WO2008062788A1

WO2008062788A1 - Hollow-fiber membrane for immersion filtration, hollow-fiber membrane module for immersion filtration employing the same, apparatus for immersion filtration, and method of immersion filtration

Info

Publication number: WO2008062788A1
Application number: PCT/JP2007/072458
Authority: WO
Inventors: Manabu Sasakawa; Naoya Kanno; Kenji Honjou
Original assignee: Mitsubishi Rayon Engineering Co., Ltd.
Priority date: 2006-11-20
Filing date: 2007-11-20
Publication date: 2008-05-29
Also published as: JP5795459B2; KR20090071643A; JP2014231059A; CN101541404B; CN101541404A; JPWO2008062788A1; KR101156411B1

Abstract

A hollow-fiber membrane for immersion filtration which has one or more protrudent parts on the outer surface; and a hollow-fiber membrane module for immersion filtration which is produced by bonding and fixing two or more such hollow-fiber membranes to a housing. Even when membrane filtration in a high-concentration suspension is continued, the effect of physically cleaning the membranes or module by air bubbling is high and an excess deposit is less apt to accumulate on the membrane surface. Consequently, the membranes and module suffer no decrease in water permeability during the continuation of operation.

Description

Specification

Hollow fiber membrane for immersion filtration, hollow fiber membrane module for immersion filtration using the same, immersion filtration device, and immersion filtration method

Technical field

[0001] The present invention relates to a hollow fiber membrane for immersion filtration, a hollow fiber membrane module for immersion filtration using the same, and an immersion filtration filter that is suitable for immersion suction filtration of liquids with high pollution properties (particularly due to organic contaminants). The present invention relates to an apparatus and an immersion filtration method.

This application (together, November 2006 No. 2006-313248, filed on November 20, 2006) Priority is claimed based on this, and the contents thereof are incorporated herein.

Background art

[0002] In recent years, a “hollow fiber membrane filtration method” in which a hollow fiber membrane is immersed in water to be treated in water and sewage treatment or industrial wastewater treatment to separate and remove impurities from the water to be treated has become widespread!

However, the “Hollow Fiber Membrane Filtration Method” causes a suspended layer of organic matter and suspended matter in the treated water to form on the outer surface of the hollow fiber membrane over a long period of operation, and the hollow fiber membrane is clogged or solid. It has been pointed out that there is a problem of channel blockage (fouling). Falling can lead to increased transmembrane pressure and reduced filtration flux, which adversely affects the overall operating efficiency of the water treatment system.

[0003] The reduction in operation efficiency of the water treatment system due to fouling can be eliminated by physical cleaning of the hollow fiber membrane. For example, it is possible to control the degree of fouling within a certain range by introducing an operation cycle method in which physical washing is performed after a filtration process for a predetermined time and the filtration process and physical washing are repeated. For physical cleaning, reverse flow cleaning that reverses membrane filtered water; cleaning by flushing water on the primary surface of the hollow fiber membrane, that is, the surface in contact with the treated water (flushing); air publishing that vibrates the hollow fiber membrane with air Remove attached substances by physical action! / ,!

[0004] Flushing and air bubbling, which are the physical cleaning methods described above, are effective means for reducing fouling and are indispensable for stabilizing the filtration operation. When the concentration of suspended solids in the water to be treated is high, physical cleaning is required to obtain a sufficient cleaning effect. It is necessary to increase the strength.

However, if the physical washing is too strong, the hollow fiber membranes may come into contact with each other or the suspended solids in the water to be treated may be rubbed, and the surface of the hollow fiber membrane may be scratched, possibly resulting in yarn breakage. There was a thing.

[0005] In order to solve this problem, improvement of the shape and strength of the hollow fiber membrane has been studied.

For the purpose of improving the shape of the hollow fiber membrane, Patent Document 1 describes a hollow fiber membrane whose shape is changed in an inclined manner. According to Patent Document 1, by changing the shape of the hollow fiber membrane in an inclined manner, the flow pressure loss is reduced as compared with the conventional hollow fiber membrane, the permeate flow velocity distribution is smoothed, and the load on the membrane local area is reduced. Since the contamination is dispersed, the publishing and backwashing properties when performing membrane cleaning are improved, and the filtration operation can be prolonged.

