WO2013146838A1

WO2013146838A1 - Separation membrane element having surface fastener, and membrane module

Info

Publication number: WO2013146838A1
Application number: PCT/JP2013/058914
Authority: WO
Inventors: 研司小森; 善文尾高; 修治古野; 健太岩井
Original assignee: 東レ株式会社
Priority date: 2012-03-30
Filing date: 2013-03-27
Publication date: 2013-10-03
Also published as: JPWO2013146838A1

Abstract

This invention pertains to a separation membrane element comprising: a separation membrane pair in which two separation membranes having permeation-side surfaces and supply-side surfaces are arranged such that the permeation-side surfaces are mutually facing; surface fasteners arranged on the permeation-side surfaces of the separation membranes so as to detachably fasten facing separation membranes; and a sealing section provided in the rim sections of the separation membrane pair, that seal between the separation membrane pair.

Description

Separation membrane element and membrane module having hook-and-loop fastener

The present invention relates to a separation membrane suitable for water treatment fields such as drinking water production, water purification treatment, waste water treatment, and food industry.

In recent years, separation membranes in the form of flat membranes and hollow fiber membranes that have come to be used for purification of sewage and wastewater include membrane separation elements provided with a separation membrane, and membranes provided with a plurality of the above-mentioned membrane separation elements. It is used for water purification treatment in the equipment of the separation module. Separation membranes used in separation methods using membrane separation elements include microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, reverse osmosis membranes, and forward osmosis membranes in terms of their pore size and separation function. Membranes are used to obtain drinking water from, for example, seawater, brine, and water containing harmful substances, and are used for the production of industrial ultrapure water, wastewater treatment, recovery of valuable materials, etc. Depending on the separation performance.

Patent Document 1 proposes a bag-like flat membrane element in which the peripheral end surfaces of two flat membranes are sealed with a resin adhesive as a flat membrane element and a manufacturing method thereof.

Patent Document 2 discloses a filter including a first filtration membrane, a first adhesive net made of a thermoplastic polymer, a drainage woven fabric, a second adhesive net of a thermoplastic polymer, and a second filtration membrane. Composite materials are described. The first and second filtration membranes are bonded to the drainage woven fabric by the first and second adhesive nets.

Japanese Unexamined Patent Publication No. 2000-117067 Japan Special Table 2011-519716

In the technique of Patent Document 1, there is a possibility that the amount of permeated water may be reduced due to contact between the permeation side surfaces of the separation membrane facing each other during filtration. In the technique of Patent Document 2, since the separation membrane and the woven fabric are fixed by the adhesive net, it is necessary to replace the element or the entire module when a part of the membrane is damaged.

The object of the present invention is to solve the above-mentioned problems of the prior art, improve the permeated water amount, and provide a technique capable of replacing only a membrane including a damaged portion with a new one.

In order to achieve the above object, the separation membrane element of the present invention is a separation membrane in which two separation membranes having a permeation side surface and a supply side surface are arranged so that the permeation side surfaces face each other. A membrane fastener, a hook-and-loop fastener disposed on the permeation side surface of the separation membrane so as to detachably engage between the opposing separation membranes, and a peripheral edge of the separation membrane pair. And a sealing portion for sealing.

By using the separation membrane of the present invention, the permeate side is fixed by a hook-and-loop fastener at the time of filtration operation, and at the same time, a flow path is formed, and high permeation performance can be obtained. In addition, even when the membrane is damaged due to long-term operation, it is possible to easily replace only the membrane including the damaged portion, thereby improving maintainability.

FIG. 1A is a cross-sectional view of a separation membrane pair whose peripheral portion is sealed with resin, and is a cross-sectional view in a plane parallel to the thickness direction of the separation membrane pair. 1B is a cross-sectional view of the separation membrane pair of FIG. 1A in a plane parallel to the plane of the membrane and passing through the center of thickness of the separation membrane pair (that is, a cross-sectional view of the separation membrane pair of FIG. . FIG. 2 is a cross-sectional view in a plane parallel to the thickness direction of another form of separation membrane pair. FIG. 3A is a cross-sectional view schematically showing a separation membrane pair whose peripheral edge is sealed with a jig, and is a cross-sectional view in a plane parallel to the thickness direction of the separation membrane pair. FIG. 3B is a plan view of the separation membrane pair of FIG. 3A. FIG. 4 is a plan view showing an example of a fixing jig used for the membrane element. FIG. 5 is a schematic diagram illustrating an example of a water treatment apparatus including a membrane module. FIG. 6 is a plan view showing an example of an application pattern of an adhesive that bonds the surface fastener and the base material. FIG. 7A is a cross-sectional view schematically showing a separation membrane pair whose peripheral portion is clipped, and is a cross-sectional view in a plane parallel to the thickness direction of the separation membrane pair. FIG. 7B is a plan view of the separation membrane pair of FIG. 7A.

1. Separation Membrane Element As shown in FIG. 1A, the separation membrane element 101 includes a separation membrane pair 1A,

surface fasteners

6 and 7, and a resin layer 8 as a sealing portion. The separation membrane pair 1A includes two separation membranes 2 and a resin layer 8 that are disposed so that the surfaces on the permeate side face each other. The separation membrane 2 may be any of a nanofiltration membrane, an ultrafiltration membrane, and a microfiltration membrane. In the present embodiment, the separation membrane 2 particularly includes a separation functional layer 4 and a base material 5.

