JP4576863B2 - Filtration membrane element, membrane separation device and filtration method - Google Patents

Description

  The present invention relates to a filtration membrane element used for membrane separation of a stock solution, a membrane separation apparatus using the same, and a filtration method.

  The structure of a conventional general filtration membrane element will be described with reference to FIG. In the figure, 1 is a filtration membrane element, 2 is a support, 3 is a port for taking out permeate, 4 is an opening for allowing the permeate to communicate with both sides of the support, 5 is a filtration membrane, and 6 is a filtration membrane. 5 and a flow path member provided between the support body 2 and the support body 2. The filtration membrane 5 is a separation membrane having a fractionation characteristic in which a polymer functional membrane is generally formed on a fabric as a base material, such as a nonwoven fabric or taffeta, and is adhered to the support 2 in a tight state in a liquid-tight manner. Attached.

  The filtration membrane element 1 is immersed in the stock solution, applies negative pressure through the port 3 to filter the stock solution through the filtration membrane 5, and the permeate passing through the filtration membrane 5 is attached to the support 2 at the port 3. To suck through. At this time, the filtration membrane 5 has a characteristic that the base material is easily stretched because it is a fabric, and is stretched to the support 2 side by the negative pressure on the port 3 side, so that the filtration membrane 5 and the support 2 are in close contact with each other. There exists a problem that the effective membrane area of a filtration membrane falls.

  Therefore, between the filtration membrane 5 and the support 2, as described above, in order to avoid a reduction in the effective membrane area of the filtration membrane due to the close contact between the filtration membrane 5 and the support 2, a net, a nonwoven fabric, a tricot, Etc. are interposed (for example, Patent Documents 1 and 2). However, in order to provide the flow path member 6 in this way, the cost of the flow path member 6 is added to the production cost, which hinders inexpensive production. Furthermore, the process of arrange | positioning the flow-path material 6 between the support body 2 and the filtration membrane 5 is required.

  Further, as another filter membrane element structure, as disclosed in Patent Document 3, a ridge parallel to a water-permeable spacer such as a tricot spacer made of tricot knitted fabric, a net spacer, or a porous spacer is used. There is a filtration membrane element in which a filter spacer is provided as a flow path spacer, two or more of the flow path spacers are used as a support, and a filtration membrane is attached in a liquid-tight manner. However, if a protrusion is provided on the water-permeable spacer to form a flow path spacer, the flow path spacer and the filtration membrane can be prevented from sticking to each other. The spacer which has and the some protrusion for providing in the said spacer are required. At the same time, a step of assembling a plurality of protrusions with respect to the water-permeable spacer, for example, by adhesion is required. Therefore, considering the number of parts, the number of processes required for assembly, and inspection of individual parts essential for stable assembly, it is not suitable for industrially inexpensive production. Furthermore, as shown in Patent Document 3, if the height of the protruding portion is high, the filtration membrane element inevitably has a large volume, and a compact structure is not obtained. As a result, there is a concern that the effective membrane area of the filtration membrane per unit volume cannot be increased as the membrane separation device, and the size of the device is increased.

  In addition, as disclosed in Patent Document 4, it is easy to collect the permeated liquid that has permeated the filtration membrane by forming a plurality of recesses having a width of 1 mm or less on the surface of the support without interposing the flow path material. There is also a membrane element that does this. However, although the flow path of the membrane permeate can be secured by the concave portion, the filtration membrane adheres to the portion other than the concave portion of the support to inhibit the liquid filtration, and as a result, the membrane area itself can be effectively utilized. I can't. According to the disclosure of Patent Document 4, since the area of the filtration membrane that can be in close contact with the support is about 80% of the effective membrane area, the area of the filtration membrane that contributes to filtration is only about 20% remaining. become.

Thus, conventionally, it has been difficult to prevent adhesion between the support and the filtration membrane without using the flow path material.
Japanese Unexamined Patent Publication No. 7-31855 Japanese Patent No. 3219579 Japanese Patent No. 3401890 Japanese Patent No. 2897799

  An object of the present invention is to provide a filtration membrane element, a membrane filtration device, and a filtration method that can prevent adhesion between the filtration membrane and a support without using a channel material and with a smaller number of parts than in the past.

The present invention for achieving the above object is characterized by the following configurations (1) to (7).
(1) A filtration membrane element having a filtration membrane and a support that supports the filtration membrane, wherein the support is made of a water-impermeable material and has a plurality of ranges within the range of supporting the filtration membrane. A filtration membrane element having projections, wherein a ratio of a total area of the plurality of projections to the filtration membrane area is in a range of 0.15 to 0.35.
(2) The filtration membrane element according to (1), wherein the support is formed by injection molding.
(3) The filtration membrane element according to (1) or (2), wherein the height of the protrusion is at least 0.35 mm.
(4) The filtration membrane element according to any one of (1) to (3), wherein the plurality of protrusions are adjacent to each other with an interval of 1 mm to 3 mm.
(5) The filtration membrane element according to any one of (1) to (4), wherein the filtration membrane is laminated directly on the support.
(6) A membrane separation device comprising the filtration membrane element according to any one of (1) to (5) above.
(7) A liquid filtration method using the filtration membrane element according to any one of (1) to (7) above.

