Membrane filtration equipment and biological treatment systems

Abstract

The present invention relates to a membrane filtration device and a biological treatment system that can prevent impurities from clogging the inside of a hollow fiber membrane bundle and improve filtration efficiency. [Solution] The device comprises a hollow fiber membrane bundle consisting of a plurality of cylindrical hollow fiber membranes, a first support member supporting one end of the hollow fiber membrane bundle, and a gap-forming member provided closer to the other end of the hollow fiber membrane bundle than the first support member, and the hollow fiber membrane bundle has an outer diameter at the location where the gap-forming member is provided that is larger than the outer diameter at the location supported by the first support member.

Description

[Technical Field]

[0001] The present invention relates to a membrane filtration device and a biological treatment system. [Background technology]

[0002] Conventionally, hollow fiber membrane modules have been known that include a plurality of hollow fiber membranes, a binding section that bundles one end of the plurality of hollow fiber membranes, a sealing section that seals the other end of the plurality of hollow fiber membranes, and a housing that accommodates the plurality of hollow fiber membranes, the binding section, and the sealing section (Patent Document 1, etc.). The hollow fiber membrane module described in Patent Document 1 is configured so that a raw liquid contained in the housing is filtered (separated into a permeate and impurities) by permeating through the hollow fiber membranes. The permeate flows inside the hollow fiber membranes and is supplied to the outside of the hollow fiber membrane module. Meanwhile, the impurities remain attached to the surface of the hollow fiber membranes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-049414 Summary of the Invention [Problem to be solved by the invention]

[0004] In the hollow fiber membrane module described in Patent Document 1, multiple hollow fiber membranes are closely packed together, which causes a problem that impurities become clogged inside the hollow fiber membrane bundle made up of multiple hollow fiber membranes, resulting in reduced filtration efficiency.

[0005] The present invention relates to a membrane filtration device and a biological treatment system that can prevent impurities from clogging the inside of a hollow fiber membrane bundle and improve filtration efficiency. [Means for solving the problem]

[0006] The membrane filtration device of the present invention comprises a hollow fiber membrane bundle consisting of a plurality of cylindrical hollow fiber membranes, a first support member supporting one end of the hollow fiber membrane bundle, and a gap-forming member provided closer to the other end of the hollow fiber membrane bundle than the first support member, and the hollow fiber membrane bundle has an outer diameter at the location where the gap-forming member is provided that is larger than the outer diameter at the location supported by the first support member.

[0007] The membrane filtration device according to the present invention may further include a second support member that supports the other end of the hollow fiber membrane bundle, and the hollow fiber membrane bundle may have an outer diameter at the portion where the gap-forming member is provided that is larger than the outer diameters at the portion supported by the first support member and the portion supported by the second support member.

[0008] The membrane filtration device of the present invention may further include an axial member provided inside the hollow fiber membrane bundle and between the first support member and the second support member, and the gap forming member may be attached to an axial midpoint of the axial member and configured to form a gap inside the hollow fiber membrane bundle.

[0009] In the membrane filtration device of the present invention, the gap forming member is formed in a ring shape having a through hole in the center through which the axial member can be inserted, and a plurality of openings may be formed at intervals in the circumferential direction between the outer edge and the inner edge of the gap forming member.

[0010] The biological treatment system according to the present invention includes a biological treatment tank, the membrane filtration device provided inside the biological treatment tank, and a gas supply unit capable of supplying gas into the inside of the biological treatment tank. [Effects of the Invention]

[0011] According to the membrane filtration device and biological treatment system of the present invention, clogging of the hollow fiber membrane bundle with impurities can be suppressed, and filtration efficiency can be improved. [Brief explanation of the drawings]

[0012] [Figure 1]1 is a schematic diagram showing a biological treatment system according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing a membrane filtration device according to an embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA' in FIG. [Figure 4] FIG. 2 is an enlarged perspective view showing a part of the membrane filtration device according to the present embodiment. [Figure 5] FIG. 2 is an exploded perspective view showing the gap forming member according to the embodiment. [Figure 6] FIG. 1 is a schematic diagram showing a biological treatment process according to an embodiment of the present invention. [Figure 7] FIG. 10 is a schematic diagram showing a membrane filtration device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments for carrying out the present invention will be described below with reference to the drawings. Note that the following embodiments do not limit the inventions according to the claims, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. Furthermore, in the present embodiments, the scale and dimensions of each component may be exaggerated, and some components may be omitted.