The separation functional layer 4 is laminated on the base material 5, and the surface of the base material 5 opposite to the separation functional layer 4 is disposed on the permeation side surface of the separation membrane 2 and the

surface fastener

6 or 7. It is the surface to be done. In the present invention, the configuration of the separation membrane 2 is not limited to the illustrated example. The separation membrane is not limited as long as it separates components in the fluid supplied to the surface of the separation membrane and obtains a permeated fluid that has permeated the separation membrane. The separation membrane may include a porous support layer between the separation functional layer and the substrate.

The separation functional layer 4 is provided on the surface of the separation membrane 2 on the supply side, that is, the surface with which the liquid before being filtered contacts. As the separation function layer, a known configuration can be adopted.

If the thickness of the separation functional layer of the separation membrane is too thin, defects such as cracks may occur and the filtration performance may deteriorate. If it is too thick, the water permeability may decrease. 1 μm to 500 μm), preferably 0.05 to 0.2 mm (50 μm to 200 μm).

As the separation functional layer, a crosslinked polymer is preferably used in terms of pore size control and durability, and in terms of component separation performance, a separation functional layer formed by polycondensation of a polyfunctional amine and a polyfunctional acid halide and An organic-inorganic hybrid functional layer is preferred. These separation functional layers are preferably formed on a porous support layer provided on a substrate. The separation functional layer may be a porous support layer such as a cellulose membrane, a polyvinylidene fluoride membrane, a polyethersulfone membrane, or a polysulfone membrane, and may be a layer having both a separation function and a support function. . That is, the separation functional layer and the porous support layer may be realized as a single layer. In particular, the separation membrane preferably includes a base material and a separation functional layer, and the separation functional layer is preferably made of a polyvinylidene fluoride resin.

It is preferable that a layer in which the resin constituting the separation functional layer and the base material are mixed is interposed between the base material and the separation functional layer. When the polyvinylidene fluoride-based blend resin enters from the surface of the base material into the inside, the separation functional layer is firmly fixed to the base material by a so-called anchor effect. As a result, separation of the separation functional layer from the substrate is suppressed. The separation functional layer may exist only on one side of the base material, or may exist on both sides. The separation functional layer may have a symmetric structure or an asymmetric structure with respect to the base material. Moreover, when the separation functional layer exists on both surfaces of the substrate, the separation functional layers on both sides may be continuous or discontinuous through the substrate.

In a separation membrane comprising a separation functional layer and a substrate, the substrate has a function of supporting the separation functional layer and giving strength to the separation membrane. The material constituting the base material is not particularly limited, such as an organic base material or an inorganic base material, but an organic base material is preferable from the viewpoint of easy weight reduction. Examples of the organic substrate include woven and knitted fabrics and nonwoven fabrics made of organic fibers such as cellulose fibers, cellulose triacetate fibers, polyester fibers, polypropylene fibers, and polyethylene fibers. In particular, a nonwoven fabric whose density control is relatively easy is preferable.

A hook-and-loop fastener is a structure which is arrange | positioned on the permeation | transmission side surface of a separation membrane, and attaches | detaches between the separation membranes which oppose. The term “engagement” is paraphrased as “sticking”, “engagement”, “locking”, “connection”, and the like. That is, the hook-and-loop fastener can fix the relative position of the other separation membrane with respect to one separation membrane between two separation membranes, and can release this fixation. It is a possible structure. Specifically, a hook-and-loop fastener is a member that can be attached to and detached from other hook-and-loop fasteners. For example, the hook-and-loop fastener is a member that is formed such that the surfaces facing each other and other hook-and-loop fasteners are engaged with each other, or is opposed. Examples include members each having a large number of male parts and female parts on the surface. The hook-and-loop fastener may be rephrased as “an engagement portion” or the like.
For example, the hook-and-loop fastener can include a sheet-like base material provided with an engaging surface on at least one side and an engaging element provided on the engaging surface of the base material. When the engagement surfaces of the two surface fasteners come into contact with each other, the surface fasteners are detachably engaged via the engagement elements. Specifically, the engaging element may be formed so that elements having different structures can be engaged with each other, or may be formed so that elements having the same structure can be engaged with each other.
In a hook-and-loop fastener including a loop-hook type or snap type engaging element, elements having different structures are engaged with each other. Further, in a hook-and-loop fastener including a mushroom-type engagement element, engagement elements having the same structure are engaged with each other. In addition to the loop-hook structure, other structures such as a structure in which irregularities mesh with each other may be adopted.

The

surface fasteners

6 and 7 in FIG. 1A are an example of the form of the surface fastener provided on the separation membrane. The

surface fastener

6 or 7 is provided on the permeate side surface of the separation membrane 2. The surface fastener 6 includes a base material 61 and a hook portion 9 that is an engaging element provided on one surface of the base material 61, and the surface fastener 7 is provided on the base material 71 and one surface of the base material 71. And a loop portion 10 which is an engaging element. In the form of FIG. 1A, the hook-and-loop fastener 6 includes only a hook portion (hook-like fiber) 9 as an engaging element, and the hook-and-loop fastener 7 includes only a loop portion (loop-like fiber) 10 as an engaging element.