  In the present invention, the “height of the protrusion” will be described with reference to FIG. 2 showing a partial cross-sectional view of the support. The distance to. In the cross section, a substantially discontinuous inflection point 9 existing between the projection 7 and the plane portion 8 is defined as a boundary between the projection 7 and the plane portion 8.

  Further, the “area of the protrusion” in the present invention will be described with reference to FIG. FIG. 3 is a top view (a) of a part of the support body as viewed in the direction of the base surface and a side sectional view (b) thereof. The “area of the protrusion” is indicated by hatching in FIG. Thus, it refers to the projected area of the protrusion in the base surface direction. Therefore, if the vertical and horizontal dimensions of the filtration membrane in FIG. 3 are a × b, the sum of the areas of the plurality of protrusions is the same as the hatched area, and the ratio R to the filtration membrane area is defined by the following equation: .

  R = total of the areas of the plurality of protrusions / (a × b)

  According to the filtration membrane element of the present invention, the adhesion between the filtration membrane and the support can be prevented without using a flow path material, the filtration membrane area can be effectively used, and it can be manufactured inexpensively with a small number of parts. be able to.

  That is, a filtration membrane element having a filtration membrane and a support that supports the filtration membrane, wherein the support is made of a water-impermeable material and has a plurality of protrusions within a range that supports the filtration membrane. And the ratio of the total area of the plurality of protrusions to the filtration membrane area is in the range of 0.15 to 0.35, so that the flow passage material can be used while effectively utilizing the area of the filtration membrane. Even without using, the adhesion between the filtration membrane and the support can be prevented.

  Here, in the case of using a support molded by injection molding, the immersion can effectively prevent the adhesion between the filtration membrane and the support without using the flow path material while effectively using the area of the filtration membrane. The membrane element can be manufactured at low cost. Further, when a projection having a height of at least 0.35 mm is used, a space larger than that of the conventional technique can be formed between the support and the filtration membrane.

  In addition, when a plurality of individual protrusions are adjacent to each other with an interval of 1 mm to 3 mm, it is possible to prevent the space between the support and the filtration membrane from being narrowed due to the slackness of the filtration membrane.

  And in this invention, since the above-mentioned effect can be show | played, a filtration membrane can be laminated | stacked directly on a support body, without using a flow-path material. As a result, the filtration membrane element that can prevent the adhesion between the filtration membrane and the support and can effectively use the filtration membrane area can be manufactured at a low cost with a small number of parts.

  Therefore, if such a filtration membrane element is used, it becomes an inexpensive membrane separation apparatus, and the total cost of liquid filtration can be reduced.

  An example of the best embodiment of the present invention will be described below with reference to FIG. In this figure, 1 is a filter membrane element, 2 is a support, 3 is a port for sucking a permeate provided on the support, 4 is an opening for allowing the permeate to communicate with both sides of the support, and 5 is a filter. A film 7 is a protrusion.

  The filtration membrane element 1 is configured by laminating the filtration membrane 5 directly on the support 2, and no flow path material is interposed.

  Although it will not be limited if it consists of a water-impermeable material as a support body, when handling property is considered, resin which is lightweight compared with a metal can be used. Of these, ABS resins and vinyl chloride resins having a wide range of chemical resistance are preferable because they are used for liquid membrane separation. Furthermore, ABS resin is preferable from the viewpoint of environmental load reduction or recyclability in disposal. The support is preferably integrally molded by injection molding in view of the fact that it can be manufactured at low cost if the number of parts constituting the support is small.

  The support 2 is provided with a plurality of protrusions. In the present embodiment, the protrusion is provided in the central portion 12 and has a region where the protrusion does not exist in the peripheral edge portion 11. And the filtration membrane 5 is liquid-tightly fixed by this peripheral part 11 and the adhesive agent.

  The protrusions are provided such that the ratio of the total area of the protrusions to the area of the filtration membrane is in the range of 0.15 to 0.35. When this ratio is less than 0.15, the contact area of the projections with respect to the filtration membrane is reduced, and as a result, the frictional force between the filtration membrane and the projection per projection increases, and the filtration membrane may be damaged due to wear. is there. On the other hand, if it exceeds 0.35, the influence of impeding the permeability of the liquid from the filtration membrane becomes large at the portion where the filtration membrane and the protrusion are in close contact. More preferably, it is the range of 0.2-0.3.