[0014] [Membrane filtration equipment applications] The membrane filtration device according to this embodiment can be applied to known water treatment systems, such as a biological treatment system that treats a liquid to be treated using microorganisms, or a solid-liquid separation system that separates a liquid to be treated into solid and liquid by flotation separation, precipitation separation, etc. In this embodiment, a case where the membrane filtration device is applied to a biological treatment system will be described as an example.

[0015] [Overall configuration of biological treatment system] As shown in Figure 1, the biological treatment system 1 includes a raw water storage tank 10 for storing raw water, a biological treatment tank 20 for biologically treating the raw water, a membrane filtration device 30 installed inside the biological treatment tank 20, a gas supply unit 40 capable of supplying gas to the inside of the biological treatment tank 20, and a treated water storage tank 50 for storing treated water obtained in the biological treatment tank 20.

[0016] The biological treatment system 1 also includes a raw water supply pipe 2 for supplying raw water from a raw water source (not shown) to the raw water storage tank 10, a raw water transfer pipe 3 for transferring the raw water stored in the raw water storage tank 10 to the biological treatment tank 20, a gas supply pipe 4 for supplying gas from the gas supply unit 40 to the biological treatment tank 20, a treated water transfer pipe 5 (axial member 37 described later) for transferring the treated water obtained in the biological treatment tank 20 to the treated water storage tank 50, and a treated water supply pipe 6 for supplying the treated water stored in the treated water storage tank 50 to a supply destination (not shown).

[0017] The raw water storage tank 10, the biological treatment tank 20, and the treated water storage tank 50 are each containers having a storage space capable of storing liquid. The biological treatment tank 20 is configured to generate treated water by treating the stored raw water using microorganisms. The microorganisms may be aerobic or anaerobic. A known blower, for example, can be used as the gas supply unit 40. The configuration of the membrane filtration device 30 will be described later.

[0018] The upstream end of the raw water supply pipe 2 is connected to the raw water source, and the downstream end is inserted through the raw water storage tank 10 and installed within the raw water storage tank 10. The upstream end of the raw water transfer pipe 3 is inserted through the raw water storage tank 10 and installed within the raw water storage tank 10, and the downstream end is inserted through the biological treatment tank 20 and installed within the biological treatment tank 20. The upstream end of the gas supply pipe 4 is connected to the gas supply unit 40, and the downstream end is inserted through the biological treatment tank 20 and connected to a lower swirl flow generating unit 33 (described later) of the membrane filtration device 30. The upstream end of the treated water transfer pipe 5 (shaft member 37 (described later)) is inserted through the biological treatment tank 20 and connected to a permeate storage space 36a (described later) of the membrane filtration device 30, and the downstream end is inserted through the treated water storage tank 50 and installed within the treated water storage tank 50. The treated water supply pipe 6 has an upstream end that passes through the treated water storage tank 50 and is provided inside the treated water storage tank 50, and a downstream end that is connected to a supply destination.

[0019] Examples of raw water include domestic wastewater, sewage from toilets, rainwater, surface water, groundwater, drain water from electrical and mechanical equipment such as air conditioners and dehumidifiers, and condensation generated by mobile objects and structures. Destinations of supply include users who use the treated water as drinking water, water for daily use in commercial facilities and homes, toilet flushing water, and watering gardens, roads, and parks, as well as other water treatment devices or water treatment systems for further water treatment of the treated water. The biological treatment system 1 may be configured without the raw water supply pipe 2 and the treated water supply pipe 6.

[0020] The connections with each pipe are configured to be airtight in the raw water storage tank 10, the biological treatment tank 20, and the treated water storage tank 50. Therefore, the storage spaces of the raw water storage tank 10, the biological treatment tank 20, and the treated water storage tank 50 are each airtight spaces.

[0021] The supply of raw water from the raw water source to the raw water storage tank 10 may be carried out by pressurizing the raw water using a pump (not shown), or by creating a negative pressure inside the raw water storage tank 10 using a negative pressure generator (not shown) such as a suction blower, and utilizing the internal pressure difference between the raw water source and the raw water storage tank 10. The same applies to the transfer of raw water from the raw water storage tank 10 to the biological treatment tank 20 and the supply of treated water from the treated water storage tank 50 to the destination. The transfer of treated water from the biological treatment tank 20 to the treated water storage tank 50 is carried out by creating a negative pressure inside the treated water storage tank 50 using the above-mentioned negative pressure generator, and utilizing the internal pressure difference between the biological treatment tank 20 and the treated water storage tank 50.

