It can be arbitrarily adjusted by controlling with the device 18.

  By supplying the cleaning liquid to the membrane module 2a while repeating the feeding and pulling in this way, a reciprocating flow of the cleaning liquid is generated in each hollow fiber membrane 1 of the membrane module 2a. The solid matter adhering to the micropores can be efficiently peeled off, and the apparent amount of the cleaning liquid that passes through the hollow fiber membrane 1 is increased, so that the solid matter peeling effect can be obtained higher. Is. In particular, the pressure when the cleaning liquid is fed into the hollow fiber membrane 1 causes the hollow fiber membrane 1 to swell instantaneously so as to increase in diameter. At this time, the diameter of the micropores of the hollow fiber membrane 1 increases, The solid matter clogged with the pores is peeled off with the cleaning liquid and pushed to the outside. By repeating the feeding and pulling of the cleaning liquid, the diameter of the micropores of the hollow fiber membrane 1 is increased to solidify the fine pores. The effect of removing the fine particles is repeatedly performed, and the effect of removing the solid matter having fine pores can be highly obtained. Therefore, it is possible to obtain a higher cleaning effect with the cleaning liquid than when the cleaning liquid is allowed to flow through the hollow fiber membrane 1 only in one direction. The process of supplying the cleaning liquid by repeatedly sending and returning to the membrane module 2a is shown in the range of C in the graph of FIG.

  After the hollow fiber membrane 1 is cleaned by supplying the cleaning liquid by repeatedly feeding and retracting it to the membrane module 2a as described above, the positive / negative pressure pump 34 is operated in the positive operation for sending out the cleaning liquid in the cleaning tank 25. Switch. In this manner, the cleaning liquid is continuously sent out to supply the cleaning liquid to the hollow fiber membrane 1 of the membrane module 2a and reinject to repel the solid content peeled off from the hollow fiber membrane 1 or the solid matter that has not been peeled off. Is completely peeled off to finish the cleaning of the hollow fiber membrane 1 with the cleaning liquid. This finishing cleaning process is shown in the range of D in the graph of FIG. It is preferable to adjust the supply amount of the cleaning liquid to the membrane module 2a so as to have the same volume as the internal volume of the entire hollow fiber membrane 1 of the membrane module 2a in both the process C and the process D.

  Thereafter, the cleaning liquid supply valve 28 is closed and the water supply valve 29 is opened to supply water from the water supply pipe 27 to the cleaning tank 25 so that the inside of the cleaning tank 25 is made only water. Therefore, if the operation of the positive / negative pressure pump 34 is maintained in the positive operation, the water in the cleaning tank 25 can be continuously sent out and supplied to the hollow fiber membrane 1 of the membrane module 2a. The hollow fiber membrane 1 can be rinsed by being injected into and extruded. By rinsing the hollow fiber membrane 1 with water in this way, the hollow fiber membrane 1 can be finished and washed, and the washing liquid can be pushed away from the hollow fiber membrane 1 with water and discharged. When the liquid to be treated is filtered with the thread membrane 1, it is possible to prevent the cleaning liquid from being mixed into the filtrate. The process of rinsing with water is shown in the range of E in the graph of FIG. The amount of water supplied to the membrane module 2a is preferably adjusted so as to be about three times the internal volume of the entire hollow fiber membrane 1 of the membrane module 2a.

  As described above, the cleaning of the hollow fiber membrane 1 of the membrane module 2a with the cleaning agent can be completed. During this cleaning, the filtration of the liquid to be processed by the membrane modules 2b and 2c, the air diffuser 2b, The aeration by 2c is continuously performed, and the filtration operation of the filtration device is continued. Therefore, it is not necessary to stop the entire filtration operation of the filtration device even while the hollow fiber membrane 1 of the membrane module 2a is being washed with the cleaning agent, thereby preventing the productivity of treating the liquid to be treated from being lowered. It is something that can be done.

