JP2005330371A - Water-containing gel, its manufacturing method, and microbe carryer using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-containing gel specialy superior in carrying property of microbes, and a manufacturing method of the water-containing gel, and a microbe carryer. <P>SOLUTION: This water-containing gel is formed by refrigerating and thawing a gelled substance obtained by blending a mixture of an end isocyanate group-containing polyurethane resin (C) being a reaction product of a liquid polyol (A) in an amount% of at least 70 wt.%, a polyisocyanate (B) a filler (D), with a copolymer formed by copolymerization reaction of ethylene oxide (a) and propylene oxide (b) in the range of the weight ratio (a)/(b) of 50/50 to 90/10, with water. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a water-containing gel particularly excellent in the ability to support microorganisms, a method for producing the water-containing gel, and a microorganism carrier.

It has already been reported that a hydrophilic polyurethane resin that has been water-cured can be used as a microorganism support (see Patent Document 1). However, wastewater treatment facilities (aeration tanks, etc.) in which the carrier is used vary in shape, scale, and purpose, and the flow characteristics required of the carrier are wide. Therefore, adjusting the specific gravity of the carrier is an important factor in order to meet various flow characteristics demands.
In addition, the carrier described in Patent Document 1 has a problem that the wastewater treatment capacity is low because the surface is smooth, the surface area is small, and the amount of microorganisms attached is small.

In addition to the above, a method for producing a carrier having a specific gravity adjusted by incorporating a filler for adjusting specific gravity into a photocurable resin and adjusting the specific gravity by light irradiation is known (Patent Document 2, Patent Document 3 and Patent Document 4). reference).
However, in the methods described in Patent Documents 2 to 4, since the filler for adjusting the specific gravity to be added blocks actinic rays, it is impossible to add more than a certain amount of filler, so there is a limit to the range of specific gravity adjustment. It was.

WO01 / 81442 JP-A-10-152511 Japanese Patent Laid-Open No. 10-168105 Japanese Patent Laid-Open No. 2002-000265

  An object of the present invention is to provide a water-containing gel that is particularly excellent in the ability to support microorganisms, a method for producing the water-containing gel, and a microorganism carrier.

    The hydrogel according to the present invention is a copolymer obtained by copolymerizing a weight ratio (a) / (b) of ethylene oxide (a) and propylene oxide (b) in the range of 50/50 to 90/10. Obtained by blending water with a mixture of a liquid polyol (A) containing 70 wt% or more and a terminal isocyanate group-containing polyurethane resin (C) and filler (D), which is a reaction product of polyisocyanate (B) It is characterized in that the compound is frozen and thawed.

    In the hydrogel according to the present invention, the hydrogel has a volume expansion ratio of 4 to 20 times that of the resin (C) before gelation, and the filler (D) has an average particle size of 0.1 to 150 μm. The blending ratio of water is in the range of 4 to 20 parts by weight of water per 1 part by weight of the resin (C), and the blending ratio of the filler (D) is 0.1 to 200 fillers per 1 part by weight of the resin (C). A range of parts by weight is preferred.

    The method for producing a hydrogel according to the present invention comprises a copolymerization reaction in which the weight ratio (a) / (b) of ethylene oxide (a) and propylene oxide (b) is in the range of 50/50 to 90/10. Water was added to a mixture of a liquid polyol (A) containing 70% by weight or more of a copolymer and a terminal isocyanate group-containing polyurethane resin (C) and filler (D), which is a reaction product of polyisocyanate (B). The obtained gelled product is characterized by being frozen and thawed.

    The microorganism carrier according to the present invention is characterized by containing the above hydrous gel.

In the present invention, the specific gravity can be adjusted by adding a filler to a conventionally known hydrous gel, so that it can be applied to various facilities and the surface area is increased, so that the treated microorganisms are transferred to the carrier in several stages. There is a remarkable effect that it becomes easy to adhere and, as a result, the processing capability becomes high.
Moreover, since the water-containing gel becomes uneven by freezing and thawing, the treated microorganisms are likely to adhere to the carrier in several stages, and as a result, there is a remarkable effect that the treatment capacity is increased.

  The volume expansion ratio described in the present invention is represented by the following formula.

Volume expansion ratio = volume of hydrogel obtained by blending water / terminal isocyanate group-containing polyurethane resin before blending water (C)
The gel described in the present invention means that free isocyanate groups derived from the terminal isocyanate group-containing polyurethane resin (C) react with each other in the presence of water to form a polymer such as a urea compound.