[0022] [Configuration of membrane filtration equipment] 1 to 5, the membrane filtration device 30 includes a tubular member 31 extending in the vertical direction, an upper swirl flow generating section 32 provided above the tubular member 31, and a lower swirl flow generating section 33 provided below the tubular member 31. The membrane filtration device 30 also includes a hollow fiber membrane bundle 34 consisting of a plurality of tubular hollow fiber membranes 34a, a first support member 35 supporting one end of the hollow fiber membrane bundle 34, a second support member 36 supporting the other end of the hollow fiber membrane bundle 34, a shaft member 37 provided between the first support member 35 and the second support member 36, and a gap forming member 38 provided closer to the other end of the hollow fiber membrane bundle 34 than the first support member 35.

[0023] The tubular member 31 is formed in a cylindrical shape with open upper and lower ends. As a result, the tubular member 31 is configured to be able to form a circulation flow path that circulates a fluid between the internal space of the tubular member 31 and the external space. In this embodiment, the downstream end of the gas supply pipe 4 is connected to the lower swirling flow generating unit 33, and gas is released into the internal space of the tubular member 31 via the lower swirling flow generating unit 33. As a result, the fluid circulates through the circulation flow path by rising in the internal space of the tubular member 31 and flowing out from the upper end of the tubular member 31 into the external space of the tubular member 31, and then descending in the external space of the tubular member 31 and flowing into the internal space of the tubular member 31 from the lower end of the tubular member 31.

[0024] The downstream end of the gas supply pipe 4 may be inserted through the biological treatment tank 20 and provided in the external space of the tubular member 31, so that the gas is released into the external space of the tubular member 31. In this case, the fluid circulates through the circulation flow path by rising in the external space of the tubular member 31 and flowing into the internal space of the tubular member 31 from the upper end of the tubular member 31, and then descending in the internal space of the tubular member 31 and flowing out from the lower end of the tubular member 31 into the external space of the tubular member 31.

[0025] The upper swirl flow generating section 32 is configured to generate a swirling flow in the flow from the internal space of the tubular member 31 toward the external space. Specifically, the upper swirl flow generating section 32 has a plurality of blades 32a provided at predetermined intervals in the circumferential direction of the tubular member 31, and is configured to generate a swirling flow in the flow from the internal space of the tubular member 31 toward the external space by causing a fluid to flow between the blades 32a. Each blade 32a is formed in a wall shape extending along the radial direction of the tubular member 31 and is curved in the circumferential direction of the tubular member 31. Furthermore, each blade 32a is configured to be non-rotatable.

[0026] The lower swirl flow generating section 33 is configured to generate a swirling flow in the flow from the external space to the internal space of the cylindrical member 31. Specifically, the lower swirl flow generating section 33 has a plurality of blades 33a provided at predetermined intervals in the circumferential direction of the cylindrical member 31, and is configured to generate a swirling flow in the flow from the external space to the internal space of the cylindrical member 31 by causing a fluid to flow between the blades 33a. Each blade 33a is formed in a wall shape extending along the radial direction of the cylindrical member 31 and is curved in the circumferential direction of the cylindrical member 31. Furthermore, each blade 33a is configured to be non-rotatable.

[0027] The upper swirl flow generating section 32 and the lower swirl flow generating section 33 have such a configuration, so that a spiral swirl flow can be generated simply by flowing a fluid between the blades (blade 32a and blade 33a), and the swirl flow can remove impurities adhering to the surface of the hollow fiber membrane 34a. Furthermore, because the blades (blade 32a and blade 33a) are configured to be non-rotatable, the cost of installing a motor, the power cost for the blades (blade 32a and blade 33a), and the cost of replacing parts can be reduced.

