WO2017082095A1

WO2017082095A1 - Membrane filtration unit and water treatment method

Info

Publication number: WO2017082095A1
Application number: PCT/JP2016/082246
Authority: WO
Inventors: 哲也取違; 井手口　誠; 真介古野; 洋一窪田
Original assignee: 三菱レイヨン株式会社
Priority date: 2015-11-10
Filing date: 2016-10-31
Publication date: 2017-05-18
Also published as: CN108349757A; KR20180052732A; JP6319463B2; JPWO2017082095A1

Abstract

The purpose of the present invention is to provide a membrane filtration unit that can be made more compact and manufactured at lower cost than a conventional membrane filtration unit, and a water treatment method using the membrane filtration unit. Provided is a membrane filtration unit (1) provided with a plurality of hollow fiber membrane elements (2), a frame (3) for holding the plurality of hollow fiber membrane elements (2), and an exhaust pipe (4) connected to the lower part of the frame (3), wherein at least part (support columns (40) and air supply header (60)) of the frame (3) also serves as an air supply pipe for supplying air to the exhaust pipe (4). Also provided is a water treatment method using the same.

Description

Membrane filtration unit and water treatment method

The present invention relates to a membrane filtration unit and a water treatment method.
This application claims priority based on Japanese Patent Application No. 2015-220574 for which it applied to Japan on November 10, 2015, and uses the content here.

As a method of treating various wastewater (industrial wastewater, domestic wastewater, etc.) containing organic matter, microorganisms (bacteria, etc.) and their debris, wastewater is treated biochemically with activated sludge in an activated sludge water tank, A membrane separation activated sludge method is known in which sludge and treated water are solid-liquid separated by a membrane filtration unit immersed in an activated sludge water tank.

Known membrane filtration units include a hollow fiber membrane module having a plurality of hollow fiber membrane elements arranged therein, and an air diffuser having a plurality of air diffusers arranged below the hollow fiber membrane module. (For example, refer to Patent Document 1).

JP 2007-152179 A

In the conventional membrane filtration unit, the hollow fiber membrane module and the air diffuser are produced separately. Therefore, it is necessary to connect the frame of the hollow fiber membrane module and the frame of the air diffuser with bolts and nuts. In order to connect the frames, extra space is provided for connecting the bolts to each frame, the labor for drilling the bolt holes in the connecting parts, and the work for connecting the frames. It takes time and effort. Therefore, a membrane filtration unit becomes large and the manufacturing cost of a membrane filtration unit becomes high.
Moreover, in the conventional membrane filtration unit, it is necessary to separately provide an air supply pipe for supplying gas to the air diffuser pipe of the air diffuser. The air supply pipe is disposed outside each frame, and is fixed to the frame or the like of the hollow fiber membrane module with a U bolt or the like. Therefore, the space required for installing the membrane filtration unit including the air supply pipe is further increased. Further, the manufacturing cost is further increased by increasing the number of parts.

The present invention provides a membrane filtration unit that can be reduced in size and cost as compared with a conventional membrane filtration unit.

The present invention has the following aspects.
[1] a plurality of membrane elements;
A frame for holding the plurality of membrane elements;
A diffuser tube connected to the lower part of the frame;
The membrane filtration unit, wherein at least a part of the frame also serves as an air supply pipe for supplying gas to the diffuser pipe.
[2] The frame includes two vertical members arranged in a substantially vertical direction to sandwich the membrane element,
The membrane filtration unit according to [1], wherein at least a part of the vertical member also serves as an air supply pipe that supplies gas to the diffuser pipe.
[3] The frame includes two vertical members arranged in a substantially vertical direction to sandwich the membrane element,
The membrane filtration unit according to [1] or [2], wherein the vertical member has a guide portion that guides the membrane element in a substantially vertical direction.
[4] The membrane filtration unit according to any one of [1] to [3], wherein the membrane packing density determined from the following formula (I) is 150 to 350 m ² / m ² .

Where D is the membrane packing density, n is the number of membrane elements arranged in the membrane filtration unit, E _i is the surface area of the membrane in the i-th membrane element, and U is required for installation of the membrane filtration unit It is a large area.
[5] The frame includes two vertical members arranged in a substantially vertical direction to sandwich the membrane element,
The membrane filtration unit according to any one of [1] to [4], wherein at least a part of the vertical member is made of resin.
[6] The membrane filtration unit according to [5], wherein the resin is a polyvinyl chloride resin.
[7] The frame includes two vertical members arranged in a substantially vertical direction that sandwich the membrane element, and a horizontal member connected to the two vertical members,
The membrane filtration unit according to any one of [1] to [6], wherein the air diffuser also serves as at least a part of the transverse member.
[8] The membrane element includes a sheet-like membrane, an upper housing to which an upper end of the membrane is fixed, and a lower housing to which the lower end of the membrane is fixed,
The plurality of membrane elements are arranged such that the membranes face each other, the longitudinal directions of the upper housing and the lower housing are aligned, and a predetermined interval X is provided between the adjacent upper housings and between the adjacent lower housings. And
The frame includes two vertical members arranged in a substantially vertical direction to sandwich the membrane element from the longitudinal direction side of the upper housing and the lower housing,
The vertical member includes an upper support plate, and the outer surface B of the membrane element in which the side surface A of the upper support plate in the width direction perpendicular to the longitudinal direction of the upper housing and the lower housing is disposed on the outermost side. Or the side surface A protrudes so that the maximum step Y between the side surface A and the surface B is greater than 0 and less than or equal to the interval X. The membrane filtration unit according to any one of [1] to [7].
[9] Any one of [1] to [8], wherein the membrane element includes a sheet-like membrane, and the membrane-like outer diameter of the sheet-like membrane is 1 mm or more and 5 mm or less. The membrane filtration unit described in 1.
[10] The membrane filtration unit according to any one of [1] to [9], wherein the membrane element includes a sheet-like membrane, and the membrane element has a support.
[11] The membrane filtration unit according to any one of [1] to [10], wherein the overall height is 1 m or more and 1.5 m or less.
[12] The membrane filtration unit according to any one of [1] to [11], wherein the weight per membrane surface area is 1.0 kg / m ² or less.
[13] A water treatment method comprising solid-liquid separation using the membrane filtration unit according to any one of [1] to [12].
[14] The water treatment method according to [13], wherein the membrane filtration unit according to any one of [1] to [12] is used in an activated sludge water tank.
[15] The water treatment method according to [13], wherein the membrane filtration unit according to [11] is used in an activated sludge water tank having a water depth of 1.5 m or less.

The membrane filtration unit of the present invention can be made more compact and less costly than conventional membrane filtration units.

It is a perspective view which shows an example of the membrane filtration unit of this invention. It is a perspective view which shows an example of a hollow fiber membrane element. It is a perspective view which shows an example of a flame | frame (however, except a pressing board). It is a top view which shows the state which removed the water collection pipe and the pressing board from the membrane filtration unit of FIG. It is a top view which shows the state which arranged the membrane filtration unit of FIG. 4 in parallel. It is a perspective view which shows a mode that a hollow fiber membrane element is inserted in a flame | frame. It is a perspective view which shows an example of an elastic member. It is a perspective view which shows a mode that the elastic member was attached to the hollow fiber membrane element arranged in the flame | frame. It is a perspective view which shows a mode that a pressing plate is fixed to the upper support plate of a flame | frame. It is a perspective view which shows a mode that a water collection pipe | tube is connected to a hollow fiber membrane element. It is a perspective view which shows the other example of the membrane filtration unit of this invention. It is a perspective view which shows the other example of the membrane filtration unit of this invention.

[Membrane filtration unit]
<First Embodiment>
FIG. 1 is a perspective view showing a first embodiment of the membrane filtration unit of the present invention.
The membrane filtration unit 1 includes a plurality of flat hollow fiber membrane elements 2; a frame 3 that holds the plurality of hollow fiber membrane elements 2; an air diffuser 4 that is connected to the lower part of the frame 3; A water collecting pipe 5 is provided above and connected to each hollow fiber membrane element 2.

(Hollow fiber membrane element)
FIG. 2 is a perspective view showing an example of a hollow fiber membrane element.
The hollow fiber membrane element 2 includes a hollow fiber membrane sheet 12 in which a plurality of hollow fiber membranes 10 are aligned in one direction; and the upper end of the hollow fiber membrane 10 in the length direction of the hollow fiber membrane sheet 12 is fixed. A lower housing 16 in which the lower end of the hollow fiber membrane 10 of the hollow fiber membrane sheet 12 is fixed; and an upper housing disposed on both sides of the hollow fiber membrane sheet 12. Two vertical rods 18 connecting the end of 14 and the end of the lower housing 16; an upper fitting protrusion formed to protrude from the end of the upper housing 14 outward in the longitudinal direction of the upper housing 14 20; a lower fitting convex portion 22 formed to protrude outward in the longitudinal direction of the lower housing 16 from the end portion of the lower housing 16; a water intake formed to protrude upward from one end portion of the upper housing 14; With mouth 24

The upper end of the hollow fiber membrane sheet 12 is inserted into a rectangular tube-shaped upper housing 14 whose both ends are sealed, and the liquid is removed by a potting material (not shown) while the end of the hollow fiber membrane 10 is kept open. It is fixed tightly.
The lower end of the hollow fiber membrane sheet 12 is inserted into a rectangular tube-shaped lower housing 16 sealed at both ends, and the liquid is removed by a potting material (not shown) while the end of the hollow fiber membrane 10 is kept open. It is fixed tightly.

Examples of the material of the hollow fiber membrane 10 include polysulfone resin, polyacrylonitrile, cellulose derivatives, polyolefin (polyethylene, polypropylene, etc.), fluorine resin (polyvinylidene fluoride, polytetrafluoroethylene, etc.), polyamide, polyester, polymethacrylate. , Polyacrylate, those obtained by introducing a substituent into a part of these resins, and resins made of a copolymer of monomers constituting these polymers. Of these, polyvinylidene fluoride is preferable because it is excellent in acid resistance and alkali resistance.
The hollow fiber membrane 10 preferably contains one or more of these resins.

The membrane outer diameter of each of the hollow fiber membranes 10 constituting the hollow fiber membrane sheet 12 aligned in one direction is 1 mm or more and 5 mm from the viewpoint of water treatment efficiency, durability of the hollow fiber membrane, and integration rate. Is preferably 1.2 mm or more and 4 mm or less, more preferably 1.3 mm or more and 3 mm or less, and particularly preferably 1.5 mm or more and 2.5 mm or less.

The material of the upper housing 14 and the lower housing 16 is preferably a material having mechanical strength and durability. For example, polycarbonate, polysulfone, polyolefin, polyvinyl chloride, acrylic resin, acrylonitrile-butadiene-styrene (ABS) resin, modified Examples include polyphenylene ether. The upper housing 14 and the lower housing 16 preferably contain one or more of these resins.

Examples of potting materials include cured products of thermosetting resins (epoxy resins, unsaturated polyester resins, etc.), polyurethane resins, silicone fillers, and various hot melt resins.

The vertical rod 18 supports the hollow fiber membrane sheet-like material 12 composed of the hollow fiber membranes 10 aligned in one direction, and avoids the bending of the hollow fiber membrane sheet-like material 12, thereby preventing the hollow fiber membrane element 2 from being bent. A support that maintains its shape. Since the hollow fiber membrane element 2 has the vertical rod 18, the hollow fiber membrane element 2 can be carried and handled easily when the membrane filtration unit 1 is assembled or exchanged, and the hollow fiber membrane element to the frame 3 is improved. 2 and removal of the hollow fiber membrane element 2 from the frame 3 are facilitated.

Examples of the material of the downpipe 18 include resin (polyvinyl chloride, fluorine-based resin, polyolefin, ABS resin, polycarbonate, etc.) and metal (stainless steel, titanium, etc.). The material of the downpipe 18 is preferably a resin from the viewpoint of excellent acid resistance against hydrochloric acid, sulfuric acid, etc., and from the viewpoint of excellent chemical resistance, polyvinyl chloride or fluororesin is more preferable, inexpensive, and other Polyvinyl chloride resin is more preferable from the viewpoint that the adhesiveness with the member is good and the production of the hollow fiber membrane element 2 is easy. The “polyvinyl chloride resin” is a resin containing a structural unit derived from vinyl chloride, and is preferably polyvinyl chloride.

The vertical rod 18 is a round pipe because the hollow fiber membrane 10 is oscillated by aeration from the air diffusing tube 4 and the hollow fiber membrane 10 is less damaged when rubbed against the vertical rod 18 than the square pipe. Is preferred.
As the round pipe, a commercially available polyvinyl chloride pipe is preferable because it is light and inexpensive. Examples of the polyvinyl chloride pipe include a hard polyvinyl chloride pipe (JIS K 6741) and a hard polyvinyl chloride pipe for water supply (JIS K 6742).

The upper fitting convex portion 20 is fitted into a guide groove 42a of a guide portion 42 in a vertical member 30 of the frame 3 described later, and suppresses lateral displacement of the hollow fiber membrane element 2 in the upper housing 14.

The lower fitting convex portion 22 is fitted into a guide groove 42a of a guide portion 42 in a vertical member 30 of the frame 3 described later, and suppresses lateral displacement of the hollow fiber membrane element 2 in the lower housing 16. The hollow fiber membrane element 2 and the frame 3 are relatively movable in a substantially vertical direction by sliding along the longitudinal direction of the guide groove 42a of the guide portion 42.

The water intake 24 is for taking out the liquid filtered by the hollow fiber membrane 10 and collected in the water collection space in the upper housing 14 to the outside of the hollow fiber membrane element 2.

(flame)
FIG. 3 is a perspective view showing an example of a frame (excluding a pressing plate).
The frame 3 includes two vertical members 30 arranged so as to sandwich the hollow fiber membrane element 2 from the longitudinal direction sides of the upper housing 14 and the lower housing 16 and in a substantially vertical direction; An upper horizontal member 32 that is disposed between the upper members of the two vertical members 30 and connects the central portions in the horizontal direction; and a lower horizontal member 34 that connects the lower members of the vertical members 30 to each other. The member 34 also serves as the diffuser tube 4.
At least a part of the frame 3 also serves as an air supply pipe that supplies gas to the diffuser pipe 4.

(Vertical member)
The vertical member 30 includes two support columns 40 arranged in a substantially vertical direction; two guide portions 42 arranged inside the support column 40 so as to sandwich the upper horizontal member 32; and two through pipes 44a. An upper support plate 44 having two support columns 40 connected to each other and having the upper ends of the guide portions 42 joined to the side surfaces thereof; two support columns 40 connected to the two through pipes 46a and the guide portions on the side surfaces thereof. A lower support plate 46 to which the lower end of 42 is joined; a bolt 48 (see FIG. 1) and a nut (not shown) on the upper support plate 44 so as to press the hollow fiber membrane element 2 sandwiched between the longitudinal members 30 from above. The holding plate 50 (see FIG. 1) fixed by the bolts; and fixed to the lower support plate 46 with bolts (not shown) and nuts 52 so as to support the hollow fiber membrane element 2 sandwiched between the vertical members 30 from below. Support plate 54 An air supply port 56 attached to the upper end of one of the two through tubes 44a; an air supply port 56 attached to the upper end of the through tube 44a to which no air supply port is attached. A cap 58; an air supply header 60 connected to the lower ends of the two through pipes 46a and one end of the three diffuser pipes 4; and a hanging fitting 62 attached to the upper support plate 44.

By using the support column 40 as a pipe, the support column 40 can also serve as an air supply tube for supplying gas to the diffuser tube 4.
By sealing the upper end of the through pipe 44a of the upper support plate 44 to which the support column 40 not used as the air supply pipe is connected with the cap 58, gas leakage from other than the diffuser pipe 4 can be suppressed.

Examples of the material of the support column 40 include resin (polyvinyl chloride, fluorine-based resin, polyolefin, ABS resin, polycarbonate, etc.) and metal (stainless steel, titanium, etc.). As a material of the support column 40, a resin is preferable because it is inexpensive, easy to manufacture the vertical member 30, lightweight, and excellent in chemical resistance, and has good adhesion to other members. A polyvinyl chloride resin is more preferable because the vertical member 30 is more easily manufactured.

The column 40 is preferably a round pipe from the standpoints of mechanical strength and reduction in membrane damage due to the absence of a corner portion of the membrane when the hollow fiber membrane 10 is rubbed against the pipe by peristalsis such as aeration.
As the round pipe, a commercially available polyvinyl chloride pipe is preferable because it is light and inexpensive. Examples of the polyvinyl chloride pipe include a hard polyvinyl chloride pipe (JIS K 6741) and a hard polyvinyl chloride pipe for water supply (JIS K 6742).

As shown in FIG. 4, the guide portion 42 is a corrugated plate member in which a plurality of guide grooves 42 a extending in a substantially vertical direction is formed, and guides the hollow fiber membrane element 2 in a substantially vertical direction.
The guide groove 42 a suppresses the lateral displacement of the hollow fiber membrane element 2 in the upper housing 14 by fitting the upper fitting convex portion 20 of the upper housing 14.
The guide groove 42 a is configured to suppress lateral displacement of the hollow fiber membrane element 2 in the lower housing 16 by fitting the lower fitting convex portion 22 of the lower housing 16. Also, the lower fitting convex portion 22 slides along the longitudinal direction of the guide groove 42a, thereby enabling the hollow fiber membrane element 2 and the frame 3 to move relatively in the substantially vertical direction.

Since the vertical member 30 has the guide portion 42, the vertical member 30 arranged so that the guide portions 42 face each other restricts relative horizontal movement between the hollow fiber membrane element 2 and the frame 3. In addition, the hollow fiber membrane element 2 can be sandwiched so as to enable relative vertical movement between the hollow fiber membrane element 2 and the frame 3.

Examples of the material of the guide part 42 include resin (polyvinyl chloride, fluorine-based resin, polyolefin, ABS resin, polycarbonate, etc.) and metal (stainless steel, titanium, etc.). The material of the guide portion 42 is preferably a resin because it is inexpensive, easy to manufacture the vertical member 30, lightweight, and excellent in chemical resistance, and has an adhesive property to other members. A polyvinyl chloride resin is more preferable because the vertical member 30 is more easily manufactured.

The upper support plate 44 and the lower support plate 46 are provided with a through pipe for connecting the support column 40. In addition, irregularities corresponding to the shape of the corrugated guide portion 42 are formed on the side surfaces of the upper support plate 44 and the lower support plate 46 that are joined to the guide portion 42, and the upper support plate 44 and the lower support plate 46. The upper support plate 44 and the lower support plate 46 can be sufficiently joined to the guide portion 42 by fitting the recesses and projections of the guide portion 42 to the guide portion 42.

Examples of the material of the upper support plate 44 and the lower support plate 46 include resin (polyvinyl chloride, fluorine resin, polyolefin, ABS resin, polycarbonate, etc.) and metal (stainless steel, titanium, etc.). The material of the upper support plate 44 and the lower support plate 46 is preferably a resin because it is inexpensive, easy to manufacture the vertical member 30, is lightweight, and is excellent in chemical resistance. A polyvinyl chloride resin is more preferable from the viewpoint that the adhesiveness with the member is good and the manufacture of the longitudinal member 30 is easier.

The pressing plate 50 presses the hollow fiber membrane element 2 sandwiched between the vertical members 30 from above.
The pressing plate 50 suppresses the lifting of the hollow fiber membrane element 2 due to aeration from the air diffusing tube 4 and also suppresses the vibration of the hollow fiber membrane element 2 to reduce wear due to friction between the hollow fiber membrane elements 2. .

The material of the pressing plate 50 is selected according to the mechanical strength necessary for suppressing the lifting of the hollow fiber membrane element 2. The material of the pressing plate 50 is preferably a metal (stainless steel, titanium, etc.) from the viewpoint of high mechanical strength. If there is no problem in mechanical strength, resin or fiber reinforced plastic may be used.
The pressing plate 50 is preferably fixed to the upper support plate 44 with bolts and nuts. In the adhesion with an epoxy resin or the like, the pressing plate 50 cannot be detachably fixed, and it is difficult to take out the hollow fiber membrane element 2.

It is preferable to dispose an elastic member (not shown) between the pressing plate 50 and the hollow fiber membrane element 2. By disposing an elastic member between the pressing plate 50 and the hollow fiber membrane element 2, even if there is a variation in the height of the hollow fiber membrane element 2, the elastic member is deformed so that each hollow fiber membrane element 2 is deformed. The hollow fiber membrane element 2 can be reliably pressed in contact therewith. As a result, the vibration of the hollow fiber membrane element 2 is further suppressed.

The elastic member is made of a thermosetting elastomer (ethylene-propylene-diene rubber (hereinafter also referred to as EPDM), nitrile rubber, fluororubber, silicone rubber, urethane rubber, etc.), thermoplastic elastomer (styrene-based elastomer, olefin-based). Elastomer, vinyl chloride elastomer, ester elastomer, urethane elastomer, amide elastomer, etc.). The material of the elastic member is not limited to a thermosetting elastomer and a thermoplastic elastomer, and may be a thermoplastic resin such as polyethylene or polypropylene, or a thermosetting resin such as polyurethane, as long as it is relatively soft. May be.

The durometer hardness of the elastic member is preferably in the range of A10 to 95. If the durometer hardness of the elastic member is within the above range, the stress generated when the plurality of hollow fiber membrane elements 2 are firmly pressed can be sufficiently relaxed, and the vibration buffering action of the hollow fiber membrane elements 2 can be achieved. The durometer hardness of the elastic member is more preferably in the range of A40 to 90. If the durometer hardness of the elastic member is A40 or more, the amount of the elastic member used to obtain sufficient mechanical strength to hold down the hollow fiber membrane element 2 can be suppressed, so that the cost can be suppressed. If the durometer hardness of the elastic member is A90 or less, since the flexibility of the elastic member is increased, the effect of suppressing damage by suppressing the vibration of the hollow fiber membrane element 2 is further increased.
The durometer hardness of the elastic member is defined by JIS K 6253 (ISO 7619).

The support plate 54 supports the hollow fiber membrane element 2 sandwiched between the vertical members 30 from below.
The material of the support plate 54 is selected according to the mechanical strength required to support the mass of the hollow fiber membrane element 2. The material of the support plate 54 is preferably a metal (stainless steel, titanium, etc.) from the viewpoint of high mechanical strength. If there is no problem in mechanical strength, resin or fiber reinforced plastic may be used.
The support plate 54 is preferably fixed to the lower support plate 46 with bolts and nuts. In the case of adhesion using an epoxy resin or the like, there is a risk of peeling on the adhesion surface.

The air supply header 60 is a member made of an H-shaped pipe.
By using the air supply header 60 as a pipe, the air supply header 60 can also serve as an air supply pipe that supplies gas to the diffuser pipe 4.
The lower ends of the two through pipes 46a of the lower support plate 46 are connected to the two upper ends of the vertical pipes of the air supply header 60, respectively, and the center and the horizontal pipes of the two vertical pipes of the air supply header 60 are connected. One end of each of the three diffusing tubes 4 is connected to the center of each. Caps (not shown) are attached to the two lower ends of the longitudinal pipes of the air supply header 60.

Examples of the material of the air supply header 60 include resin (polyvinyl chloride, fluorine-based resin, polyolefin, ABS resin, polycarbonate, etc.) and metal (stainless steel, titanium, etc.). As the material of the air supply header 60, a resin is preferable because it is inexpensive, easy to manufacture the vertical member 30, is lightweight, and has excellent chemical resistance. Adhesiveness to other members Polyvinyl chloride resin is more preferable because it is easy to manufacture the vertical member 30.

A blower (not shown) is connected to an air supply port 56 attached to the through pipe 44a of the upper support plate 44 via a hose (not shown).
By connecting the blower, the hose, the air supply port 56, the through pipe 44a, the support column 40, the through pipe 46a, the air supply header 60, and the air diffusion tube 4 in this order, the support column 40, which is a part of the frame 3, is used together as the air supply tube. However, gas can be supplied from the blower to the diffuser tube 4.

Of the members constituting the vertical member 30, the material of at least some of the members is a resin because it is inexpensive, easy to manufacture the vertical member 30, lightweight, and excellent in chemical resistance. It is preferable that Of the members constituting the vertical member 30, the material of two or more members is preferably a resin from the viewpoint that the adhesiveness between the members is good and the manufacture of the vertical member 30 is easier, and the polyvinyl chloride type More preferably, it is a resin.

(Upper horizontal member)
The upper lateral member 32 is an L-shaped member that is disposed so as to be sandwiched between the hollow fiber membrane elements 2 and connects the upper portions of the two longitudinal members 30 and the central portions in the horizontal direction.
The upper lateral member 32 has its end fixed to the central portion in the horizontal direction of the upper support plate 44 by a bolt (not shown) and an eye nut (hanging bracket 62).
The material of the upper lateral member 32 is preferably a metal (stainless steel, titanium, etc.) from the viewpoint of high mechanical strength.

(Air diffuser)
The air diffusing tube 4 is a cylindrical member.
A plurality of air diffusion holes 4 a opened upward are formed in the peripheral wall of the air diffusion tube 4.
A sludge discharge pipe 4 b extending downward is provided at the center of the air diffusion pipe 4.
The diffuser pipe 4 also serves as the lower horizontal member 34 of the frame 3 by connecting both ends thereof to the air supply header 60 below the vertical member 30.

(Catchment pipe)
The water collecting pipe 5 includes a plurality of connecting pipes 5a extending in the vertical direction connected to the water intake ports 24 of the hollow fiber membrane elements 2, a collecting pipe 5b extending in the horizontal direction connected to the plurality of connecting pipes 5a, and a collecting pipe 5b. A water intake pipe 5c extending upward from the center.

The connection pipe 5a of the water collection pipe 5 is connected to the water intake 24 of each hollow fiber membrane element 2, and the water intake pipe 5c of the water collection pipe 5 is connected to a suction pump (not shown) via a hose (not shown). The
By operating the suction pump, the liquid filtered by the hollow fiber membrane 10 and collected in the water collection space in the upper housing 14 is taken out from the hollow fiber membrane element 2 to the water collection pipe 5 and assembled, and then the water collection pipe 5 to the outside of the membrane filtration unit 1.

(Arrangement of each member in the membrane filtration unit)
As shown in FIG. 4, the plurality of hollow fiber membrane elements 2 are such that the hollow fiber membrane sheet-like material 12 faces each other, the longitudinal directions of the upper housing 14 and the lower housing 16 are aligned, and between and adjacent to the adjacent upper housings 14. It arrange | positions so that the predetermined | prescribed space | interval X may be opened between the lower housings 16 which fit.

The space | interval X is the space | interval (maximum distance of the surface of a housing, and the surface of an adjacent housing) in the location where the adjacent housing is the most separated.
The interval X is preferably 3 to 25 mm, and more preferably 5 to 15 mm. If the interval X is equal to or greater than the lower limit of the above range, a gas-liquid mixed flow due to aeration easily flows between the hollow fiber membranes 10, so that sludge is not blocked between the membranes and a more stable operation is possible. If the space | interval X is below the upper limit of the said range, the membrane filtration unit 1 can be further compactized.

The two vertical members 30 of the frame 3 are arranged so as to sandwich the hollow fiber membrane element 2 from the longitudinal direction side of the upper housing 14 and the lower housing 16.
The upper transverse member 32 of the frame 3 is disposed so as to be sandwiched between the hollow fiber membrane elements 2.
By disposing the longitudinal member 30 and the upper transverse member 32 of the frame 3 as described above, the hollow fiber membrane sheet-like material of the hollow fiber membrane element 2 arranged on the outermost side among the plurality of hollow fiber membrane elements 2. The 12 membrane surfaces are exposed to the outside of the membrane filtration unit 1.

At this time, the side surface A of the short portion of the upper support plate 44 of the vertical member 30, that is, the side surface A of the upper support plate 44 in the width direction orthogonal to the longitudinal direction of the upper housing 14 and the lower housing 16 is the outermost side. 4 is the same as the outermost surface B ′ of the outer surfaces B (ie, the upper housing 14 and the lower housing 16) of the hollow fiber membrane element 2 disposed in the same plane, that is, in the same plane, or FIG. It is preferable that the side surface A protrudes so that the maximum step Y between the side surface A and the surface B is equal to or less than 0 distance X as shown in FIG.

If the side surface A and the surface B ′ are on the same plane, the hollow fiber membrane element 2 is disposed in the frame 3 without waste, and the membrane filtration unit 1 can be further compacted.
If the side surface A protrudes so that the maximum step Y between the side surface A and the surface B is less than 0 distance X or less, the outermost hollow fiber membrane elements 2 face each other as shown in FIG. When the membrane filtration units 1 are arranged side by side and the side surfaces A are brought into contact with each other, a gap is formed between the surfaces B of the hollow fiber membrane elements 2 arranged on the outermost side in each membrane filtration unit 1, and The interval between the hollow fiber membrane elements 2 does not become too large. The maximum level difference Y between the side surface A and the surface B is such that the distance between the hollow fiber membrane elements 2 arranged on the outermost side in each membrane filtration unit 1 is the distance X between the hollow fiber membrane elements 2 in the membrane filtration unit 1. From the point of being the same, it is preferable that it is half of the interval X.

(Membrane filling density of membrane filtration unit)
The membrane filtration unit 1, film packing density determined from the following formula (I) is preferably from 150 ~ 350m ^² / ^m ^2, more preferably 200 ~ 300m ^² / ^m ^2.

Where D is the membrane packing density, n is the number of hollow fiber membrane elements 2 arranged in the membrane filtration unit 1, and E _i is the total surface area of the hollow fiber membranes 10 in the i-th hollow fiber membrane element 2. U is an area required for installing the membrane filtration unit 1.

If the membrane packing density of the membrane filtration unit 1 is equal to or higher than the lower limit of the above range, the membrane filtration unit 1 can be made more compact. If the membrane packing density of the membrane filtration unit 1 is less than or equal to the upper limit of the above range, an appropriate gap is formed between the hollow fiber membranes 10 and a gas-liquid mixed flow due to aeration easily flows, so that sludge is not blocked between the membranes. This enables stable operation.

(Assembly of membrane filtration unit)
The assembly of the membrane filtration unit 1 will be described with reference to the drawings.

As shown in FIG. 6, the lower fitting convex portion 22 of the lower housing 16 in the hollow fiber membrane element 2 is formed in the guide groove 42 a of the guide portion 42 in the vertical member 30 of the frame 3 (however, excluding the pressing plate 50). Fit.
The hollow fiber membrane element 2 is inserted into the frame 3 while being guided downward by sliding the lower fitting convex portion 22 along the longitudinal direction of the guide groove 42a.
At the same time that the lower housing 16 is brought into contact with the support plate 54, the upper fitting convex portion 20 of the upper housing 14 in the hollow fiber membrane element 2 is fitted into the guide groove 42a.
In this way, the hollow fiber membrane element 2 is sandwiched by the two longitudinal members 30 from the longitudinal direction sides of the upper housing 14 and the lower housing 16.
The same operation is repeated for the number of hollow fiber membrane elements 2.

When an elastic member is disposed between the press plate 50 and the hollow fiber membrane element 2, for example, an elastic member 6 shown in FIG. 7 is prepared. The elastic member 6 has an elongated flat plate-like base material portion 6a; the same width as the gap between the hollow fiber membrane elements 2, and the same pitch as the pitch of the hollow fiber membrane elements 2 arranged in the frame 3. And a plurality of convex portions 6b formed.
As shown in FIG. 8, the four elastic members 6 are arranged in the upper housing 14 of the hollow fiber membrane element 2 arranged in the frame 3 so that the convex portion 6 b is fitted in the gap between the hollow fiber membrane elements 2. Attach to both ends in the longitudinal direction.

As shown in FIG. 9, the hollow fiber membrane element 2 is inserted through the elastic member 6 by inserting bolts 48 into the bolt holes of the pressing plate 50 and the upper support plate 44 and attaching nuts (not shown) to the bolts 48. The pressing plate 50 is fixed to the upper support plate 44 in the vertical member 30 of the frame 3 so as to be pressed from above.

As shown in FIG. 10, by arranging a plurality of hollow fiber membrane elements 2 in the frame 3, the water intake ports 24 of the hollow fiber membrane elements 2 aligned in a line are connected to the connection pipe 5 a of the water collecting pipe 5. Thus, the water collecting pipe 5 is attached above the hollow fiber membrane element 2.
As described above, the membrane filtration unit 1 in which the plurality of hollow fiber membrane elements 2 are held by the frame 3 is obtained.

(Mechanism of action)
In the membrane filtration unit 1 described above, the air diffuser 4 is connected to the lower part of the frame 3 holding the plurality of hollow fiber membrane elements 2. That is, it is set as the structure where the hollow fiber membrane module and the air diffuser which were produced separately in the conventional membrane filtration unit were integrated. Therefore, unlike the conventional case, there is no need to connect the frame of the hollow fiber membrane module and the frame of the air diffuser with bolts and nuts, and for providing a connecting portion for passing the bolt through each frame for connecting the frames. There is no need for extra space, and there is no need for processing for drilling bolt holes in the connecting portion, and no work for connecting the frames. For this reason, it is possible to realize downsizing and cost reduction as compared with the conventional membrane filtration unit.

Further, in the membrane filtration unit 1 described above, the support column 40 and the air supply header 60 which are a part of the frame 3 also serve as an air supply pipe for supplying gas to the air diffusing pipe 4. Unlike the unit, there is no need to separately provide an air supply pipe for supplying gas to the air diffuser pipe of the air diffuser. Therefore, the space required for installing the membrane filtration unit can be reduced by the amount of the supply pipe, and the number of parts can be reduced. Therefore, further downsizing and cost reduction can be realized as compared with the conventional membrane filtration unit.

Further, in the membrane filtration unit 1 described above, the air diffuser 4 also serves as the lower horizontal member 34 that is a part of the frame 3, so that it is not necessary to separately provide a horizontal member at the lower portion of the frame 3. . Therefore, further downsizing and cost reduction can be realized as compared with the conventional membrane filtration unit.

By the way, water facilities in buildings are often installed in the basement of buildings. In the water supply system installed in the basement of the building, there are problems that the reaction tank is shallow, the ceiling of the basement is low, and a lifting device such as a hoist is not permanently installed. Therefore, when maintaining the membrane filtration unit, it is often difficult to pull up the membrane filtration unit from the reaction tank. Even if the membrane filtration unit can be pulled up from the reaction tank, sludge may flow out of the reaction tank and contaminate the sanitary equipment. Therefore, the membrane filtration unit is not pulled up from the reaction tank and maintenance is not performed outside the reaction tank, and the hollow fiber membrane element is pulled upward from the membrane filtration unit slightly lifted in the reaction tank to perform maintenance and membrane exchange. It is hoped that.

In the membrane filtration unit 1 described above, the frame 3 includes two vertical members 30 arranged so as to sandwich the hollow fiber membrane element 2 and extending in a substantially vertical direction, and the vertical member 30 is a hollow fiber. Since it has the guide part 42 which guides the membrane element 2 in a substantially vertical direction, the hollow fiber membrane element 2 is detachably arranged in the frame 3. That is, the hollow fiber membrane element 2 can be drawn upward from the membrane filtration unit 1 and the hollow fiber membrane element 2 can be inserted into the membrane filtration unit 1 from above. Therefore, since the hollow fiber membrane element 2 can be taken out from the membrane filtration unit 1 without taking the membrane filtration unit 1 out of the reaction tank, in a site where it is difficult to pull up the membrane filtration unit 1 with a water supply facility in a building, etc. Work such as maintenance can be easily performed.

The membrane filtration unit 1 described above preferably has an overall height of 1 m or more and 1.5 m or less. If the total height of the membrane filtration unit 1 is equal to or greater than the lower limit of the range, the membrane area per module volume can be maintained, and if the total height is equal to or less than the upper limit of the range, the unit is put into a treatment facility with a ceiling restriction Becomes easy.

In addition, since the above maintenance and the like are performed smoothly, the transportation cost can be reduced. From the viewpoint of the water treatment efficiency and the installation stability of the membrane filtration unit, the weight per membrane surface area of the membrane filtration unit 1 is 0.00. It is preferably 4 kg / m ² or more and 1.0 kg / m ² or less, and more preferably 0.5 kg / m ² or more and 0.7 kg / m ² or less.

<Second Embodiment>
FIG. 11 is a perspective view showing a second embodiment of the membrane filtration unit of the present invention. About the thing of the same structure as 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.
The membrane filtration unit 1 of the second embodiment is an example in which gas is supplied from one of the two vertical members 30 of the frame 3 to the diffuser tube 4.
The change from the first embodiment is that the air supply port 56 is attached to one of the through pipes 44a of the upper support plate 44 of one of the two vertical members 30, and the other through pipes 44a are all capped. 58 is a point; a sludge discharge pipe 4b is provided at the end of the air diffuser 4 opposite to the side to which the gas is supplied.

<Third Embodiment>
FIG. 12 is a perspective view showing a third embodiment of the membrane filtration unit of the present invention. The same components as those in the first embodiment or the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
The membrane filtration unit 1 according to the third embodiment is an example in which a column that also serves as an air supply pipe in the vertical member 30 of the frame 3 is formed in a rectangular tube shape.
The change from the second embodiment is that two struts 40 made of round pipes in the vertical member 30 of the frame 3 are changed to one square column-shaped strut 41; The H-shaped air supply header 60 is changed to a rectangular tube-shaped air supply header 61.
The support column 41 and the air supply header 61 are connected via a through pipe (not shown) formed in the lower support plate 46.

<Other embodiments>
The membrane filtration unit of the present invention includes a plurality of membrane elements, a frame holding the plurality of membrane elements, and an air diffuser connected to a lower portion of the frame, and at least a part of the frame supplies gas to the air diffuser. What is necessary is just to also serve as an air supply pipe | tube, and it is not limited to the thing of the example of illustration.

For example, the membrane element is preferably a hollow fiber membrane element having a high packing density, but may be a flat membrane element.
The vertical rod in the membrane element is not limited to a round pipe, and may be a square pipe as long as there is no problem of mechanical strength and membrane damage due to rubbing with the pipe. The cross-sectional shape of the square pipe is not limited to a quadrangle, and may be another shape such as a hexagon.
The fitting convex portion in the membrane element for guiding the membrane element in the substantially vertical direction may be a guide groove. In this case, the guide groove in the guide portion of the vertical member of the counterpart frame is a fitting convex portion.

The struts in the vertical members of the frame are not limited to round pipes, but may be square pipes as long as there are no problems such as mechanical strength and damage caused by rubbing when the hollow fiber membrane comes into contact. The cross-sectional shape of the square pipe is not limited to a quadrangle, and may be another shape such as a hexagon.
Of the pillars in the vertical member of the frame, those that do not serve as the air supply pipes may be solid cylindrical. In this case, it is not necessary to attach a cap to the through pipe 44a to which the columnar column is connected.
The number of columns in the vertical member of the frame may be one or more per vertical member, and may be set as appropriate according to the size of the membrane filtration unit. As shown in FIG. 1, the number of pillars in the vertical member of the frame is a frame-like structure when connected to the upper support plate and the lower support plate, and the vertical member is stable without wobbling. Two per member are preferred.

The guide portion in the vertical member of the frame may be divided vertically so as to divide the guide groove in the middle. However, if the guide part is divided vertically, positioning with respect to the lower guide part becomes difficult when the membrane element is inserted.
The upper support plate and the lower support plate in the vertical member of the frame may have the same shape or different shapes. Since only one mold for forming a molded product is required, the upper support plate and the lower support plate preferably have the same shape from the viewpoint that no extra cost is generated.
The presser plate and the support plate in the vertical member of the frame may be integrated with the upper support plate and the lower support plate, respectively, as long as there is no problem in mechanical strength.

The fastening means for fastening each member is not limited to bolts and nuts, and may be other means (for example, a giant clam vise).
The number of water collecting pipes is not limited to one. For example, when the membrane element is long in the substantially vertical direction, the transmembrane differential pressure increases only with the upper water collecting pipe. Another water collecting pipe may be connected to the lower housing in order to reduce the transmembrane pressure difference in the longitudinal direction of the membrane.

[Water treatment method]
The water treatment method of the present invention includes solid-liquid separation using the membrane filtration unit of the present invention. In the solid-liquid separation step in the water treatment method, a known aspect can be adopted except that the membrane filtration unit of the present invention is used.
For example, various wastewaters (industrial wastewater, domestic wastewater, etc.) containing organic matter, microorganisms (bacteria, etc.) and their debris are biochemically treated with activated sludge in the activated sludge water tank, and in the activated sludge water tank Water treatment can be performed by solid-liquid separation of sludge and treated water by the immersed membrane filtration unit of the present invention.
When the total height of the membrane filtration unit 1 is 1 m or more and 1.5 m or less, the activated sludge water tank may have a water depth of 1.5 m or less.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

Example 1
The membrane filtration unit 1 of FIG. 11 was produced as follows.
The air diffuser 4 was made by opening seven air diffuser holes 4a in a hard polyvinyl chloride tube (VP13, outer diameter 18 mm, inner diameter 13 mm).
An H-shaped air supply header 60 made of a rigid polyvinyl chloride pipe having three holes for connecting the air diffusion pipe 4 is attached to each end of the three air diffusion pipes 4 with an adhesive for polyvinyl chloride. Glued and fixed.

A lower support plate 46 provided with two through pipes 46a made of rigid polyvinyl chloride pipes (VP30, outer diameter 38 mm, inner diameter 31 mm) is prepared, and penetrates through the two upper ends of the vertical pipes of the air supply header 60 The tube 46a was fixed with an adhesive for polyvinyl chloride. Caps (not shown) were bonded and fixed to the two lower ends of the longitudinal pipes of the air supply header 60 with an adhesive for polyvinyl chloride.
A support plate 54 made of stainless steel (SUS304) having an L-shaped cross section was fixed to the lower support plate 46 with a hexagon socket bolt and a nut 52.
A strut 40 made of a hard polyvinyl chloride pipe (VP30, outer diameter 38 mm, inner diameter 31 mm) was fixed to each of the two through pipes 46a of the lower support plate 46 with an adhesive for polyvinyl chloride.

An upper support plate 44 provided with two through pipes 44a made of a rigid polyvinyl chloride pipe (VP30, outer diameter 38 mm, inner diameter 31 mm) is prepared, and the through pipe 44a is attached to the upper ends of the two columns 40 with polyvinyl chloride. Glued and fixed with an adhesive.
The end portions of the upper cross member 32 made of stainless steel (SUS304) having an L-shaped cross section were fastened and fixed to each of the two upper support plates 44 with hexagon socket bolts and eye nuts (suspending fittings 62). Thereby, the upper part of the membrane filtration unit 1 was reinforced, and the membrane filtration unit 1 could be suspended and pulled up from the reaction vessel.

The lower end of the guide portion 42 was bonded to the side surface of the lower support plate 46, and the upper end of the guide portion 42 was bonded to the side surface of the upper support plate 44. In this way, a total of four guide portions 42 were attached.
A socket serving as an air supply port 56 was adhered and fixed to the upper end of one of the four through pipes 44a with an adhesive for polyvinyl chloride. As a result, the air supply port 56 and the air diffuser 4 communicate with each other.
Caps 58 were adhered and fixed to the upper ends of the other three through pipes 44a with an adhesive for polyvinyl chloride. As a result, the air supplied from the air supply port 56 is structured not to leak from the portion other than the air diffuser 4.

The lower fitting convex portion 22 of the hollow fiber membrane element 2 (membrane area: 5 m ² ) shown in FIG. 2 is fitted into the guide groove 42a of the guide portion 42 and slid downward as shown in FIG. Then, the hollow fiber membrane element 2 was inserted into the frame. A total of ten hollow fiber membrane elements 2 were inserted into the frame 3. The thickness of the hollow fiber membrane element 2 in the vicinity of the center of the housing was 13 mm, and these were arranged at a pitch of 23 mm. Therefore, the interval X between the hollow fiber membrane elements 2 in the vicinity of the center of the housing was 10 mm.

The elastic member 6 made of EPDM shown in FIG. 7 (the thickness of the base material portion 6a not including the convex portion 6b: 6 mm, durometer hardness: A70) is set to the gap between the hollow fiber membrane elements 2 as shown in FIG. The hollow fiber membrane elements 2 arranged in the frame 3 were attached to both ends in the longitudinal direction of the upper housing 14 so that the convex portions 6b were fitted to each other.
As shown in FIG. 9, hexagon socket head bolts 48 are inserted into the bolt holes of the stainless steel (SUS304) pressing plate 50 and the upper support plate 44, and nuts (not shown) are attached to the bolts 48. These were tightened until they contacted all the hollow fiber membrane elements 2 without any gaps. In this way, the pressing plate 50 was fixed to the upper support plate 44 so as to press the hollow fiber membrane element 2 from above via the elastic member 6.

As shown in FIG. 10, the water collecting pipe 5 was attached above the hollow fiber membrane element 2 by connecting the water intake port 24 of the hollow fiber membrane element 2 and the connecting pipe 5 a of the water collecting pipe 5.
As described above, a membrane filtration unit 1 in which a plurality of hollow fiber membrane elements 2 were held by a frame 3 was obtained.

The outer dimensions of the membrane filtration unit 1 were width: 825 mm, depth: 260 mm, and height: 1296 mm.
The film packing density was 233 m ² / m ² (= 5 m ² × 10 / (0.825 m × 0.26 m)).
The maximum step Y between the side surface A and the surface B in FIG. 4 was 5 mm. Therefore, when the plurality of membrane filtration units 1 are arranged side by side without any gap, the interval between the hollow fiber membrane elements 2 arranged on the outermost side in each membrane filtration unit 1 is the hollow fiber membrane element 2 in the membrane filtration unit 1. The interval X between them could be the same as 10 mm. Even when a plurality of membrane filtration units 1 are juxtaposed, the gap between the hollow fiber membrane elements 2 can be 10 mm in all parts other than the part to which the upper transverse member is fixed, thereby reducing the membrane packing density. It was confirmed that the hollow fiber membrane elements 2 could be arranged without any problem.

The membrane filtration unit 1 is immersed in a reaction tank that performs biochemical treatment by the membrane-separated activated sludge method, a hose is connected to the water collection pipe 5, and the raw water is filtered by suction at 1.25 m ³ / h by a suction pump. When a hose is connected to the air supply port 56 and blown with a blower at 13.4 Nm ³ / h for aeration, the operation is continued for one month, and the suction differential pressure of the membrane filtration is stable without increasing. I was able to drive.
From the above results, it was confirmed that the membrane filtration unit 1 that is compact and capable of stable operation can be obtained at low cost by using a part of the frame 3 constituting the membrane filtration unit 1 as an air supply pipe.

The membrane filtration unit of the present invention is used for the treatment of highly polluted water (secondary or tertiary treatment in a sewage treatment plant, solid-liquid separation in a septic tank, solid-liquid separation of SS (suspended material) in industrial wastewater, etc.), It is suitably used for aseptic water, drinking water, high-purity pure water production applications, air purification applications, and the like.

1 membrane filtration unit, 2 hollow fiber membrane element, 3 frame, 4 air diffuser tube, 4a air diffuser hole, 4b sludge discharge tube, 5 water collecting tube, 5a connecting tube, 5b collecting tube, 5c water intake tube, 6 elastic member, 6a base Material part, 6b convex part, 10 hollow fiber membrane, 12 hollow fiber membrane sheet, 14 upper housing, 16 lower housing, 18 vertical shaft, 20 upper fitting convex part, 22 lower fitting convex part, 24 water intake, 30 vertical members, 32 upper horizontal members, 34 lower horizontal members, 40 struts, 41 struts, 42 guide sections, 42a guide grooves, 44 upper support plates, 44a through pipes, 46 lower support plates, 46a through pipes, 48 bolts, 50 Presser plate, 52 nut, 54 support plate, 56 air supply port, 58 cap, 60 air supply header, 61 air supply header, 62 hanging bracket, A Aspect, B surfaces, B 'surface, X interval, Y maximum step.

Claims

A plurality of membrane elements;
A frame for holding the plurality of membrane elements;
A diffuser tube connected to the lower part of the frame;
The membrane filtration unit, wherein at least a part of the frame also serves as an air supply pipe for supplying gas to the diffuser pipe.
The frame includes two vertical members arranged in a substantially vertical direction to sandwich the membrane element,
The membrane filtration unit according to claim 1, wherein at least a part of the vertical member also serves as an air supply pipe that supplies gas to the diffuser pipe.
The frame includes two vertical members arranged in a substantially vertical direction to sandwich the membrane element,
The membrane filtration unit according to claim 1 or 2, wherein the vertical member has a guide portion that guides the membrane element in a substantially vertical direction.
The membrane filtration unit according to any one of claims 1 to 3, wherein the membrane packing density determined from the following formula (I) is 150 to 350 m 2 / m 2 .

Where D is the membrane packing density, n is the number of membrane elements arranged in the membrane filtration unit, Ei is the surface area of the membrane in the i-th membrane element, and U is required for installation of the membrane filtration unit It is an area.
The frame includes two vertical members arranged in a substantially vertical direction to sandwich the membrane element,
The membrane filtration unit according to any one of claims 1 to 4, wherein a material of at least a part of the vertical member is a resin.
The membrane filtration unit according to claim 5, wherein the resin is a polyvinyl chloride resin.
The frame includes two vertical members arranged in a substantially vertical direction that sandwich the membrane element, and a horizontal member connected to the two vertical members,
The membrane filtration unit according to any one of claims 1 to 6, wherein the air diffuser also serves as at least a part of the transverse member.
The membrane element comprises a sheet-like membrane, an upper housing to which the upper end of the membrane is fixed, and a lower housing to which the lower end of the membrane is fixed,
The plurality of membrane elements are arranged such that the membranes face each other, the longitudinal directions of the upper housing and the lower housing are aligned, and a predetermined interval X is provided between the adjacent upper housings and between the adjacent lower housings. And
The frame includes two vertical members arranged in a substantially vertical direction to sandwich the membrane element from the longitudinal direction side of the upper housing and the lower housing,
The vertical member includes an upper support plate, and the outer surface B of the membrane element in which the side surface A of the upper support plate in the width direction perpendicular to the longitudinal direction of the upper housing and the lower housing is disposed on the outermost side. Or the side surface A protrudes so that the maximum step Y between the side surface A and the surface B is greater than 0 and less than or equal to the interval X. The membrane filtration unit according to any one of claims 1 to 7.
The membrane filtration according to any one of claims 1 to 8, wherein the membrane element comprises a sheet-like membrane, and the membrane outer diameter of the sheet-like membrane is 1 mm or more and 5 mm or less. unit.
The membrane filtration unit according to any one of claims 1 to 9, wherein the membrane element comprises a sheet-like membrane, and the membrane element has a support.
The membrane filtration unit according to any one of claims 1 to 10, wherein the total height is 1 m or more and 1.5 m or less.
The membrane filtration unit according to any one of claims 1 to 11, wherein the weight per membrane surface area is 1.0 kg / m 2 or less.
A water treatment method comprising solid-liquid separation using the membrane filtration unit according to any one of claims 1 to 12.
The water treatment method according to claim 13, wherein the membrane filtration unit according to any one of claims 1 to 12 is used in an activated sludge water tank.
The water treatment method according to claim 13, wherein the membrane filtration unit according to claim 11 is used in an activated sludge water tank having a water depth of 1.5 m or less.