JP2008259978A - Hollow fiber membrane element and hollow fiber membrane module using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow fiber membrane element in which the hollow fiber membrane can be easily cleaned.
When pressurized air is supplied from an air introduction pipe 18 into the diffuser main pipe 14, bubbles are ejected from the diffuser holes 16 of the diffuser cylinder 15. Since the hollow fiber membrane bundle 20 is vibrated from the inside by the bubbles, the dirt of the hollow fiber membranes inside the hollow fiber membrane bundle 20 is easily washed.
[Selection] Figure 1

Description

  The present invention relates to a hollow fiber membrane element used by being immersed in a biological treatment tank or the like and a hollow fiber membrane module using the same.

  The hollow fiber membrane module is often used in a state where it is immersed in a biological treatment tank or the like when used in the field of water treatment with relatively high turbidity. In the case of such an immersion filtration type hollow fiber membrane module, there is a problem that, when filtration is continued, dirt due to suspended matter (SS) or the like adheres to the membrane surface and the filtration performance deteriorates. .

  Conventionally, dirt attached to the film surface is removed by air bubbling from below the film. However, dirt on the surface of the hollow fiber membrane positioned outside the hollow fiber membrane bundle is easy to remove, but dirt on the surface of the hollow fiber membrane inside the hollow fiber membrane bundle is difficult to remove, so air bubbling alone is sufficient. Recovery of filtration performance was difficult.

Patent Document 1 discloses an immersion filtration type hollow fiber membrane cartridge. In this hollow fiber membrane cartridge, a plurality of through holes 3c are formed in the adhesive fixing layer 3b on the lower side of the hollow fiber membrane bundle, and the hollow fiber membranes are washed by vibration caused by bubbles released from the through holes 3c. It is like that.
JP 2005-342690 A JP 2006-239642 A JP 2003-326140 A

  In the hollow fiber membrane modules of Patent Documents 1 and 2, the air supply unit and the hollow fiber membrane are mixed in the lower fixing part, but it is difficult to generate fine bubbles and the cleaning effect is not sufficient.

  Furthermore, in the module of Patent Document 2, an air supply pipe and an ejection hole are provided in the lower fixing part. In such a module, an air supply pipe and an ejection hole are processed in the adhesive layer of the fixing part. More man-hours and higher processing costs.

  The present invention has a simple structure, can wash the entire hollow fiber membrane bundle constituting the hollow fiber membrane bundle, can easily recover the filtration performance, and when applied to a biological treatment tank, aeration It is an object of the present invention to provide a hollow fiber membrane element and a hollow fiber membrane module using the same, in which both cleaning by aeration and aeration can be performed in parallel.

  As a means for solving the problem, the invention of claim 1 is a hollow fiber membrane element in which a number of hollow fiber membranes are arranged around a support tube, and the support tube also serves as a diffuser tube. A hollow fiber membrane element is provided.

  In the hollow fiber membrane element having a support tube, by making the support tube also serve as an air diffuser having an air diffusion function, there is no need to provide a separate air diffuser, and air is diffused from inside the hollow fiber membrane element. The cleaning effect is enhanced, and aeration can be performed simultaneously with cleaning by aeration or separately from cleaning by aeration.

  The invention of claim 2 is a hollow fiber membrane element in which a number of hollow fiber membranes are arranged around a support tube as a means for solving the problem, wherein the support tube includes an outer air diffuser tube and an air diffuser tube. The immersion filtration type hollow fiber membrane element according to claim 1, which has a double pipe structure having a water collecting pipe disposed therein.

  In this way, the support tube that supports a large number of hollow fiber membranes (hollow fiber membrane bundles) has a double structure consisting of an air diffuser tube and a water collecting tube, so that air diffuses (air bubbling) from the inside to the outside of the hollow fiber membrane bundle. Therefore, it becomes easy to remove the dirt of the entire hollow fiber membranes constituting the hollow fiber membrane bundle.

  Invention of Claim 3 provides the hollow fiber membrane element of the immersion filtration system of Claim 1 in which the diffuser cylinder which has a large number of pores is connected to the non-porous main pipe. .

  By adjusting the attachment position of the diffuser cylinder, air can be diffused from a desired position (both ends, the central part, or other positions). The connection between the non-porous tube and the scattering cylinder may be a screwing method, a fitting method, or the like with a sealing material interposed as necessary. Using such a diffuser cylinder makes it easy to adjust the position to diffuse by changing the installation position of the diffuser cylinder, and adjusting the diffuser amount by selecting and using a diffuser cylinder with a different number of pores Becomes easier.