[0028] Furthermore, when the microorganisms performing biological treatment are aerobic microorganisms, the following advantage is also obtained. That is, the swirling flow promotes agitation of the fluid and improves the dissolution efficiency of gas released into the biological treatment tank 20, thereby improving the efficiency of raw water treatment by the aerobic microorganisms. In addition, even if the raw water contains foreign matter (solid matter) such as hair, the impellers (impeller 32a and impeller 33a) can shear and break down the foreign matter, further improving the efficiency of raw water treatment by the aerobic microorganisms.

[0029] In addition, when the downstream end of the gas supply pipe 4 is inserted through the biological treatment tank 20 and installed in the external space of the tubular member 31, and gas is released into the external space of the tubular member 31, the upper swirling flow generating unit 32 turns the flow from the external space of the tubular member 31 toward the internal space into a swirling flow, and the lower swirling flow generating unit 33 turns the flow from the internal space of the tubular member 31 toward the external space into a swirling flow.

[0030] The hollow fiber membrane bundle 34 has a plurality of hollow fiber membranes 34a arranged in the vertical direction. The hollow fiber membrane bundle 34 has an upper end portion of each hollow fiber membrane 34a supported by a first support member 35 and a lower end portion of each hollow fiber membrane 34a supported by a second support member 36, thereby forming a bundle as a whole.

[0031] Each hollow fiber membrane 34a is formed in a cylindrical shape with open upper and lower ends. Each hollow fiber membrane 34a is configured to filter (separate into permeated liquid and impurities) the liquid to be filtered by passing the liquid from the external space toward the internal space of the hollow fiber membrane 34a. The permeated liquid flows down the internal space of the hollow fiber membrane 34a and is supplied to a permeated liquid storage space 36a (described later) of the second support member 36. In this embodiment, each hollow fiber membrane 34a is configured to filter treated water obtained in the biological treatment tank 20.

[0032] The hollow fiber membrane 34a can be a known filtration membrane such as an MF membrane (microfiltration membrane), an UF membrane (ultrafiltration membrane), an NF membrane (nanofiltration membrane), an RO membrane (reverse osmosis membrane), etc. Examples of materials for the hollow fiber membrane 34a include polyethylene, polypropylene, polyvinylidene fluoride, an ethylene-vinyl alcohol copolymer, polyamide, polyimide, polyetherimide, polystyrene, polysulfone, polyvinyl alcohol, polyphenylene ether, polyphenylene sulfide, polysulfone, polyethersulfone, polyvinylidene fluoride, polyacrylonitrile, a polyvinyl chloride-polyacrylonitrile copolymer, polyamide, cellulose acetate, and polytetrafluoroethylene.

[0033] The first support member 35 is attached to the upper swirl flow generating section 32. The first support member 35 is formed in a topped cylindrical shape with an open lower end, and is configured to support the upper end of the hollow fiber membrane bundle 34. For example, the first support member 35 is configured to support the upper end of the hollow fiber membrane bundle 34 by adhesively fixing the upper end of the hollow fiber membrane bundle 34 to the inner circumferential surface of the first support member 35. One method for adhesively fixing the upper end of the hollow fiber membrane bundle 34 to the inner circumferential surface of the first support member 35 is to fill a potting material between the inner circumferential surface of the first support member 35 and the surface of the hollow fiber membranes 34a and then harden the potting material.

[0034] The second support member 36 is formed in a cylindrical shape with a bottom and an open upper end, and is configured to support the lower end of the hollow fiber membrane bundle 34. For example, the second support member 36 is configured to support the lower end of the hollow fiber membrane bundle 34 by fixing the lower end of the hollow fiber membrane bundle 34 to the inner circumferential surface of the second support member 36. One method for fixing the lower end of the hollow fiber membrane bundle 34 to the inner circumferential surface of the second support member 36 is to fix the inner circumferential surface of the second support member 36 and the surfaces of the hollow fiber membranes 34a with a filler, for example.

[0035] Furthermore, when the second support member 36 supports the lower end of the hollow fiber membrane bundle 34, the second support member 36 is configured to form a permeate storage space 36a between the bottom of the second support member 36 and the lower end of the hollow fiber membrane bundle 34. The permeate storage space 36a is a space capable of storing permeate that has permeated through each hollow fiber membrane 34a, and is in communication with the internal space of each hollow fiber membrane 34a.

