JP2022124332A - Filtration method and filtration apparatus - Google Patents

Abstract

To provide a filtration method in which a hollow fiber membrane is less prone to blockage.SOLUTION: Provided is a filtration method for removing suspended solids from raw water using an immersed hollow fiber membrane module 40 having a plurality of hollow fiber membranes 41 and placed in a treatment water tank 20. The filtration method repeats the following steps in a predetermined pattern: while supplying raw water to the treatment water tank 20, suctioning the lumen of the hollow fiber membrane 41 to extract the water having permeated the hollow fiber membrane 41 from the outside to the inside, removing the pressure difference between the inside and outside of the hollow fiber membrane 41 by stopping the suction of the lumen of the hollow fiber membrane 41, and back washing the hollow fiber membrane 41 by feeding pressurized water into the lumen of the hollow fiber membrane 41. In the step of extracting the permeate, the flux of the permeate is set to satisfy 125 e-0.032*T≤F≤56.8*e0.016*T where the temperature of raw water is T [°C], the flux of the permeate in the hollow fiber membrane 41 is F [L/m2*h], and the bottom of the natural logarithm is e.SELECTED DRAWING: Figure 2

Description

The present invention relates to filtration methods and filtration devices.

Filtration devices that perform filtration using hollow fiber membranes are used. As a method for increasing the processing capacity of a filtration device, it is easy to increase the filtration area. desired. As a method for increasing the flux, it is effective to adopt a cross-flow system configuration in which the raw water flows along the membrane surface (see, for example, Patent Document 1).

JP 2015-29951 A

Even in the case of a cross-flow system configuration, if the flux is increased, the hollow fiber membranes are likely to clog. When the hollow fiber membrane is clogged, it is necessary to stop the operation for a long period of time because cleaning with chemicals or the like is required. Therefore, an object of the present invention is to provide a filtration method and a filtration device in which hollow fiber membranes are less likely to clog.

A filtration method according to an aspect of the present invention is a filtration method that removes suspended solids from raw water using an immersion-type hollow fiber membrane module that has a plurality of hollow fiber membranes and is placed in a treatment water tank. a step of extracting permeated water that permeates the hollow fiber membrane from the outside to the inside by sucking the lumen of the hollow fiber membrane while supplying the raw water to the treated water tank; a step of removing the pressure difference between the inside and outside of the hollow fiber membrane by stopping the suction of the hollow fiber membrane; a step of backwashing the hollow fiber membrane by supplying pressurized water to the lumen of the hollow fiber membrane; is repeated in a predetermined pattern, and in the step of removing the permeated water, the temperature of the raw water is T [° C.], the flux of the permeated water in the hollow fiber membrane is F [L / m ² · h], natural logarithm The base of is e, and the flux of the permeate is set so as to satisfy 125·e ^−0.032·T ≦F≦56.8·e ^0.016·T .

In the filtration method described above, it is preferable that the flux of the permeated water is further set to 50 L/m ² ·h or more in the step of removing the permeated water.

In the filtration method described above, the temperature of the raw water is preferably 40° C. or higher in the step of removing the permeated water.

In the filtration method described above, in the backwashing step, air bubbles may be supplied to the treated water tank below the hollow fiber membrane module.

A filtration device according to an aspect of the present invention is a filtration device that removes suspended solids from raw water, and includes a treated water tank to which the raw water is supplied, and a plurality of hollow fiber membranes disposed inside the treated water tank. and a suction pump for sucking the lumen of the hollow fiber membrane, and a discharge line for discharging permeated water that has permeated the hollow fiber membrane from the outside to the inside from the hollow fiber membrane module, The temperature of the raw water is set to T [°C] and the flux of the permeated water in the hollow fiber membrane is set to F [L] by the backwash line that supplies pressurized water to the lumen of the hollow fiber membrane and the discharge line. /m ² · h], where e is the base of the natural logarithm, 125 · e ^{−0.032 · T} ≤ F ≤ 56.8 · e ^{0.016 · T} is discharged so that the permeate is discharged, the above stop operation for removing the pressure difference between the inside and outside of the hollow fiber membranes by stopping the suction of the lumen of the hollow fiber membranes by the discharge line; and stopping the suction of the lumens of the hollow fiber membranes by the discharge line. an operation control unit that controls the discharge line and the backwash line so as to repeat a backwash operation in which pressurized water is supplied from the backwash line to the lumen of the hollow fiber membrane in a predetermined pattern; Prepare.

