JP2882710B2 - Core-sheath fibrous gel and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core-sheath fibrous gel useful as a carrier for a bioreactor and the like, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, studies have been made to immobilize biocatalysts such as enzymes and microorganisms and utilize their functions efficiently. One of the methods for immobilizing the biocatalyst is a comprehensive immobilization method in which the biocatalyst is wrapped as it is using a polymer material, and agar, alginate, carrageenan, polyacrylamide are commonly used as the polymer material in this method. , Polyvinyl alcohol, polyethylene glycol,
There are photocurable resins and the like. Examples of the shape of the carrier include a sphere, a die, a sheet, a tube, and a fiber. Conventionally, there has been known a research example in which a granular carrier such as a sphere or a dice is put into a wastewater treatment tank to improve the efficiency. However, in the case of a granular carrier, the carrier may flow out of the system. There is
Equipment such as a filter is required. On the other hand, since the fibrous carrier has a wide active surface, the reaction efficiency can be expected to increase, and if the fibers are bundled and one end is fixed to the tank,
The carrier does not flow out of the system, and a device such as a filter is not required. As a conventional fibrous carrier, there is known a method in which ordinary fibers are used as a carrier to wait for the attachment of a biocatalyst, or a method in which only a polymer gel is processed into a fibrous form to cover or attach the biocatalyst.

[0003]

Since a carrier using ordinary fibers cannot entrap and fix a biocatalyst, only a surface to which the biocatalyst is attached can participate in the reaction. Further, the affinity for the biocatalyst is poor, and the biocatalyst attached to the surface is easily peeled off, which is not preferable as a carrier. The carrier made by processing the gel itself into a fibrous form can entrap and fix the biocatalyst and is excellent in the habitability of microorganisms.However, due to the low strength of the gel, it can be used for wastewater treatment and water flow in various bioreactors. Be cut off. Further, when the specific gravity of the fibrous carrier is larger than 1, there is a problem that the fibrous carrier is settled in water or the fibers are entangled by aeration or the like, thereby deteriorating the reaction efficiency. An object of the present invention is to provide a fibrous carrier that does not settle or become entangled in water and has high strength and excellent affinity with a biocatalyst.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, the sheath portion is a gel made of a water-soluble synthetic polymer (A), and the core portion is a gel. Has found a core-sheath fibrous gel which is a fiber composed of spun yarn having a specific gravity of 1 or less, and has completed the present invention. Here, the core fiber plays a role of reinforcing and adjusting the specific gravity, and the sheath gel made of the water-soluble synthetic polymer (A) plays a role of fixing the biocatalyst. Therefore, if the amount of the gel composed of the water-soluble synthetic polymer (A) to be coated is too small, there is no great difference from a normal biofilm, and the efficiency as a bioreactor carrier deteriorates. In order for the biocatalyst to be effectively fixed, the thickness of the gel composed of the water-soluble synthetic polymer (A) must be 10 or less.
μm or more is preferable, and 50 μm or more is more preferable.
The fiber of the spun yarn having a specific gravity of 1 or less (preferably 0.98 or less) used in the present invention is not particularly limited as long as it has a strength enough to be used in a reaction tank, but a diameter of 20 μm or more Is preferred. For example, a spun yarn of a synthetic fiber such as a polyethylene-based or polypropylene-based fiber may be used. Examples of the water-soluble synthetic polymer (A) constituting the gel composed of the water-soluble synthetic polymer (A) include polyvinyl alcohol, polyacrylamide, and polyethylene glycol. Although the invention does not cover the biocatalyst in the polymer gel within the scope of the present invention, considering the efficiency in the bioreactor, the biocatalyst in which the biocatalyst is actively included in the polymer gel is preferable. The biocatalyst used here is not particularly limited, and any microorganisms and enzymes can be immobilized by the present invention. In addition, a gel containing the water-soluble synthetic polymer (A) of the present invention may be supplemented with a microorganism medium, a filler for adjusting the specific gravity of the produced gel, and the like, as long as the gelation is not inhibited.

Next, a method for producing a core-sheath fibrous gel will be described. First, a mixed aqueous solution containing a water-soluble synthetic polymer (A) as a main component of a gel and a water-soluble polysaccharide (B) capable of gelling by contact with a cation is prepared.
When adding a biocatalyst such as a microorganism or an enzyme, a medium for the microorganism, or a filler for adjusting the specific gravity, the mixture is added to the mixed aqueous solution. Here, specific examples of the water-soluble polysaccharide (B) capable of gelling upon contact with a cation include alginate, carrageenan, mannan, chitosan and the like, with sodium alginate being particularly preferred. Next, an aqueous solution comprising the components (A) and (B) is discharged from a nozzle together with a fiber having a specific gravity of 1 or less, and is brought into contact with an aqueous solution containing a cation to form a core-sheath fibrous gel. Specific examples of the cation used here include metal cations such as calcium ion, magnesium ion, strontium ion, barium ion, aluminum ion, potassium ion, cerium ion, and nickel ion; and organic cations such as ammonium ion. Compounds containing one type are mentioned, but calcium chloride is particularly preferred.

Finally, the core-sheath fibrous gel can be obtained by gelling the water-soluble synthetic polymer (A) which is the main component of the gel. As a method for gelling the water-soluble synthetic polymer (A), a method of contacting with a polymerization initiator and a crosslinking agent to polymerize and crosslink, a method of irradiating light or an electron beam to crosslink, and freezing and thawing at least once. A method of forming microcrystals by performing the method, a method of gelling by contact with an aqueous solution of a compound having a syneresis effect of the water-soluble synthetic polymer (A), and the like can be considered. In particular, when the biocatalyst is immobilized, a method of gelling by a method that does not inhibit its activity is preferable. In particular, a method in which freezing and thawing is performed one or more times, and a method in which a polymer is brought into contact with an aqueous solution of a compound having a syneresis effect are preferred. Freeze and thaw 1
In the case where the freezing is performed more than once, the freezing temperature is preferably −5 ° C. or lower in order to generate sufficient fine crystals. Furthermore, the freeze-thaw operation may be repeated to increase the strength of the gel.

When the aqueous solution of the water-soluble synthetic polymer (A) is brought into contact with an aqueous solution of a compound having a synergic effect, the aqueous solution of the compound having a synergic effect of the water-soluble synthetic polymer (A) may be sodium sulfate, ammonium sulfate, sulfuric acid, or the like. Potassium, magnesium sulfate, aluminum sulfate, sodium citrate, ammonium citrate, potassium citrate, magnesium citrate, aluminum citrate, sodium tartrate,
An aqueous solution containing at least one of compounds such as ammonium tartrate, potassium tartrate, magnesium tartrate, and aluminum tartrate is exemplified, and a sulfate aqueous solution is particularly preferred.

[0008] The core-sheath fibrous gel thus produced has a strength not to be deformed or damaged for a long period of time in various types of reaction tanks, and is not immersed in water or various chemicals. , Continuous operation becomes possible. In addition, the fiber does not sink or become entangled in water, and its usefulness as a biological reaction carrier having high reaction efficiency is exhibited.

[0009]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 Polyvinyl alcohol (hereinafter abbreviated as PVA) manufactured by Kuraray Co., Ltd. (average degree of polymerization 4000, degree of saponification 99.85)
Mol%) was washed with warm water at 40 ° C. for about 1 hour, water was added to the PVA so that the PVA concentration became 10 wt%, and the total amount was 400
g and adjusted to pH 6. This is autoclaved for 1
After treatment at 20 ° C. for 30 minutes to dissolve PVA, the mixture was allowed to cool to room temperature. 200 g of a 4% aqueous sodium alginate solution was added to and mixed with the PVA aqueous solution, and further collected from a wastewater treatment tank of the Kuraray Okayama Plant (1-2-1, Kaigan-dori, Okayama-shi, Okayama) and concentrated. 200 g of the obtained activated sludge (MLSS 80000 mg / l (hereinafter abbreviated as mg / l)) was added, and the mixture was sufficiently stirred. The spiked polypropylene yarn (200 μm in diameter) was injected through the injection needle-shaped outlet having an inner diameter of 0.2 mm at the tip of this mixed solution.
m, specific gravity 0.91). The outlet is 0.
It was immersed in a ₂ mol / l aqueous solution of calcium chloride (CaCl ₂ ), and the ejected material was pulled off at a speed of 5 m / min. The residence time of the discharged material in the CaCl ₂ aqueous solution was 1 minute. Upon contact with the discharged CaCl ₂ aqueous solution, the surface of the yarn was immediately covered and solidified. After gently washing this with distilled water,
And then thawed at room temperature.
These freezing and thawing operations were repeated twice. As a result, an opaque brown flexible core-sheath fibrous gel was obtained. The obtained core-sheath fibrous gel was cut at an interval of 50 cm, aligned 100 pieces at a time, and one end was fixed. This was immersed in an activated sludge aeration tank at Kuraray Okayama Plant for 10 days. Since the color of the core-sheath fibrous gel changed from light brown to dark brown, proliferation of activated sludge was observed. In addition, since the shape of the core-sheath fibrous gel did not change before and after the culture, it was revealed that the durability of the core-sheath fibrous gel was excellent. Untreated effluent from Kuraray Okayama Plant was converted to TOC (Tot)
al Organic Carbon) 100mg
20 liters of the drainage liquid obtained by adjusting to 1 / l was put into a test aeration tank, and one end of 1 kg of the core-sheath fibrous gel was fixed to the bottom of the test aeration tank. Since the specific gravity of the core portion was 1 or less, the core-sheath fibrous gel was almost vertically arranged in water. Therefore, even when aerated, the core-sheath fibrous gel did not become entangled. When the TOC value of the treatment liquid obtained by aeration for 30 minutes was measured, it was 2 mg / l, and it was found that sufficient biological activity was obtained.

Comparative Example 1 PVA manufactured by Kuraray Co., Ltd. (average degree of polymerization: 4,000, degree of saponification: 99.85 mol%) was washed with warm water at 40 ° C. for about 1 hour, and then PVA was added so that the PVA concentration became 10% by weight. Water was added to adjust the total amount to 400 g, and the pH was adjusted to 6. This was treated in an autoclave at 120 ° C. for 30 minutes to dissolve PVA and then allowed to cool to room temperature. 200 g of a 4% aqueous sodium alginate solution was added to and mixed with the PVA aqueous solution, and further collected from a wastewater treatment tank of the Kuraray Okayama Plant (1-2-1, Kaigan-dori, Okayama-shi, Okayama) and concentrated. 200 g of the obtained activated sludge (MLSS 80000 mg / l) was added, and the mixture was sufficiently stirred. This mixed solution was discharged together with a rayon spun yarn (diameter: 200 μm, specific gravity: 1.52) from a discharge port in the form of an injection needle having an inner diameter of 0.2 mm at the tip. The discharge port is 0.2 mol / l calcium chloride (CaC
l ₂ ) The product was immersed in an aqueous solution, and the discharged material was pulled off at a speed of 5 m / min. The residence time of the discharged matter in the CaCl ₂ aqueous solution is 1
Minutes. The ejected material immediately solidified by covering the surface of the yarn upon contact with the CaCl ₂ aqueous solution. After washing this lightly with distilled water, it was frozen in a freezer at −20 ° C. for 24 hours,
This was thawed at room temperature, and the freeze and thaw operations were repeated twice. As a result, an opaque brown flexible core-sheath fibrous gel was obtained. The obtained core-sheath fibrous gel was cut at an interval of 50 cm, aligned 100 pieces at a time, and one end was fixed. This was immersed in an activated sludge aeration tank at Kuraray Okayama Plant for 10 days. Since the color of the core-sheath fibrous gel changed from light brown to dark brown, proliferation of activated sludge was observed. Untreated effluent from Kuraray Okayama Plant has TOC value of 100
20 liters of the drainage liquid obtained by adjusting the concentration to mg / l was put into a test aeration tank, and one end of 1 kg of the core-sheath fibrous gel was fixed to the bottom of the test aeration tank. Since the specific gravity was greater than 1, the core-sheath fibrous gel was lying on the bottom surface of the aeration tank in water, and even when aeration was performed, the core-sheath fibrous gel was not tangled vertically but entangled.

Comparative Example 2 The same polypropylene spun yarn as that used in Example 1 was cut at an interval of 50 cm, aligned in 10 pieces, and fixed at one end. This was immersed in an activated sludge aeration tank at Kuraray Okayama Plant for 10 days. A small amount of activated sludge was attached to the surface of the yarn. Untreated effluent from Kuraray Okayama Plant was converted to TOC (Tot)
al OrganicCarbon) value 100 mg / l
Was placed in a test aeration tank, and one end of a 1 kg polypropylene spun yarn was fixed to the bottom of the test aeration tank. Since the specific gravity was 1 or less, the core-sheath fibrous gels were arranged almost vertically in water. However, when the TOC value of the treatment liquid obtained by aeration for 30 minutes was 65 mg / l, Activity was inadequate.

Comparative Example 3 PVA manufactured by Kuraray Co., Ltd. (average degree of polymerization: 4000, degree of saponification: 99.85 mol%) was washed with warm water at 40 ° C. for about 1 hour, and then PVA was added to the PVA so that the PVA concentration became 10 wt%. Water was added to adjust the total amount to 400 g, and the pH was adjusted to 6. This was treated in an autoclave at 120 ° C. for 30 minutes to dissolve PVA and then allowed to cool to room temperature. Activated sludge (MLSS 80000) obtained by adding and mixing 200 g of a 4% aqueous sodium alginate solution to the aqueous PVA solution, collecting the PVA aqueous solution from a wastewater treatment tank at the Kuraray Okayama Plant, and performing a concentration operation.
(mg / l) was added and stirred well. Only this mixed solution was discharged from a discharge port in the form of an injection needle having an inner diameter of 0.2 mm at the tip. The discharge port was immersed in a 0.2 mol / l calcium chloride (CaCl ₂ ) aqueous solution,
s speed. The residence time of the discharged material in the CaCl ₂ aqueous solution was 1 minute. The discharge solidified immediately upon contact with the CaCl ₂ aqueous solution. This was lightly washed with distilled water, frozen in a freezer at −20 ° C. for 24 hours, and then thawed at room temperature. This freezing and thawing operation was repeated twice. As a result, an opaque brown flexible fibrous gel was obtained. The obtained fibrous gel was cut every 50 cm, and 100 pieces were aligned, and one end was fixed. This was immersed in an activated sludge aeration tank at Kuraray Okayama Plant for 10 days. Since the color of the fibrous gel changed from light brown to dark brown, proliferation of activated sludge was recognized. However, since the fibrous gel was cut by immersion in the aeration tank, it was found that there was a problem in the strength of the fibrous gel.

[0013]

As is clear from the above examples, the reaction is achieved by using a core-sheath fibrous gel in which the sheath is a gel made of a water-soluble synthetic polymer and the core is a fiber having a specific gravity of 1 or less. The fiber can be applied to a bioreactor such as wastewater treatment as a high-strength fibrous carrier with good reaction efficiency without sedimentation or entanglement of fibers in the tank.

Claims (4)

(57) [Claims] (1) A sheath part is a gel made of a water-soluble synthetic polymer (A), and a core part is made of a spun yarn having a specific gravity of 1 or less.
Fiber and is a core-sheath fibrous gel that. 2. A mixed aqueous solution containing a water-soluble synthetic polymer (A) and a water-soluble polysaccharide (B) capable of gelling upon contact with a cation is formed from a spun yarn having a specific gravity of 1 or less.
2. The core-sheath fibrous material according to claim 1, wherein the water-soluble synthetic polymer (A) is gelled after being discharged from a nozzle together with the fiber and formed by contacting the discharged material with an aqueous solution containing cations. Gel production method. 3. The method for producing a core-sheath fibrous gel according to claim 2, wherein the method of gelling the water-soluble synthetic polymer (A) is a method of freezing and thawing at -5 ° C. or less once or more. . 4. The core-sheath fibrous material according to claim 2, wherein the method of gelling the water-soluble synthetic polymer (A) is a method of contacting with a solution having a syneresis effect of the water-soluble synthetic polymer (A). Gel production method.