In addition, the purpose of improving the strength of the hollow fiber membrane is described in Patent Literature 2 which has a specific viscosity average molecular weight, a molecular weight distribution, and a polyethylene hollow fiber porous membrane force having a specific pore structure. .

Patent Document 1: Japanese Patent Laid-Open No. 7-96152

Patent Document 2: JP 2001-269556 A

Disclosure of the invention

Problems to be solved by the invention

[0006] However, in the hollow fiber membrane of Patent Document 1, an increase in the permeate flow rate can be expected due to the inclined structure, but Patent Document 1 does not have a specific disclosure regarding improvement in operational stability and cleanability. Issues remain in terms of long-term operational stability. In addition, in order to obtain such a membrane, the hollow fiber membrane production process is inevitably complicated, and the productivity is low and the production cost is high.

In addition, the hollow fiber porous membrane of Patent Document 2 can be expected to improve the scratch resistance against suspended components in the liquid to be treated, but it is expected that wear due to contact between the hollow fiber porous membranes will occur, and long-term operation will occur. From the point of view, it does not lead to a solution. Moreover, it is difficult to reduce the physical cleaning strength only by improving the strength of the membrane, and it does not lead to a fundamental solution.

[0007] The present invention has been made in view of the above circumstances, and a filtration operation in which deposits hardly accumulate on the membrane surface even when hollow fiber membrane filtration in a high-concentration suspension is continued. The water permeability performance It is an object of the present invention to provide a hollow fiber membrane for immersion filtration that can be continued for a long time without lowering, a hollow fiber membrane module for immersion filtration, an immersion filtration device, and an immersion filtration method using the same.

Means for solving the problem

As a result of intensive studies, the present inventors have provided a protrusion on the outer surface of the hollow fiber membrane, so that the outer surface of the hollow fiber membrane in the case of applying the hollow fiber membrane to immersion filtration of a highly pollutant liquid is obtained. It was clarified that the detergency was improved, and the present invention was completed.

That is, the present invention is a hollow fiber membrane for immersion filtration having one or more protrusions on the outer surface.

[0009] Further, the present invention is a hollow fiber membrane module for immersion filtration, wherein a plurality of the hollow fiber membranes for immersion filtration are bonded and fixed to a housing.

Furthermore, the present invention is an immersion filtration apparatus in which the hollow fiber membrane module for immersion filtration is installed in an immersion water tank.

The present invention also covers a hollow fiber membrane module for immersion filtration in which an immersion water tank is filled with water to be treated, and a plurality of hollow fiber membranes for immersion having one or more protrusions on the outer surface are bonded and fixed to a housing. It is an immersion filtration method in which the filtrate is immersed in treated water to obtain filtrate from the hollow portion of the hollow fiber membrane for immersion filtration.

The invention's effect

[0010] By using a hollow fiber membrane having one or more protrusions on the outer surface for immersion filtration, the physical cleaning effect on the outer surface of the membrane is improved. As a result, even when membrane filtration in a high-concentration suspension is continued, deposits do not accumulate excessively on the outer surface, and the filtration operation can be continued for a long time without reducing water permeability. .

Brief Description of Drawings

FIG. 1 is a schematic view showing an example of an embodiment of a hollow fiber membrane having a protrusion.

FIG. 2 is a schematic view showing an example of an embodiment of a hollow fiber membrane module according to the present invention.

FIG. 3 is a view showing a processing flow of an immersion filtration test of an example.

FIG. 4 is a diagram showing a graph of experimental results of Examples. Explanation of symbols

1 housing

2 Fixing resin

3 Hollow fiber membrane

4 water inlet

5 protrusion

6 screen

7 Flow rate adjustment tank

8 supply pump

9 Stirring motor 10 Stirring blade

11 Denitrification tank

12 circulation pump

13 Membrane immersion tank 14 Circulating water flow meter 15 Supply piping

16 air diffuser

17 Air flow meter

18 blower

19 hollow fiber membrane module

20 Backwash pump

21 pressure gauge

22 filtration pump

23 Membrane filtered water flow meter

24 membrane water tank

25 Water tank drain for denitrification

26 membrane immersion tank drain

27 Blower supply valve 28 membrane filtration valve

29 Backwash valve

BEST MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, the present invention will be specifically described with a focus on preferred embodiments.

FIG. 1 is a view showing an example of an embodiment of a hollow fiber membrane for immersion filtration having a protrusion on the outer surface. It is important that the hollow fiber membrane 3 for immersion filtration is provided with a protrusion 5 on its outer surface.

[0014] The manufacturing method of the hollow fiber membrane 3 for immersion filtration having the protrusions 5 may be such that the protrusions 5 may be polymerized later on the hollow fiber membrane having no protrusion structure, or the hollow fiber membrane for immersion filtration. 3 Although it may be shaped into a shape having protrusions 5 at the time of manufacture! /, It is possible to reduce the manufacturing process and manufacturing cost, so it is possible to shape at the time of manufacturing the hollow fiber membrane 3 for immersion filtration. preferable.

[0015] The shape of the protrusion 5 is not particularly limited as long as the protrusion 5 has a protrusion on the outer surface of the immersion filtration hollow fiber membrane 3. However, a large amount of the immersion filtration hollow fiber membrane 3 can be stably and continuously formed. In particular, the structure as shown in FIG. 1 having at least one protrusion 5 having a continuous shape in the longitudinal direction on the outer surface of the hollow fiber membrane 3 for immersion filtration is particularly preferable.

The number of protrusions 5 having a shape that is continuous in the longitudinal direction is not particularly limited, but when a plurality of hollow fiber membranes 3 for immersion filtration are arranged, the number of protrusions 5 that are adjacent to the surroundings is determined. In order to effectively obtain the cleaning effect, it is particularly preferable to have 8 or more. On the other hand, if the number of the protrusions 5 is too large, there is a risk of reducing the filtration capacity due to a reduction in the effective filtration area of the hollow fiber membrane 3 for immersion filtration. Therefore, the number of the protrusions 5 is such that the projected area ratio of the protrusions 5 to the outer surface of the hollow fiber membrane 3 for immersion filtration when the protrusions 5 are excluded is in the range of 1 to 20%. It is preferable to adjust so that it becomes. This is because when the projected area ratio is 1% or more, an excellent cleaning effect by the protrusions 5 tends to be exhibited. More preferably, it is 5% or more.

In addition, by setting the projected area ratio to 20% or less, there is a tendency that the cleaning effect by the protrusions 5 and the above-described filtration processing ability can be compatible. More preferably, it is 15% or less.

[0016] In addition, the protrusion 5 is formed by removing and depositing deposits deposited on the surface of the hollow fiber membrane 3 by physical cleaning. To make it easier to get out, the shape of the protrusion 5 is parallel from the root to the tip, or the root force is reduced toward the tip, and the shape is preferred.

The protrusion structure provided on the outer periphery of the hollow fiber membrane 3 for immersion filtration makes the adhering layer deposited on the outer surface discontinuous, and excessively on the outer surface of the adjacent hollow fiber membrane 3 for immersion filtration. It is intended to physically peel and remove the deposits by contacting them. For this reason, it is preferable that the protrusion 5 does not have deposits. Therefore, it is more preferable that the structure having a significantly reduced filtration function does not substantially have a preferable filtration function.

[0017] The width of the protrusion 5 is not particularly limited! /, But is preferably 5 1 m or more! /. This is because when the width of the protruding portion 5 is 5 m or more, deformation or breakage of the protruding portion 5 occurs due to the swinging of the submerged hollow fiber membrane 3 during filtration or mutual collision. This is because there is a tendency. Further, this is because the shape of the protruding portion 5 at the time of manufacturing the hollow fiber membrane is stable, and the productivity of the hollow fiber membrane 3 for immersion filtration tends to be good. More preferably, it is 15 111 or more.

The width of the protrusion 5 is not particularly limited, but is preferably 50 m or less. This is because by setting it to 50 πι or less, an excellent membrane surface cleaning effect tends to be expected while maintaining the effective filtration area of the hollow fiber membrane 3 for immersion filtration. More preferably, it is 40 m or less.

[0018] The distance between the protrusions 5 can be appropriately selected as necessary. In consideration of uniform cleaning of the membrane surface, the protrusions 5 are substantially equal to the outer surface of the hollow fiber membrane 3 for immersion filtration. It is preferable that they are arranged at intervals.

[0019] The height of the projection 5 is not particularly limited, but is sufficiently higher than the deposit layer deposited on the outer surface of the hollow fiber membrane 3 for immersion filtration in order to obtain an excellent membrane surface cleaning effect. I like it.

The deposit layer deposited on the outer surface of the hollow fiber membrane 3 for immersion filtration and its height are different forces S depending on the quality of the treated water S, especially in sewage drainage applications where the particle concentration in the treated water is relatively high. The height of the protrusion 5 is preferably 5 m or more. More preferably, it is on 10 μm ^ A. Further, the height of the protrusion 5 is not particularly limited, but is preferably 3 times or less the width of the root portion. This is because when the ratio is set to 3 times or less, deformation or breakage of the protrusion 5 tends to occur due to the oscillation of the hollow fiber membrane 3 for immersion filtration during filtration or mutual collision. . More preferably, it is 2 times or less.

The height of the protrusion 5 in the present invention refers to the distance from the outer surface of the hollow fiber membrane to the tip of the protrusion when the protrusion is excluded.

[0020] The hollow fiber membrane 3 for immersion filtration according to the present invention is a membrane in a portion without the projections 5 that preferably has an inner diameter of S50 to 1000 m from the viewpoint of shape stability and handleability. The thickness is preferably in the range of 5 to 300 mm.

[0021] The hollow fiber membrane 3 for immersion filtration of the present invention can be used for generally known reverse osmosis membranes, ultrafiltration membranes, microfiltration membranes and large pore membranes, but preferably limited. It can be used as an outer filtration membrane, a microfiltration membrane and a large pore membrane, and is in the range of 0.005 to 5111. Further, the material of the hollow fiber membrane 3 for immersion filtration is not particularly limited, and polysulfone, polyethersulfone, polyacrylonitrile, polyimide, polyetherimide, polyamide, polyetherketone, polyetheretherketone, polyethylene, polypropylene, poly-4-methylenepentene. Cellulose, cellulose acetate, polyvinylidene fluoride, polyethylene-tetrafluoroethylene copolymer, polytetrafluoroethylene, and the like. These composite materials can also be used.

[0022] When the protrusions 5 are polymerized later on the hollow fiber membrane having no protrusion structure, different materials may be used, but the hollow fiber membrane and the protrusions 5 In consideration of adhesion and the like, it is preferable to use the same material for each.

FIG. 2 is a diagram showing an example of an embodiment of a hollow fiber membrane module for immersion filtration using the hollow fiber membrane for immersion filtration of the present invention.

In the hollow fiber membrane module 19 for immersion filtration of the present invention in FIG. 2, a plurality of hollow fiber membranes 3 for immersion filtration are bundled in a sheet shape, and at least one end of the hollow fiber membrane 3 for immersion filtration is kept open. The force S obtained by the manufacturing method in which the hollow fiber membrane bundle is potted with the fixing resin 2 that is adhered and fixed to the housing 1 is measured. At least one end of the housing 1 is provided with a pipe that is open to the outside and communicates with an internal passage for passing a processing solution contained in the housing 1.

[0024] The hollow fiber membrane bundle used in the hollow fiber membrane module 19 for immersion filtration of the present invention may be a simple bundle of hollow fiber membranes 3 for immersion filtration. From the standpoint of performance, hollow fiber membrane bundles are wound in multiple strands on a saddle frame body, hollow fiber membranes 3 are used as weft yarns, or several knitted fabrics are laminated. What was used as the laminated body can be used conveniently. The form of these hollow fiber membrane bundles can be appropriately selected according to the hollow fiber membrane 3 for immersion filtration used.

[0025] The material of the housing 1 used in the hollow fiber membrane module 19 for immersion filtration of the present invention may be any material as long as it has mechanical strength and durability. For example, polycarbonate, polysulfone, polyolefin, PVC (polychlorinated) Bull), acrylic resin, ABS resin, modified PPE (polyphenylene ether) and the like can be used. When incineration is required after use, it is preferable to use a hydrocarbon-based resin such as polyolefin that can be completely burned without producing toxic gas by combustion.

[0026] As described above, the hollow fiber membrane 3 for immersion filtration is fixed in the housing 1 with the fixing resin 2 while the opening surface communicates with the internal path while maintaining the opening surface.

As the fixing resin 2 used here, an epoxy resin, a urethane resin, an epoxy acrylate resin, a silicon resin, various hot melt resins, and the like can be used, and can be appropriately selected.

The viscosity (20 ° C) of the fixing resin 2 during the fixing operation of the immersion filtration hollow fiber membrane 3 is not particularly limited, but the fixing resin 2 is impregnated between the plurality of immersion filtration hollow fiber membranes 3. It is preferable that the power to ease is 5000 mPa's or less. More preferably, it is 3000 mPa's or less.

[0027] As a method for potting the hollow fiber membrane bundle with the fixing resin 2 and bonding and fixing to the housing 1, a known method such as a centrifugal bonding method or a stationary bonding method is used. In order to improve the curing shrinkage and strength of the fixing resin 2, the fixing resin 2 can be made to contain a fibrous material such as glass fiber or carbon fiber, or fine powder such as carbon black, alumina or silica. Monkey. [0028] When the hollow fiber membrane module 19 for immersion filtration of the present invention is installed in an immersion filtration device and the immersion filtration is performed, an air diffuser is provided below the hollow fiber membrane module 19 for immersion filtration. Is preferred. This makes it easier for the suspended solids concentrated near the membrane surface by immersion filtration to be discharged out of the module by air publishing.

[0029] In this case, since the immersion filtration is stable for a long period of time and the physical washing of the hollow fiber membrane tends to be performed more reliably, it is preferable that the hollow fiber membrane module 19 for immersion filtration does not have a casing. It is preferable that the distance between the housings 1 at both ends is fixed by a support or the like that connects the adhesive fixing portions at both ends.

[0030] In the hollow fiber membrane module 19 for immersion filtration of the present invention, the filling rate of the hollow fiber membrane 3 for immersion filtration is 25 to 25% in order to increase the filtration capacity per volume and increase the cleaning efficiency by air publishing. A range of 70% is preferable.

In addition, in order to provide the membrane fiber hollow membrane 3 for moderate filtration with appropriate rocking performance and to obtain an excellent cleaning effect on the membrane surface, the relaxation rate force of the hollow fiber membrane 3 for membrane filtration between the housings 1 It is preferably 5% or more. On the other hand, if it is too relaxed, bending or damage of the hollow fiber membrane 3 for immersion filtration tends to occur during immersion filtration, so this relaxation rate is preferably 5% or less.

[0031] When air bubbling is performed from the lower part of the hollow fiber membrane module 19 for immersion filtration in order to obtain a physical cleaning effect by sufficiently swinging the hollow fiber membrane 3 for immersion filtration, the concentration of particles in the water to be treated For sewage drainage applications with a relatively high value, the air supply rate per projected floor area of the module is preferably 50 m ³ / m ² / h or more. On the other hand, excessive air bubbling causes bending and damage of the hollow fiber membrane 3 for immersion filtration and tends to increase energy consumption. Therefore, the air supply amount should be 200 m ³ / m ² / h or less. Is preferred

Yes

Air publishing can be performed continuously during immersion filtration. If necessary, cycle operation in which immersion filtration and air bubbling are repeated at regular intervals may be employed.

[0032] In the hollow fiber membrane module 19 for immersion filtration of the present invention, it is important that the protrusions 5 are provided on the outer surface of each hollow fiber membrane 3 for immersion filtration. Immersion by air publishing Due to the vibration of the filtration hollow fiber membrane 3, the protrusion 5 comes into contact with the deposits excessively deposited on the outer surface of the adjacent hollow fiber membrane 3 and can be effectively removed.

When the plurality of submerged filtration hollow fiber membranes 3 oscillate due to the protrusions 5, the effective filtration portions of the adjacent hollow fiber membranes are in direct contact with each other. It is possible to prevent the deposits on the film surface from being consolidated and to prevent the deposits from being firmly fixed to the fine pores of the effective filtration portion, and to effectively peel and remove the deposits on the film surface.

Further, by forming the protrusions 5, the effective filtration portions in the circumferential direction of the hollow fiber membrane can be formed discontinuously.

As a result, the deposit on the effective filtration portion also becomes discontinuous in the circumferential direction of the hollow fiber membrane, and the cohesive force between the deposits decreases, so the deposit is easily peeled and removed by air publishing etc. # One way.

[0033] The present invention can be applied to various immersion filtration methods. For example, the present invention can be used for immersion pressure filtration, but is more suitable for immersion suction filtration for a highly contaminated liquid as described above. It is a thing. The present invention can be suitably used particularly for water and sewage treatment and industrial wastewater treatment. By immersing the hollow fiber membrane module for immersion filtration of the present invention in treated water and reducing the pressure of the hollow part of the hollow fiber membrane for immersion filtration, filtered water can be obtained from the hollow part.

Example

[Example 1]

Density 0.96g / cm, Menoleto Flow Rate 1. Og / 10min high density polyethylene Novatec HD HY540 (manufactured by Nippon Polyethylene Co., Ltd.), discharge port diameter 25mm, inner ring slit width 4. Omm double pipe structure Using a hollow fiber shaping nozzle with 12 cutouts on the outer periphery, air is introduced by self-priming and melt spinning at a spinning temperature of 165 ° C and a winding speed of 70 m / min. The unstretched hollow fiber having 12 protrusions continuous in the longitudinal direction on the outer periphery was obtained.

This unstretched hollow fiber was 80% cold-drawn, then hot-stretched between slit heaters heated to 113 ° C until the total draw amount reached 600%, and further heated to the same temperature. It was made porous with a slit heater. The hollow fiber membrane thus obtained had an inner diameter of 354 m, a film thickness of 100 mm with no protrusions, a porosity of 72%, a protrusion height of 19 m, and a protrusion width of 20 m. It was.

At this time, the ratio of the projected area of the protrusion to the outer surface with respect to the outer surface of the hollow fiber membrane when the protrusion was excluded was 14%.

4800 hollow fiber membranes for immersion were bundled to produce a hollow fiber membrane module for immersion filtration having an effective membrane length of 403 mm and a membrane area of 3 m ² as shown in FIG.

At this time, the filling rate of the hollow fiber membrane in the most dense place was 60%, and the relaxation rate was 1.5%.

[0035] (Comparative Example 1)

Using a hollow fiber shaping nozzle with a discharge tube diameter of 25 mm and inner ring slit width of 4. Omm, and other conditions were the same as in Example 1, with an inner diameter of 354 mm, film thickness of 100 mm, 111, A hollow fiber membrane having no protrusions and a porosity of 72% was obtained.

This hollow fiber membrane was bundled to produce a hollow fiber membrane module for immersion filtration under the same conditions as in Example 1.

[0036] [Immersion filtration test]

Using a unit in which 20 hollow fiber membrane modules of Example 1 and Comparative Example 1 were integrated in parallel with each other at an interval of 18 mm, an immersion filtration test was conducted at a sewage treatment facility using the treatment flow shown in FIG. .

In FIG. 3, the raw water that has flowed into the screen 6 is temporarily stored in the flow rate adjusting tank 7 after the impurities are removed, and then supplied to the denitrification water tank 11 using the supply pump 8. The raw water supplied to the denitrification water tank 11 enters the membrane immersion water tank 13 via the supply pipe 15 and is circulated by the circulation pump 12 at a predetermined circulation rate.

The raw water is biologically purified by activated sludge in the denitrification water tank 11 and the membrane immersion water tank 13. Removal of nitrogen components in the raw water is performed by so-called nitrification denitrification reaction by circulating sludge between the denitrification water tank 11 and the membrane immersion tank 13. The organic matter (BOD) in the raw water is aerobically oxidized and decomposed by the air discharged mainly from the air discharge portion of the air diffuser pipe 16 disposed in the membrane immersion water tank 13.

In addition, air is always discharged from the air diffuser 16 by the blower 18, and the hollow fiber membrane module is discharged. It is also used as a physical cleaning means for the tool No. 19.

The purified water is separated from the activated sludge by membrane filtration using the hollow fiber membrane module 19. The filtered water is supplied to the membrane treatment water tank 24 by the filtration pump 22, and after being disinfected as necessary, it is discharged as treated water.

In this test, the recovery side of the treated water is intermittently sucked by the filtration pump 22 and filtered, intermittent suction filtration is adopted, and intermittent suction filtration with a filtration time of 7 minutes and a stop time of 1 minute is performed for one cycle. The operation was carried out as

Immersion filtration test: activated sludge concentration in experiment 8000mg / L, filtration flow rate per membrane area 0.23m ³ / m ² / d, air bubbling for cleaning at 120m ³ / m ² / h per projected floor area It went continuously. In addition, in the unit in which the hollow fiber membrane module of Example 1 or Comparative Example 1 was integrated, both units were operated in parallel in the same immersion water tank under the same operating conditions, and the membrane differential pressure at that time was The change of was measured. The results are shown in Fig. 4.

[0037] From FIG. 4, the unit in which the hollow fiber membrane module having the protrusion (Example 1) is integrated with the unit in which the hollow fiber membrane module having no protrusion structure (Comparative Example 1) is integrated. In comparison, the increase in membrane differential pressure is suppressed despite the same operating conditions, and by using hollow fiber membranes with protrusions on the outer surface of each hollow fiber membrane, a high concentration of suspension Even when membrane filtration is continued in the liquid, the physical cleaning effect by air publishing is enhanced, making it difficult for excessive deposits to accumulate on the membrane surface, and the operation continues without reducing water permeability. The power of S The power of S

Industrial applicability

[0038] According to the present invention, suspended substances and organic substances in raw water that do not use extra cleaning energy in the treatment of purified water, industrial water, sewage, human waste, industrial wastewater, etc. and immersion filtration in a combined septic tank, etc. A hollow fiber membrane for immersion filtration, a hollow fiber membrane module for immersion filtration, and an immersion filtration device using the same, which can reduce membrane fouling due to adhesion layers, clogging, etc. And a dipping filtration method is provided.

Claims

The scope of the claims

[I] A hollow fiber membrane for immersion filtration having one or more protrusions on the outer surface.

[2] The hollow fiber membrane for immersion filtration according to claim 1, wherein the protrusion has a continuous shape in the longitudinal direction of the hollow fiber membrane.

[3] The hollow fiber membrane for immersion filtration according to claim 1, wherein the height of the protrusion is 511 m or more.

[4] The hollow fiber membrane for immersion filtration according to claim 1, wherein the protrusion has a width of 511 m or more.

[5] The immersion filtration according to claim 1, wherein the projected area ratio of the protrusion to the outer surface of the hollow fiber membrane when the protrusion is excluded is in the range of 1 to 20%. Hollow fiber membrane.

[6] A hollow fiber membrane module for immersion filtration in which a plurality of hollow fiber membranes for immersion filtration having one or more protrusions on the outer surface are fixedly attached to a housing.

[7] An immersion filtration apparatus in which the hollow fiber membrane module for immersion filtration according to claim 6 is installed in an immersion water tank.

8. The immersion filtration device according to claim 7, further comprising an air diffuser at a lower part of the hollow fiber membrane module for immersion filtration.

[9] A hollow fiber membrane module for immersion filtration in which a plurality of hollow fiber membranes for immersion having one or more protrusions on the outer surface are bonded and fixed to the housing is filled in the water to be treated. Immersion filtration method in which filtration water is obtained from the hollow part of the hollow fiber membrane for immersion filtration.

10. The immersion filtration method according to claim 9, wherein the filtration using the hollow fiber membrane for immersion filtration is performed while air publishing from an air diffuser.

[I I] The immersion filtration method according to claim 9 or 10, wherein suction filtration using the hollow fiber membrane for immersion filtration is performed by decompressing a hollow portion of the hollow fiber membrane for immersion filtration.