JPH1156359A - Method for immobilization of microbe and microbial carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the activity of microbes through remarkably decreasing the degree of death of the microbes in immobilization and also to make a microbial carrier having comparatively high strength by specifying the concentration of a polymerization inhibitor in a raw material liquid of a mixture between microbes, etc., and a polymer-forming material. SOLUTION: This microbial carrier is prepared by mixing (A) microbes and/or activated sludge with (B) a polymer-forming material (e.g. a monomer, a prepolymer and an oligomer) in which a polymerization inhibitor is contained in a concentration of <=300 mg/l, preferably 50-250 mg/l, to form a raw material liquid, and then by gelation to entrap and immobilize the component A into the polymer material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for immobilizing microorganisms and a microorganism carrier, and more particularly to an improvement in activity and strength of an immobilized carrier of an inclusive immobilization type and an adherent immobilization type.

[0002]

2. Description of the Related Art Biological treatment of wastewater and sewage has been employed in wastewater treatment in various fields because of its lower processing cost than physical treatment. However, among microorganisms, for example, microorganisms having a low growth rate, such as nitrifying bacteria, have a reduced number of bacteria particularly at low water temperature in winter, and the reaction rate is significantly reduced.

[0003] From the above, it has recently been proposed to significantly increase the reaction rate by introducing a microorganism carrier having a high concentration of microorganisms by immobilizing the microorganisms themselves or activated sludge into a polymer material into a wastewater treatment tank. Is being done. The method of immobilizing microorganisms can be roughly classified into an entrapping immobilization type and an adhering immobilization type.The entrapping immobilization type is a method in which microorganisms and activated sludge are held inside a carrier, whereas the adhering immobilization type is a method in which microorganisms or activated sludge are retained This is a method in which it is naturally attached to the surface of a carrier.

[0004]

However, microbial carriers molded in the entrapment-fixing type and the attachment-fixing type have the following disadvantages. In the case of the inclusive fixation type, there is a disadvantage that the microorganism is easily killed at the time of immobilization or after the immobilization, and a long acclimatization period for increasing the activity of the microorganism is required. In addition, there is a disadvantage that the strength of the carrier is weak because the inside of the microorganism carrier is not sufficiently gelled (solidified), and the service life in wastewater treatment is short.

[0005] In the case of the adhesion-fixing type, microorganisms or activated sludge adhere to the gelled carrier, so that the death of microorganisms is hardly a problem as in the case of entrapping and fixing. However, in this case, the inside of the carrier is sufficiently gelled (solidified). ), The strength of the carrier is weak, and the service life in wastewater treatment is short. The present invention has been made in view of such circumstances, and it is possible to significantly reduce the degree of death of microorganisms during immobilization, maintain the activity, and form a microorganism carrier having a strong carrier strength. An object of the present invention is to provide a method for immobilizing microorganisms and a carrier thereof.

[0006]

In order to achieve the above object, the present invention provides a microorganism and / or activated sludge, a monomer,
In the method for immobilizing microorganisms, the microorganism and / or the activated sludge are entrapped and immobilized in the polymer material by gelling a raw material mixture obtained by mixing a polymer material such as a prepolymer and an oligomer. The concentration of the polymerization inhibitor contained in the polymer material is 300 m
g / L or less, preferably 50 to 250 mg / L.

Further, in order to solve the above-mentioned object, the present invention provides a microorganism which adheres and immobilizes microorganisms and / or activated sludge on a gelled carrier obtained by mixing water with a polymer material such as a monomer, a prepolymer or an oligomer. Wherein the concentration of the polymerization inhibitor contained in the polymer material used for the attachment and immobilization is 400 mg / L or less, preferably 50 to 300 mg / L.

In order to solve the above-mentioned object, the present invention provides a polymer material such as a monomer, a prepolymer or an oligomer having a polymerization inhibitor content of 300 mg / L or less, preferably 50 to 250 mg / L, and a microorganism. The microorganisms and / or activated sludge are encapsulated and fixed in the polymer material by gelling a raw material liquid mixed with and / or activated sludge.