Further, as shown in FIG. 2, the two facing surface fasteners may have the same configuration. That is, the separation membrane element 102 shown in FIG. 2 includes the separation membrane pair 1B, and the loop portion 9 and the hook portion 10 are provided on both permeation side surfaces of the separation membrane 2 facing each other in the separation membrane pair 1B. The hook-and-loop fastener 11 provided with both is provided.

Thus, the hook-and-loop fastener can detachably connect the opposing separation membranes. The material constituting the surface fastener is not particularly limited, but plastic, particularly polyester, polyamide, polypropylene, and the like are preferably used. As these hook-and-loop fasteners, commercially available products such as Kuraray "Magic Tape (registered trademark)", YKK "Quicklon (registered trademark)", "Power Hook (registered trademark)", and Sumitomo 3M "mechanical fastener" are used. It is possible.

Regarding the form in which a part of the separation membrane is connected by the hook-and-loop fastener, even if the opposing separation membrane is connected only through the hook-and-loop fastener, a support plate provided with the hook-and-loop fastener is arranged between the opposing membranes and supported. Although it may be connected to the plate via a hook-and-loop fastener, a form in which the plate is connected only via the hook-and-loop fastener is preferable in terms of weight reduction and cost.

As an example of the form in which the separation membrane pair is connected only through the hook-and-loop fastener except for the sealing portion, FIG. 1A includes a hook-like fiber 9 included in one hook-and-loop fastener in the hook-and-loop fastener facing the hook-and-loop fiber 9. It refers to being hooked on the looped fiber 10. That is, in the separation membrane pair, one separation membrane is fixed to the other separation membrane through hooks of hook-shaped resin of the hook-and-loop fastener and loop-shaped fibers. Such fixing is called engagement. Further, by applying a force in the direction in which the opposing separation membranes are separated from each other, the engagement is released and the fixation by the surface fastener is released. Thus, in the separation membrane pair 1A, the two separation membranes 2 can be repeatedly desorbed from each other on the opposing surfaces.

The ease of attaching and detaching the two opposing transmission-side surfaces can be adjusted by the material of the hook-and-loop fastener, the shape, size, fiber diameter, and number per unit area of the loop-like fibers and hook-like fibers. .

The ease of attaching and detaching the surface fastener can be evaluated by the peel strength (peel strength) described in JIS-L-3416: 2000. The range of the peel strength is preferably 0.1 N / cm or more, more preferably 0.5 N / cm or more, and further preferably 1.0 N / cm or more, from the viewpoint of suppressing membrane shaking and deflection during filtration.

In the present embodiment, as shown in FIG. 1A, two opposing transmission-side surfaces are connected by hook-and-

loop fasteners

6 and 7, so that even if the above-described back pressure cleaning is performed, the pressure is applied to the sealed portion. Instead of concentrating, it is also distributed to the inner part. Therefore, the occurrence of separation between separation membranes is suppressed, and an effect that water leaks from the supply side to the permeation side hardly occurs. In addition, since the opposing surfaces can be detached by the hook-and-loop fastener, when a part of the separation membrane is damaged, it is easy to separate the corresponding membrane from the paired membrane and exchange it with another membrane. .

The ratio R1 of the area A2 of the hook-and-loop fastener portion to the internal area A1 excluding the peripheral portion (described later) of the separation membrane is 10% or more, 25% or more, or from the viewpoint of suppressing membrane shaking and deflection during filtration, or 50% or more is preferable. Further, the ratio R1 may be 100%, and from the viewpoint of securing a flow path of permeated water, the ratio R1 may be less than 100%, 80% or less, 70% or less, or It may be 60% or less.

When the ratio R1 is less than 100%, the pattern of the surface fastener in a plan view (that is, a shape in a plane parallel to the surface direction of the separation membrane) is not particularly limited. Examples of the shape of the hook-and-loop fastener include a stripe shape, a lattice shape, a mesh shape, a polka dot shape, and a tile shape. The tile shape is a pattern in which polygonal surface fasteners such as triangles and quadrangles are arranged at intervals. The positions where the surface fasteners are provided are preferably uniformly distributed without being biased toward a part of the separation membrane.

The surface fastener and the substrate can be fixed by providing an adhesive resin. Components that make up the resin layer between the hook-and-loop fastener and the base material are instantaneous, hot melt, two-component room temperature curable resin, thermosetting resin, elastomer, thermoplastic resin, elastic, emulsion, etc. Although not particularly limited, from the viewpoint of durability, curing speed, and cost, a hot melt system, a two-component room temperature curing resin system, a thermosetting resin system, an elastomer system, and a thermoplastic resin system are preferable, among which durability, From the viewpoint of productivity, a two-component room temperature solidified resin system such as urethane resin and epoxy resin is most preferably used.

The adhesive resin provided between the surface fastener and the base material is provided only on a part of the surface of the base material 6 in order to ensure water permeability from the base material 6 to the gap 3. As described above, in the area A1 of the surface of the base material 6 excluding the peripheral edge portion (portion where water cannot be passed for fixing separation membranes), the ratio R1 occupied by the area of the portion A2 where the surface fastener is provided is less than 100%. If so, this condition is satisfied. Even if the ratio R1 is 100%, the ratio R2 of the area A3 of the region where the adhesive resin is provided in the area A1 may be less than 100%. A specific example of the ratio R2 is the same as the ratio R1. Also, the application pattern of the adhesive resin can be changed to a stripe shape, a lattice shape, a mesh shape, a polka dot shape, a tile shape, and the like, and it is preferable that the adhesive resin is uniformly applied without being partially biased.

