JP2008023415A - Spiral membrane module and water treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spiral membrane module which has a sufficient removal rate even in a very low concentration zone, at the same time, has a long life, and further, has a high membrane filling efficiency of the module, and a water treatment method using the spiral membrane module. <P>SOLUTION: An internal passage material 15 is inserted into a bag-like membrane 10 having an opening on a side, and the opening is inserted into a slit 17 of a perforated tube 20 and bonded. A plurality of bag-like membranes 10 are wound around the perforated tube 20 through an external passage material 21 to form a spiral membrane module 26. The membrane module 26 is arranged in a tank 40, an end of the perforated tube 20 is connected to an extraction tube 41, the other end of the perforated tube 20 is closed up, water to be treated is pressure-fed from an inlet 42, and the process water is brought out from the extraction tube 41. The bag-like membrane 10 is a membrane laminate comprising a first flat membrane having an ion-exchange group, and a second flat membrane having a removal function of fine particles. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a spiral membrane module and water for separating a trace amount of metal, organic substance, colloidal substance, etc. contained in a fluid to be treated in the treatment of a liquid such as water, an aqueous solution, an organic solvent, or in the treatment of a gas-liquid mixture. More particularly, the present invention relates to a spiral membrane module and a water treatment method capable of reducing the concentration of metal ions, fine particles, and the like in ultrapure water to an extremely low concentration.

The demand for high-purity ultrapure water used in semiconductor manufacturing processes is becoming stricter year by year. According to ITRS 2005, a roadmap for reducing metal ion concentration in ultrapure water to 0.5 ng / L or less was presented in 2008. However, semiconductor manufacturers have lower metal concentrations and higher purity ultrapure. Seeking water. Water treatment manufacturers have reduced the metal ion concentration ahead of schedule, and some of the latest ultrapure water production facilities can produce ultrapure water with most metals reduced to 0.5 ng / L. Furthermore, as a method of reducing the metal ion concentration in ultrapure water, there is a method of installing an ion exchange filter just before the use point, but the shape of the commercially available ion exchange filter is a flat membrane such as a nonwoven fabric or a porous membrane. A pleat type is generally used (Japanese Patent Laid-Open No. 2003-251118).
JP 2003-251118 A

  Pleated ion exchange filters tend to bias the flow of pleats into the folds, making it impossible to obtain a sufficient removal rate in the ultra-low concentration range as described above. .

  In particular, it is known that a pleated filter using a porous membrane weakens the strength of the membrane if the amount of ion-exchange groups introduced is excessive, and the ion-exchange capacity must be limited. There was a drawback that the life was even shorter than that used.

  The present invention provides a spiral membrane module having a sufficient removal rate for extremely low concentrations of metal ions and fine particles, a long lifetime, and a high membrane filling efficiency of the module, and a water treatment using this spiral membrane module It aims to provide a method.

  The spiral membrane module of claim 1 includes a wound body in which a plurality of bag-like membranes are wound around a perforated tube, and an internal flow path material is disposed inside the bag-like membrane, In the spiral membrane module in which the inside of the bag-like membrane communicates with the perforated cylinder, and an external flow path material is disposed between the bag-like membranes, the membrane of the bag-like membrane is ion-exchanged. It is a flat membrane having a pore diameter of 0.01 to 100 μm having a group.

  The spiral membrane module according to claim 2 includes a wound body in which a plurality of bag-like membranes are wound around a perforated tube, and an internal flow path material is disposed inside the bag-like membrane, In the spiral membrane module in which the inside of the bag-like membrane communicates with the perforated cylinder, and an external flow path material is disposed between the bag-like membranes, the membrane of the bag-like membrane is ion-exchanged. It is a laminated film of a first flat film having a group and a pore diameter of 0.01 to 100 μm and a second flat film having a fine particle removing function.

  The spiral membrane module of claim 3 is characterized in that, in claim 2, the second flat membrane is a porous membrane having a pore diameter of 0.01 to 1 μm and a film thickness of 10 to 500 μm.

  A spiral membrane module according to a fourth aspect is characterized in that, in the second or third aspect, the filling efficiency of the laminated film is 50% or more.