[0036] The shaft member 37 is provided inside the hollow fiber membrane bundle 34 and is formed in a tubular shape extending in the vertical direction (the arrangement direction of each hollow fiber membrane 34a). In this embodiment, the shaft member 37 functions as the treated water transfer piping 5. Therefore, the upstream end of the shaft member 37 is inserted through the biological treatment tank 20, the upper swirl flow generating section 32, the first support member 35, and the second support member 36, and is configured to communicate with the permeate storage space 36a of the second support member 36. In addition, the downstream end of the shaft member 37 is inserted through the treated water storage tank 50 and is provided inside the treated water storage tank 50, and is configured to communicate with the storage space of the treated water storage tank 50.

[0037] Like the lower end of the hollow fiber membrane bundle 34, the upstream end of the shaft member 37 is fixed to the inner circumferential surface of the second support member 36, and is thereby supported by the second support member 36. Examples of a method for fixing the upstream end of the shaft member 37 to the inner circumferential surface of the second support member 36 include a method of fixing the inner circumferential surface of the second support member 36 and the surface of the shaft member 37 with a filler.

[0038] 4 and 5, the gap forming member 38 is formed in an annular shape having an insertion hole 100a at the center thereof through which the shaft member 37 can be inserted. Specifically, the gap forming member 38 has a cylindrical portion 100 having the insertion hole 100a, an annular upper flange portion 101 extending radially outward from the upper end of the cylindrical portion 100, and an annular lower flange portion 102 extending radially outward from the lower end of the cylindrical portion 100.

[0039] The upper flange 101 and the lower flange 102 are provided at the upper and lower ends of the tubular portion 100, respectively; in other words, a gap is formed between the upper flange 101 and the lower flange 102, which facilitates flow into the hollow fiber membrane bundle 34 and increases the opportunity for contact between each hollow fiber membrane 34a and the fluid, thereby improving the cleaning efficiency and filtration efficiency of the hollow fiber membrane bundle 34.

[0040] A plurality of openings 103 are formed at intervals in the circumferential direction between the outer edge and inner edge of the gap forming member 38. Specifically, a plurality of openings 103 (eight in this embodiment) are formed at intervals in the circumferential direction between the outer edge and inner edge of the upper flange 101 and between the outer edge and inner edge of the lower flange 102.

[0041] The gap forming member 38 having the above configuration is attached to the axial midpoint of the shaft member 37 and is configured to form a gap inside the hollow fiber membrane bundle 34. Specifically, as shown in Fig. 5 , the gap forming member 38 is separated into a first gap forming member 38A and a second gap forming member 38B with a radial center portion as the boundary, and the first gap forming member 38A and the second gap forming member 38B are connected to each other so as to sandwich the shaft member 37, thereby attaching the gap forming member 38 to the shaft member 37. Then, when attached to the axial midpoint of the shaft member 37, the gap forming member 38 forms a gap inside the hollow fiber membrane bundle 34 by pushing the hollow fiber membrane bundle 34 outward in the radial direction with the upper flange portion 101 and the lower flange portion 102.

[0042] Since the gap forming member 38 is separated into the first gap forming member 38A and the second gap forming member 38B, the gap forming member 38 can be easily attached and detached to and from the shaft member 37. This reduces the workload for changing the position of the gap forming member 38, cleaning it, replacing it, and the like.

[0043] Since the membrane filtration device 30 has the gap-forming member 38, the hollow fiber membrane bundle 34 according to this embodiment is configured so that the outer diameter at the portion where the gap-forming member 38 is provided is larger than the outer diameter at the portion supported by the first support member 35 and the portion supported by the second support member 36. Furthermore, in this embodiment, the hollow fiber membrane bundle 34 is configured so that the outer diameter at the portion where the gap-forming member 38 is provided is smaller than the inner diameter of the tubular member 31.

[0044] In this embodiment, the above-mentioned "outer diameter at the portion where the gap forming member 38 is provided," "outer diameter at the portion supported by the first support member 35," and "outer diameter at the portion supported by the second support member 36" are each the diameter of the smallest encompassing circle that encompasses the hollow fiber membrane bundle 34.

[0045] In this embodiment, the member supporting the upper end of the hollow fiber membrane bundle 34 is described as the first support member 35, and the member supporting the lower end of the hollow fiber membrane bundle 34 is described as the second support member 36, but this is not limited thereto, and the member supporting the lower end of the hollow fiber membrane bundle 34 may be the first support member, and the member supporting the upper end of the hollow fiber membrane bundle 34 may be the second support member. Furthermore, it is sufficient that at least one end of the hollow fiber membrane bundle 34 (the upper end or the lower end) is supported, and the member supporting that end on that one side may be the first support member. In other words, a configuration without a second support member may be used.