The hook-and-loop fastener may also serve as a base material. For example, in FIG. 1A, the base material 71 of the surface fastener may also serve as the base material 5 of the separation membrane 2.
It is preferable that the permeation side surfaces of the facing separation membrane are sealed at the peripheral edge of the separation membrane. That is, the separation membrane element includes a sealing portion that is provided at the peripheral portion of the separation membrane and seals between the separation membranes. Sealing means that the supply water does not flow directly into the gap 3 by adhesion, pressure bonding, welding, fusion, folding, fixing by other members such as a clip, etc. (that is, if the supply water does not permeate the separation membrane) (So that it cannot flow into the gap 3).

In particular, from the viewpoint that it is possible to easily remove the seal for replacement of the membrane, the sealing portion is formed by an adhesive or can be separated from the separation membrane, and the separation membrane is fixed. It is preferable that it is a member to do.

When the sealing part is an adhesive, it is bonded by heating only the peripheral part of the film provided with the sealing part to soften or plasticize the adhesive, or in contact with a solvent soluble in the adhesive By removing the agent, it is possible to remove the seal without damaging the inner separation functional layer from the peripheral edge.

Examples of the sealing portion that can be separated from the separation membrane include a clip or a member such as a spacer and a bolt. In this case, the sealing can be removed by removing the member that is the sealing portion from the separation membrane.

As an example of the sealing structure by bonding, FIGS. 1A and 1B show a resin layer 8 as a sealing portion, and as an example of fixing by other members, FIGS. 3A and 3B show a spacer 12 and a washer 13. And bolts 14 are described.

The resin layer 8 is disposed on the periphery of the separation membrane so as to surround the gap 3. The resin layer 8 is bonded to both of the two permeation-side surfaces facing each other in the separation membrane pair, thereby sealing the gap between the separation membranes in the separation membrane pair. Thus, a bag-like film is formed.

The components constituting the peripheral resin layer include, but are not particularly limited to, instantaneous systems, hot melt systems, two-component room temperature curing resin systems, thermosetting resin systems, elastomer systems, thermoplastic resin systems, elastic systems, and emulsion systems. However, from the viewpoint of durability, curing speed, and cost, a hot melt system, a two-component room temperature curing resin system, a thermosetting resin system, an elastomer system, and a thermoplastic resin system are preferable. Especially, when durability and productivity are important Two-component room temperature solidified resin systems such as urethane resin and epoxy resin are preferable, and when it is assumed that the film is frequently replaced, a hot melt system or a thermoplastic resin system that can be easily removed is preferable. .

3A and 3B, a spacer 12, a washer 13, a bolt 14, and a nut 30 are provided in place of the resin layer 8.

As the spacer 12, for example, a metal or resin member is used. The spacer 12 is a member having a shape along the peripheral edge of the separation membrane, and is disposed between the two separation membranes 2. Specifically, the spacer 12 is a rectangular frame member.

The bolt 14 and the nut 30 are made of metal or resin, for example. The bolt 14 penetrates the two separation membranes 2 and the spacer 12. The two separation membranes 2 are fixed by bolts 14 and nuts 30 with the spacer 12 interposed therebetween. The bolt 14 can be pulled out from the separation membrane 2 by being loosened. Thus, the bolt 14 fixes the spacer 12 between the separation membranes 2 and seals between the separation membranes 2.

In this case, a washer 13 may be disposed between the bolt 14 and the separation membrane 2 on the supply side surface of the separation membrane 2. The washer 13 can further suppress damage to the separation membrane and enhance adhesion. The washer 13 is a member made of, for example, metal or resin. As shown in FIG. 3B, the washer 13 is a member having a shape along the peripheral edge of the separation membrane 2, and more specifically, a rectangular frame member having substantially the same shape as the spacer 12.

Further, the separation membrane may be secured by a clip instead of the bolt-nut structure. As shown in FIGS. 7A and 7B, the clip 31 holds the two separation membranes 2 at the peripheral edge of the separation membrane 2 so that the spacer 12 is sandwiched between the separation membranes. As the clip 31, a member whose opening degree can be changed or a member whose opening degree is fixed can be used. In FIG. 7B, a total of four clips 31 arranged so as to correspond to one side of the separation membrane 2 are provided for one separation membrane pair. In addition to this, for example, an L-shaped clip may be used. The L-shaped clip is arranged so as to correspond to two adjacent sides in the rectangular shape of the separation membrane 2.

7A. Frame members 32 are arranged on both surfaces of the separation membrane pair 1D in FIG. 7A, that is, the surfaces on the supply side of the two separation membranes. The frame member 32 is a rectangular frame-shaped member along the peripheral edge of the separation membrane 2, and is made of, for example, metal or resin.

In any of the forms described above, in the separation membrane pair, the interval between the permeation side surfaces of the separation membrane (the distance indicated by the arrow in FIG. 1A) is preferably 50 μm or more. As a result, a permeate-side flow path can be secured and the flow resistance is reduced. Moreover, it is preferable that the space | interval of a permeation | transmission side surface is 5000 micrometers or less. As a result, a relatively large membrane area per module can be secured.