  Hereinafter, the present invention will be described in more detail.

In the liquid polyol (A) used in the present invention, the weight ratio (a) / (b) of ethylene oxide (a) to propylene oxide (b) is 50/50 to 90/10, preferably 50/50 to 80 It contains 70 to 100% by weight, preferably 80 to 100% by weight, of a copolymer obtained by copolymerization reaction in the range of / 20.
The liquid polyol (A) is a linear or branched polyol copolymer that is liquid at room temperature.

  The liquid polyol (A) is preferred because it has a low viscosity and is easy to handle and the degree of hydrophilicity can be easily adjusted. Specifically, as the liquid polyol (A), for example, a random copolymer of ethylene oxide and propylene oxide, a product obtained by adding the following low molecular weight polyol at the time of or after the production of this copolymer, or the like is used. be able to. The low molecular polyol component is included in the liquid polyol (A) component in an amount of 0 to 30% by weight, preferably 0 to 20% by weight.

  Further, as the copolymer, a hydrophilic one having an average of 2 or more, preferably 2 to 4 alcoholic hydroxyl groups in one molecule and having a number average molecular weight of about 500 to 50,000 can be suitably used.

  Examples of the low molecular polyol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3 -Butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene Glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,4-cyclohexanedi Glycols such as tanol and neopentyl glycol; glycerin, trimethylolpropane, trimethylolethane, trimethylolmethane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol, mannitol And trivalent or higher alcohols.

  Moreover, the said low molecular polyol can be mix | blended with liquid polyol (A), and can also be used as a mixture.

  As the polyisocyanate (B) in the present invention, a number average molecular weight of about 2 to 4, preferably 2 to 4, containing about 2 to 4 isocyanate groups in one molecule conventionally used for the production of polyurethane resins. These compounds can be suitably used.

  Specific examples of the polyisocyanate (B) include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate, and cyclic aliphatic isocyanates such as hydrogenated xylylene diisocyanate and isophorone diisocyanate; Organic diisocyanates such as isocyanates, aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate itself, or these organic diisocyanates and polyhydric alcohols, low molecular weight polyester resins, adducts of water or the above organic diisocyanates Similar cyclized polymers, and isocyanurates / biurets of the above-mentioned organic diisocyanates.

  Typical commercially available products of polyisocyanate (B) include, for example, `` Barnock D-750 '', `` Barnock 800 '', `` Barnock DN-950 '', `` Barnock 970 '', `` Burnock 15-455 '' (above , Manufactured by Dainippon Ink & Chemicals, Inc., trade name), Death Module L, Death Module N, Death Module HL, Death Module IL, Death Module N3390 (above, Bayer AG, Germany) (Product name), “Takenate D-102”, “Takenate 202”, “Takenate 110N”, “Takenate 123N” (above, Takeda Pharmaceutical Co., Ltd., trade name), “Coronate L”, “Coronate HL” “Coronate EH”, “Coronate 203” (trade name, manufactured by Nippon Polyurethane Industry Co., Ltd.) and “Duranate 24A-90CX” (trade name, manufactured by Asahi Kasei Kogyo Co., Ltd.).

In the present invention, the terminal isocyanate group-containing polyurethane resin (C) which is a reaction product of the polyisocyanate (B) and the liquid polyol (A) has an isocyanate group in the component (B) with respect to the hydroxyl group in the component (A). It mix | blends so that it may become excess, and it synthesize | combines by making it react normally at 10 degreeC or more, Preferably it is 20-200 degreeC for several minutes-several hours. The obtained resin (C) is usually a transparent solid or highly viscous liquid resin.
The blending ratio of the polyisocyanate (B) and the liquid polyol (A) is usually about 1.01 to 2 mol of the isocyanate group in the component (B) with respect to 1 mol of the hydroxyl group in the component (A). Is a ratio in the range of about 1.1 to 2 moles. If the isocyanate group exceeds 2 moles, a large amount of unreacted polyisocyanate (B) remains, which is not preferable. On the other hand, if the isocyanate group is less than 1.01 mol, it is not preferable because it is too high in molecular weight and gelled.

The number average molecular weight of the terminal isocyanate group-containing polyurethane resin (C) to be obtained is not particularly limited, but is usually in the range of about 1,000 to 100,000.
The filler (D) used in the present invention can increase the surface area and improve the carrying ability of the hydrogel to microorganisms by blending it with the hydrogel.