[0046] [Biological treatment method] A biological treatment method using the biological treatment system 1 will be described with reference to FIG.

[0047] First, raw water transfer treatment is performed in the biological treatment system 1. Specifically, raw water stored in the raw water storage tank 10 is transferred to the biological treatment tank 20 via the raw water transfer piping 3 (arrow A in FIG. 6). As described above, the transfer of raw water from the raw water storage tank 10 to the biological treatment tank 20 can be performed by pressurizing the raw water using a pump (not shown), or by creating a negative pressure inside the biological treatment tank 20 using a negative pressure generating device (not shown) such as a suction blower, and utilizing the internal pressure difference between the raw water storage tank 10 and the biological treatment tank 20. The biological treatment tank 20 stores the raw water transferred from the raw water storage tank 10.

[0048] Next, biological treatment is carried out in the biological treatment system 1. Specifically, in the biological treatment tank 20, organic matter contained in the raw water is decomposed by microorganisms to produce treated water. If the microorganisms performing the biological treatment are aerobic microorganisms, aeration treatment is carried out. Specifically, gas is supplied from the gas supply unit 40 to the internal space of the tubular member 31 via the gas supply pipe 4 and the lower swirling flow generating unit 33.

[0049] Next, filtration and treated water transfer are performed in the biological treatment system 1. Specifically, a negative pressure generator (not shown), such as a suction blower, creates a negative pressure in the treated water storage tank 50, causing the internal pressure of the treated water storage tank 50 to become lower than the internal pressure of the biological treatment tank 20. As a result, the treated water stored in the biological treatment tank 20 permeates through the hollow fiber membranes 34a and flows into the permeate storage space 36a (arrow B in FIG. 6), and is transferred to the treated water storage tank 50 via the shaft member 37 and the treated water transfer piping 5 (arrow C in FIG. 6). As the treated water in the biological treatment tank 20 permeates through the hollow fiber membranes 34a, it is filtered (separated into permeate and impurities) by the hollow fiber membranes 34a. The treated water storage tank 50 stores the treated water transferred from the biological treatment tank 20.

[0050] Finally, the surfaces of the hollow fiber membranes 34a are cleaned in the biological treatment system 1. Specifically, a swirling flow is generated in the circulation flow path by supplying gas from the gas supply unit 40 through the gas supply pipe 4 and the lower swirling flow generating unit 33 to the internal space of the tubular member 31, and the swirling flow removes impurities adhering to the surfaces of the hollow fiber membranes 34a. The impurities removed from the hollow fiber membranes 34a float or settle (separated into impurities and liquid) when the supply of gas from the gas supply unit 40 is stopped, or float in the liquid in the biological treatment tank 20.

[0051] The raw water transfer process, biological treatment, filtration process, treated water transfer process, and cleaning process may be performed by a control unit (not shown). Specifically, the control unit may control the pump, negative pressure generator, and gas supply unit 40 to perform these processes.

[0052] [Advantages of the biological treatment system according to this embodiment] The membrane filtration device 30 of this embodiment comprises a hollow fiber membrane bundle 34 consisting of a plurality of cylindrical hollow fiber membranes 34a, a first support member 35 that supports one end of the hollow fiber membrane bundle 34, and a gap-forming member 38 that is provided closer to the other end of the hollow fiber membrane bundle 34 than the first support member 35, and the outer diameter of the hollow fiber membrane bundle 34 at the portion where the gap-forming member 38 is provided is larger than the outer diameter at the portion supported by the first support member 35.

[0053] According to the membrane filtration device 30 having such a configuration, gaps are formed inside the hollow fiber membrane bundle 34, which increases the opportunity for each hollow fiber membrane 34a to come into contact with the fluid, thereby improving the cleaning efficiency and filtration efficiency of the hollow fiber membrane bundle 34. Furthermore, compared to a case where the gap-forming member 38 is not provided, clogging due to impurities accumulating inside the hollow fiber membrane bundle 34 is suppressed, which makes it possible to extend the membrane life of each hollow fiber membrane 34a and further improve the filtration efficiency of the hollow fiber membrane bundle 34.