In the drawings referred to in this specification such as FIG. 1A and FIG. 3A, the surface fastener (at least the base material of the surface fastener) reaches the sealing portion, that is, overlaps the resin layer 8 or the spacer 12. Have been placed. However, the present invention is not limited to these configurations, and the sealing portion only needs to be provided so as to surround at least a part of the hook-and-loop fastener. For example, the hook-and-loop fastener is arranged only in a region surrounded by the resin layer 8 or the spacer 12, that is, only inside the resin layer 8 or the spacer 12 so as not to overlap the resin layer 8 or the spacer 12. May be.

2. Next, a method for producing a separation membrane used in the present invention will be described. This separation membrane forms a separation functional layer by attaching a film-forming stock solution containing a polyvinylidene fluoride resin and a pore-opening agent to one or both surfaces of a base material and coagulating it in a coagulating liquid containing a non-solvent. Can be manufactured. At this time, the means for attaching the film-forming stock solution to the surface of the substrate may be application of the film-forming stock solution or immersion of the substrate in the film-forming stock solution. When applying the film-forming stock solution to the substrate, the film-forming stock solution may be applied to one side of the substrate, or the film-forming stock solution may be applied to both sides. Only the separation functional layer may be formed separately from the base material, and then both layers of the base material and the separation functional layer may be joined.

In coagulating the membrane-forming stock solution, only the film of the membrane-forming stock solution for forming the separation functional layer formed on the substrate may be brought into contact with the coagulation solution, or the substrate and its substrate Both the film of the membrane-forming stock solution for forming the separation functional layer formed on the material may be immersed in the coagulation liquid. In order to bring only the film of the film-forming solution into contact with the coagulation liquid, for example, a method of bringing the film formed on the substrate into contact with the surface of the coagulation bath so that it is on the lower side, a glass plate, a metal plate, etc. There is a method in which a base material is brought into contact with a smooth plate and attached so that the coagulation bath does not wrap around the base material side, and the base material having a film-forming solution film is immersed in the coagulation bath together with the plate. In the latter method, the base material may be attached to the plate and then the film of the film forming stock solution may be formed, or the film of the film forming raw solution may be formed on the base material and then attached to the plate.

In addition to the above-described polyvinylidene fluoride resin, a pore-forming agent and a solvent for dissolving them may be added to the film-forming stock solution as necessary.

In the case of adding a pore-opening agent having an action of promoting porous formation to the film-forming stock solution, the pore-opening agent may be any one that can be extracted by the coagulation liquid, and is preferably highly soluble in the coagulation liquid. For example, polyoxyalkylenes such as polyethylene glycol and polypropylene glycol, aqueous polymer such as polyvinyl alcohol, polyvinyl butyral, and poracrylic acid, and glycerin can be used.

In the present invention, a surfactant containing a polyoxyalkylene structure, a fatty acid ester structure or a hydroxyl group can be used as the pore opening agent. Use of a surfactant makes it easy to obtain the target pore structure.

As polyoxyalkylene structure,
-(CH ₂ CH ₂ O) _n -,-(CH ₂ CH ₂ (CH ₃ ) O) _n- ,
-(CH ₂ CH ₂ CH ₂ O) _n -,-(CH ₂ CH ₂ CH ₂ CH ₂ O) _n-
From the viewpoint of hydrophilicity in particular,
-(CH ₂ CH ₂ O) _n-
So-called polyoxyethylene represented by

Examples of the fatty acid ester structure include fatty acids having a long-chain aliphatic group. The long-chain aliphatic group may be linear or branched, and examples of the fatty acid include stearic acid, oleic acid, lauric acid, and palmitic acid. Moreover, fatty acid ester derived from fats and oils, such as beef tallow, palm oil, coconut oil, etc. are also mentioned.

Examples of the surfactant having a hydroxyl group include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, glycerin, sorbitol, glucose, and sucrose.

The surfactant used as a pore opening agent in the present invention preferably contains two or more of a polyoxyalkylene structure, a fatty acid ester structure and a hydroxyl group.

Of these, surfactants containing all of the polyoxyalkylene structure, fatty acid ester structure and hydroxyl group are particularly preferably used. For example, polyoxyethylene sorbitan fatty acid ester includes polyoxyethylene sorbitan monostearate, polyoxyethylene palm Oil fatty acid sorbitan, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene fatty acid ester, polyethylene glycol monostearate, polyethylene glycol monooleate, polyethylene glycol monolaurate Can be mentioned. These surfactants are particularly preferable because they not only improve the dispersibility of the inorganic fine particles, but also have the characteristics that even if they remain in the porous layer and are dried, the water permeability and blocking properties are not lowered.

When a solvent for dissolving polyvinylidene fluoride resin, other organic resin, pore-opening agent and the like is used in the film forming stock solution, N-methylpyrrolidone (NMP), N, N— Dimethylacetamide (DMAc), N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetone, methyl ethyl ketone, and the like can be used. Of these, NMP, DMAc, DMF, and DMSO, which are highly soluble in polyvinylidene fluoride resins, can be preferably used.

In addition, a non-solvent can be added to the film forming stock solution. The non-solvent does not dissolve the polyvinylidene fluoride resin or other organic resins, and acts to control the size of the pores by controlling the solidification rate of the polyvinylidene fluoride resin and other organic resins. To do. As the non-solvent, water and alcohols such as methanol and ethanol can be used. Of these, water and methanol are preferred from the viewpoint of ease of wastewater treatment and price. These may be mixed.