  According to a fourth aspect of the present invention, there is provided the submerged filtration type hollow fiber membrane element according to the first aspect, wherein the air diffuser has a large number of pores in at least a part of the peripheral surface.

  A large number of pores serving as the diffuser pores may be formed evenly in all or part of the diffuser tube, or the density of the pores (ie, the number of pores per unit area) may be partially different. It may be formed.

  According to a fifth aspect of the present invention, in the diffuser pipe, a stretchable porous member is coated around a metal or plastic main pipe having a large number of pores in at least a part of a peripheral surface thereof. A hollow fiber membrane element of the immersion filtration system according to 1, is provided.

  The stretchable porous member has no visible hole in a normal state (a state where no pressure is applied), but when the pressure is applied, the stretchable porous member itself expands to open a fine hole. Therefore, when the air supplied into the main pipe is ejected from the fine pores, the stretchable porous member covering the main pipe expands to form fine pores, and air (bubbles) is ejected from the fine holes. .

  As a stretchable porous member, a rubber or resin sheet-like member provided with a large number of fine holes can be used. It is particularly preferable to use a rubber membrane made of a thin rubber film.

  According to a sixth aspect of the present invention, there is provided the immersion filtration type hollow fiber membrane element according to the first aspect, wherein the air diffuser is a cylindrical stretchable porous member.

  Thus, the whole can be reduced in weight by covering a cylindrical elastic porous member around a water collection pipe | tube. In this case, the hollow fiber membrane bundle is substantially supported by the water collecting pipe.

  In the invention according to claim 7, both ends of the support tube and both ends of the multiple hollow fiber membranes are fixed to the upper water collecting cap and the lower water collecting cap, respectively, and water is collected from both ends. A hollow fiber membrane element of the immersion filtration type according to any one of the above.

  When water is collected from both ends, the water collection efficiency (the amount of filtration per unit time) is increased, but dirt is attached to the entire length of the hollow fiber membrane bundle. However, in the present invention, the support tube has a double structure of a diffuser tube and a water collecting tube, and can diffuse air from the inside to the outside of the hollow fiber membrane bundle, so that the entire hollow fiber membrane bundle can be easily washed and the filtration performance Recovery is easy.

The invention of claim 8 is a hollow fiber membrane module of an immersion filtration system comprising a plurality of hollow fiber membrane elements according to any one of claims 2 to 7 as a means for solving other problems,
The water collecting pipes of the plurality of hollow fiber membrane elements are connected to one or more water collecting main pipes,
Provided is an immersion filtration type hollow fiber membrane module in which the air diffuser pipes of the plurality of hollow fiber membrane elements are connected to an air supply pipe.

  Since the hollow fiber membrane module of the present invention uses a plurality of the above-described hollow fiber membrane elements, for example, when immersed in a biological treatment tank and subjected to filtration operation, the hollow fiber membrane module is removed from the support tube of the hollow fiber membrane element. Since the inside of the tank can be aerated by aeration and the hollow fiber membrane bundle can be cleaned in parallel, the filtration efficiency is very high.

  The invention of claim 9 provides a hollow fiber membrane module of the immersion filtration type according to claim 8, wherein the plurality of hollow fiber membrane elements are supported by a frame. By supporting the frame, the strength of the module is increased.

  The invention of claim 10 is characterized in that the plurality of hollow fiber membrane elements are detachably connected to the water collection main pipe and the air supply pipe at least at the upper end side, and the collection of the plurality of hollow fiber membrane elements is provided. The immersion filtration type hollow fiber membrane module according to claim 8 or 9, wherein a water pipe and a diffuser pipe are respectively connected to the water collection main pipe and the air supply pipe.

  By making the hollow fiber membrane element detachable, it is only necessary to connect or remove the hollow fiber membrane element at the time of installation work or replacement work, which facilitates the work.

  The invention of claim 11 is any one of claims 8 to 10, wherein the air diffuser pipes of the plurality of hollow fiber membrane elements are connected to an air supply pipe via an air introduction pipe connected to the air diffuser pipe. An immersion filtration type hollow fiber membrane module according to item 1 is provided. .

  In the hollow fiber membrane element of the present invention, since a uniform flow is generated between the hollow fiber membranes, the amount of cake is reduced and the filtration performance is improved.