The filler (D) is mixed with the hydrogel to adjust the specific gravity of the hydrogel and the dispersion medium such as water and alcohol in which the hydrogel (dispersoid) is dispersed, and the flow characteristics required for the carrier. Can be adjusted as appropriate.
The filler (D) is classified into those used for increasing the specific gravity of the hydrogel and those used for decreasing the specific gravity of the hydrogel.

  The former filler (D) (hereinafter referred to as “high specific gravity filler”) is insoluble or sparingly soluble in water having a true specific gravity of 1.2 or more, preferably in the range of 1.5 to 3.0, from the viewpoint of high specific gravity effect. A powder is preferred. Specifically, clay (clay) -based, talc (magnesium silicate) -based, barita (barium sulfate) -based, mica (mica) -based, alumina-based, silica-based pigments and colloidal silica, activated carbon, carbon powder, zeolite , Diatomaceous earth, charcoal, and sepiolite porous powder. Representative examples of commercially available products include, for example, Himicron HE-5 (average particle size 1.6 μm, specific gravity 1.2) manufactured by Takehara Chemical Industry Co., Ltd., Micromica MK-100 (average particle size 4 μm, specific gravity 2.7) manufactured by Corp Chemical Co., Ltd. ), MK-200 (average particle size 8 μm, specific gravity 2.7), Micro Chemical Micco-MK-300 (average particle size 15 μm, specific gravity 2.7), Micro Mica ME-100 (average particle size 8 μm, specific gravity) 2.6), MB-20 manufactured by Toshiba Ballotini (average particle size 10 μm, specific gravity 2.5), Kintor DSW-3 (average particle size 1.5 mm, specific gravity 1.6), WA (average particle size 1.5 mm, specific gravity 1.6), Cataler Kintoll WB (average particle size 1.5 mm, specific gravity 2.0), Nippon Enviro Chemicals white birch A (average particle size 60 μm, specific gravity 1.6), Nippon Enviro Chemicals white birch C (average particle size 70 μm, specific gravity 2.0), Hakuho M (average particle size 75 μm, specific gravity 2.0), carborafin (average particle size 40 μm, specific gravity 2. 0), Nitto Zeolite No. 2 (average particle size 1.5 mm, specific gravity 2.08), Omi Mining Corporation Sepiolite P-150 (average particle size 75 μm, specific gravity 2.3), Omi Mining Corporation Sepiolite P-300 (average particle size 75 μm, 2.3), white clay A (average particle size 12 μm, specific gravity 2.8), white clay B (average particle size 5 μm, specific gravity 2.3), Biei white clay industry white clay C (average particle size 140 μm) , Specific gravity 2.8) and the like.

  The latter filler (D) (hereinafter referred to as “low specific gravity filler”) having a true specific gravity of 0.01 to 0.95, preferably 0.02 to 0.50 is suitable. By using the specific gravity filler for reducing the specific gravity within the above range, the effect of reducing the specific gravity can be sufficiently obtained, and handling at the time of production is easy. Examples of such low specific gravity fillers include hollow glass beads and hollow celite. Typical examples of commercially available products are Niigata Ferilite 200/7 (average particle size 150 μm, specific gravity 0.7), Nihon Ferrite Co., Ltd. Fiilite 52/7 (average particle size 300 μm, specific gravity 0.7), Nippon Ferrite Co., Ltd. Expandel WE20 (average particle size 25 μm, specific gravity 0.04), Fuji Silysia Chemical Ltd. Fuji Balloon S-35 (average particle size 40 μm, specific gravity 0.24) ), S-40 manufactured by Fuji Silysia Chemical Co., Ltd. (average particle size of 40 μm, specific gravity of 0.26), S-45 manufactured by Fuji Silysia Chemical Co., Ltd. (average particle size of 40 μm, specific gravity of 0.28), H-30 manufactured by Fuji Silysia Chemical Co., Ltd. (average particle size) 40 μm, specific gravity 0.20), Taisetsu Balloon K (average particle size 28 μm, specific gravity 0.31) manufactured by Biei Shirachi Kogyo Co., Ltd., Taisetsu Balloon C (average particle size 120 μm, specific gravity 0.24) manufactured by Biei Shirachi Kogyo Co., Ltd. (Average particle size 20 μm, specific gravity 0.34).

  Although the compounding quantity of a filler (D) is not specifically specified, Usually, it is 0.1-200 weight part per 1 weight part of resin (C), Preferably it is 1-100 weight part. Moreover, the well-known thing used conventionally can be used for the magnitude | size and shape of a filler (D).