In the composition of the film forming stock solution, the polyvinylidene fluoride resin is 5% to 30% by weight, the pore-opening agent is 0.1% to 15% by weight, the solvent is 45% to 94.8% by weight, and the non-solvent is It is preferably in the range of 0.1% to 10% by weight. In particular, when the amount of the polyvinylidene fluoride resin is extremely small, the strength of the porous layer is lowered, and when the amount is too large, the water permeability may be lowered. Therefore, the range of 8 wt% to 20 wt% is more preferable. If the amount of the pore-opening agent is too small, the water permeability may decrease, and if the amount is too large, the strength of the porous layer may decrease. In addition, if it is extremely large, it may remain excessively in the polyvinylidene fluoride resin and elute during use, and the quality of the permeated water may deteriorate or the water permeability may change. Therefore, a more preferable range is 0.5 to 10% by weight. Furthermore, when the amount of the solvent is too small, the stock solution is easily gelled, and when the amount is too large, the strength of the porous layer is lowered, so that the range of 60% by weight to 90% by weight is more preferable. If the amount of non-solvent is too large, gelation of the stock solution tends to occur, and if it is extremely small, control of the size of pores and macrovoids becomes difficult. Therefore, it is more preferably 0.5% by weight to 5% by weight.

On the other hand, as the coagulation bath, a non-solvent or a mixed solution containing a non-solvent and a solvent can be used. When a non-solvent is used for the film-forming stock solution, the non-solvent in the coagulation bath is preferably at least 80% by weight of the coagulation bath. If the amount is too small, the coagulation rate of the polyvinylidene fluoride resin becomes slow, and the pore diameter becomes large. More preferably, it is in the range of 85% by weight to 100% by weight. On the other hand, when a non-solvent is not used for the film-forming stock solution, it is preferable to reduce the content of the non-solvent in the coagulation bath, compared to the case where a non-solvent is also used for the film-forming stock solution. preferable. When there are many nonsolvents, the coagulation | solidification speed | rate of a polyvinylidene fluoride type resin will become quick, the surface of a porous layer may become dense, and water permeability may fall. The range of 60% by weight to 99% by weight is more preferable. By adjusting the content of the non-solvent in the coagulation bath, the pore size on the surface of the porous layer and the size of the macrovoids can be controlled. If the temperature of the coagulation bath is too high, the coagulation rate will be too fast. Conversely, if the temperature is too low, the coagulation rate will be too slow, so it is usually selected within the range of 15 ° C to 80 ° C. preferable. More preferably, it is in the range of 20 ° C to 60 ° C.

The membrane element can further include a water collection port. The permeated water that is filtered by the separation membrane and flows through the gap 3 between the separation membranes is taken out of the membrane element through the water collection port.

The water collecting port of the membrane element may be arranged either at the peripheral edge or inside of the separation membrane pair. For example, as an example of the form of the membrane element that can be suitably used for the treatment of sewage wastewater, it is preferable to include a water collection port for allowing permeate to flow out from the peripheral portion of the separation membrane pair, and a fixing jig that supports the water collection port It is preferable that a separation membrane pair is attached to.

For example, one of the separation membrane pairs 1A, 1B, 1C, or 1D shown in any of FIGS. 1A, 2, 3A, and 7A and the fixing jig 15 shown in FIG. 4 may be provided.

FIG. 4 shows a form in which the fixing jig 15 is applied to the separation membrane element 101 of FIG. 1A as a specific example. The fixing jig 15 is disposed on the periphery of the separation membrane pair 1A (to be along one side of the separation membrane rectangle) so as to be sandwiched between the separation membranes 2 of the separation membrane pair. A water collecting pipe 16 passes through the fixing jig 15, and an end portion of the water collecting pipe 16 functions as a water collecting port 161. The permeated water is discharged from the gap 3 through the water collecting pipe 16 to the outside of the separation membrane pair 1A (or 1B or 1C).

Also, this membrane element can be used as a part of a membrane module. The membrane module includes a plurality of membrane elements and a housing that accommodates these membrane elements.

3. Membrane module and sewage wastewater treatment apparatus The sewage wastewater treatment apparatus illustrated in FIG. In FIG. 5, the membrane module 17 includes a housing 171 and a plurality of membrane elements 18 accommodated in the housing 171 so as to have a space between the adjacent membrane elements 18 in parallel with each other. The plurality of membrane elements 18 are arranged in parallel.

The wastewater treatment apparatus includes a membrane module 17, a membrane immersion water tank 19, an air diffuser 20, a blower 21, and a suction pump 23.

The membrane immersion water tank 19 stores water to be treated such as organic waste water. The membrane module 17 is immersed in the water to be treated. The membrane module 17 is arranged so that the membrane surface direction of the membrane element 18 inside thereof is vertical.

The air diffuser 20 is provided below the membrane module 17. The air diffuser 20 supplies the gas from the blower 21 to the membrane surface of the separation membrane.

The suction pump 23 sucks the permeated water 22 filtered by the membrane module 17 and collects it outside the membrane module 17.

In the sewage treatment apparatus configured as described above, a liquid to be treated such as waste water passes through a separation membrane by a suction force of a pump (not shown). At this time, suspended substances such as microbial particles and inorganic particles contained in the liquid to be treated are filtered. Then, the permeated water that has passed through the separation membrane flows to the permeation side of the separation membrane, and is taken out of the membrane immersion water tank 19 through the water collection port.