  Further, the hollow fiber membrane element of the present invention is suitable for both cleaning and aeration by aeration because the hollow fiber membrane can be easily cleaned, the filtration performance can be easily recovered, and the bubble diameter to be diffused can be controlled. is there.

  The hollow fiber membrane module using the hollow fiber membrane element of the present invention can perform a stable filtration operation for a long period of time.

<Hollow fiber membrane element>
(1) Hollow fiber membrane element of FIG. 1 FIG. 1 is a longitudinal sectional view of a hollow fiber membrane element 10A which is an embodiment of the present invention.

  The hollow fiber membrane element 10 </ b> A has a large number of hollow fiber membranes (hollow fiber membrane bundles) 20 arranged around the support tube 11.

  The support tube 11 has a double tube structure having an outer diffuser tube 12 and a water collecting tube 13 disposed inside the diffuser tube 12. The air diffuser 12 and the water collecting tube 13 are made of metal, plastic, or a combination thereof.

  The air diffuser 12 has a diffuser cylinder 15 having a large number of pores (air diffuser holes) 16 connected to one end of an air diffuser main pipe 14 having no holes. As the dust cylinder 15, a known porous cylinder can be used, and for example, one made of a synthetic resin such as ABS resin described in JP-A-8-155484, or one made of ceramics can be used.

  The diffuser main pipe 14 and the diffuser cylinder 15 are detachably connected by a screwing method or a fitting method. The opening direction of the air diffusion holes 16 is not particularly limited, and may be any of a direction facing the hollow fiber membrane bundle 20, a diagonally upward direction, a diagonally downward direction, and a direction in which these directions are mixed. An air introduction pipe 18 for introducing air into the diffusion pipe 12 from the outside is connected to the upper end side of the diffusion main pipe 14.

The diameter and density (the number of holes per unit area) of the fine holes (aeration holes) 16 of the diffusion cylinder 15 can be appropriately set in consideration of the number of hollow fiber membranes constituting the hollow fiber membrane bundle 20 and the like. For example, the diameter can be in the range of 0.01 to 1 mm, and the density can be in the range of 100 to 10,000 pieces / cm ² .

The water collecting pipe 13 is disposed such that the central axis in the length direction thereof coincides with the central axis of the diffuser main pipe 14. The ratio of the outer diameter (d ₁ ) of the water collecting pipe 13 and the inner diameter (d ₂ ) of the diffuser main pipe 14 is not particularly limited, and d ₁ / d ₂ is in the range of 0.2 to 0.8. Can be. The outer diameter of the diffuser main pipe 14 can be about 10 to 30 mm.

  The hollow fiber membranes constituting the hollow fiber membrane bundle 20 are publicly known, one having an outer diameter of about 1 to 3 mm, an inner diameter of about 0.5 to 2 mm, and a length of 30 to 300 cm per one hollow fiber membrane element. Several hundreds can be used.

  The upper ends of the hollow fiber membrane bundle 20, the diffuser main pipe 14 and the water collecting pipe 13 are fixed and integrated in the upper ring 32 with a resin 33 such as urethane resin or epoxy resin. An upper water collecting cap 31 is screwed around the upper ring 32 so as to be integrated. The ends of the hollow fiber membrane bundle 20 facing the inside of the upper water collecting cap 31 and the water collecting pipe 13 are opened, and the diffuser main pipe 14 is sealed with the resin 33 and is not opened.

  The lower ends of the hollow fiber membrane bundle 20, the diffuser main pipe 14, and the water collecting pipe 13 are fixed and integrated in a lower ring 42 with a resin 43 such as urethane resin or epoxy resin. A lower water collecting cap 41 is screwed around the lower ring 42 so as to be integrated. The ends of the hollow fiber membrane bundle 20 and the water collecting pipe 13 facing the lower water collecting cap 41 are opened, and the diffuser main pipe 14 is sealed with the resin 43 and is not opened.

  Such a fixing method using the resins 33 and 43 applies a known hollow fiber membrane bundle resin sealing method, and seals both ends of the hollow fiber membrane bundle 20, the diffuser main pipe 14 and the water collecting pipe 13 with resin. After stopping, a method of cutting and opening both ends of the hollow fiber membrane bundle 20 and the water collecting pipe 13 can be applied.

  The inside of the upper cap 31 is an upper water collecting chamber 35 and is connected to the water collecting main through a communication pipe 36 when used. The lower cap 41 is a lower water collecting chamber 45.