[0054] The membrane filtration device 30 according to this embodiment further includes a second support member 36 that supports the other end of the hollow fiber membrane bundle 34, and the outer diameter of the hollow fiber membrane bundle 34 at the location where the gap-forming member 38 is provided is larger than the outer diameters of the locations supported by the first support member 35 and the second support member 36. With the membrane filtration device 30 having this configuration, gaps are formed inside the hollow fiber membrane bundle 34, increasing the opportunity for each hollow fiber membrane 34a to come into contact with the fluid, thereby improving the cleaning efficiency and filtration efficiency of the hollow fiber membrane bundle 34. Furthermore, clogging due to impurities remaining inside the hollow fiber membrane bundle 34 is suppressed, thereby extending the membrane life of each hollow fiber membrane 34a and further improving the filtration efficiency of the hollow fiber membrane bundle 34.

[0055] The membrane filtration device 30 according to this embodiment further includes a shaft member 37 disposed inside the hollow fiber membrane bundle 34 and between the first support member 35 and the second support member 36, and a gap-forming member 38 is attached to the shaft member 37 midway in the axial direction, so as to form a gap inside the hollow fiber membrane bundle 34. With the membrane filtration device 30 having such a configuration, the formation of gaps inside the hollow fiber membrane bundle 34 increases the opportunity for each hollow fiber membrane 34a to come into contact with the fluid, thereby improving the cleaning efficiency and filtration efficiency of the hollow fiber membrane bundle 34. Furthermore, clogging due to the accumulation of impurities inside the hollow fiber membrane bundle 34 is suppressed, so the membrane life of each hollow fiber membrane 34a can be extended and the filtration efficiency of the hollow fiber membrane bundle 34 can be further improved.

[0056] In the membrane filtration device 30 according to this embodiment, the gap forming member 38 is formed in an annular shape having an insertion hole 100a at the center through which the shaft member 37 can be inserted, and a plurality of openings 103 are formed at intervals in the circumferential direction between the outer edge and the inner edge of the gap forming member 38. With the membrane filtration device 30 having such a configuration, gaps can be formed inside the hollow fiber membrane bundle 34, while ensuring the smooth flow of gas and liquid into the hollow fiber membrane bundle 34.

[0057] The biological treatment system 1 according to this embodiment includes a biological treatment tank 20, a membrane filtration device 30 provided inside the biological treatment tank 20, and a gas supply unit 40 capable of supplying gas to the inside of the biological treatment tank 20. The biological treatment system 1 having such a configuration can promote biological treatment by aerobic microorganisms and perform cleaning of the filtration membrane in the biological treatment tank 20, thereby realizing space savings.

[0058] [Variations] The membrane filtration device and biological treatment system according to the present invention are not limited to the above-described embodiments, and various modifications can be made within the scope of the technical concept of the present invention.

[0059] In the above-described embodiment, a configuration in which both the upper and lower ends of the hollow fiber membrane bundle 34 are supported has been described. However, the present invention is not limited to this. Alternatively, a configuration in which only the lower end of the hollow fiber membrane bundle 34 is supported by the lower support member and the upper end of each hollow fiber membrane 34a is blocked, or a configuration in which each hollow fiber membrane 34a is looped around the lower support member and the looped portion is floated may also be used.

[0060] In the above-described embodiment, the membrane filtration device 30 has been described as having a configuration in which the tubular member 31 is included, but the present invention is not limited to this, and the membrane filtration device 30 may have a configuration in which the tubular member 31 is not included.

[0061] In the above-described embodiment, a configuration has been described in which only one gap forming member 38 is attached to the axially intermediate portion of the shaft member 37, but the present invention is not limited to this, and a plurality of gap forming members may be attached to the axially intermediate portion of the shaft member 37. Also, for example, a configuration may be adopted in which the cylindrical portion 100 of the gap forming member 38 is formed long in the axial direction, and a plurality of flanges including an upper flange portion 101 and a lower flange portion 102 are provided at intervals in the axial direction of the cylindrical portion 100.

[0062] In the above-described embodiment, the gap forming member 38 has been described as having a tubular portion 100, an upper flange portion 101, and a lower flange portion 102, but this is not limited to this, and various configurations may be adopted as long as a gap can be formed inside the hollow fiber membrane bundle 34, such as a configuration in which the gap forming member 38 is composed of only one flange portion.

[0063] In the above-described embodiment, a configuration in which the gap forming member 38 is separated into the first gap forming member 38A and the second gap forming member 38B has been described, but this is not limited to this and the gap forming member 38 may be configured as a single member (a member in which the first gap forming member 38A and the second gap forming member 38B are integrated).

[0064] In the above-described embodiment, the shaft member 37 functions as the treated water transfer pipe 5, but the present invention is not limited to this, and the shaft member 37 and the treated water transfer pipe 5 may be configured separately. That is, the upper and lower ends of the shaft member 37 may be supported by the first support member 35 and the second support member 36, respectively, and the upper end of the shaft member 37 may be configured to communicate with the upstream end of the treated water transfer pipe 5.

[0065] 7, the first support member 35 may be configured to form a permeate storage space 35a between the top of the first support member 35 and the upper end of the hollow fiber membrane bundle 34. Similar to the permeate storage space 36a, the permeate storage space 35a is a space capable of storing permeate that has permeated through each hollow fiber membrane 34a. The permeate storage space 35a is in communication with the internal space of each hollow fiber membrane 34a, the shaft member 37, and the treated water transfer piping 5. In other words, the upper end of the shaft member 37 is in communication with the upstream end of the treated water transfer piping 5 via the permeate storage space 35a.

[0066] 7, the permeate that has permeated the hollow fiber membrane 34a flows through the internal space of the hollow fiber membrane 34a and into the permeate storage space 35a and the permeate storage space 36a. The permeate that has flowed into the permeate storage space 35a is transferred to the treated water storage tank 50 via the treated water transfer piping 5. The permeate that has flowed into the permeate storage space 36a is transferred to the treated water storage tank 50 via the shaft member 37, the permeate storage space 35a, and the treated water transfer piping 5.

[0067] The second support member 36 may not have the permeate storage space 36a. That is, the permeate that has permeated the hollow fiber membrane 34a may flow through the internal space of the hollow fiber membrane 34a into the permeate storage space 35a and then be transferred to the treated water storage tank 50 via the treated water transfer pipe 5.

[0068] It is clear from the claims that the above-mentioned modifications are included within the scope of the present invention. [Explanation of symbols]

[0069] 1: Biological treatment system 2: Raw water supply piping 3: Raw water transfer piping 4: Gas supply piping 5: Treated water transfer piping 6: Treated water supply pipe 10: Raw water storage tank 20: Biological treatment tank 30: Membrane filtration equipment 31: Cylindrical member 32: Upper swirl flow generating section 32a: Blade part 33: Lower swirl flow generation section 33a: Blade part 34: Hollow fiber membrane bundle 34a: Hollow fiber membrane 35: First support member 35a: Permeate storage space 36: Second support member 36a: Permeate storage space 37: Shaft member 38: Gap forming member 38A: First gap forming member 38B: Second gap forming member 40: Gas supply section 50: Treated water storage tank 100: Cylindrical part 100a: Insertion hole 101: Upper flange 102: Lower flange 103 :Aperture

Claims

1. a hollow fiber membrane bundle consisting of a plurality of cylindrical hollow fiber membranes; a first support member that supports one end of the hollow fiber membrane bundle; a second support member that supports the other end of the hollow fiber membrane bundle; a shaft member provided inside the hollow fiber membrane bundle and between the first support member and the second support member; a gap forming member provided closer to the other end of the hollow fiber membrane bundle than the first support member; Equipped with the hollow fiber membrane bundle has an outer diameter at a portion where the gap forming member is provided that is larger than the outer diameters at a portion supported by the first support member and a portion supported by the second support member; The gap forming member is attached to an axial midpoint of the shaft member and is configured to form a gap inside the hollow fiber membrane bundle. Membrane filtration equipment.

2. the gap forming member is formed in an annular shape having an insertion hole at the center through which the shaft member can be inserted, A plurality of openings are formed at intervals in the circumferential direction between the outer edge and the inner edge of the gap forming member. The membrane filtration device according to claim 1.

3. A biological treatment tank; The membrane filtration device according to claim 1 or 2, which is provided inside the biological treatment tank; a gas supply unit capable of supplying gas into the inside of the biological treatment tank; Equipped with Biological treatment systems.

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