On the other hand, the air diffuser 20 generates bubbles in parallel with the filtration, and an upward flow parallel to the membrane surface of the membrane element is generated by the air lift action of the bubbles. By this upward flow, the filtrate deposited on the membrane surface is separated.

The liquid to be treated is not limited to sewage wastewater, but can be used for water purification, clean water treatment, wastewater treatment, industrial water production, etc. in the water treatment field, river water, lake water, groundwater, seawater, sewage Waste water can be used as treated water.

The water permeability of the separation membrane and the gap on the permeation side in Examples and Comparative Examples were measured as follows.

[Production of separation membrane element]
Two separation membranes produced by the method described later are cut out at 12 cm square, and a separation membrane pair is produced by the method described in each example and comparative example, and a fixing jig (FIG. 4) with a water collecting port is attached. Thus, a separation membrane element was produced.

[Water permeability of separation membrane]
The separation membrane element thus obtained was immersed in a water tank having a height of 20 cm, a width of 20 cm, and a depth of 20 cm. Distilled water was preliminarily permeated at 25 ° C. for 5 minutes at a head height of 1 m, and then permeated water was collected for 5 minutes by permeating distilled water. Based on the amount of permeated water thus obtained in 5 minutes, the amount of permeated water [m ³ / (m ² · s · Pa)] was calculated.

[Gap on the transmission side]
The separation membrane element was cut in the thickness direction, and the gap of the separation membrane was measured with a microscope (Model: VHX-1000 manufactured by Keyence Corporation) in the cross section.

Example 1
Polyvinylidene fluoride (PVDF, weight average molecular weight 280,000) was used as a resin component for the film-forming stock solution. Further, polyethylene glycol (PEG 20,000, weight average molecular weight 20,000) was used as a pore-opening agent, N, N-dimethylformamide (DMF) was used as a solvent, and H ₂ O was used as a non-solvent. These were sufficiently stirred at a temperature of 95 ° C. to prepare a film-forming stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 13.0% by weight
Polyethylene glycol (PEG 20,000): 5.5% by weight
N, N-dimethylformamide (DMF): 78.0% by weight
H ₂ O: 3.5% by weight

Using a non-woven fabric made of rectangular polyester fiber having a density of 0.42 g / cm ³ and a size of 50 cm width × 150 cm length as the base material, the film-forming stock solution was cooled to 30 ° C., and then applied to the base material. Immediately immersed in pure water at 20 ° C. for 5 minutes and further immersed in hot water at 90 ° C. for 2 minutes to wash away N, N-dimethylformamide as a solvent and polyethylene glycol as a pore opening agent, A separation membrane was produced by drying in a hot air dryer for 30 minutes.

Next, two pieces were cut out at 12 cm square from the obtained separation membrane. Of these, a loop-shaped surface fastener 7 is provided on the permeation side of one separation membrane, and a hook-shaped surface fastener 6 is provided on the entire permeation side of the other separation membrane using an epoxy resin adhesive. Pasted. As shown in FIG. 6, an adhesive 26 is applied in the form of dots between the surface fastener 6 and the separation membrane 2 and between the surface fastener 7 and the separation membrane 2, and the ratio of the adhesive portion to the area of the surface fastener. Was 25%. An ethylene vinyl acetate copolymer resin having a width of about 5 mm and a height of about 3 mm was applied to the outer peripheral portion of the separation membrane, that is, the peripheral portion.

The gap on the permeate side of the separation membrane pair thus obtained was 0.5 mm (500 μm). Furthermore, when a separation membrane element was prepared by attaching a fixing jig for a water collecting port to the end, and the water permeability of the separation membrane was measured, 21.0 × 10 ⁻⁹ m ³ / (m ² · s · Pa )Met.

Then, after heating the adhesive part at the peripheral part of the pair of separation membranes to 100 ° C. to soften the ethylene vinyl acetate copolymer, the peripheral part and the surface fastener part inside thereof are peeled off, and then the peripheral part is adhered again. When the water permeability of the separation membrane pair obtained was measured, it was 21.1 × 10 ⁻⁹ m ³ / (m ² · s · Pa), which was almost the same as that before peeling.

(Example 2)
A separation membrane was prepared and evaluated in the same manner as in Example 1 except that the type of the hook-and-loop fastener was changed so that the gap on the permeation side of the separation membrane was 0.05 mm (50 μm). As a result, the water permeability of the separation membrane was 20.2 × 10 ⁻⁹ m ³ / (m ² · s · Pa), which was almost the same value as in Example 1.

Then, after heating the adhesive part at the peripheral part of the pair of separation membranes to 100 ° C. to soften the ethylene vinyl acetate copolymer, the peripheral part and the surface fastener part inside thereof are peeled off, and then the peripheral part is adhered again. When the water permeability of the separation membrane pair obtained was measured, it was 20.1 × 10 ⁻⁹ m ³ / (m ² · s · Pa), which was almost the same as that before peeling.

(Example 3)
A separation membrane element was prepared and evaluated in the same manner as in Example 1 except that the type of the hook-and-loop fastener was changed so that the gap on the permeation side of the separation membrane was 2 mm (2000 μm). 2 × 10 ⁻⁹ m ³ / (m ² · s · Pa), which was substantially the same value as in Example 1.