The method of mixing the terminal isocyanate group-containing polyurethane resin (C), filler (D) and water is preferable because the method of adding the filler and water to the resin (C) after mixing the filler and water is easy to uniformly disperse. It is not limited.
In the present invention, 4 to 20 parts by weight, preferably 10 to 20 parts by weight, and further 12 to 15 parts by weight of water per 1 part by weight of the resin (C) are mixed and stirred to mix the resin (C), A uniform liquid mixture of the filler (D) and water is obtained. In this mixture, a water-containing polyurethane gel containing a large amount of water is obtained by the crosslinking reaction of the resin (C) with a part of the water. By blending water in the above range, a hydrogel having a volume expansion ratio of 4 to 20 times that of the resin (C) before gelation can be obtained.

In the present invention, the liquid mixture of the resin (C), filler (D) and water starts to be crosslinked and becomes a hydrous gel.
For this reason, the liquid mixture is applied to a releasable substrate such as a glass plate or a silicon processed sheet, or a substrate such as polyethylene terephthalate, polyvinyl chloride, or aluminum, or a substrate such as a processed product by flow coating, a bar coater or a roll coater. After applying and the like by cross-linking and curing, a molded body film can be obtained by peeling from the substrate.

In this case, both sides can be applied to the sheet-like substrate as necessary.
The molded body may be obtained by putting the above mixture into a mold and then performing a crosslinking reaction. Furthermore, the molded body taken out from the molded body coating or the mold can be appropriately subjected to secondary processing such as cutting, cutting, and pulverization to obtain a desired shape.

Next, the gelled product obtained is frozen and thawed. The freezing temperature should just be 0 degrees C or less. Further, thawing is at 10 ° C. or higher, preferably 20 ° C. or higher.
By performing freezing and thawing, bubbles are generated inside the hydrous gel, and a porous hydrous gel can be produced.

The hydrogel thus obtained preferably has elasticity and preferably has a compressive fracture strength of 0.1 kg / cm ² or more.

    The production method of the present invention comprises a copolymer obtained by copolymerizing a weight ratio (a) / (b) of ethylene oxide (a) and propylene oxide (b) in the range of 50/50 to 90/10. A gel obtained by blending water with a mixture of a liquid polyol (A) containing 70% by weight or more and a terminal isocyanate group-containing polyurethane resin (C) and filler (D), which is a reaction product of polyisocyanate (B) It can be produced by freezing and thawing the compound. A detailed description of the manufacturing method has been given above and is omitted here.

  The microorganism-supporting body of the present invention is obtained by using the above-mentioned hydrated gel as a supporting body and supporting the microorganism on this.

The microorganisms that can be attached to the carrier are not particularly limited, and can be used for both anaerobic microorganisms and aerobic microorganisms. Moreover, it is suitable as a carrier for adhering one or two or more kinds of microorganisms. For example, it is also suitable as a carrier for adhering a mixture of various microorganisms such as activated sludge.
Specific examples of microorganisms include, for example, molds such as Aspergillus, Penicillium, and Fusarium; yeasts such as Saccharomyces, Faphia, and Candida; Zymomonas, Nitrosomonas, Nitrobacter, Paracoccus, and Vibrio Examples include bacteria such as genus, genus Methanosarcina, and Bacillus.

  For example, the microorganisms can be attached to the water-containing gel as the carrier simply by putting them in a fermenter or bioreactor in which the microorganisms are suspended.

  Alternatively, the hydrated gel as a carrier is put in the medium in advance, and the microorganism can be attached by culturing the microorganism after inoculation. After attaching the microorganisms, they can be put into a bioreactor. The amount of the carrier to be introduced into a culture tank, fermenter, bioreactor or the like is not particularly defined, but is usually preferably in the range of about 1 to 60% by volume of the medium.

  The carrier is most suitable for use in a wastewater treatment facility, a fluidized bed type bioreactor, a stirring type bioreactor, or the like, but can also be applied to a fixed bed type bioreactor or the like.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1
Random copolymerized triol (ethylene oxide / propylene oxide component) of ethylene oxide / propylene oxide = 80/20 (weight ratio) branched with glycerol having 3 moles of tolylene diisocyanate and a number average molecular weight of 3,000 (hydroxyl equivalent: 1,000) (90 wt%) 1 mol was mixed and reacted at 80 ° C. for 10 hours to obtain a trifunctional terminal isocyanate group-containing polyurethane resin having a number average molecular weight of about 4,000.

  110 parts by weight of tap water was added to 10 parts by weight of this polyurethane resin and stirred well to obtain a cloudy resin aqueous solution. Further, 20 parts by weight of glass beads having a specific gravity of 2.5 and an average particle diameter of 10 to 12 μm (trade name “MB-20” manufactured by Toshiba Barodini Co.) were uniformly dispersed therein to obtain an aqueous liquid composition. This was cast onto a polyethylene plate to a thickness of 2 mm and left at room temperature for 1 hour to obtain a pudding-like hydrogel.

    This was peeled, frozen at −6 ° C. to −7 ° C., and thawed with lukewarm water at 40 ° C. Next, this was cut to obtain a 5 mm square carrier. As a result of immersing this carrier in water overnight, the specific gravity was 1.19.

Example 2
A support was obtained in the same manner as in Example 1 except that 80 parts by weight of talc (trade name “BST” manufactured by Nippon Talc Co., Ltd.) having a specific gravity of 3.1 and an average particle diameter of 4 to 5 μm was used. As a result of immersing this carrier in water overnight, the specific gravity was 1.68. A 5 mm square carrier was obtained in the same manner as in Example 1.

Example 3
A support was obtained in the same manner as in Example 1 except that 12 parts by weight of hollow glass beads having a specific gravity of 0.34 and an average particle diameter of 1 to 50 μm (trade name “Q-Ce1579” manufactured by Toshiba Barodini Co., Ltd.) were used. As a result of immersing this carrier in water overnight, the specific gravity was 0.93. A 5 mm square carrier was obtained in the same manner as in Example 1.

Comparative Example 1
A support was obtained in the same manner as in Example 1 except that glass beads were not used. As a result of immersing this carrier in water overnight, the specific gravity was 1.01.

Comparative Example 2
A carrier was obtained in the same manner as in Example 1 except that the freezing and thawing processes were not performed. As a result of immersing this carrier in water overnight, the specific gravity was 1.01.

Example 4
A 2.5 liter container was set in a constant temperature bath at 20 ° C., and a stirrer capable of sufficient stirring was set. In this container, 1000 ml of artificial sewage ammonia medium was placed (Table 1).

  By immersing 200 ml of the carrier prepared in Examples 1 to 3 and Comparative Example 1 in a wastewater treatment facility for 10 days, microorganisms were attached to the surface of the carrier.

  150 ml each of the carrier to which the microorganisms were attached was added to the artificial ammonia medium, and the amount of ammonia decreased was measured while adjusting the pH to 7.5 to 8.5. The results are shown in Table 2.

In Examples 1 to 3, the rate of ammonia decrease was faster than that of the comparative example.
Table 1
Artificial ammonia wastewater composition

Table 2
Reduction rate of ammonia nitrogen

Claims (7)

Liquid polyol containing 70% by weight or more of a copolymer obtained by a copolymerization reaction in a weight ratio (a) / (b) of ethylene oxide (a) to propylene oxide (b) in the range of 50/50 to 90/10 Freeze and thaw the gelled product obtained by blending water into a mixture of the terminal isocyanate group-containing polyurethane resin (C) and filler (D), which is a reaction product of (A) and polyisocyanate (B). A hydrous gel characterized by comprising The water-containing gel according to claim 1, wherein the water-containing gel has a volume expansion ratio of 4 to 20 times that of the resin (C) before gelation. 2. The hydrogel according to claim 1, wherein the filler (D) has an average particle size in the range of 0.1 to 150 μm. The water-containing gel according to claim 1, wherein the water content is in the range of 4 to 20 parts by weight of water per 1 part by weight of the resin (C). 2. The hydrogel according to claim 1, wherein the blending ratio of the filler (D) is in the range of 0.1 to 200 parts by weight of the filler (D) per 1 part by weight of the resin (C). Liquid polyol containing 70% by weight or more of a copolymer obtained by a copolymerization reaction in a weight ratio (a) / (b) of ethylene oxide (a) to propylene oxide (b) in the range of 50/50 to 90/10 Freeze and thaw the gelled product obtained by blending water into a mixture of the terminal isocyanate group-containing polyurethane resin (C) and filler (D), which is a reaction product of (A) and polyisocyanate (B). A method for producing a water-containing gel, comprising: A microorganism-supporting material comprising the hydrogel according to Item 1.