  After the cleaning of the hollow fiber membrane 1 of the membrane module 2a with the cleaning agent as described above, the control device 18 switches the membrane switching valves 17a, 17b, 17c and the air switching valves 22a, 22b, 22c. By controlling the above, the hollow fiber membrane 1 of the membrane module 2b is washed with a cleaning agent.

  That is, among the membrane switching valves 17a, 17b, and 17c, the membrane switching valves 17a and 17c open the communication between the liquid collection pipes 16a and 16c and the liquid collection header pipe 15 and collect the film cleaning pipes 42a and 42c. The membrane switching valve 17b is controlled to close the communication with the liquid pipes 16a and 16c, and the membrane switching valve 17b closes the communication between the liquid collection pipe 16b and the liquid collection header pipe 15 and connects the membrane cleaning pipe 42b and the liquid collection pipe 16b. Control is performed to switch between opening and closing so as to open the communication. Of the switching valves 22a, 22b, and 22c for aeration, the switching valves 22a and 22c for aeration open the communication between the air supply pipes 21a and 21c and the air supply header pipe 20 and are also used for the air cleaning pipes 43a and 43c. The air diffuser switching valve 22b closes the communication between the air diffuser pipe 21b and the air diffuser header pipe 20 and supplies air to the air diffuser cleaning pipe 43b. Control for switching between opening and closing is performed so as to open communication with the pipe 21b.

  Therefore, in the same manner as described above, the hollow fiber membrane 1 of the membrane module 2b can be washed with a cleaning agent, and at the same time, the liquid to be treated can be filtered by the membrane modules 2a and 2c and the air can be diffused by the air diffusers 2a and 2c. It is possible to wash the hollow fiber membrane 1 of the next membrane module 2b while continuing the filtration operation. And after finishing washing | cleaning of the hollow fiber membrane 1 of the membrane module 2b with a washing | cleaning agent, by controlling the switching valve 17a, 17b, 17c for membranes and switching valve 22a, 22b, 22c for aeration with the control apparatus 18, The hollow fiber membrane 1 of the membrane module 2c is washed with a cleaning agent, and each membrane module 2 can be washed sequentially while continuing the filtration operation.

  Next, the cleaning of the air diffuser 3 using the cleaning liquid will be described with reference to FIG. FIG. 4 shows a method of cleaning the air diffuser 3a among the air diffusers 3a, 3b, 3c. Of the membrane switch valves 17a, 17b, 17c, the membrane switch valves 17b, 17c Control is performed so that the communication between the liquid pipes 16b and 16c and the liquid collection header pipe 15 is opened, and the communication between the membrane cleaning pipes 42b and 42c and the liquid collection pipes 16b and 16c is closed. The membrane switching valve 17a is controlled so as to close the communication between the liquid collection pipe 16a and the liquid collection header pipe 15 and open the communication between the film cleaning pipe 42a and the liquid collection pipe 16a.

  Of the switching valves 22a, 22b and 22c for aeration, the switching valves 22b and 22c for aeration are in a state where the communication between the air supply pipes 21b and 21c and the air supply header pipe 20 is open, and The communication between the pipes 43b and 43c and the air supply pipes 21b and 21c is controlled to be closed. The air diffusion switching valve 22a performs control for switching between opening and closing so as to close communication between the air diffusion pipe 21a and the air diffusion header pipe 20 and open communication between the air diffusion cleaning pipe 43a and the air supply pipe 21a. It is.

  Further, the cleaning liquid supply valve 28 and the water supply valve 29 are controlled by the control device 18 so that the cleaning liquid and water are supplied from the cleaning liquid supply pipe 26 and the water supply pipe 27 to the cleaning tank 25. When adjusting the concentration of the cleaning liquid with water, both the cleaning liquid supply valve 28 and the water supply valve 29 are opened to supply both the cleaning liquid and water to the cleaning tank 25, but it is not necessary to adjust the concentration of the cleaning liquid. In some cases, only the cleaning liquid supply valve 28 may be opened to supply only the cleaning liquid. The concentration of the cleaning liquid can be adjusted by detecting the supply amount of the cleaning liquid and water with the liquid level gauge 30 and controlling the opening and closing of the cleaning liquid supply valve 28 and the water supply valve 29. In addition, the water supplied from the water supply pipe 27 may be water such as tap water, but when the wastewater is filtered as described above, the filtered water is used. You can also. When water filtered in this way is used, additional new water becomes unnecessary.

  Further, the controller 18 controls the cleaning liquid switching valve 38 to close the communication between the liquid feeding pipe 33 and the membrane cleaning header pipe 39 and to open the communication between the liquid feeding pipe 33 and the diffuser cleaning header pipe 40. The opening and closing of the cleaning liquid switching valve 38 is switched.

  In this state, the control device 18 controls the positive / negative pressure pump 34 to operate. The operation of the positive / negative pressure pump 34 is first performed in a positive operation in which the cleaning liquid in the cleaning tank 25 is sent out. When the cleaning liquid in the cleaning tank 25 is sent out through the liquid supply pipe 33 in this way, the cleaning agent is supplied from the liquid supply pipe 33 to the diffuser cleaning header pipe 40 through the cleaning switching valve 38 as indicated by the arrow in FIG. The Since the communication between the diffuser cleaning pipes 43b and 43c and the air supply pipes 21b and 21c is closed as described above, the cleaning liquid supplied to the diffuser cleaning header pipe 40 is as shown by the arrows in FIG. The gas is supplied from the diffuser cleaning pipe 43a to the air supply pipe 21a after passing through the diffuser switching valve 22a. The cleaning liquid supplied to the air supply pipe 21a is injected into the air diffuser 3a and further discharged to the outside through the nozzle holes of the air diffuser 3a.

  This injection of the cleaning liquid is performed by controlling the operation of the positive / negative pressure pump 34 so that the cleaning liquid having a volume 1.5 to 3 times the internal volume of the aeration unit 3a is supplied to the aeration unit 3a. . FIG. 5 shows a graph of the relationship between the amount of cleaning liquid supplied by the positive / negative pressure pump 34 and time. In the graph of FIG. 5, this injection process of the cleaning liquid is shown in a range A. Thus, the diffuser 3a can be cleaned by injecting and pushing the cleaning liquid into the diffuser 3a.

  Next, the operation of the positive / negative pressure pump 34 is stopped, and the positive and negative pressure pumps 34 are left in a state where the cleaning liquid is injected into the diffuser 3a. In this manner, the cleaning liquid is allowed to stand with the cleaning liquid injected into the diffuser 3a, so that the cleaning liquid penetrates into the solid content adhering to the inside of the air diffuser 3a and the nozzle hole, and the solid content is swollen to be easily peeled off. It can be made. The standing time is not particularly limited, but is preferably about 10 to 90 minutes. The process of leaving still with the cleaning liquid injected into the diffuser 3a is shown in the range of B in the graph of FIG.

  After this, the positive / negative pressure pump 34 is operated again. At this time, the forward / reverse switching operation of the positive / negative pressure pump 34 is performed, and the forward operation for sending the cleaning liquid in the cleaning tank 25 to the aeration unit 3a and the reverse operation for returning the sent cleaning liquid to the cleaning tank 25 side are repeated. Control is performed by the control device 18. The amount of cleaning liquid fed and the amount of withdrawal are such that the amount of feeding is greater than the amount of withdrawal, and the number of repetitions of feeding and withdrawal of this cleaning liquid is not particularly limited, but 20 to 20 About 40 times is preferable. As for the amount and pressure of the cleaning liquid being fed and withdrawn, the flow rate and pressure of the cleaning liquid in the liquid feeding pipe 33 are measured by the forward / reverse flow meter 36 and the positive / negative pressure meter 35, and the operation of the positive / negative pressure pump 34 is controlled based on this measurement result. It can be arbitrarily adjusted by controlling with the device 18.

  In this way, by supplying the cleaning liquid to the air diffuser 3a while repeating the feeding and pulling back, a reciprocating flow of the cleaning liquid is generated in the air diffuser 3a, and this reciprocating flow adheres to the inside of the air diffuser 3 and the nozzle hole. The solid matter can be efficiently peeled off, and the apparent amount of the cleaning liquid that passes through the air diffuser 3 is increased, so that the solid matter peeling effect can be further enhanced. Therefore, it is possible to obtain a higher cleaning effect with the cleaning liquid than when the cleaning liquid is allowed to flow and pass through the diffuser 3a only in one direction. The process of supplying the cleaning liquid by repeatedly sending and returning to the air diffuser 3a is shown in the range of C in the graph of FIG.

  After the air diffuser 3a is cleaned by supplying the cleaning liquid by repeatedly feeding and pulling back to the air diffuser 3a as described above, the positive / negative pressure pump 34 is operated in the positive operation for sending the cleaning liquid in the cleaning tank 25. Switch to. In this way, the cleaning liquid is continuously sent out to supply the cleaning liquid to the diffuser 3a, and then reinjected, so that the solids peeled off from the diffuser 3a can be washed away or the solids not peeled off can be completely peeled off. The cleaning of the diffuser 3a with the cleaning liquid is finished. This finishing cleaning process is shown in the range of D in the graph of FIG. It is preferable to adjust the supply amount of the cleaning liquid to the air diffuser 3a so as to have the same capacity as the internal volume of the air diffuser 3a in both the process C and the process D.

  Thereafter, the cleaning liquid supply valve 28 is closed and the water supply valve 29 is opened to supply water from the water supply pipe 27 to the cleaning tank 25 so that the inside of the cleaning tank 25 is made only water. Therefore, if the operation of the positive / negative pressure pump 34 is maintained in the positive operation, the water in the cleaning tank 25 can be continuously sent out and supplied to the diffuser 3a, and the water is injected into the diffuser 3a. The air diffuser 3a can be rinsed by being pushed out from the nozzle hole. Thus, by rinsing the diffuser 3a with water, the diffuser 3a can be finished and cleaned. The process of rinsing with water is shown in the range of E in the graph of FIG. The amount of water supplied to the air diffuser 3a is preferably adjusted so as to have a capacity about three times the internal volume of the air diffuser 3a.

  As described above, the cleaning of the air diffuser 3a with the cleaning agent can be completed. During this cleaning, the liquid to be treated is filtered by the membrane modules 2b and 2c and the air diffused by the air diffusers 3b and 3c. The filtration operation of the filtration device is continued. Therefore, it is not necessary to stop the entire filtration operation of the filtration device even while the diffuser 3a is washed with the cleaning agent, and it is possible to prevent the productivity of treating the liquid to be treated from being lowered. is there.

  After the cleaning of the air diffuser 3a with the cleaning agent as described above, the control device 18 controls the switching of the membrane switching valves 17a, 17b, 17c and the air switching valves 22a, 22b, 22c. Thus, the diffuser 3b is cleaned with a cleaning agent.

  That is, among the membrane switching valves 17a, 17b, and 17c, the membrane switching valves 17a and 17c open the communication between the liquid collection pipes 16a and 16c and the liquid collection header pipe 15 and collect the film cleaning pipes 42a and 42c. The membrane switching valve 17b is controlled to close the communication with the liquid pipes 16a and 16c, and the membrane switching valve 17b closes the communication between the liquid collection pipe 16b and the liquid collection header pipe 15 and connects the membrane cleaning pipe 42b and the liquid collection pipe 16b. Controlled to open communication. Of the switching valves 22a, 22b, and 22c for aeration, the switching valves 22a and 22c for aeration open the communication between the air supply pipes 21a and 21c and the air supply header pipe 20 and are also used for the air cleaning pipes 43a and 43c. The air diffuser switching valve 22b closes the communication between the air diffuser pipe 21b and the air diffuser header pipe 20 and supplies air to the air diffuser cleaning pipe 43b. Control for switching between opening and closing is performed so as to open communication with the pipe 21b.

  Therefore, in the same manner as described above, the diffuser 3b can be cleaned with a cleaning agent, and at the same time, the liquid to be treated can be filtered by the membrane modules 2a and 2c and the diffused by the diffusers 2a and 2c. While continuing the filtration operation, the next air diffuser 3b can be cleaned. Then, after the cleaning of the air diffuser 3b with the cleaning agent is finished, the controller 18 controls the switching of the membrane switching valves 17a, 17b, 17c and the air switching valves 22a, 22b, 22c to thereby diffuse the air diffuser 3c. The air diffuser 3 can be sequentially washed while continuing the filtration operation.

  In the above embodiment, an example is shown in which three membrane modules 2a, 2b, and 2c are used as the membrane module 2. However, the number of membrane modules 2 is not limited to this and is one. May be. In addition, two or three or more n membrane modules 2a, 2b,... 2n can be used as the membrane module 2. When n membrane modules 2a, 2b,... 2n are used in this way, n membrane switching valves 17a, 17b,... 17n and air switching valves 22a, 22b,. It is used.

An example of embodiment of this invention is shown and it is the schematic which shows a normal filtration driving | operation. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example of an embodiment of the present invention and is a schematic diagram illustrating a filtration operation during washing of a hollow fiber membrane. It is a graph which shows the relationship between the supply amount of washing | cleaning liquid at the time of washing | cleaning a hollow fiber membrane same as the above, and time. It shows an example of embodiment of this invention and is the schematic which shows the filtration driving | operation at the time of washing | cleaning of an aeration part. It is a graph which shows the relationship between supply_amount | feed_rate of the washing | cleaning liquid at the time of wash | cleaning an air diffusion part same as the above, and time.

Explanation of symbols

1 Hollow fiber membrane 2 Membrane module 3 Air diffuser

Claims (5)

  A membrane module formed with a hollow fiber membrane, and an air diffuser disposed below the membrane module. The membrane module is immersed in a liquid to be treated so that the liquid to be treated is exposed from the outside of the hollow fiber membrane. In a filtration apparatus that performs filtration by passing through a hollow interior and diffuses with a gas ejected from the air diffuser into the liquid to be treated to wash the hollow fiber membrane of the membrane module. A cleaning method for a filtration device, wherein the hollow fiber membrane is washed with a cleaning agent by supplying a cleaning liquid into the hollow fiber membrane of the membrane module in a direction opposite to the flow of the material while repeatedly feeding and retracting.   The rinsing of the hollow fiber membrane is performed by supplying water into the hollow fiber membrane of the membrane module in a direction opposite to the flow of the liquid to be treated after washing the hollow fiber membrane with the cleaning liquid. 2. A method for cleaning the filtration device according to 1.   In the filtration apparatus having a plurality of membrane modules, the hollow fiber membranes of some of the membrane modules other than the plurality of membrane modules that have been filtered off while being filtered are washed with a cleaning agent. The method for cleaning a filtration device according to claim 1 or 2, wherein the cleaning is performed.   A membrane module formed with a hollow fiber membrane, and an air diffuser disposed below the membrane module. The membrane module is immersed in a liquid to be treated so that the liquid to be treated is exposed from the outside of the hollow fiber membrane. In a filtration device that performs filtration by passing it into the hollow interior and also diffuses the gas from the air diffuser into the liquid to be treated to clean the hollow fiber membrane of the membrane module. A cleaning method for a filtration device, wherein the air diffuser is cleaned with a cleaning agent by supplying the cleaning liquid repeatedly while feeding and pulling back.   In the filtration device having a plurality of membrane modules and aeration units, among the plurality of membrane modules, the filtration operation was stopped while performing the operation of filtering with some of the membrane modules and aeration with the aeration unit. The method for cleaning a filtration device according to claim 4, wherein the air diffuser disposed corresponding to some of the membrane modules is cleaned with a cleaning agent.

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