(2) Hollow fiber membrane element of FIG. 2 FIG. 2 is a longitudinal sectional view of a hollow fiber membrane element 10B according to another embodiment of the present invention. The hollow fiber membrane element 10A in FIG. 1 has the same structure except for a part. Only different parts will be described below.

  The support tube 11 has a double tube structure having an outer diffuser tube 12 and a water collecting tube 13 disposed inside the diffuser tube 12. The air diffuser 12 and the water collecting tube 13 are made of metal, plastic, or a combination thereof.

  The air diffuser 12 has a large number of air diffusers 16 only on the lower end side, and the air diffuser 15 in FIG. 1 is not used. The air diffuser 16 may also be formed in other parts (the center part and the upper end part) of the air diffuser 12.

  One end side of the air introduction pipe 18 penetrates the resin 33 and communicates with the diffuser pipe 12, and the other end side penetrates the curved surface portion of the upper water collecting cap 31. In the case of this embodiment, the width of the hollow fiber membrane element 10B including the air introduction tube 18 is made narrower than the configuration in which the air introduction tube 18 is extended in the lateral direction as in the hollow fiber membrane element 10A of FIG. be able to.

  The upper end side of the air diffusing tube 12 is connected to the upper adapter 17a, and the lower end side of the air diffusing tube 12 is connected to the lower adapter 17b. Each connecting portion is detachably connected by a screwing method or a fitting method. An air introduction pipe 18 that introduces air into the diffusion pipe 12 from the outside is connected to the upper end side of the diffusion pipe 12.

  The upper end side of the upper adapter 17 a is fixed and integrated with the resin 33 together with the upper end side of the hollow fiber membrane bundle 20 and the water collecting pipe 13. The lower end side of the lower adapter 17 b is fixed and integrated with the resin 43 together with the hollow fiber membrane bundle 20 and the lower end side of the water collecting pipe 13.

(3) Hollow fiber membrane element of Fig. 3 Fig. 3 is a longitudinal sectional view of a hollow fiber membrane element 10C which is still another embodiment of the present invention. The hollow fiber membrane element 10A in FIG. 1 has the same structure except for a part. Only different parts will be described below.

  The support tube 11 has a double tube structure having an outer diffuser tube 12 and a water collecting tube 13 disposed inside the diffuser tube 12. The air diffuser 12 and the water collecting tube 13 are made of metal, plastic, or a combination thereof.

  The air diffuser 12 includes a rubber membrane 19 and a support tube 12a ′ for supporting the rubber membrane 19, and the cylindrical rubber membrane 19 is in close contact with the surface of the support tube 12a ′ having a large number of ventilation holes 16 over the entire surface. It is covered. Both ends of the rubber membrane 19 are fixed to the upper adapter 17a and the lower adapter 17b.

  The rubber membrane does not have a visible hole in a normal state (a state in which no pressure is applied), but when subjected to pressure, the rubber membrane itself expands to form a fine hole. As such a rubber membrane, there are fine holes in a stretchable rubber sheet as disclosed in JP-A-2006-75771, JP-A-2007-14898, JP-A-2004-33889, and the like. Can be used.

(4) Hollow fiber membrane element of FIG. 4 FIG. 4 is a longitudinal sectional view of a hollow fiber membrane element 10D which is still another embodiment of the present invention. The structure is similar to that of the hollow fiber membrane element 10C in FIG. 3, and different portions will be mainly described.

  The support tube 11 has a double tube structure having an outer rubber membrane 19 (corresponding to the diffuser tube 12 in FIG. 3) and a water collecting tube 13 disposed therein. The water collection pipe 13 is made of metal, plastic, or a combination thereof. The rubber membrane 19 is placed in close contact with the surface of the water collection tube 13. Both ends of the rubber membrane 19 are fixed to the upper adapter 17a and the lower adapter 17b.

  In the present embodiment, the water collection pipe 13 also serves as a support pipe 12 'in the hollow fiber membrane element 10C. Since the rubber membrane 19 serving as the air diffuser is expanded and opened by pressurization, and since the rubber membrane 19 is in close contact with the water collecting tube 13, the outer diameter of the air diffuser 12 in the hollow fiber membrane element 10C is larger. Can be reduced. For this reason, when the membrane elements have the same outer diameter, the filling rate of the hollow fiber membrane is higher than that of the hollow fiber membrane element 10C.