  The spiral membrane module according to claim 5 is the spiral membrane module according to any one of claims 1 to 4, wherein the bag-like membrane has a substantially rectangular shape having first, second, third, and fourth sides, The first, second, and third sides are sealed, the fourth side is an open portion, the fourth side is connected to the perforated tube, and the bag-like membrane is wound. The wound body is turned so that the second side parallel to the fourth side faces the outer peripheral surface of the wound body, and the inside of the bag-like film is interposed through the fourth side. Is communicated with the inside of the perforated tube.

  The water treatment method according to claim 6 is characterized in that metal ions and fine particles in the water to be treated are reduced by passing the water to be treated through the spiral membrane module according to any one of claims 1 to 5. It is what.

  The water treatment method according to claim 7 is characterized in that, in claim 6, the metal ion concentration in the water to be treated is 5 ng / L or less.

  Since the spiral membrane module of the present invention is a spiral type in which a bag-like membrane is wound, the membrane filling efficiency is improved as compared with the pleated type. Moreover, since the flat membrane surface area is large, the metal removal performance is excellent and the capacity is high.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a single bag-like membrane used in a spiral membrane module according to an embodiment of the present invention. FIGS. 2 to 4 are explanatory views showing a method of winding a bag-like membrane around a perforated tube, FIG. 5 is a perspective view of a spiral membrane module, and FIGS. 6 and 7 show a water flow method. It is sectional drawing shown.

  As shown in FIG. 2, the bag-like film 10 used in this embodiment is a square or rectangular shape, and includes a first side part 11, a second side part 12, and a third side part 13. And a fourth side portion 14.

  As shown in FIG. 1, the bag-like membrane 10 folds the separation membrane film 9 made of a laminated membrane of the first flat membrane and the second flat membrane into two at the second side portion 12, The separation membrane films folded at one side 11 and the third side 13 are preferably bonded (fused) with a heat-fusible material, and the fourth side 14 is opened without bonding. It is a bag-like thing. In addition, in place of the second side portion 12 folded in two, the two separation membrane films are overlapped, and the first side portion 11, the second side portion 12, and the third side portion 13 are overlapped. You may use the bag-like film | membrane made to adhere | attach.

  An internal channel material (for example, made of a mesh spacer) 15 is inserted and disposed in the bag-like film 10.

  A plurality of the bag-like membranes 10 are wound around a pipe-shaped perforated tube 20. This perforated cylinder 20 is a hollow cylinder, and is a perforated cylinder provided with a plurality of slits 17 extending in the longitudinal direction of the shaft on the peripheral surface. The slit 17 corresponds to a hole.

  As shown in FIGS. 2 and 3, the fourth side portion 14 of each bag-like film 10 is inserted into the slit 17, and the edge of the side portion 14 of the bag-like film 10 is preferably slit using a heat-fusible material. It joins to the edge or inner surface of 17 watertightly.

  In general, the RO membrane is sealed by using a tape-like adhesive. However, since elution from the adhesive may be a problem, it is preferable to use a heat-fusible material for fusion.

  After fusing, an external flow path material 21 made of mesh spacers or the like is interposed between the bag-shaped films 10 and the bag-shaped film 10 and the external flow path material 21 are wound around the perforated tube 20 as shown in FIG. Turn to a spiral membrane module 26 (FIG. 5).

  In this winding, a heat-fusible material may be applied to the bag-like film 10 along the second side portion 12. After winding, by fusing the portions along the second side 12 of the bag-like film 10 with this heat-fusible material, the flow path between the bag-like films 10 is connected to the end face of the wound body. Communicate with the outside through

  In this spiral membrane module 26, both end surfaces of the wound body may communicate with the outside of the membrane module 26, or only one end surface may communicate with the outside of the membrane module.

  For the spiral membrane module 26 configured in this manner, raw water was passed between the bag-like membranes 10 from the end face of the membrane module 26 and passed through the bag-like membrane 10 as shown in FIGS. Permeate is removed from the perforated tube 20.

  6 and 7, the membrane module 26 is accommodated in a cylindrical casing 30, and one end of the perforated tube 20 is protruded from the casing 30. Note that the other end of the perforated tube 20 is sealed. The end face of the casing 30 is provided with an inlet hole 31 for raw water.

  As shown in FIG. 7, the casing 30 containing the membrane module 26 is housed in a pressure-resistant water tank 40, and one end of the perforated tube 20 is fitted into the treated water outlet 42 of the water tank (housing) 40, for example. Connecting.