ADVANTAGE OF THE INVENTION According to this invention, the filtration method and filtration apparatus which a hollow fiber membrane is hard to clog can be provided.

It is a mimetic diagram showing composition of a filtering device concerning one embodiment of the present invention. 1. It is a graph which shows the upper limit and lower limit of the flow rate of the permeate|transmission water in the filtration apparatus of FIG. FIG. 2 is a flow chart showing a procedure of filtration processing in the filtering device of FIG. 1. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. For the sake of convenience, the dimensions of various members in the drawings are adjusted so that they are easy to see.

FIG. 1 is a schematic diagram showing the configuration of a filtering device 1 according to one embodiment of the present invention. The filtering device 1 removes suspended solids from raw water. Filtration device 1 is a wastewater regeneration system in which reusable water is obtained by separating, for example, washing wastewater discharged from a manufacturing facility or the like by a reverse osmosis membrane device. can be used as a primary processor to remove

The filtration device 1 includes a raw water tank 10 for storing raw water, a treated water tank 20 for storing an amount of raw water suitable for filtration, a supply line 30 for supplying raw water from the raw water tank 10 to the treated water tank 20, and the treated water tank 20. an air supply line 50 for supplying air bubbles to the treated water tank 20; a discharge line 60 for discharging permeated water filtered by the hollow fiber membrane module 40; and a discharge line 60 An intermediate tank 70 for storing permeated water discharged from, a backwash line 80 for supplying pressurized water to the hollow fiber membrane module 40, a permeated water tank 90 for storing permeated water overflowing the intermediate tank 70, and an operation control unit 100 that controls the operation of other components.

The raw water tank 10 stores raw water supplied from a raw water source or a pretreatment facility. The raw water tank 10 may be used to inject, for example, a neutralizing agent, a flocculating agent, etc. into the raw water. The raw water tank 10 may have a heater 11 for heating the raw water and a temperature sensor 12 for detecting the temperature of the raw water so that the temperature of the raw water can be adjusted to a desired temperature.

The lower limit of the raw water temperature is preferably 40°C, more preferably 50°C. On the other hand, the upper limit of the raw water temperature is preferably 90°C, more preferably 80°C. By making the temperature of the raw water equal to or higher than the lower limit, the capacity of the filtering device 1, that is, the amount of permeated water obtained per unit time can be increased. Further, by setting the temperature of the raw water to the above upper limit or less, it is possible to use a general hollow fiber membrane module 40 that does not have heat resistance, so that equipment costs and maintenance costs can be suppressed.

The treated water tank 20 is supplied with raw water from a supply line 30 and reserves a certain amount of raw water. The treated water tank 20 is arranged so as to return overflowed raw water to the raw water tank 10 . The treated water tank 20 is formed to have the minimum size that allows the hollow fiber membrane modules 40 to be immersed in the raw water, and the raw water is brought into contact with the hollow fiber membrane modules 40 in a fluid state, thereby suppressing clogging of the hollow fiber membrane modules 40. is preferred.

The supply line 30 has a raw water pump 31 and can be controlled to continuously supply a constant amount of raw water from the raw water tank 10 to the treated water tank 20 . Thereby, a constant flow of raw water can be formed in the treated water tank 20 as described above. It is preferable that the supply line 30 supplies raw water to the lower part of the treated water tank 20 and forms a vertically upward water flow along the hollow fiber membrane module 40 as a whole.

The hollow fiber membrane module 40 has a plurality of hollow fiber membranes 41 and a water collection header 42 communicating with the lumen of the hollow fiber membranes 41 . The hollow fiber membrane module 40 is an immersion type membrane module in which the hollow fiber membranes 41 are arranged so as to be immersed in raw water. The hollow fiber membrane module 40 is preferably arranged such that the hollow fiber membranes 41 extend vertically along the flow of raw water in the treated water tank 20 . A discharge line 60 is connected to the water collecting header 42 of the hollow fiber membrane module 40 .

The air supply line 50 supplies air bubbles below the hollow fiber membrane module 40 in the treated water tank 20 . For this reason, the air supply line 50 can be configured to have an air diffusion pipe 51 disposed at the bottom of the treated water tank 20 and having a plurality of small holes for discharging air bubbles. The air supply line 50 may be configured to supply air as the bubble-forming gas, but it has a gas cylinder 52 and supplies, for example, nitrogen gas or the like that provides a decarboxylation effect as the bubble-forming gas. can be configured as

The discharge line 60 sucks the lumen of the hollow fiber membranes 41 through the water collecting header 42 and discharges permeated water that has passed through the hollow fiber membranes 41 from the hollow fiber membrane module 40 . The discharge line 60 includes a suction pump 61 for sucking the lumen of the hollow fiber membrane 41 , a flow meter 62 for detecting the amount of permeated water flowing out from the hollow fiber membrane module 40 , and a permeate at the outlet of the hollow fiber membrane module 40 . and an inlet switching valve 64 and an outlet switching valve 65 for switching with the backwash line 80 . The suction pump 61 is configured to be controllable in rotational speed and operates at the rotational speed instructed by the operation control unit 100 .

The intermediate tank 70 stores the permeated water discharged from the hollow fiber membrane module 40 through the discharge line 60 . The intermediate tank 70 stores a certain amount of permeated water, and supplies the stored permeated water to the backwash line 80 as water for washing the hollow fiber membranes 41 .

The backwash line 80 pressurizes the permeated water stored in the intermediate tank 70 and supplies it through the water collection header 42 to the lumen of the hollow fiber membranes 41 . In this embodiment, the backwash line 80 shares the suction pump 61 with the discharge line 60 . Therefore, the backwash line 80 includes a suction portion 81 connecting the outlet of the intermediate tank 70 and the inlet of the suction pump 61 (downstream side of the inlet switching valve 64), the outlet of the suction pump 61 and the hollow fiber of the discharge line 60. It has a discharge section 82 that connects the take-out portion (upstream side of the inlet switching valve 64 ) from the membrane module 40 and a supply section 83 that supplies the washing liquid to the discharge section 82 . The backwash line 80 further has a suction switching valve 84 provided in the suction section 81, a discharge switching valve 85 provided in the discharge section 82, and a supply switching valve 86 provided in the supply section 83 for switching the flow path. .

The permeated water tank 90 is a buffer for storing the permeated water overflowing the intermediate tank 70 and supplying it to the next process.

The operation control unit 100 particularly controls the suction pump 61, the inlet switching valve 64 and the outlet switching valve 65 of the discharge line 60, and the suction switching valve 84, the discharge switching valve 85 and the supply switching valve 86 of the backwash line 80. , the operation of the filtering device 1 is controlled so that clogging of the hollow fiber membranes 41 is suppressed and permeated water is efficiently obtained.

The operation control unit 100 performs filtration operation for discharging the permeated water from the hollow fiber membrane module 40 through the discharge line 60 , stop operation for stopping the suction of the lumen of the hollow fiber membranes 41 by the discharge line 60 , and The discharge line 60 and the backwash line 80 are controlled so that the backwash operation of supplying pressurized water to the lumen of the hollow fiber membrane 41 is repeated in a predetermined pattern. More specifically, the operation control unit 100 repeats the filtration operation for the filtration time and the stop operation for the predetermined stop time a predetermined number of times, performs the filtration operation again for the filtration time, and then performs the backwash operation according to the predetermined procedure. Repeat the operation pattern. Further, when the suction pressure detected by the pressure sensor 63 reaches a predetermined value, the operation control unit 100 supplies chemicals from the supply unit 83 to automatically perform chemical cleaning for dissolving and removing deposits on the hollow fiber membranes 41. In this case, the operator is notified to prompt execution of chemical cleaning.

During the filtration operation, the operation control unit 100 sets a target value for the permeated water flux F [L/m ² ·h] in the hollow fiber membrane 41, and the detected value of the flow meter 62 is the flux F. The rotational speed of the suction pump 61 is feedback-controlled so as to achieve a value corresponding to the target value.

As a result of research by the present inventor, it was confirmed that in a region where the flux F is relatively small, the clogging of the hollow fiber membrane 41 is suppressed as the water temperature T [° C.] increases, but is not affected by the flux F. . Specifically, the total amount Q [m ³ ] of permeated water per unit area of the hollow fiber membrane 41 obtained before the hollow fiber membrane 41 requires chemical cleaning is e ^−0.032·T and F Proportional. Therefore, the lower limit Fmin of the flux F required to obtain the required total amount of permeate Q, using the base e of the natural logarithm and the constant a, is Fmin=a Q e ^{−0 .032·T} .

On the other hand, it was confirmed that in a region where the flux F is relatively small, the clogging of the hollow fiber membranes 41 is suppressed as the water temperature T increases, but promoted as the flux F increases. Specifically, the total amount Q of permeated water obtained until the hollow fiber membrane 41 requires chemical cleaning is proportional to e ^0.036·T and inversely proportional to F ² . For this reason, the upper limit Fmax of the flux F required to obtain the required total amount of permeate Q is expressed as Fmax=b/√Q·e ^0.016·T using the constant b. be able to.

If the upper limit value Fmax of the flux F is not equal to or greater than the lower limit value Fmin, it means that there is no operating condition under which the required total amount Q of permeated water can be obtained. If the total amount Q is set so that the lower limit value Fmin and the upper limit value Fmax are equal when the raw water temperature T is 15° C., Fmin=125·e ^−0.032·T , Fmax=56.8·e ^{0. 016·T} . Further, when the raw water temperature T is 35° C. and the total amount Q is set so that the lower limit value Fmin and the upper limit value Fmax are equal, Fmin=250·e ^−0.032·T , Fmax=44·e ^{0. 016·T} . FIG. 2 graphically shows these lower limit value Fmin and upper limit value Fmax. As this graph shows, the higher the temperature T of the raw water, the greater the range of the flux F in which the required total amount Q of permeate can be obtained.

For the above reasons, the operation control unit 100 satisfies the target value of the permeate flux F of 125 · e ^{−0.032 · T} ≤ F ≤ 56.8 · e ^{0.016 · T} during the filtration operation. If the temperature of the raw water can be maintained at 35 ° C. or higher, the permeate flux F is 250 · e ^{−0.032 · T} ≤ F ≤ 44 · e ^{0.016 · T} It is more preferable to set so as to satisfy

Also, the permeate flux F is preferably 50 L/m ² ·h or more. By reducing the flux F of permeated water, it is possible to lengthen the time until chemical cleaning becomes necessary. Since it is necessary to do so, the equipment cost of the filtering device 1 increases. Therefore, the facility cost can be reduced by setting the permeate flux F to 50 L/m ² ·h or more.

FIG. 3 shows in detail the operation of the filtering device 1 by the operation control unit 100, that is, the procedure of the filtering method performed by the filtering device 1. As shown in FIG. The filtration method of the illustrated procedure is itself an embodiment of the filtration method according to the present invention.

The procedure of the filtration method by the filtration device 1 includes a filtration operation start step (step S1), a suction pressure confirmation step (step S2), a chemical cleaning step (step S3), a filtration time confirmation step (step S4), and a filtration number confirmation step ( Step S5), a stop operation start step (step S6), a stop time confirmation step (step S7), and a backwash operation step (step S8).

In the overoperation start step of step S1, raw water is supplied from the supply line 30 to the lower part of the hollow fiber membrane module 40 in the treated water tank 20, and the hollow fiber membranes 41 are sucked through the discharge line 60 to remove the hollow fibers. Permeated water that permeates the membrane 41 from the outside to the inside is taken out from the hollow fiber membrane module 40 . Specifically, in the overoperation start step, the inlet switching valve 64 and the outlet switching valve 65 of the discharge line 60 are opened, and the suction switching valve 84, the discharge switching valve 85 and the supply switching valve 86 of the backwash line 80 are closed. In this state, the suction pump 61 is started. The rotation speed of the suction pump 61 is feedback-controlled so that the detected value of the flowmeter 62 becomes a value corresponding to the target value of the flux F, as described above.

In the suction pressure confirming process of step S2, the detected value of the pressure sensor 63 is confirmed, and if the predetermined limit pressure is reached, the process proceeds to step S03, and if the limit pressure is not reached, the process proceeds to step S04. When the suction pressure detected by the pressure sensor 63 reaches the limit pressure, it is determined that the hollow fiber membrane 41 is clogged to such an extent that chemical cleaning is required.

In the chemical cleaning process of step S3, chemical cleaning is executed or an operator is requested to perform chemical cleaning. Chemical cleaning is preferably performed after confirmation by an operator. Therefore, when the chemical cleaning step is executed, the control in FIG. 3 can be temporarily terminated, and the control can be restarted by the operator who has confirmed the state of the filtering device 1 . Since cleaning of the hollow fiber membranes 41 using chemicals is well known, detailed description of the procedure will be omitted.

In the filtration time confirmation step of step S4, the time after the start of the filtration operation is confirmed to confirm whether or not a predetermined filtration time has elapsed. If the filtering time has not elapsed, the process returns to step S2, and if the filtering time has elapsed, the process proceeds to step S5. This filtration time is set according to the size and physical properties of the suspended solids in the raw water, and can be set, for example, from 5 minutes to 60 minutes.

In step S5, in the filtration number confirmation process, the number of times the filtration operation was performed is confirmed. Note that the counting of the filtering operation is reset when the chemical cleaning process of step S3 or the backwashing operation process of step S8 is performed. If the number of times of filtration operation has reached the predetermined number of repetitions, the process proceeds to step S8, and if the number of times of filtration operation has not reached the predetermined number of times of repetition, the process proceeds to step S6.

In the step S6 stop operation start process, the suction pump is stopped to stop suctioning the lumen of the hollow fiber membrane 41 . As a result, the pressure difference between the inside and outside of the hollow fiber membranes 41 is removed, so that the hollow fiber membranes may be exposed to the effects of gravity, the flow of raw water, vibration of the hollow fiber membranes 41, rubbing of air bubbles supplied from the air supply line 50, and the like. Suspicious particles adhering to the outer peripheral surface of 41 are detached from the hollow fiber membrane 41 . As a result, the filtering ability of the hollow fiber membrane 41 is recovered to some extent.

In the stop time confirmation process of step S7, the time after starting the stop operation is confirmed, and it is confirmed whether or not a predetermined stop time has elapsed. If the stopping time has not elapsed, this step S7 is executed again, and if the filtering time has elapsed, the process returns to step S1. This stop time is appropriately set in consideration of the ease of detachment of suspended solids, etc., and can be set to, for example, 30 seconds or more and 3 minutes or less.

In the backwash operation step of step S8, pressurized permeated water is supplied from the backwash line 80 to the lumen of the hollow fiber membranes 41 to add the hollow fiber membranes 41 from the inside to the outside. A backwash operation is performed to remove suspended solids adhering to the outer peripheral surface. Specifically, the inlet switching valve 64 and the outlet switching valve 65 of the discharge line 60 are closed, the suction switching valve 84 and the discharge switching valve 85 of the backwash line 80 are opened, and then the suction pump 61 is started.

In this backwashing step, it is preferable to supply air bubbles to the lower part of the hollow fiber membrane module 40 from the air supply line 50 to promote the removal of turbidity from the hollow fiber membranes 41 . The time for the backwash operation is appropriately set in consideration of the easiness of detachment of suspended solids, etc., and can be set, for example, from 30 seconds to 3 minutes. When the backwash operation is finished, the process returns to step S1.

Since the filtering device 1 obtains permeated water by removing suspended solids from raw water in such a procedure, the hollow fiber membranes 41 are less likely to clog. Therefore, the filtering device 1 has low running costs and low maintenance costs.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various changes and modifications are possible.

In the filtration apparatus according to the present invention, the discharge line and the backwash line may be provided independently, each having its own pump. Moreover, in the filtration device according to the present invention, the backwash line may supply water supplied from the outside to the filtration module. In this case the intermediate tank may be omitted.

In the filtration apparatus according to the present invention, the flux of permeated water in the hollow fiber membrane may be adjusted by other means such as a flow control valve instead of adjusting the rotational speed of the suction pump. The filtration device according to the present invention may also be configured such that permeate is supplied to the permeate tank from the bottom of the intermediate tank so that the intermediate tank can be emptied.

The present invention will be described in more detail below based on examples. In addition, the present invention is not limited only to these examples.

Experiments were conducted to obtain permeated water by filtering raw water under different conditions using a test facility having the same configuration as that of the above-described embodiment. As the hollow fiber membrane module, an immersion type module having a PTFE hollow fiber membrane with an average pore size of 100 nm and an effective filtration area of 0.1 m ² was used. As the raw water, the waste liquid discharged from the washing process during the production of the acrylic polymer fibers was used. This raw water contained 10% DMSO (dimethylsulfoxide) and had a turbidity of 40.