<Hollow fiber membrane module>
FIG. 5 is a front view of the hollow fiber membrane module 100. Although the hollow fiber membrane element 10A is used in FIG. 5, hollow fiber membrane elements 10B, 10C, and 10D may be used.

  A total of 12 hollow fiber membrane elements 10A (6 are not visible from the front side on the opposite side) are attached to the frame 101. The shape and structure of the frame body 101 are not particularly limited as long as the hollow fiber membrane element 10A can be fixed and held.

  The air introduction pipes 18 communicated with the air diffusion pipes 12 of the hollow fiber membrane element 10A are connected to two air supply pipes 105 (one is not visible from the front on the opposite side). Are connected to two water collecting main pipes 106 (one is not visible from the front on the opposite side) via the upper water collecting cap 31 and the communication pipe 36.

  Although the shape and structure of the communication pipe 36 are not particularly limited, for example, a structure including a socket part 71 and a stud part 72 as shown in FIG. 6 can be used. The socket part 71 and the stud part 72 are detachable, and when combined, a through-hole through which liquid can pass is formed in the length direction. As such a socket part 71 and the stud part 72, a brand name one-touch socket (made by Wamoto Co., Ltd.) etc. can be used, for example. This is a so-called one-touch type, and can be easily attached or removed with one hand, so the membrane element can be easily replaced.

  The socket part 71 has a screw hole part 71 a and is connected by screwing the screw hole part 71 a into a screw hole formed in the upper water collecting cap 31. The stud portion 72 has a screw hole portion 72a, and the screw hole portion 72a is connected by being screwed into the screw holes respectively included in the water collecting main pipe 106.

  The communication pipe 36 is formed by fitting the stud portion 72 into the socket portion 71 so as to be integrated, and the integrated socket portion 71 and the stud portion 72 are rotatable, and the stat portion 72 can be easily removed from the socket portion 71. Therefore, the replacement work or the like of the hollow fiber membrane element 10A becomes easy.

  Next, in the hollow fiber membrane module 100 of FIG. 5, operation | movement at the time of using the hollow fiber membrane element 10A, 10B, 10C, 10D shown in FIGS. 1-4 is demonstrated.

(1) Embodiment using the hollow fiber membrane element 10A of FIG. 1 or the hollow fiber membrane element 10B of FIG. 2 The hollow fiber membrane module 100 is used by being immersed in a biological treatment tank. The pump connected to the permeated water line is operated, and suction filtration is performed from the upper cap 31 side of the hollow fiber membrane element 10A (or hollow fiber membrane element 10B).

  The permeated water filtered by the hollow fiber membrane bundle 20 flows into the upper water collecting chamber 35 and the lower water collecting chamber 45 located at both ends of the hollow fiber membrane bundle 20. The permeated water that has flowed into the upper water collecting chamber 35 passes through the communication pipe 36 and moves into the water collecting main pipe 106 and is sent to the permeated water line. The permeated water that has flowed into the lower water collecting chamber 45 flows into the upper water collecting chamber 35 through the water collecting pipe 13, and then moves into the water collecting main pipe 106 through the communication pipe 36. Sent to the line.

  In such a filtration operation, aeration is performed to clean the membrane surface (that is, to suppress the amount of filtration cake formed on the membrane surface). Moreover, the filter cake formed at the time of filtration is removed while using back pressure washing performed with the filtration stopped. The air diffuser supplies air to each air introduction pipe 18 in a pressurized state from an air supply pipe 105 connected to an air source. In the case of the hollow fiber membrane element 10A of FIG. 1, air is ejected from the air diffuser 16 of the diffuser cylinder 15, and in the case of the hollow fiber membrane element 10B of FIG. 2, air is ejected from the air diffuser 16 of the diffuser tube 12. . The ejected bubbles (air) move from the inner side to the outer side and from the lower side to the upper side of the hollow fiber membrane bundle 20, so that the entire hollow fiber membrane bundle 20 is vibrated and the hollow fiber membrane bundle 20 When the foam comes into contact with the hollow fiber membrane constituting the membrane, the membrane surface is removed.

  In addition to the cleaning of the membrane surface or in parallel with the cleaning of the membrane surface, the aeration tube 12 can perform aeration for the purpose of aeration of the biological treatment tank.

(2) Embodiment using the hollow fiber membrane element 10C of FIG. 3 The filtration operation method is the same as that of the embodiment using the hollow fiber membrane element 10A of FIG. 1 or the hollow fiber membrane element 10B of FIG. Only the state is different.