  Raw water (treated water) is pressurized and supplied into the water tank 40 from the raw water inlet 41 of the water tank 40. The raw water flows into the case 30 from the inflow hole 31, passes through the bag-like membrane 10, and is taken out from the outlet 42 through the perforated tube 20.

  In FIG. 7, inflow holes 31 are provided on both end faces of the casing 30, but the inflow holes 31 may be provided only on one side (for example, the lower end face in the figure).

  In the case of the water flow method shown in FIGS. 6 and 7, in order to backwash the membrane module 26, clean water and further air as needed are fed into the bag-like membrane 10 through the perforated tube 20, and backwashing is performed. Drainage is taken out from the end face of the membrane module 26.

  Although not shown, contrary to the above, the raw water is caused to flow into each bag-like membrane 10 through the perforated cylinder 20, the whole amount of raw water is permeated, and the permeated water is discharged from both end surfaces of the membrane module 26. You may make it make it.

  The spiral membrane module 26 uses a laminated film of a first flat film having an ion exchange group and a second flat film having a fine particle removing function, and both the ion exchange ability and the fine particle removal ability are used. Excellent. In addition, the spiral membrane module can have a larger membrane area than the pleated module.

  As the flat membrane into which the ion exchange groups are introduced, a porous membrane, a nonwoven fabric, a woven fabric, or the like can be selected as appropriate. Since a thicker one has better performance, a nonwoven fabric is particularly preferable. The pore diameter of the flat membrane introduced with ion exchange groups is preferably 0.01 to 100 μm, particularly preferably 1 to 50 μm. If the pore diameter is too small, the pressure loss increases and is not practical. In that case, it is necessary to reduce the film thickness or increase the film area. However, if the film thickness is too thin, breakthrough is accelerated, which is not preferable. The film thickness of the ion exchange group-introduced flat membrane is preferably 50 to 1000 μm. More preferably, it is 100-500 micrometers.

  As the flat membrane having the function of removing fine particles, a porous membrane, a nonwoven fabric, a woven fabric, or the like can be appropriately selected, and a porous membrane is particularly preferable. The pore diameter of the flat membrane having a fine particle removing function is 0.01 to 1 μm, preferably 0.01 to 0.1 μm. As described above, when the pore diameter is small, the pressure loss increases. However, it is preferable that the flat membrane having the fine particle removing function is as thin as possible. A suitable film thickness is 10 to 500 μm, more preferably 50 to 300 μm.

  The flow path material may be any material such as a porous film, a nonwoven fabric, a woven fabric, a net, a mesh, a grooved sheet, and a corrugated sheet. When the pressure loss of the flow path material is large, it becomes difficult to spread the supply water over the entire membrane surface. Therefore, the hole diameter of the flow path material is preferably 50 to 1000 μm. The film thickness is preferably 100 to 1000 μm. When the film thickness is too large, the filling amount decreases, and therefore 100 to 500 μm is more preferable.

  The heat-fusible material may be any material that is solid at room temperature and can be fused by heating, such as polyethylene, ethylene / vinyl acetate copolymer (EVA), polyurethane, acrylic resin, other thermoplastic resins, Although at least one or more of thermoplastic elastomers are used, polyethylene is preferred.

  Materials such as perforated cylinders, flat membranes, channel materials, etc. include polyolefins such as polyethylene and polypropylene, fluororesins such as PTFE, CTFE, PFA, polyvinylidene fluoride, halogenated polyolefins such as polyvinyl chloride, nylon-6, Polyamide such as nylon-66, urea resin, phenol resin, melamine resin, polystyrene, cellulose, cellulose acetate, cellulose nitrate, polyether ketone, polyether ketone ketone, polyether ether ketone, polysulfone, polyether sulfone, polyimide, polyether Imide, polyamideimide, polybenzimidazole, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyacrylonitrile, polyether Tolyl, and the material can be used, such as a copolymer thereof, it is not limited thereto. In consideration of price, processability, chemical stability, mechanical strength, etc., polyolefin or fluororesin is preferably used. In particular, it is not limited to one kind of material, and various materials can be selected as necessary. Moreover, when using a woven fabric and a nonwoven fabric, you may use composite fibers, such as a core-sheath structure, for the fiber.

  The ion exchange groups introduced into the flat membrane are sulfonic acid groups, phosphoric acid groups, phosphonic acid groups, phosphinic acid groups, carboxylic acid groups, hydroxyl groups, phenol groups, quaternary ammonium groups, primary to tertiary amine groups, pyridine groups, There is an amide group, but not limited to this. These functional groups may be not only H-type and OH-type but also salt-type such as Na.

  In the present invention, a flat membrane into which at least one of these functional groups is introduced is used. As combinations of ion exchange groups, combinations of sulfonic acid groups and quaternary ammonium salts, sulfonic acid groups and carboxylic acid groups, and sulfonic acid groups, quaternary ammonium salts and carboxylic acid groups are preferably used.

  The method for introducing a functional group varies depending on the type of resin, and an appropriate method for introduction is selected. In the case of polystyrene resin, crosslinking and introduction of sulfonic acid groups are possible by adding an appropriate amount of paraformaldehyde to the sulfuric acid solution and heating. Alternatively, ion exchange resins or finely pulverized ion exchange resins may be kneaded during film formation and synthesis to introduce ion exchange groups. If the functional group cannot be directly introduced depending on the resin material, first, a highly reactive monomer such as styrene (referred to as a reactive monomer) is introduced and then the functional group is introduced in two or more stages. Then, the target functional group may be introduced. These reactive monomers include, but are not limited to, glycidyl methacrylate, styrene, chloromethyl styrene, acrolein, vinyl pyridine, acrylonitrile and the like.

  The pore diameter of the fine particles that can be removed by the present invention is 0.05 to 0.2 μm.

In the spiral membrane module used in the present invention, the filling efficiency of the laminated membrane can be defined by the following formula, and a membrane module of preferably 50% or more (more preferably 60% or more) can be used.
Filling efficiency = (membrane area × film thickness) / [(membrane module outer cross-sectional area−perforated cylinder outer cross-sectional area) × membrane module
Length)
= Membrane volume / filled part volume

  In the present invention, organic substances and colloidal substances are not targeted, but organic substances and colloidal substances can be removed as long as they are charged. In addition, ultrapure water contains about 1 ppb of organic matter and hardly contains colloidal substances.

  In this invention, when the density | concentration of the metal ion contained in to-be-processed water is very low density | concentration, it can use especially suitably, Specifically, it is preferable that it is to-be-processed water with a metal ion density | concentration of 5 ng / L or less.

[Example 1]
A polypropylene non-woven fabric (film thickness 200 μm, average pore size 7 μm) is immersed in a mixture of styrene 87.8%, divinylbenzene 12% and azobisisobutyronitrile 0.2% for 5 hours, then pulled up and heated in a heating furnace at 85 ° C. For 20 hours. This was repeated 5 times to obtain a styrene-coated polyester nonwoven fabric. The styrene-coated polyester nonwoven fabric was sufficiently immersed and washed in the order of acetone, ultrapure water, ethanol, and ultrapure water to remove unreacted substances. Thereafter, it was immersed in an 80% sulfuric acid aqueous solution and heated at 90 ° C. for 8 hours to introduce sulfonic acid groups. The obtained cation exchange nonwoven fabric was washed with ultrapure water and hydrochloric acid in this order to obtain an H type.

  The above-mentioned 100 mm × 650 mm square ion-exchange nonwoven fabric and a polyethylene porous membrane (thickness 100 μm, average pore diameter 0.05 μm) having the same shape and size as the ion-exchange nonwoven fabric are laminated, and the inner channel material is made of polypropylene. A non-woven fabric (film thickness: 200 μm, average pore diameter: 45 μm, 90 mm × 320 mm square) was bent and sandwiched, and two symmetrical sides were sealed by thermal fusion to produce a 100 × 325 mm rectangular bag-like film.

Eight of these bag-like membranes were fused at equal intervals to a perforated cylinder having a length of 100 mm, an outer diameter of 40 mm, and an inner diameter of 30 mm, and wound in a spiral shape with an external flow path material sandwiched between the bag-like membranes. . The wound body wound in a spiral shape was filled into a polyethylene cylindrical casing having an outer diameter of 80 mm and an inner diameter of 70 mm, and sealed with a lid-like sealing structure material. The filling rate of the filled flat membrane was 60%, and the membrane area was 0.52 m ² .

  This casing was installed in the water tank 40 as shown in FIG.

  The raw water is supplied through the inflow hole 31 and flows out from the outlet 42 through the perforated tube 20.

  Dilute the standard solution for atomic absorption so that the metal concentration of raw water (Na, Mg, Al, K, Ca, Cr, Fe, Cu, Zn) is 5 ng / L, and add ultrapure water added by line injection. When water treatment was performed at 10 L / min, the concentration of all metals in the treated water could be reduced to 0.5 ng / L or less. The results are shown in Table 1. The filter differential pressure was 0.03 MPa. The measurement was performed by concentrating the sampling water and then analyzing with ICPMS (Yokogawa Analytical Systems Agilent-4500).

[Comparative Example 1]
The same ion exchange nonwoven fabric, polyethylene porous membrane, and channel material as in Example 1 were laminated to produce a pleated filter. The perforated cylinder, the cylindrical casing, and the lid-like sealing structure material have the same dimensions as those in Example 1, but the casing has holes and the sealing structure material does not have holes. The filling rate of the filled flat membrane was 34%, and the membrane area was 0.30 m ² . When the same liquid as in Example 1 was passed through, water quality as shown in Table 1 was obtained. The differential pressure of the membrane module was 0.04 MPa.

[Example 2]
Using the same membrane module as in Example 1, a particulate removal test was performed. As the fine particles, polystyrene latex standard particles (JSR STADEX SC-0050-D, particle size average value 0.048 μm) were used. Latex particles are added so that the number of fine particles in the feed water (pore size 0.05 μm) is 50 particles / mL, and water is passed through the membrane module at 10 L / min. When measured using a measuring instrument, the results shown in Table 2 were obtained. The number of fine particles in the treated water was 0.9 / mL, which was 1 / mL or less.

1 is a perspective view of a single bag-like membrane used in a spiral membrane module according to an embodiment of the present invention. It is a perspective view which shows the connection method of a bag-like film | membrane and a perforated cylinder. It is sectional drawing which shows the connection method of a bag-like film | membrane and a perforated cylinder. It is sectional drawing which shows the method of winding a bag-like film | membrane around a perforated pipe | tube. It is a perspective view of a spiral membrane module. It is sectional drawing which shows the water flow method. It is sectional drawing of the water tank which accommodated the membrane module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Bag-like film | membrane 15 Internal flow-path material 17 Slit 20 Perforated cylinder 21 External flow-path material 26 Spiral type membrane module 40 Water tank

Claims (7)

A plurality of bag-like membranes are provided with a wound body wound around a perforated tube, an internal flow path material is disposed inside the bag-like membrane, and the inside of the bag-like membrane is the perforated tube Communicated with
In the spiral membrane module in which an external channel material is disposed between the bag-like membranes,
The spiral membrane module, wherein the bag-like membrane is a flat membrane having an ion exchange group and a pore diameter of 0.01 to 100 µm. A plurality of bag-like membranes are provided with a wound body wound around a perforated tube, an internal flow path material is disposed inside the bag-like membrane, and the inside of the bag-like membrane is the perforated tube Communicated with
In the spiral membrane module in which an external channel material is disposed between the bag-like membranes,
The bag-like membrane is a laminated membrane of a first flat membrane having an ion exchange group and a pore diameter of 0.01 to 100 μm and a second flat membrane having a fine particle removing function. Spiral type membrane module.   The spiral membrane module according to claim 2, wherein the second flat membrane is a porous membrane having a pore diameter of 0.01 to 1 µm and a thickness of 10 to 500 µm.   4. The spiral membrane module according to claim 2, wherein the filling efficiency of the laminated membrane is 50% or more. In any one of Claims 1 thru | or 4,
The bag-like membrane has a substantially square shape having first, second, third, and fourth sides, the first, second, and third sides are sealed, and the fourth side is It is an open portion, the fourth side is connected to the perforated tube, the bag-like film is wound to form a wound body, and a second side parallel to the fourth side is It faces the outer peripheral surface of the wound body,
A spiral-type membrane module characterized in that the inside of the bag-like membrane is communicated with the inside of the perforated tube through the fourth side portion.   A water treatment method, wherein metal ions and fine particles in the water to be treated are reduced by passing the water to be treated through the spiral membrane module according to any one of claims 1 to 5.   The water treatment method according to claim 6, wherein a metal ion concentration in the water to be treated is 5 ng / L or less.

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