  On the other hand, if the height of the protrusion is too low, a sufficient space cannot be formed between the support and the filtration membrane due to a pressure difference between the stock solution side and the permeation side during use. Therefore, the height of the protrusion is preferably at least 0.35 mm. On the other hand, in view of making the thickness of the filtration membrane element compact and increasing the area of the packed filtration membrane as the membrane separation device, it is preferable that the height of the protrusion is low. When the protrusions are integrally formed on the support by injection molding, the specific protrusion height is restricted to the protrusion pattern from the viewpoint of ease of forming. For example, in injection molding, an elongated columnar shape tends to be difficult to mold, but when the projection shown in FIG. 3 has a vertically long pattern, the projection height is preferably equal to or less than the projection width.

  Furthermore, it is preferable that the individual protrusions are adjacent to each other with an interval of 1 mm to 3 mm. If the distance between adjacent projections is too narrow, the space through which the permeated liquid that has permeated the filtration membrane can be reduced, so that the resistance to permeate flow increases and the filtration efficiency decreases. On the other hand, if the interval between adjacent projections is too wide, the filtration membrane loosens between the projections and falls, and the phenomenon that the filtration membrane falls is reduced, and the space through which the permeate can circulate becomes smaller. As a result, the resistance to permeate flow increases and the filtration efficiency decreases.

  In addition, as shown in FIG. 9, a separate recess 23 may be provided in the support body 2 having a protrusion so that the permeated liquid may be guided to the port 3.

  Moreover, as the filtration membrane 5, what is obtained by apply | coating a film-forming stock solution on a porous base material and forming a separation functional membrane can be used. Here, examples of the porous substrate that indicates the separation functional membrane include woven fabrics, nonwoven fabrics, nets, and the like made of polyester, polypropylene, polyamide, etc., but nonwoven fabrics are preferably used from the viewpoint of film forming properties and cost. It is done. Examples of separation functional membranes include polyvinyl chloride resins, polyvinylidene fluoride resins, polysulfone resins, and polyacrylonitrile resins that are easy to form in solution and have excellent physical durability and chemical resistance. , Polyethersulfone-based resins, or membranes composed of these as main components are used.

<Example 1>
The experimental system 13 shown in FIG. 5 was configured, and the amount of permeated water of the filtration membrane was measured.

  In the experimental system 13 shown in FIG. 5, the water tank 14 was filled with RO water generated through a reverse osmosis membrane, and the cell 15 was submerged. As shown in FIG. 6, the cell 15 has a protrusion on the surface, a support plate 18 having a diameter of 75 mm provided with a water passage having a diameter of 3 mm in the center, and a filtration membrane 19 having a diameter larger than that of the support plate 18. The support plate 18 and the filter membrane 19 were pressed to make the gasket 20 liquid-tight, and a cell body 21 and a cell lid 22 for fixing them. In addition, a tube 16 is communicated with the cell 15, and the other end surface of the tube 16 is disposed so as to open at a height at which a water head difference of 1 m is formed with respect to the liquid level of the water tank 14. Therefore, the permeated water that has passed through the filtration membrane 19 disposed in the cell 15 passes through the tube 16 due to the head difference, is led to the container 17, and the filtrate amount led to the container 17 within a certain time is measured as the permeated water amount. did.

  The support plate 18 has projections (hatched portions) having the pattern shown in FIG. 7A, the ratio of the total area of the projections to the filtration membrane area is 0.15, and the interval between adjacent projections is 2 mm. A projection having a height of 0.5 mm was used. The height of the protrusion was set to ½ of the width of the protrusion of 1 mm in view of ease of injection molding.

  The results are shown in Table 1. As a result of measuring the total amount of permeated water of the filtration membrane for 3 minutes, 78.8 g / min (water temperature converted to 25 ° C.) of permeated water was obtained.

  Conversion to the amount of permeated water per minute at 25 ° C. was performed according to the following formula.

Permeated water amount [g / min. At 25 ° C] = Total permeated water amount [g] x 25 ° C conversion factor ÷ Measurement time [min.]
Here, the 25 ° C. conversion coefficient is the ratio of the viscosity of water at the water temperature at the time of measurement to the viscosity of water at a water temperature of 25 ° C.

<Example 2>
The support plate 18 has projections (hatched portions) having the pattern shown in FIG. 7B, the ratio of the total area of the projections to the filtration membrane area is 0.35, and the interval between adjacent projections is 1 mm, The permeated water amount of the filtration membrane was measured in the same manner as in Example 1 except that a projection having a height of 0.5 mm was used.