  The air diffuser supplies air to each air introduction pipe 18 in a pressurized state from an air supply pipe 105 connected to an air source. The air supplied to the support pipe 12 'is ejected from the vent hole 16, whereby the rubber membrane 19 is expanded. Thereby, a large number of fine holes are opened in the rubber membrane 19, fine bubbles are ejected therefrom, and the film surface is washed.

(3) Embodiment using the hollow fiber membrane element 10D of FIG. 4 The filtration operation method is the same as the embodiment using the hollow fiber membrane element 10C of FIG. 3, and only the air diffused state is different.

  When air is diffused, air is supplied from the air supply pipe 105 connected to the air source to each air introduction pipe 18 in a pressurized state. The air supplied to the air introduction pipe 18 is supplied between the water collection pipe 13 and the rubber membrane 19 through a hole provided in the rubber membrane 19 at the connection portion between the air introduction pipe 18 and the rubber membrane 19. Inflates. Thereby, many fine holes are opened in the rubber membrane 19, and fine bubbles are ejected therefrom.

The longitudinal end view of the hollow fiber membrane element of this invention. The longitudinal end view of the hollow fiber membrane element of the present invention which is another embodiment. Furthermore, the longitudinal end view of the hollow fiber membrane element of this invention which is another embodiment. Furthermore, the longitudinal end view of the hollow fiber membrane element of this invention which is another embodiment. The front view of the hollow fiber membrane module of this invention. The front view of one component in FIG.

Explanation of symbols

10A, 10B, 10C, 10D Hollow fiber membrane element 11 Support tube 12 Air diffuser tube 13 Water collecting tube 16 Ventilation hole 17a, 17b Adapter 18 Air introduction tube 20 Hollow fiber membrane bundle 31 Upper water collecting cap 35 Upper water collecting chamber 41 Lower water collecting chamber Cap 45 Lower catchment chamber

Claims (11)

  A hollow fiber membrane element in which a number of hollow fiber membranes are arranged around a support tube, wherein the support tube also serves as an air diffusion tube.   A hollow fiber membrane element in which a number of hollow fiber membranes are arranged around a support tube, wherein the support tube has an outer air diffuser tube and a water collecting tube disposed inside the air diffuser tube The hollow fiber membrane element of the immersion filtration system according to claim 1, wherein   2. The immersion filtration type hollow fiber membrane element according to claim 1, wherein the air diffuser tube is formed by connecting a diffuser cylinder having a large number of pores to a non-porous main tube.   2. The immersion filtration type hollow fiber membrane element according to claim 1, wherein the air diffuser has a large number of pores in at least a part of a peripheral surface thereof.   The immersion filtration system according to claim 1, wherein the diffuser tube is a metal or plastic main tube having a large number of pores on at least a part of a peripheral surface thereof and covered with a stretchable porous member. Hollow fiber membrane element.   The hollow fiber membrane element of the immersion filtration system according to claim 1, wherein the air diffuser is a cylindrical stretchable porous member.   The both ends of a support tube and the both ends of many hollow fiber membranes are being fixed to the upper water collection cap and the lower water collection cap, respectively, and water is collected from both ends side, The any one of Claims 1-6. Hollow fiber membrane element of the immersion filtration method. A hollow fiber membrane module of an immersion filtration method comprising a plurality of hollow fiber membrane elements according to any one of claims 2 to 7,
The water collecting pipes of the plurality of hollow fiber membrane elements are connected to one or more water collecting main pipes,
An immersion filtration type hollow fiber membrane module in which a diffuser pipe of the plurality of hollow fiber membrane elements is connected to an air supply pipe.   9. The immersion filtration type hollow fiber membrane module according to claim 8, wherein the plurality of hollow fiber membrane elements are supported by a frame.   The plurality of hollow fiber membrane elements are detachably connected to the water collection main pipe and the air supply pipe at least on the upper end side, and the water collection pipe and the air diffusion pipe of the plurality of hollow fiber membrane elements are respectively The hollow fiber membrane module of the immersion filtration system according to claim 8 or 9, which is communicated with the water collecting main pipe and the air supply pipe. The immersion filtration according to any one of claims 8 to 10, wherein the air diffusion pipes of the plurality of hollow fiber membrane elements are connected to an air supply pipe via an air introduction pipe connected to the air diffusion pipe. Type hollow fiber membrane module.

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