The amount of raw water supplied to the treated water tank was 1,000 mL/min. The filtration time was 9 minutes, the stop time was 1 minute, and the backwash operation was performed for 1 minute after the third filtration operation. That is, during the filtration operation, the stop operation was performed twice out of three times, and the backwash operation was performed the remaining one time. The flux of the hollow fiber membrane in the backwash operation was set to 120 L/m ² ·h.

The above operation was performed while changing the temperature of the raw water and the flux in the filtration operation, and the operation time until the suction pressure reached the limit pressure was confirmed. The limit pressure was set to 40 kPa. The results are summarized in Table 1 below.

Based on the data in Table 1, Table 2 below shows the results of calculating the total amount of permeated water obtained during the operating time until the limit pressure is reached under each condition.

Thus, within the range satisfying 125 · e ^{−0.032 · T} ≤ F ≤ 56.8 · e ^{0.016 · T} , while suppressing clogging of the hollow fiber membrane, a sufficient filtration amount of 30 m ³ or more It was confirmed that the The turbidity of the obtained permeated water was stably 1.0 or less.

1 filtration device 10 raw water tank 11 heater 12 temperature sensor 20 treated water tank 30 supply line 31 raw water pump 40 hollow fiber membrane module 41 hollow fiber membrane 42 water collection header 50 air supply line 51 air diffuser 52 gas cylinder 60 discharge line 61 suction pump 62 flow rate total 63 pressure sensor 64 inlet switching valve 65 outlet switching valve 70 intermediate tank 80 backwash line 81 suction section 82 discharge section 83 supply section 84 suction switching valve 85 discharge switching valve 86 supply switching valve 90 permeated water tank 100 operation control section

Claims (5)

A filtration method for removing suspended solids from raw water using an immersion-type hollow fiber membrane module having a plurality of hollow fiber membranes and placed in a treatment water tank,
A step of removing permeated water that has permeated the hollow fiber membrane from the outside to the inside by sucking the lumen of the hollow fiber membrane while supplying the raw water to the treated water tank;
a step of removing the pressure difference between the inside and outside of the hollow fiber membrane by stopping the suction of the lumen of the hollow fiber membrane;
backwashing the hollow fiber membranes by supplying pressurized water to the lumen of the hollow fiber membranes;
is repeated in a predetermined pattern,
^In the step of removing the permeated water, the permeated water is A filtration method in which the water flux is set to satisfy 125·e ^−0.032·T ≦F≦56.8·e ^0.016·T . The filtration method according to claim 1, wherein in the step of removing the permeated water, the flux of the permeated water is further set to 50 L/m ² ·h or more. The filtration method according to claim 1 or 2, wherein the temperature of the raw water is set to 40°C or higher in the step of removing the permeated water. 4. The filtration method according to any one of claims 1 to 3, wherein in said backwashing step, air bubbles are supplied below said hollow fiber membrane module in said treated water tank. A filtering device for removing suspended solids from raw water,
a treated water tank to which the raw water is supplied;
a hollow fiber membrane module disposed inside the treated water tank and having a plurality of hollow fiber membranes;
a discharge line that has a suction pump that sucks the lumen of the hollow fiber membrane and discharges permeated water that has permeated the hollow fiber membrane from the outside to the inside from the hollow fiber membrane module;
a backwash line for supplying pressurized water to the lumen of the hollow fiber membrane;
With the discharge line, the temperature of the raw water is T [° C.], the flux of the permeated water in the hollow fiber membrane is F [L / m ² h], and the base of natural logarithm is e, 125 · e ^{−0 .032 T} ≤ F ≤ 56.8 e Filtration operation for discharging the permeated water so as to satisfy ^{0.016 T} ;
stop operation for removing the pressure difference between the inside and outside of the hollow fiber membranes by stopping the suction of the lumen of the hollow fiber membranes by the discharge line; and stopping the suction of the lumens of the hollow fiber membranes by the discharge line. Backwashing operation for supplying pressurized water from the backwash line to the lumen of the hollow fiber membrane,
in a predetermined pattern, an operation control unit that controls the discharge line and the backwash line;
A filtration device.

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