  The results are shown in Table 1. As a result of measuring the total permeated water amount of the filtration membrane for 3 minutes, the permeated water of 75.0 g / min (water temperature 25 degreeC conversion value) was obtained.

<Comparative Example 1>
A support plate 18 having no projections and having a water passage at the center is used. Further, between the support plate 18 and the filtration membrane 19, a wire diameter of 0.35 mm and an intersection thickness of 0. The permeated water flow rate of the filtration membrane was measured in the same manner as in Example 1 except that a net having a diameter of 7 mm, a pitch of 4.3 mm, and a mesh foot angle of 37.5 degrees was cut into a circular shape having a diameter of 70 mm.

  The results are shown in Table 1. As a result of measuring the total permeated water amount of the filtration membrane for 3 minutes, 67.1 g / min (water temperature converted to 25 ° C.) of permeated water was obtained.

<Comparative Example 2>
The support plate 18 has projections (hatched portions) having the pattern shown in FIG. 8A, the ratio of the total area of the projections to the filtration membrane area is 0.10, and the interval between adjacent projections is 3 mm. The permeated water amount of the filtration membrane was measured in the same manner as in Example 1 except that a projection having a height of 0.5 mm was used.

  The results are shown in Table 1. As a result of measuring the total amount of permeated water of the filtration membrane for 3 minutes, 64.5 g / min (water temperature converted to 25 ° C.) of permeated water was obtained.

<Comparative Example 3>
The support plate 18 has projections (hatched portions) having the pattern shown in FIG. 8B, the ratio of the total area of the projections to the filtration membrane area is 0.38, and the spacing between adjacent projections is 0. The amount of water permeated through the filtration membrane was measured in the same manner as in Example 1 except that a projection having a projection height of 5 mm was used.

  The results are shown in Table 1. As a result of measuring the total permeated water amount of the filtration membrane for 3 minutes, 63.2 g / min (water temperature 25 ° C. converted value) of permeated water was obtained.

<Comparative example 4>
The support plate 18 has protrusions (hatched portions) having the pattern shown in FIG. 8C, the ratio of the total area of the protrusions to the filtration membrane area is 0.12, and the distance between adjacent protrusions is 3. The amount of permeated water of the filtration membrane was measured in the same manner as in Example 1 except that 1 mm and a protrusion having a height of 0.5 mm were used.

  The results are shown in Table 1. As a result of measuring the total amount of permeated water of the filtration membrane for 3 minutes, 59.2 g / min (water temperature converted at 25 ° C.) was obtained.

  The results are summarized in Table 1.

  The submerged membrane element of the present invention can be applied to water treatment for drinking water, water treatment for drainage, and the like, but the application range is not limited thereto.

It is the schematic perspective view which decomposed | disassembled some conventional filtration membrane elements. It is a schematic partial cross section figure of a support body. It is a schematic partial top view and a schematic partial side cross-sectional view of the support (the hatched portion indicates a protrusion). It is the schematic perspective view which decomposed | disassembled some filtration membrane elements which show one Embodiment of this invention. It is a general | schematic flowchart of the experimental system used by the Example and the comparative example. It is sectional drawing of the cell used by the Example and the comparative example. It is the figure which projected and showed the protrusion-shaped pattern of the support body used in the Example to the plane part 8 direction. It is the figure which projected and showed the protrusion-shaped pattern of the support body used by the comparative example to the plane part 8 direction. It is the schematic perspective view which decomposed | disassembled some filtration membrane elements which show other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Filtration membrane element 2 Support body 3 Port 4 Opening part 5 Filtration membrane 6 Channel material 7 Protrusion 8 Plane part 9 Inflection point 10 Effective membrane surface 11 Peripheral part 12 Center part 13 Experimental system 14 Water tank 15 Cell 16 Tube 17 Container 18 Support plate 19 Filtration membrane 20 Gasket 21 Cell body 22 Cell lid 23 Recess

Claims (7)

  A filtration membrane element comprising a filtration membrane and a support that supports the filtration membrane, wherein the support is made of a water-impermeable material and has a plurality of protrusions in a range that supports the filtration membrane. And the ratio of the total area of the plurality of protrusions to the area of the filtration membrane is in the range of 0.15 to 0.35.   The filtration membrane element according to claim 1, wherein the support is formed by injection molding.   The filtration membrane element according to claim 1 or 2, wherein the height of the protrusion is at least 0.35 mm.   The filtration membrane element according to any one of claims 1 to 3, wherein the plurality of protrusions are adjacent to each other with an interval of 1 mm to 3 mm.   The filtration membrane element in any one of Claims 1-4 with which the said filtration membrane is laminated | stacked directly on the said support body.   A membrane separation device comprising the filtration membrane element according to claim 1.   A filtration method for a liquid, wherein the filtration membrane element according to claim 1 is used.

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