JP2015226884A - Hollow fiber membrane module and cleaning method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow fiber membrane module which can efficiently remove a suspended substance near an upper end stationery part of a hollow fiber, and a cleaning method for the module.SOLUTION: A hollow fiber membrane module includes: a container 1 having a raw water inlet 5, a treated water outlet 4 and a concentrated water outlet 6; plural hollow fiber membranes 2 which separate treated water into permeated water and concentrated water; a permeated water chamber 7 with which the insides of the hollow fiber membranes 2 are communicated; a potting part 3A which fixes the upper end part of the hollow fiber membrane 2 and defines the permeated water chamber 7 in the container 1; and a cleaning part 10. The cleaning part 10 has plural nozzles 12 penetrating the potting part 3A, and cleaning water is ejected through an ejection port 12A provided at a lower end part of the nozzle 12.

Description

  The present invention relates to a hollow fiber membrane module, and more particularly to a hollow fiber membrane module that can efficiently wash turbidity trapped in a membrane and a cleaning method thereof.

  When performing filtration processing of polluted water using a hollow fiber membrane module, if turbidity adheres to the hollow fiber membrane, the filtration life of the hollow fiber membrane module is shortened or the filtration flow rate is reduced. Therefore, for example, in Patent Document 1, the liquid to be treated rises along the sheet-like hollow fiber membrane, changes to a flow in a substantially horizontal direction at the upper part of the sheet-like hollow fiber membrane, and then continues to the sheet-like hollow fiber membrane. A hollow fiber membrane module is disclosed in which means for allowing flow between the hollow fiber membranes is provided, and residues such as fibrous matter and hair are prevented from being entangled between the hollow fiber membranes.

  Further, in Patent Document 2, the hollow fiber membrane bundle is disposed on the radiation centered on the radial center of the upper fixing portion, and the upper fixing portion is provided with the rising bubbles for air scrubbing and the water to be treated by the rising bubbles. There is disclosed a hollow fiber membrane module that includes an inverted conical lower plate that constitutes a water flow direction changing member that guides an upward flow outward, and that makes it difficult for impurities to accumulate near the root of the hollow fiber membrane bundle.

  However, the hollow fiber membrane modules disclosed in Patent Documents 1 and 2 only change the flow of fluid, and cannot completely suppress the adhesion of turbidity. Moreover, once the turbidity adhered, the progress of the adhesion could not be stopped.

  In Patent Document 3, the hollow fiber portion near the resin partition wall at the upper end of the protective cylinder is made gas-impermeable, and a stable air pocket is created immediately below the resin partition wall, so that the solid content in the hollow fiber membrane portion near the resin partition wall is made. A hollow fiber membrane module that prevents adhesion of water is disclosed. However, this configuration has a problem that the membrane area of the hollow fiber membrane is reduced. Moreover, it was necessary to suppress the drying of the hollow fiber membrane.

  In Patent Document 4, the upper end of a filtration screen made of a hollow fiber membrane knitted fabric is fixed with an upper fixing member, the lower end is fixed with a lower fixing member, and scrubbing air supplied from an air supply port provided in the upper fixing member. The structure which injects air toward the base part of a filtration screen via the air discharge | release means provided in the vicinity of the lower fixing member is disclosed. The sprayed scrubbing air forms bubbles and rises while cleaning the surface of the hollow fiber membrane knitted fabric. However, with this configuration, only the gas is supplied from below the filtration screen, and the upper end portion of the filtration screen where turbidity tends to remain cannot be efficiently washed.

  In Patent Document 5, the hollow fiber membrane module includes a core tube extending in the axial direction disposed near the center of the cylindrical container, and backwashing in which water flows in a flow opposite to that during filtration; Performing back-flow cleaning in which water is caused to flow in a radial direction from a plurality of holes provided in the base plate. However, backwashing allows flushing water to flow through the entire hollow fiber membrane, and backwashing causes flushing water to flow in the vicinity of the core tube (in the center of the container), effectively cleaning the upper end of the hollow fiber bundle where turbidity tends to remain. I couldn't.