Then, after heating the adhesive part at the peripheral part of the pair of separation membranes to 100 ° C. to soften the ethylene vinyl acetate copolymer, the peripheral part and the surface fastener part inside thereof are peeled off, and then the peripheral part is adhered again. When the water permeability of the separation membrane pair obtained was measured, it was 23.3 × 10 ⁻⁹ m ³ / (m ² · s · Pa), which was almost the same as that before peeling.

(Example 4)
A separation membrane element was prepared and evaluated in the same manner as in Example 1 except that the type of the hook-and-loop fastener was changed so that the gap on the permeation side of the separation membrane was 5 mm (5000 μm). 1 × 10 ⁻⁹ m ³ / (m ² · s · Pa), which was substantially the same value as in Example 1.

Then, after heating the adhesive part at the peripheral part of the pair of separation membranes to 100 ° C. to soften the ethylene vinyl acetate copolymer, the peripheral part and the surface fastener part inside thereof are peeled off, and then the peripheral part is adhered again. When the water permeability of the separation membrane pair obtained was measured, it was 25.9 × 10 ⁻⁹ m ³ / (m ² · s · Pa), which was a value almost unchanged from that before peeling.

(Example 5)
A separation membrane element was prepared and evaluated in the same manner as in Example 1 except that a stainless steel spacer having a width of about 3 mm was disposed on the periphery of the separation membrane and fixed with bolts. It was 8 × 10 ⁻⁹ m ³ / (m ² · s · Pa), which was almost the same value as in Example 1.

Then, after fixing the peripheral part of the separation membrane pair, peeling the hook-and-loop fastener part inside, and measuring the water permeability of the separation membrane pair obtained by fixing the peripheral part again with a spacer and a bolt, 25 .8 × 10 ⁻⁹ m ³ / (m ² · s · Pa), which is almost the same as that before peeling.

(Comparative Example 1)
A separation membrane element was produced and evaluated in the same manner as in Example 1 except that a surface fastener was not provided on the permeation side of the separation membrane and resin was applied only to the periphery. The gap on the permeate side of the separation membrane is 0.4 mm or less (400 μm or less), and the water permeability of the separation membrane is 6.2 × 10 ⁻⁹ m ³ / (m ² · s · Pa), which is 1 / of that of Example 1. The value was about 4.

(Comparative Example 2)
Separation is performed in the same manner as in Example 1 except that the resin is applied only around the permeation side of the separation membrane and a flow path net (thickness: 700 μm, pitch: 5 mm × 5 mm, fiber diameter: 780 μm) is sandwiched. When the membrane element was produced and evaluated, the water permeability of the separation membrane was 16.4 × 10 ⁻⁹ m ³ / (m ² · s · Pa), which was about 3/5 of that of Example 1.

(Comparative Example 3)
The drainage woven fabric for the flow path is sandwiched, the permeation side of the separation membrane and the drainage woven fabric are applied in a dot shape with the epoxy resin in the pattern shown in FIG. 25%. Otherwise, the separation membrane element was produced and evaluated in the same manner as in Example 1. As a result, the water permeability of the separation membrane was 18.7 × 10 ⁻⁹ m ³ / (m ² · s · Pa). . After heating the adhesive part at the peripheral part of the separation membrane pair to 100 ° C. to soften the ethylene-vinyl acetate copolymer, the peripheral part and the drained woven cloth inside are peeled off, and then the drained woven cloth and the peripheral part are again separated. When the water permeability of the separation membrane pair obtained by bonding the parts was measured, it increased to 53.9 × 10 ⁻⁹ m ³ / (m ² · s · Pa), indicating that the separation membrane was damaged. all right.

Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2012-079366 filed on Mar. 30, 2012, the contents of which are incorporated herein by reference.

1A, 1B, 1C Separation membrane pair 2 Separation membrane 3 Gap 4 Separation function layer 5 Base material 6 Surface fastener (hook)
7 Loop fastener (loop)
8 Perimeter resin layer 9 Hook (hook-like fiber)
10 Loop part (loop fiber)
11 hook-and-loop fastener (loop part and hook part)
12 Spacer 13 Washer 14 Bolt 15 Fixing jig 16 Water collecting pipe 17 Membrane module 18 Membrane element 19 Membrane immersion water tank 20 Air diffuser 21 Blower 22 Permeated water 23 Suction pump 24 Water to be treated 25 Water outlet 26 Surface fastener and base Adhesive for bonding materials

Claims

Two separation membranes having a permeation side surface and a supply side surface, a separation membrane pair in which the permeation side surfaces are arranged to face each other;
A hook-and-loop fastener that is arranged so as to detachably engage between opposing separation membranes on the permeation side surface of the separation membrane;
A sealing portion that is provided at a peripheral portion of the separation membrane pair and seals between the separation membranes;
A separation membrane element comprising:
The separation membrane element according to claim 1, wherein the hook-and-loop fastener has a loop-hook structure.
The separation membrane is
A separation functional layer provided on the supply side surface;
A base material provided between the separation functional layer and the surface fastener;
A separation membrane element according to claim 1 or 2.
4. The separation membrane element according to claim 1, wherein in the separation membrane pair, a gap between the separation membranes is 50 μm or more and 5000 μm or less.
A housing;
A plurality of separation membrane elements according to any one of claims 1 to 4 housed in the housing;
A membrane module comprising: