JP2019188276A - Washing method of filtration module, and filtration equipment - Google Patents

Abstract

To provide a washing method of a filtration module capable of suppressing sufficiently decline of filtration efficiency, while suppressing increase of operation cost.SOLUTION: A washing method of a filtration module, which is a washing method of an immersion-type or external pressure-type filtration module including a plurality of hollow fiber membranes paralleled in a vertical direction, includes steps of: stopping filtration of treatment liquid; discharging the treatment liquid after the stopping step; and washing reversely the plurality of hollow fiber membranes with a medicinal solution after the discharging step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for cleaning a filtration module and a filtration apparatus.

  2. Description of the Related Art A filtration device including one or a plurality of filtration modules is used as a solid-liquid separation treatment device in a sewage treatment or pharmaceutical manufacturing process. The filtration module has a plurality of hollow fiber membranes aligned in the vertical direction, and is used by being immersed in a liquid to be treated. The filtration device performs filtration by preventing permeation of impurities contained in the liquid to be treated by the surface of the hollow fiber membrane and allowing other impurities to permeate into the hollow fiber membrane.

  However, since this filtration apparatus prevents permeation of impurities contained in the liquid to be treated by the surface of the hollow fiber membrane, impurities that have not permeated inside adhere to the surface of the hollow fiber membrane. For this reason, in this filtration device, there is a possibility that the filtration efficiency of the liquid to be originally filtered is reduced by the impurities attached to the surface of the hollow fiber membrane.

  Therefore, in this filtration apparatus, membrane fouling is prevented by intermittently performing a filtration treatment operation and washing a plurality of hollow fiber membranes during the filtration treatment operation. Specifically, a chemical solution is periodically fed back into the hollow fiber membrane as backwash water, and a plurality of hollow fiber membranes are backwashed (see JP 2002-253935 A).

JP 2002-253935 A

  According to this conventional cleaning method, filtration efficiency can be increased by removing impurities that block the pores of the plurality of hollow fiber membranes. However, even when reverse cleaning is regularly performed by this conventional cleaning method, the cleaning effect becomes insufficient as the operation processing time becomes longer, and the filtration efficiency gradually decreases. Therefore, according to this conventional cleaning method, after performing the reverse cleaning a predetermined number of times, for example, a plurality of hollow fiber membranes are immersed in a water tank in which a chemical solution is stored to clean these hollow fiber membranes. As a result, according to the conventional cleaning method, the amount of the chemical solution necessary for suppressing the decrease in filtration efficiency over time is increased, and the operation cost is increased.

  The present invention has been made based on such circumstances, and it is an object of the present invention to provide a filtration module cleaning method and a filtration device that can sufficiently suppress a decrease in filtration efficiency while suppressing an increase in operating cost. To do.

  A method for cleaning a filtration module according to an aspect of the present invention made to solve the above problems is a method for cleaning an immersion type or external pressure type filtration module including a plurality of hollow fiber membranes aligned in the vertical direction. A step of stopping filtration of the liquid to be processed, a step of discharging the liquid to be processed after the stopping step, and a step of back-washing the plurality of hollow fiber membranes with a chemical solution after the discharging step.

  Moreover, the filtration device according to one aspect of the present invention made to solve the above problems is a filtration device including a submerged or external pressure filtration module having a plurality of hollow fiber membranes aligned in the vertical direction. A filtration stopping mechanism for stopping filtration of the liquid to be treated; a discharge mechanism for discharging the liquid to be treated after the filtration is stopped by the filtration stopping mechanism; and the plurality of hollow fibers after the liquid to be treated is discharged by the discharge mechanism. A chemical solution cleaning mechanism for back-cleaning the membrane with the chemical solution.

  INDUSTRIAL APPLICABILITY The filtration method for a filtration module and the filtration device of the present invention can sufficiently suppress a decrease in filtration efficiency while suppressing an increase in operating cost.

It is a flowchart which shows the washing | cleaning method of the filtration module which concerns on one Embodiment of this invention. It is a mimetic diagram showing a filtration device concerning one embodiment of the present invention. It is a flowchart which shows the washing | cleaning method of the filtration module which concerns on embodiment different from the washing | cleaning method of the filtration module of FIG.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described.

  A cleaning method for a filtration module according to an aspect of the present invention is a method for cleaning an immersion type or external pressure type filtration module including a plurality of hollow fiber membranes arranged in the vertical direction, and stops filtration of a liquid to be treated. A step, a step of discharging the liquid to be treated after the stopping step, and a step of back-washing the plurality of hollow fiber membranes with a chemical solution after the discharging step.

  In the method for cleaning the filtration module, since the plurality of hollow fiber membranes are back-washed with the chemical solution after discharging the liquid to be treated, impurities attached to the surface of the plurality of hollow fiber membranes can be sufficiently removed. . Therefore, the washing | cleaning method of the said filtration module can fully suppress the fall of filtration efficiency. Moreover, since the cleaning method of the said filtration module does not require filling a chemical | medical solution in a container like the conventional cleaning method, it can suppress the increase in the operating cost resulting from use of a chemical | medical solution.

  The main component of the hollow fiber membrane is preferably polytetrafluoroethylene. Since polytetrafluoroethylene has high chemical resistance, deterioration can be sufficiently suppressed even if the liquid to be treated is drained and back-washed with a chemical.

  The said filtration module is an immersion type filtration module, and it is good to discharge | emit the to-be-processed liquid in the water tank in which the said several hollow fiber membrane is accommodated at the said discharge process. Thus, the filtration module is a submerged filtration module, and in the discharge step, the treatment liquid in the water tank in which the plurality of hollow fiber membranes are accommodated is discharged, thereby significantly increasing the amount of the chemical solution used. It can suppress, and the reduction effect of an operating cost can be raised significantly.

  Further, a filtration device according to another embodiment of the present invention is a filtration device including an immersion type or external pressure type filtration module having a plurality of hollow fiber membranes aligned in the vertical direction, and filters the liquid to be treated. A filtration stop mechanism that stops, a discharge mechanism that discharges the liquid to be treated after the filtration is stopped by the filtration stop mechanism, and a reverse cleaning of the plurality of hollow fiber membranes with a chemical solution after the liquid to be processed is discharged by the discharge mechanism And a chemical cleaning mechanism.

  The filtration device includes a discharge mechanism that discharges the liquid to be processed after the filtration is stopped by the filtration stop mechanism, and a chemical liquid cleaning mechanism that back-washes the plurality of hollow fiber membranes with the chemical liquid after the discharge of the liquid to be processed by the discharge mechanism. Thus, the impurities attached to the surfaces of the plurality of hollow fiber membranes can be sufficiently removed. Therefore, the said filtration apparatus can fully suppress the fall of filtration efficiency. Moreover, since the said filtration apparatus does not require filling a chemical | medical solution in a container like the conventional filtration apparatus, it can suppress the increase in the operating cost resulting from use of a chemical | medical solution.

  In the present invention, the “main component” means a component having the largest content ratio in terms of mass, for example, a component having a content of 50% by mass or more. The “external pressure type” is a system in which the liquid to be treated is transmitted to the inner peripheral surface side of the hollow fiber membrane by setting the outer peripheral surface side of the hollow fiber membrane to a high pressure. In addition, the “immersion type” refers to a method in which the inner peripheral surface side of the hollow fiber membrane is set to a negative pressure and the liquid to be treated is transmitted to the inner peripheral surface side, and is also referred to as “suction type”.

[Details of the embodiment of the present invention]
Hereinafter, a filtration method and a filtration device for a filtration module according to an embodiment of the present invention will be described in detail with reference to the drawings.

[First embodiment]
<Cleaning method for filtration module>
The cleaning method of the filtration module in FIG. 1 is a cleaning method of an immersion type filtration module including a plurality of hollow fiber membranes that are aligned in the vertical direction. The filtration method of the filtration module includes a step of stopping filtration of the liquid to be treated (stopping step), a step of discharging the liquid to be treated after the stopping step (discharge step), and the plurality of hollows after the discharging step. And a step of back-washing the yarn membrane with a chemical solution (chemical solution washing step).

  In the cleaning method for the filtration module, since the plurality of hollow fiber membranes are back-washed with a chemical solution after discharging the liquid to be treated in the discharging step, the plurality of hollow fiber membranes adhere to the surface (outer peripheral surface) of the plurality of hollow fiber membranes. Impurities can be sufficiently removed. That is, by supplying the chemical solution to the inner peripheral surface side of the plurality of hollow fiber membranes that are aligned in the vertical direction in a state where the liquid to be treated is discharged, the surface side from the pores of the plurality of hollow fiber membranes The chemical solution that permeates through the surface of the plurality of hollow fiber membranes descends. At this time, the surfaces of the plurality of hollow fiber membranes are washed with the descending chemical solution. Therefore, the method for cleaning the filtration module can clean the surface of the plurality of hollow fiber membranes with the chemical solution, and can greatly enhance the cleaning effect of the plurality of hollow fiber membranes. As a result, the filtration method for the filtration module can sufficiently suppress a decrease in filtration efficiency with time due to a longer operation processing time as in the conventional cleaning method. Moreover, since the cleaning method of the said filtration module does not require filling a chemical | medical solution in a container like the conventional cleaning method, it can suppress the increase in the operating cost resulting from use of the said chemical | medical solution.

<Filtration device>
First, with reference to FIG. 2, an example of the filtration apparatus which can implement the washing | cleaning method of the said filtration module is demonstrated. The filtration device includes an immersion filtration module 1 having a plurality of hollow fiber membranes 11 aligned in the vertical direction. The filtration device includes a plurality of filtration modules 1. The filtration device includes a filtration stop mechanism 2 that stops filtration of the liquid X to be processed, a discharge mechanism 3 that discharges the liquid X after the filtration is stopped by the filtration stop mechanism 2, and discharge of the liquid X to be processed by the discharge mechanism 3. A chemical solution cleaning mechanism 4 for back cleaning the plurality of hollow fiber membranes 11 with the chemical solution P is provided. In addition, the filtration device includes a water tank 6 that houses a plurality of filtration modules 1, a backwash water storage tank 7 that stores backwash water Q, and a treatment liquid supply mechanism that supplies a liquid X to be treated into the water tank 6. 5. The plurality of filtration modules 1 and the backwash water storage tank 7 are connected by a filtrate discharge pipe 14. In the present embodiment, filtered water that has passed through a plurality of hollow fiber membranes 11 is used as the backwash water Q. However, as the backwash water Q, permeated water that has permeated through a plurality of hollow fiber membranes 11 and then permeated through another filtration membrane such as a reverse osmosis membrane may be used. Moreover, as this backwash water Q, it is also possible to use water prepared separately from the filtered water which permeate | transmitted the several hollow fiber membrane 11, such as tap water.

  The filtration apparatus includes a discharge mechanism 3 that discharges the liquid to be processed X after the filtration by the filtration stop mechanism 2 is stopped, and a backwash of the plurality of hollow fiber membranes 11 with the chemical liquid P after the discharge of the liquid to be processed X by the discharge mechanism 3. Since the chemical solution cleaning mechanism 4 is provided, impurities attached to the surface of the plurality of hollow fiber membranes 11 can be sufficiently removed. Therefore, the said filtration apparatus can fully suppress the fall of filtration efficiency. Moreover, since the said filtration apparatus does not require filling the chemical | medical solution P in the water tank 6 like the conventional filtration apparatus, the increase in the operating cost resulting from use of the chemical | medical solution P can be suppressed.

(Filtration module)
The filtration module 1 includes a plurality of hollow fiber membranes 11 aligned in the vertical direction, an upper holding member 12 that holds the upper ends of the plurality of hollow fiber membranes 11, and a lower end portion of the plurality of hollow fiber membranes 11. And a lower holding member 13 for holding. The upper holding member 12 has a hollow shape and is connected to a filtered water discharge pipe 14 that discharges the backwash water Q that has passed through the plurality of hollow fiber membranes 11. The lower holding member 13 may have a hollow shape so that the backwash water Q that has permeated through the plurality of hollow fiber membranes 11 can be discharged, and the opening at the lower end of the plurality of hollow fiber membranes 11. May be configured to seal. When the lower holding member 13 is hollow, the opening of the lower holding member 13 is connected to the filtered water discharge pipe 14.

<Hollow fiber membrane>
The hollow fiber membrane 11 is preferably composed mainly of a thermoplastic resin. Examples of the main component of the hollow fiber membrane 11 include polyethylene, polypropylene, polyvinylidene fluoride, ethylene-vinyl alcohol copolymer, polyamide, polyimide, polyetherimide, polystyrene, polysulfone, polyvinyl alcohol, polyphenylene ether, polyphenylene sulfide, and cellulose acetate. , Polyacrylonitrile, polytetrafluoroethylene (PTFE) and the like. Among these, PTFE which is excellent in mechanical strength, chemical resistance, heat resistance, weather resistance, nonflammability and the like and is porous is preferable, and uniaxially or biaxially stretched PTFE is more preferable. As will be described later, the filtration device back-washes the surfaces of the plurality of hollow fiber membranes 11 with the chemical solution P in a state where the liquid X to be treated in the water tank 6 is discharged. Therefore, it is desired that the plurality of hollow fiber membranes 11 have high chemical resistance. In this respect, PTFE has high resistance to both acidic and alkaline chemicals P, and has sufficient resistance even when, for example, a strong acid such as 100% sulfuric acid is used as the chemical P. In addition, other polymers, additives, such as a lubricant, etc. may be suitably mix | blended with the forming material of the hollow fiber membrane 11. FIG.

(Processed liquid supply mechanism)
The to-be-processed liquid supply mechanism 5 supplies the to-be-processed liquid X in the water tank 6 when the said filtration apparatus filters the to-be-processed liquid X. FIG. Thereby, the several filtration module 1 is immersed in the to-be-processed liquid X at the time of a filtration process. The to-be-processed liquid supply mechanism 5 has the to-be-processed liquid supply pipe 5a connected to the water tank 6, and the valve 5b arrange | positioned at the to-be-processed liquid supply pipe 5a. Moreover, the to-be-processed liquid supply mechanism 5 may be provided with the to-be-processed liquid supply pipe 5a, and may have the to-be-processed liquid supply pump 5c which pumps the to-be-processed liquid X to the water tank 6 side.

(Filtration stop mechanism)
The filtration stop mechanism 2 includes a suction pump 2a and a valve 2b disposed in the filtered water discharge pipe 14, and a filtration operation control unit 2c that drives and controls the suction pump 2a and the valve 2b. The filtration stop mechanism 2 stops driving the suction pump 2a under the control of the filtration operation control unit 2c, and stops the filtration of the liquid X to be processed by closing the valve 2b.

  The filtration operation control unit 2c includes a computer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and other memories. The filtration operation control unit 2c constitutes a single control unit 8 together with a later-described discharge control unit 3c and a chemical cleaning control unit 4d.

  In addition, the said filtration apparatus is provided with the filtration process mechanism which filters the to-be-processed liquid X in the state which the some filtration module 1 immersed in the to-be-processed liquid X. FIG. The filtration processing mechanism has the same configuration as the filtration stop mechanism 2. In other words, in the filtration device, the filtration stop mechanism 2 also serves as the filtration processing mechanism. The filtration treatment mechanism opens the valve 2b under the control of the filtration operation control unit 2c in a state where the treatment liquid X is stored in the water tank 6 and a plurality of hollow fiber membranes 11 are immersed in the treatment liquid X. And the filtration process by the several filtration module 1 is performed by driving the suction pump 2a.

(Discharge mechanism)
The discharge mechanism 3 includes a liquid discharge pipe 3a to be processed connected to the water tank 6, a valve 3b disposed in the liquid discharge pipe 3a to be processed, and a discharge controller 3c that drives and controls the valve 3b. The discharge mechanism 3 discharges the liquid X stored in the water tank 6 by opening the valve 3b that is closed during the filtration process by the control of the discharge control unit 3c after the filtration stop by the filtration stop mechanism 2. To do. The discharge mechanism 3 may discharge the entire amount of the liquid to be treated X in the water tank 6, but the liquid surface of the liquid to be treated X is below the plurality of hollow fiber membranes 11, preferably the plurality of hollow fiber membranes. The valve 3b may be controlled to open and close so that the liquid X is left in the water tank 6 in a state of being located below the lower end of 11. Thus, by leaving the to-be-processed liquid X in the water tank 6, the chemical | medical solution concentration in the water tank 6 in the case of backwashing with the chemical | medical solution P is made low, and deterioration of the water tank 6 resulting from the chemical | medical solution P is suppressed. Can do.

(Chemical solution cleaning mechanism)
The chemical cleaning mechanism 4 includes a filtered water circulation pipe 4a that connects the backwash water storage tank 7 and the filtered water discharge pipe 14, a filtered water supply pump 4b and a chemical supply pipe 4c that are connected to the filtered water circulation pipe 4a, and filtered water. And a chemical liquid cleaning control unit 4d that performs drive control of the supply pump 4b and injection control of the drug Y through the drug supply pipe 4c. The filtered water circulation pipe 4a is connected to the filtered water discharge pipe 14 on the side of the plurality of filtration modules 1 from the arrangement positions of the suction pump 2a and the valve 2b. The chemical cleaning mechanism 4 drives the filtered water supply pump 4b under control of the chemical cleaning control unit 4d with the valve 2b closed to convert the backwash water Q in the backwash water storage tank 7 into a plurality of filtration modules. While being pumped to the 1 side, the drug Y is mixed in the backwash water Q that is pumped to the plurality of filtration modules 1 through the drug supply pipe 4 c. Thereby, the chemical | medical solution P with which the chemical | medical agent Y was mixed with the backwash water Q is supplied into the multiple hollow fiber membrane 11 from the upper end side via the upper side holding member 12. FIG.

  In addition, the chemical | medical solution P which permeate | transmitted from the inner peripheral surface side of the plurality of hollow fiber membranes 11 to the surface side falls along the surface of the plurality of hollow fiber membranes 11, and can be stored in the water tank 6. The chemical liquid P may be discharged from the water tank 6 by the discharge mechanism 3 after the chemical liquid cleaning by the chemical liquid cleaning mechanism 4. The chemical liquid P is stored in the water tank 6 by the liquid supply mechanism 5 to be processed in the water tank 6. The liquid X may be supplied and the filtration process may be resumed. Further, by opening the valve 3b at the time of chemical cleaning by the chemical cleaning mechanism 4, the chemical P may be appropriately discharged from the liquid discharge pipe 3a to be processed at the time of reverse cleaning by the chemical P.

  Examples of the drug Y introduced from the drug supply pipe 4c include sodium hypochlorite, inorganic acid, organic acid, sodium hydroxide, and surfactant. Examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, sodium hydrogen sulfite and the like. Examples of the organic acid include citric acid and oxalic acid.

  When the main component of the plurality of hollow fiber membranes 11 is the above-mentioned PTFE, the filtration device can increase the chemical solution concentration and enhance the cleaning effect on the surface of the plurality of hollow fiber membranes 11. From this viewpoint, when sodium hypochlorite is used as the drug Y, the lower limit of the concentration of sodium hypochlorite in the drug solution P is preferably 100 mg / L, more preferably 200 mg / L. On the other hand, the upper limit of the concentration of sodium hypochlorite in the chemical solution P is preferably 4000 mg / L, and more preferably 3500 mg / L. Moreover, when using an inorganic acid as the chemical | medical agent Y, as a minimum of the density | concentration of the inorganic acid in the chemical | medical solution P, 100 mg / L is preferable and 200 mg / L is more preferable. On the other hand, as an upper limit of the density | concentration of the inorganic acid in the chemical | medical solution P, it can be set to 40000 mg / L, for example.

  Next, each step of the filtration module cleaning method will be described in detail. In addition, before implementation of the cleaning method for the filtration module (that is, during the filtration treatment of the liquid to be treated X), the water tank 6 is filled with the liquid to be treated X, and the valves 3b and 5b are closed. . Further, the valve 2b is opened, and the suction pump 2a is driven.

(Stop process)
In the stop step (S01), the filtration of the liquid X to be processed is stopped. S01 is performed by the filtration stopping mechanism 2. In S01, the suction pump 2a is stopped by the control of the filtration operation control unit 2c, and the filtration of the liquid X to be processed is stopped by closing the valve 2b.

(Discharge process)
In the discharging step (S02), the liquid X to be treated in the water tank 6 in which the plurality of hollow fiber membranes 11 are accommodated is discharged. S02 is performed by the discharge mechanism 3. In S02, after the filtration is stopped in S01, the liquid X stored in the water tank 6 is discharged by opening the valve 3b under the control of the discharge controller 3c. In the method for cleaning the filtration module, by discharging the liquid X to be treated in the water tank 6 in S02, the usage amount of the chemical liquid P can be remarkably suppressed, and the reduction of the operation cost can be promoted. More specifically, in the conventional cleaning method, when the surface of the plurality of hollow fiber membranes 11 is cleaned with a relatively high concentration of the chemical solution P, the water tank 6 is filled with the chemical solution P, and a plurality of the liquid solutions P are contained in the chemical solution P. The hollow fiber membrane 11 was immersed. However, the space volume in the water tank 6 is much larger than the space volume on the inner peripheral side of the plurality of hollow fiber membranes 11, and the amount of the drug Y required for one chemical cleaning has been a factor in increasing the cleaning cost. . On the other hand, in the method for cleaning the filtration module, the surface of the hollow fiber membranes 11 is cleaned with the chemical solution P supplied to the inner peripheral surface side of the plurality of hollow fiber membranes 11. The amount of the drug Y used does not increase corresponding to the space volume even when the value of the drug Y increases. Therefore, the filtration method of the said filtration module can suppress the usage-amount of the chemical | medical agent Y required for one chemical | medical solution washing | cleaning, and can suppress an operating cost.

  In S02, the entire amount of the liquid to be treated X stored in the water tank 6 may be discharged, but the liquid surface of the liquid to be treated X is lower than the plurality of hollow fiber membranes 11, preferably a plurality of hollow fibers. You may leave the to-be-processed liquid X in the water tank 6 in the state located below the lower end of the film | membrane 11. FIG. That is, in S02, the valve 3b may be closed with the liquid X to be processed left in the water tank 6. The filtration method for the filtration module is to leave the liquid X to be treated in the water tank 6 in S02, thereby lowering the chemical concentration in the water tank 6 when the plurality of hollow fiber membranes 11 are cleaned with the chemical liquid in S03. The deterioration of the water tank 6 due to the chemical liquid P can be suppressed.

(Chemical cleaning process)
In the chemical solution cleaning step (S03), the plurality of hollow fiber membranes 11 are back cleaned with the chemical solution P in a state where the liquid X to be treated in the water tank 6 is discharged. S03 is performed by the chemical solution cleaning mechanism 4. In S03, with the valve 2b closed, the backwash water Q in the backwash water storage tank 7 is driven to the plurality of filtration modules 1 side by driving the filtered water supply pump 4b under the control of the chemical liquid cleaning control unit 4d. While being pumped, the drug Y is mixed into the backwash water Q that is pumped to the plurality of filtration modules 1 through the drug supply pipe 4c. Thereby, the chemical | medical solution P with which the chemical | medical agent Y was mixed with the backwash water Q is supplied into the multiple hollow fiber membrane 11 from the upper end side via the upper side holding member 12. FIG.

  In S03, the chemical solution P is supplied into the plurality of hollow fiber membranes 11 from the upper end side of the plurality of hollow fiber membranes 11, so that the chemical solution P is introduced from the holes formed above the plurality of hollow fiber membranes 11 to the surface. Easy to penetrate to the side. The chemical liquid P that has permeated from the holes formed above the plurality of hollow fiber membranes 11 to the surface side descends along the surface of the plurality of hollow fiber membranes 11. Therefore, the cleaning method for the filtration module can clean the entire surface of the plurality of hollow fiber membranes 11 with the chemical solution P that descends from above along the surface of the plurality of hollow fiber membranes 11. That is, according to the cleaning method of the filtration module, the surface of the plurality of hollow fiber membranes 11 can be cleaned with the chemical solution P supplied into the plurality of hollow fiber membranes 11 while maintaining the concentration at the time of supply. Moreover, when the main component of the plurality of hollow fiber membranes 11 is the above-mentioned PTFE, these hollow fiber membranes 11 are fibrous portions in which a particle lump (secondary particle) called a node is called a fibril. It has a fibrous skeleton connected by. According to the method for cleaning the filtration module, the chemical solution P descends while removing impurities through the fibrous skeleton, so that the fibrous skeleton can be easily and reliably washed, and as a result, the amount of the chemical solution is relatively small. The surface of the plurality of hollow fiber membranes 11 can be washed uniformly.

[Second Embodiment]
<Cleaning method for filtration module>
The method for cleaning the filtration module in FIG. 3 is a method for cleaning an immersion type filtration module including a plurality of hollow fiber membranes arranged in the vertical direction. The filtration method of the said filtration module can be performed using the filtration apparatus of FIG. 2, for example. The method for cleaning the filtration module includes a step of filtering the liquid X to be processed by a plurality of filtration modules 1 (filtering step), a step of stopping the filtration of the liquid X to be processed (stopping step), and the stopping step. And a step of back-washing the plurality of hollow fiber membranes 11 with the chemical solution P (first chemical solution cleaning step) without discharging the liquid X to be treated. Moreover, the washing | cleaning method of the said filtration module is the process (2nd process) which discharges | emits the to-be-processed liquid X after the said stop process, and the process (2nd back washing | cleaning of the hollow fiber membrane 11 with the chemical | medical solution P after the said discharge process Chemical solution cleaning step).

  The filtration method for the filtration module includes a first chemical solution washing step when the filtration process step (S11), the stopping step (S12), and the first chemical solution washing step (S13) are repeated one or more times to reduce the filtration efficiency. Instead of (S13), a discharging step (S14) and a second chemical solution cleaning step (S15) are performed. After the second chemical liquid cleaning step (S15), the water tank 6 is filled again with the liquid X to be treated, and then the filtration treatment step (S11) is performed.

  Since S13 is performed in a state where the liquid X to be processed in the water tank 6 is not discharged, the chemical liquid P that has permeated the surface side of the plurality of hollow fiber membranes 11 is diffused into the liquid X to be processed, and a plurality of hollow It hardly contributes to cleaning the surface of the yarn film 11. Therefore, if only S11 to S13 are repeated, the amount of impurities attached to the surface of the plurality of hollow fiber membranes 11 increases with time as the operation time becomes longer. Therefore, the said washing | cleaning method of the said filtration module repeats S11-S13, and when the filtration efficiency of the to-be-processed liquid X falls, it performs S14 and S15 and carries out the chemical | medical solution washing | cleaning of the surface of the several hollow fiber membrane 11. FIG.

  The timing of performing S14 and S15 may be, for example, when the membrane differential pressure of the plurality of hollow fiber membranes 11 is equal to or higher than a certain level, or may be after performing S11 to S13 a predetermined number of times.

  The filtration method for the filtration module can easily and surely suppress a decrease in filtration efficiency by washing the first chemical solution washing step (S13) and the second chemical solution washing step (S15) in combination.

(Filtering process)
S11 is performed by the above-described filtration processing mechanism having the same configuration as the filtration stopping mechanism 2. In S11, the processing liquid X is stored in the water tank 6, and the valve 2b is opened and the suction pump 2a is driven under the control of the filtration operation control unit 2c with the valves 3b and 5b closed. Filtration is performed at

  The stopping step (S12) and the discharging step (S14) can be performed in the same procedure as the stopping step (S01) and the discharging step (S02) of the cleaning method for the filtration module in FIG. Moreover, it can carry out in the procedure similar to the chemical | medical solution washing | cleaning process (03) of the washing | cleaning method of the filtration module of FIG. 1 as a 1st chemical | medical solution washing | cleaning process (S13) and a 2nd chemical | medical solution washing process (S15).

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims. The

  For example, in the above-described embodiment, the configuration using the immersion filtration module has been described. However, the filtration method for the filtration module can be used for washing the external pressure filtration module. Moreover, the said filtration apparatus can also be comprised as a filtration apparatus provided with an external pressure type filtration module.

  In the chemical solution washing step, it is not always necessary to use a chemical solution obtained by mixing a chemical with backwash water, and a plurality of filtration modules may be washed with a chemical solution using a chemical solution prepared separately from the backwash water.

  Although the said embodiment demonstrated the filtration apparatus provided with the several filtration module, the said filtration apparatus may be provided with only one filtration module.

  In the above embodiment, the configuration in which the chemical solution is supplied into the plurality of hollow fiber membranes from the upper end side of the plurality of hollow fiber membranes has been described. Therefore, it is possible to supply the chemical solution into a plurality of hollow fiber membranes.

  The method for cleaning the filtration module may further include a step of cleaning the surface of the plurality of hollow fiber membranes by supplying bubbles from below the one or more filtration modules (a bubbling cleaning step). Moreover, the said filtration apparatus may be provided under the 1 or several filtration module, and may be equipped with the 1 or several bubble supply unit which supplies a bubble from below to several hollow fiber membranes.

  As described above, the method for cleaning a filtration module of the present invention is suitable as a method for cleaning an immersion type filtration module because it can sufficiently suppress a decrease in filtration efficiency while suppressing an increase in operating cost.

DESCRIPTION OF SYMBOLS 1 Filtration module 2 Filtration stop mechanism 2a Suction pump 2b Valve 2c Filtration operation control part 3 Discharge mechanism 3a To-be-processed liquid discharge pipe 3b Valve 3c Discharge control part 4 Chemical solution washing mechanism 4a Filtrated water circulation pipe 4b Filtrated water supply pump 4c Chemical supply pipe 4d Chemical liquid cleaning control unit 5 Processed liquid supply mechanism 5a Processed liquid supply pipe 5b Valve 5c Processed liquid supply pump 6 Water tank 7 Backwash water storage tank 8 Control unit 11 Hollow fiber membrane 12 Upper holding member 13 Lower holding member 14 Filtration Water discharge pipe P Chemical liquid Q Backwash water X Processed liquid Y Chemical

Claims (4)

A method for cleaning an immersion type or external pressure type filtration module comprising a plurality of hollow fiber membranes aligned in the vertical direction,
A step of stopping filtration of the liquid to be treated;
Discharging the liquid to be treated after the stopping step;
And a step of backwashing the plurality of hollow fiber membranes with a chemical solution after the discharging step.   The method for washing a filtration module according to claim 1, wherein the main component of the hollow fiber membrane is polytetrafluoroethylene. The filtration module is an immersion filtration module,
The method for cleaning a filtration module according to claim 1 or 2, wherein, in the discharging step, the liquid to be treated in the water tank in which the plurality of hollow fiber membranes are accommodated is discharged. A filtration device comprising an immersion type or external pressure type filtration module having a plurality of hollow fiber membranes aligned in the vertical direction,
A filtration stop mechanism for stopping the filtration of the liquid to be treated;
A discharge mechanism for discharging the liquid to be treated after the filtration is stopped by the filtration stop mechanism;
A filtration device comprising: a chemical solution cleaning mechanism that reversely cleans the plurality of hollow fiber membranes with a chemical solution after the treatment liquid is discharged by the discharge mechanism.

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