  In Patent Document 6, a supply pipe for cleaning a hollow column extending along the axial direction of the cylindrical case is inserted into the central portion of the hollow fiber bundle, and gas or gas-liquid is supplied from the cleaning supply pipe to the cylindrical case. The membrane filtration module which removes the gel-like substance adhering to the membrane surface of the hollow fiber by blowing out into the pressurizing chamber is disclosed. In this membrane filtration module, the central part of the hollow fiber bundle located in the vicinity of the cleaning supply pipe can be effectively cleaned, but the end part in the vertical direction cannot be effectively cleaned. In addition, since the stock solution inlet is provided in the upper part of the wall surface of the cylindrical case and the concentrate outlet is provided in the lower part (bottom part) of the wall surface, there is a problem that a gas pool is generated.

Japanese Patent No. 4183160 JP2011-62696A Japanese Utility Model Publication No. 3-15628 JP 2000-51670 A JP 2002-204930 A JP-A-5-154356

  Although turbidity tends to remain near the upper end fixing part of the hollow fiber, this turbidity is efficiently used in backwashing treatment in which water is supplied from the treated water side and discharged from the water supply side, and bubbling washing in which air is supplied from the water supply side They could not be removed well, resulting in a decrease in the amount of treated water and hollow fiber breakage.

  This invention is made | formed in view of the above situation, and makes it a subject to provide the hollow fiber membrane module which can remove the turbidity of the upper end fixing | fixed part vicinity of a hollow fiber efficiently, and its washing | cleaning method.

  The hollow fiber membrane module of the present invention has a container having a raw water inlet, a treated water outlet, and a concentrated water outlet, a plurality of hollow fiber membranes that separate treated water into permeated water and concentrated water, and faces the hollow fiber membrane. A hollow fiber membrane module having a permeated water chamber and an upper end fixing portion that fixes the upper end portion of the hollow fiber membrane and partitions the permeated water chamber in the container, and penetrates the upper end fixing portion. It has a washing part which has a plurality of nozzles and ejects washing water from an ejection hole provided in the lower end part of the nozzle.

  It is preferable that the concentrated water outlet is provided on a side wall of the container, and the ejection hole and the concentrated water outlet are located at substantially the same height.

  Each nozzle preferably has a plurality of ejection holes so that the cleaning liquid is ejected in the radial direction. Each ejection hole may be formed so as to eject the cleaning liquid in a substantially horizontal direction, or may be formed so as to eject the cleaning liquid in an obliquely upward direction.

  It is preferable that the cleaning unit has a cleaning water pipe that extends through the side wall of the container and extends to the permeated water chamber, and the plurality of nozzles are branched from the cleaning water pipe.

  The method for cleaning a hollow fiber membrane module according to the present invention is a method for cleaning the hollow fiber membrane module, wherein the first cleaning step performs a shower cleaning in which a cleaning liquid is ejected from the ejection holes of the plurality of nozzles, and the raw water inlet. A second cleaning step for performing at least one of bubbling cleaning for blowing gas from the outlet and back cleaning for supplying backwash water from the treated water outlet, and a third cleaning step for performing flushing cleaning for supplying raw water from the raw water inlet. It is characterized by providing.

  In the second cleaning step, it is preferable to perform bubbling cleaning, back cleaning, and shower cleaning.

  According to the present invention, the cleaning water is sprayed intensively to the turbidity in the vicinity of the upper end fixing portion by ejecting the cleaning water from the ejection holes of the plurality of nozzles penetrating the upper end fixing portion, thereby efficiently cleaning the turbidity. Can be removed. By removing the turbidity, the reduction of the permeation flux of the hollow fiber membrane module can be mitigated. Moreover, the stress to the hollow fiber membrane can be reduced, and the hollow fiber membrane can be prevented from being broken.

  Moreover, the turbidity removed by the ejection of the washing water from the ejection hole can be efficiently discharged by making the ejection hole and the concentrated water outlet substantially the same height.

  The ejection holes eject the cleaning liquid in a substantially horizontal direction, so that the reach of the cleaning liquid can be expanded and a wide range of turbidity can be removed. In addition, since the ejection holes eject the cleaning liquid obliquely upward, the turbidity can be removed by spraying the cleaning liquid to a position closer to the upper end fixing portion.

  When the washing section has a washing water pipe that extends through the side wall of the container and extends to the permeate chamber, and a plurality of nozzles branch from the washing water pipe, the hollow fiber membrane formed by installing the washing section Reduction in film area can be suppressed.

  By performing bubbling cleaning, reverse cleaning and shower cleaning when cleaning the hollow fiber membrane module, not only the vicinity of the upper end fixing portion but also the entire hollow fiber membrane can be efficiently cleaned.

It is a schematic diagram of the hollow fiber membrane module which concerns on embodiment of this invention. It is principal part sectional drawing of the hollow fiber membrane module which concerns on the same embodiment. (A)-(c) is a figure which shows the example of arrangement | positioning of an ejection hole. (A)-(c) is a figure which shows the example of formation of an ejection hole. (A)-(d) is a figure which shows the flow of the water of each process in Example 1. FIG. It is a schematic diagram of the hollow fiber membrane module by a modification. (A)-(d) is a figure which shows the flow of the water of each process in the comparative example 1. FIG. It is a graph which shows the measurement result of the permeation | transmission flux in Example 1 and Comparative Example 1.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 is a schematic view showing a configuration of a hollow fiber membrane module according to the present embodiment, and FIG. 2 is a schematic cross-sectional view showing a part of the hollow fiber membrane module (around the cleaning unit 10). As shown in FIG. 1, the hollow fiber membrane module includes a container 1 that is arranged with the axial direction of the cylinder in the vertical direction (vertical direction in this embodiment). A plurality of hollow fiber membranes 2 are disposed in the container 1. The hollow fiber membrane 2 has an upper end fixed by a synthetic resin potting portion 3A as an upper end fixing portion, and a lower end embedded and sealed in the potting portion 3B. As a synthetic resin for the potting portions 3A and 3B, for example, an epoxy resin can be used.

  In FIG. 1, three hollow fiber membranes 2 are shown for the sake of clarity, but in reality, a large number of hollow fiber membranes 2 are arranged. In the present embodiment, a hollow fiber membrane module having a hollow fiber membrane 2 will be described, but any membrane module using a tubular membrane may be used.

  A permeate chamber 7 is defined on the upper side of the potting portion 3A. The upper end side of the hollow fiber membrane 2 passes through the potting portion 3A, the opening at the upper end faces the permeate water chamber 7, and the inside of the hollow fiber membrane 2 communicates with the permeate water chamber 7.

  The potting portion 3A has, for example, a disk shape, and its outer peripheral surface or outer peripheral edge portion is in watertight contact with the inner surface of the container 1. Between the potting part 3B and the inner wall of the container 1, there is a space through which raw water passes. An inlet 5 for raw water (treated water) is provided at the bottom of the container 1, and an outlet 4 for treated water (membrane permeated water) is provided at the top of the container 1. A concentrated water outlet 6 is provided at the upper part of the side surface of the container 1. The concentrated water outlet 6 is provided near the lower surface of the potting portion 3A. The distance from the potting part 3A to the upper edge of the concentrated water outlet 6 is preferably 0 to 20 mm, particularly preferably about 0 to 5 mm.

  The hollow fiber membrane module is supplied with raw water from the feed water inlet 5 by the pump P1 through the raw water pipe L1. An air introduction pipe L2 branches from the raw water pipe L1. The supply of raw water / air to the container 1 can be switched by switching opening and closing of the valve V1 provided in the raw water pipe L1 and the valve V2 provided in the air introduction pipe L2. By closing the valve V1 and opening the valve V2 to supply air, bubbles blow up from the bottom of the container 1, and bubbling cleaning can be performed.

  A treated water outlet pipe L3 is connected to the treated water outlet 4, and treated water (membrane permeated water) is discharged through the treated water outlet pipe L3. A backwash water pipe L4 is connected to the treated water outlet pipe L3 at a position between the valve V3 provided in the treated water outlet pipe L3 and the treated water outlet 4. The hollow fiber membrane 2 can be backwashed by closing the valve V3 and causing the backwash water to flow from the treated water outlet 4 to the container 1 via the backwash water pipe L4 by the pump P2. For the backwash water, raw water or treated water is used. Waste water accompanying the washing is discharged from the concentrated water outlet 6 through the blow line L5.

  In the filtration treatment by this hollow fiber membrane module, the permeated water that has permeated through the hollow fiber membrane 2 out of the water flowing in from the feed water inlet 5 is taken out from the treated water outlet 4 as treated water, and the concentrated water that has not permeated through the membrane is removed. It is discharged from the concentrated water outlet 6. As described above, the hollow fiber membrane module according to the present embodiment is an external pressure type in which raw water is passed through the outside of the hollow fiber membrane 2 by a cross flow method.

  This hollow fiber membrane module is provided with a cleaning unit 10 for cleaning the hollow fiber membrane 2 located below the potting unit 3A, that is, in the vicinity of the potting unit 3A (upper end fixing unit). .

  The cleaning unit 10 includes a cleaning water pipe 11 for supplying cleaning water into the container 1 and a plurality of nozzles 12 branched from the cleaning water pipe 11. The washing water pipe 11 extends from the outside of the container 1 through the container side wall into the permeated water chamber 7 in a substantially horizontal direction. The nozzle 12 penetrates the potting portion 3A from the cleaning water pipe 11 and extends downward in a substantially vertical direction (the axial direction of the container 1), and an ejection hole 12A (see FIG. 2) that ejects cleaning water to the tip portion (lower end portion). ) Is provided.

  When filtration is performed using the hollow fiber membrane module shown in FIG. 1, turbidity accumulates in the hollow fiber membrane 2 near the potting portion 3A. The turbidity at this location can be removed by ejecting washing water from the ejection holes 12A of the washing section 10. The suspended matter removed (peeled) from the hollow fiber membrane 2 is discharged from the concentrated water outlet 6 through the blow line L5.

The plurality of nozzles 12 are preferably arranged without deviation in a state in which the potting portion 3A is viewed in plan, for example, arranged in a lattice shape or a multiple annular shape. Further, the nozzle 12 may be disposed on the radiation centered on the radial center of the container 1. The arrangement of the nozzles 12 is not limited to these. The arrangement density of the nozzles 12 is preferably 50 to 200, particularly about 100 to 150 per unit plane area (1 m ² ) of the potting portion 3A.

  The nozzle 12 is a circular tube having a closed tip (lower end), and a plurality of ejection holes 12A are formed on the side peripheral surface of the tip. Although the number of the ejection holes 12A in each nozzle 12 is arbitrary, it is preferable that the nozzles 12 are provided at equal intervals in the circumferential direction at about 4-8. In FIG. 3A, four nozzles 12 are formed at equal intervals on the peripheral surface of the tip portion side so as to eject cleaning water in the radial direction.

  The ejection hole 12A is preferably disposed at a height between the upper edge and the lower edge of the concentrated water outlet 6. With such a configuration, the suspended matter removed from the hollow fiber membrane 2 by the washing water ejected from the ejection holes 12 </ b> A is easily discharged from the concentrated water outlet 6.

  The ejection holes 12A may be provided in a plurality of stages at intervals in the vertical direction. For example, as shown in FIG. 3B, four ejection holes 12A may be provided in two stages (a total of 8). . With such a configuration, the cleaning region can be expanded in the vertical direction. Further, as shown in FIG. 3 (c), the upper ejection holes 12A and the lower ejection holes 12A may be shifted and arranged alternately (staggered). With such a configuration, the cleaning region can be expanded in the horizontal direction.

  The ejection holes 12A may be formed so as to eject the cleaning liquid in the horizontal direction as shown in FIG. As shown in FIG.4 (b), you may form so that a washing | cleaning liquid may be ejected toward diagonally upward. As shown in FIG. 4 (b), it becomes easy to clean a portion near the lower surface of the potting portion 3A by ejecting the cleaning liquid obliquely upward. As shown in FIG. 4C, the ejection hole 12A may be formed so as to eject the cleaning liquid obliquely downward. Further, when a plurality of ejection holes 12A are provided in the vertical direction, the cleaning liquid may be ejected horizontally or obliquely upward on the upper stage side, and the cleaning liquid may be ejected horizontally or obliquely downward on the lower stage side. By adopting such a configuration, the cleaning region can be further expanded in the vertical direction.

  The shape of the ejection hole 12A is not particularly limited, but may be a circle, an ellipse, a polygon, or the like.

  Each nozzle 12 preferably has an inner diameter of 5 mm to 20 mm, particularly 6 mm to 10 mm, and an outer diameter of 6 mm to 22 mm, particularly 8 mm to 12 mm. The diameter of the ejection hole 12A is preferably 0.1 mm to 1.5 mm, particularly 0.5 mm to 1.0 mm. 12 A of ejection holes are arrange | positioned from the lower surface of 3 A of potting parts in the position of 10 mm-50 mm, Preferably 20 mm-30 mm. In addition, as shown in FIG. 2, it is preferable to arrange the ejection hole 12A and the concentrated water outlet 6 at the same height, and if configured in this way, the suspended matter removed from the hollow fiber membrane 2 is efficiently concentrated. It can be discharged from the water outlet 6.

Although the hollow fiber membrane 2 is not particularly limited, those having an inner diameter of 0.3 to 1.0 mm, an outer diameter of 0.5 to 1.5 mm, and an effective length of about 100 to 200 mm are usually used. A suitable membrane having a total membrane area of 0.02 to 0.1 m ² in which 50 to 200 hollow fiber membranes 2 are loaded in the container 1 is suitable. The membrane material of the hollow fiber membrane 2 is not particularly limited, but PVDF (polyvinylidene fluoride), polyethylene, polypropylene, or the like can be used.

  Next, a method for operating the hollow fiber membrane module configured as described above will be described with reference to FIG.

  In the filtration process by this hollow fiber membrane module, as shown in FIG. 5A, the valves V1 and V3 are opened and the pump P1 is operated. Of the water flowing in from the water supply inlet 5, the permeated water that has passed through the hollow fiber membrane 2 is taken out from the treated water outlet 4 as treated water, and the concentrated water that has not permeated through the membrane is discharged from the concentrated water outlet 6. When this filtration process is continued, turbidity accumulates in the hollow fiber membrane 2 near the potting portion 3A. Therefore, after the filtration process has been performed for a predetermined time or when the amount of permeated water has decreased, the washing water is ejected from the ejection holes 12A of the washing unit 10, and the turbidity in the vicinity of the potting unit 3A is intensively washed and removed. . The suspended matter trapped in the hollow fiber membrane 2 is efficiently washed.

  In this cleaning process, a first cleaning process, a second cleaning process, and a third cleaning process described below are performed. In the first cleaning step, shower cleaning using the cleaning unit 10 is performed. In this shower cleaning, as shown in FIG. 5B, the valves V1, V2, and V3 are closed, the cleaning water is supplied from the cleaning water pipe 11 to each nozzle 12, and is ejected from the ejection hole 12A. The washing waste water containing the separated turbidity is discharged through the blow line L5.

  After the first cleaning process, a second cleaning process is performed. In the second cleaning step, at least bubbling cleaning and back cleaning are performed. In the bubbling cleaning, as shown in FIG. 5C, the valve V2 is opened and air is blown into the lower portion of the container 1 to perform bubbling. In the back washing, the valve V3 is opened, the pump P2 is operated, and the back washing water is sent into the hollow fiber membrane 2 through the permeate water chamber 7. The washing waste water is discharged out of the system through the blow line L5. Bubbling cleaning and reverse cleaning may be performed in order, in reverse order, or simultaneously.

  In the second cleaning step, bubbling cleaning, back cleaning, and shower cleaning may be performed. The order of this bubbling cleaning, reverse cleaning and shower cleaning is arbitrary, and may be performed in any order. Moreover, any two washing | cleaning may be performed simultaneously and three washing | cleaning may be performed simultaneously.

  After this 2nd washing process, it moves to the 3rd washing process, and flushing washing is performed by flowing raw water through raw water piping L1. In this flushing cleaning, as shown in FIG. 5D, the valve V1 is opened, the pump P1 is operated, the raw water is sent into the container 1, and the cleaning wastewater is discharged from the blow line L5. Note that the supply of raw water in the flushing cleaning may be performed continuously or intermittently and repeatedly. After this flushing washing, the filtration process is resumed.

  According to the present embodiment, the turbidity in the vicinity of the upper end fixed portion that tends to remain can be efficiently cleaned and removed by ejecting the washing water from the ejection holes 12A of the washing portion 10. By removing the suspended matter, the reduction of the permeation flux of the hollow fiber membrane module is mitigated. Moreover, the stress to the hollow fiber membrane 2 can be reduced, and the yarn breakage of the hollow fiber membrane 2 can be prevented.

  In the present embodiment, the cleaning water pipe 11 of the cleaning unit 10 is provided at a position higher than the potting unit 3A, and only the tip of the nozzle 12 of the cleaning unit 10 is disposed in the treated water chamber below the potting unit 3A. Compared with the case where the cleaning water pipe 11 is provided at a position lower than the potting portion 3A, a reduction in the membrane area of the hollow fiber membrane due to the installation of the cleaning portion 10 can be suppressed.

  Moreover, the entire hollow fiber membrane 2 can be effectively cleaned by performing the shower cleaning by the cleaning unit 10 at the same time as the back cleaning and / or the bubbling cleaning.

  You may perform the washing | cleaning by the washing | cleaning part 10 at the time of a filtration process. Thereby, adhesion of turbidity to the hollow fiber membrane 2 in the vicinity of the upper end fixing portion can be suppressed.

  In the above embodiment, both ends of the hollow fiber membrane 2 are fixed by the potting portions 3A and 3B. However, the lower end of the hollow fiber membrane 2 may be closed and only the upper end may be fixed by the potting portion 3A.

  The washing part for washing the turbidity in the vicinity of the fixing part of the hollow fiber membrane described above can also be applied to an immersion type hollow fiber membrane module. In the immersion type hollow fiber membrane module, a module in which both ends are connected to a water collecting member in a liquid tank such as an activated sludge tank or a sedimentation tank, the length direction of the hollow fiber membrane is substantially vertical or substantially horizontal. It arrange | positions so that it may become. In the submerged hollow fiber membrane module, the surface of the hollow fiber membrane is washed by an upward flow of gas-liquid mixing due to bubbles ejected from the bottom of the liquid tank to be treated. It is difficult to clean the vicinity of the connection part. Therefore, a cleaning unit having the same configuration as the cleaning unit 10 having the nozzle 12 in which the ejection hole 12A is formed is installed in the liquid tank to be treated, and the ejection hole of the nozzle is disposed in the vicinity of the end of the hollow fiber membrane. Thus, turbidity can be efficiently removed.

  In the above embodiment, a space through which raw water passes is provided between the potting portion 3B and the inner surface of the container 1, but the outer peripheral surface of the disc-shaped potting portion 3B is formed on the inner surface of the container 1 as shown in FIG. It may be in watertight contact. In this case, the lower side of the potting unit 3B is an inflow chamber, and the space between the potting unit 3A and the potting unit 3B is a processing chamber. In the potting portion 3B, a hole 8 that communicates the inflow chamber and the processing chamber is provided in a vertical direction. The holes 8 are evenly arranged over the entire area of the surface of the potting portion 3B. The raw water flows into the processing chamber through the inlet 5, the inflow chamber and the hole 8. While raw water rises in the processing chamber, a part of the water permeates through the hollow fiber membrane 2, and the permeated water is taken out from the outlet 4 through the permeated water chamber 7.

[Example 1]
The hollow fiber membrane module shown in FIGS. 1 and 2 provided with the washing unit 10 was subjected to filtration treatment by passing raw water through the flow of FIG. 5A for 26 minutes. As raw water, ferric chloride (FeCl ₃ ) was added to Nogi-cho water to a concentration of 1000 mg / L, and the pH was adjusted to 6-7. The configuration of the hollow fiber membrane module is as follows.
Inner diameter of container 1: 36 mm
Container 1 height: 596 mm
Hollow fiber: Polysulfone membrane having an inner diameter of 0.9 mm, an outer diameter of 1.3 mm, and an effective length of 500 mm The number of hollow fibers: 197 The number of nozzles: 1 The structure of the nozzle 12: as shown in FIG. Ejection hole diameter 1.0mm)
Vertical position of the ejection hole 12A: the same level as the vicinity of the center of the concentrated water outlet 6

  After the filtration process, shower cleaning by the cleaning unit 10 was performed for 2 minutes (first cleaning process). Nogicho water was used as the washing water for shower washing, and water was supplied at 0.15 L / min. After the first cleaning process, shower cleaning, back cleaning and bubbling cleaning were simultaneously performed for 1 minute (second cleaning process). The amount of water supply for shower cleaning is 0.15 L / min, the amount of water supply for reverse cleaning is 0.15 L / min, and the supply amount of bubbling air is 1.0 NL / min. Module permeated water was used as the backwash water.

  After the second cleaning process, flushing cleaning was performed for 1 minute (third cleaning process). The flow of water / air in each treatment is indicated by the thick lines in FIGS. The change with time in the permeation flux of the hollow fiber membrane module was measured while alternately performing the filtration treatment for 26 minutes and the first to third washing treatments. The measurement results are shown in FIG.

[Comparative Example 1]
Except that the cleaning unit 10 was not provided, the same raw water as in Example 1 was passed through a hollow fiber membrane module having the same configuration as in Example 1 for 26 minutes to perform filtration.

  After the filtration treatment, back washing was performed for 2 minutes (first washing treatment). After the first cleaning process, back cleaning and bubbling cleaning were simultaneously performed for 1 minute (second cleaning process). The amount of water supplied for backwashing and the amount of air supplied for bubbling were the same as in Example 1, and the module permeated water was used as the water supply for backwashing. After the second cleaning process, flushing cleaning was performed for 1 minute (third cleaning process). The flow of water / air in each treatment is indicated by the thick lines in FIGS. While the filtration treatment and the first to third washing treatments were alternately performed, the change with time in the permeation flux of the hollow fiber membrane module was measured. The measurement results are shown in FIG.

  As shown in FIG. 8, the permeation flux was able to be maintained at a high value (especially after 20 hours) by performing the shower cleaning by the cleaning unit 10.

DESCRIPTION OF SYMBOLS 1 Container 2 Hollow fiber membrane 3A, 3B Potting part 4 Treated water outlet 5 Raw water inlet 6 Concentrated water outlet 7 Permeate water chamber 10 Washing part 11 Washing water piping 12 Nozzle 12A Ejection hole

Claims (8)

A container having a raw water inlet, a treated water outlet, and a concentrated water outlet;
A hollow fiber membrane for separating the water to be treated into permeated water and concentrated water, and a plurality of hollow fiber membranes arranged in the vertical direction in the container,
An upper end portion of the hollow fiber membrane is fixed, and an upper end fixing portion disposed at an upper portion in the container;
A permeated water chamber formed on the upper side of the upper end fixing portion and communicating with the inside of each hollow fiber membrane;
A washing section for washing the upper part of the hollow fiber membrane;
In the hollow fiber membrane module having
The cleaning section has a plurality of nozzles that penetrate the upper end fixing section in the vertical direction, and a cleaning water ejection hole provided in a lower end section of the nozzle. In Claim 1, the concentrated water outlet is provided in the upper part of the side wall of the container,
The ejection hole is located at a height between an upper edge and a lower edge of the concentrated water outlet.   3. The hollow fiber membrane module according to claim 1, wherein each nozzle has a plurality of ejection holes so that the washing water is ejected in a radial direction.   4. The hollow fiber membrane module according to claim 3, wherein each ejection hole is formed so as to eject the cleaning liquid in a substantially horizontal direction.   4. The hollow fiber membrane module according to claim 3, wherein each of the ejection holes is formed so as to eject the cleaning liquid obliquely upward.   6. The cleaning unit according to claim 1, wherein the cleaning unit includes a cleaning water pipe that extends through the side wall of the container and extends into the permeated water chamber, and the plurality of nozzles includes the cleaning water pipe. A hollow fiber membrane module, characterized in that it is connected to a hollow fiber membrane module. A method for cleaning the hollow fiber membrane module according to any one of claims 1 to 6,
A first cleaning step for performing shower cleaning in which a cleaning liquid is sprayed from the ejection holes of the plurality of nozzles;
A second cleaning step of performing at least one of bubbling cleaning for blowing gas from the raw water inlet and back cleaning for supplying backwash water from the treated water outlet;
A third cleaning step for performing flushing cleaning for supplying raw water from the raw water inlet;
A method for cleaning a hollow fiber membrane module, comprising:   8. The method for cleaning a hollow fiber membrane module according to claim 7, wherein in the second cleaning step, bubbling cleaning, back cleaning, and shower cleaning are performed.

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