Further, in order to solve the above-mentioned object, the present invention provides a method in which water is added to polymer materials such as monomers, prepolymers and oligomers having a polymerization inhibitor content of 400 mg / L or less, preferably 50 to 300 mg / L. It is characterized in that microorganisms and / or activated sludge are attached to the mixed and gelled carrier. According to the present invention, when the concentration of the polymerization inhibitor contained in the polymer material at the time of immobilization is comprehensively immobilized, it is 300 mg / L or less, preferably 50 to 25 mg / L.
At 0 mg / L, microorganisms are unlikely to be killed during immobilization. In addition, since the polymer material is rapidly gelled, the carrier strength of the molded microorganism carrier is increased.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the immobilization method and the microorganism carrier according to the present invention will be described below in detail with reference to the accompanying drawings. The inventors of the present invention have found that the concentration of the polymerization inhibitor contained in the polymer material to be immobilized has a significant effect on the death of microorganisms during immobilization and on the strength of the formed microorganism carrier. Generally, this polymerization inhibitor is added at about 1000 mg / L by a polymer material manufacturer. The reason for this is to prevent the polymerization of the polymer material from proceeding until the polymer material delivered from the polymer material maker to the carrier molding maker is used by the carrier molding maker. The polymerization inhibitors used herein include those termed polymerization terminators and polymerization inhibitors.

The present invention has been made based on the above findings, and in the case of an entrapping immobilization method and, in the case of a microorganism carrier formed by the method, a polymer such as a monomer, a prepolymer, or an oligomer used for immobilization. The concentration of the polymerization inhibitor contained in the material is 300 mg / L or less, preferably 50 mg / L or less.
It is configured to be ~ 250 mg / L. Further, in the case of a microorganism carrier molded for adhesion and immobilization method and adhesion, a monomer used for immobilization, a prepolymer,
The concentration of a polymerization inhibitor contained in a polymer material such as an oligomer is 400 mg / L or less, preferably 50 to 300 mg.
/ L.

Next, the theoretical basis for configuring the immobilization method and the microorganism carrier of the present invention as described above will be described.
First, the killing of microorganisms and the concentration of the polymerization inhibitor contained in the polymer material will be described. Since killing of microorganisms is a problem particularly in the case of entrapping immobilization, the case of entrapping immobilization will be described below.

In order to reduce the killing of microorganisms during entrapment and immobilization, it is necessary to gel the polymer material promptly to reduce the influence of the polymerization inhibitor in the polymer material. 3 shows the relationship between time and the concentration of a polymerization inhibitor in a polymer material. Examples of the polymerization inhibitor in the polymer material include hydroquinone (hereinafter, referred to as “HQ”), hydroquinone monomethyl ether (hereinafter, referred to as “MEHQ”), and butylhydroxyl toluene (hereinafter, referred to as “BHT”).

As can be seen from the results in FIG. 1, as the concentration of the polymerization inhibitor in the polymer material is increased, the gelation time hardly changes until the concentration of the polymerization inhibitor is about 500 to 600 mg / L. It changes within one minute, but becomes longer rapidly beyond that. From this result, it can be seen that when the killing of the microorganism is evaluated by the gelation time, the polymerization inhibitor in the polymer material may be 500 to 600 mg / L or less.

FIG. 2 shows the relationship between the residual activity of microorganisms in the carrier immediately after entrapping and immobilization, the gelation time, and the HQ concentration in the polymer material. Here, the residual activity ratio (A) is defined as a ratio of a polymer material containing a polymerization inhibitor to the respiratory activity (B) of microorganisms mixed in a polymer material containing no polymerization inhibitor and / or microorganisms in activated sludge. It is a ratio to the respiratory activity (C) of the mixed microorganisms and / or the microorganisms in the activated sludge, and is represented by the following (formula 1).

[0016]

## EQU00001 ## Residual activity ratio (A) = (C / B) .times.100 (%) (Equation 1) As can be seen from the results of FIG.
In each case of 0 mg / L, there was no difference until the elapsed time was about 3 minutes, indicating a good activity retention rate. However, when the elapsed time exceeds 3 minutes, the residual activity rate sharply decreases as the HQ concentration increases, while the HQ concentration decreases to 200 and 3 minutes.
In the case of No. 00, there was almost no difference, and a good activity retention rate was maintained.

From these results, when the killing of microorganisms at the time of entrapping and immobilization is determined only by the gelation time, the polymerization inhibitor in the polymer material may be 500 to 600 mg / L or less (see FIG. 1). However, when the concentration of the polymerization inhibitor is high, the gelling time sharply decreases when the polymerization time exceeds 3 minutes, when the activity retention rate of the carrier actually entrapped and immobilized is evaluated. Therefore, the preferred concentration of the polymerization inhibitor is 300 mg / L or less (see FIG. 2).

FIG. 3 shows the residual activity of microorganisms in the carrier three weeks after the entrapping and immobilization of the carrier in relation to the concentration of the polymerization inhibitor in the polymer material during the entrapping and immobilization. is there. The activity remaining ratio is the same as in the above (Equation 1). As can be seen from the results in FIG. 3, as the concentration of the polymerization inhibitor in the polymer material at the time of entrapping immobilization increases, the residual activity ratio of microorganisms in the carrier decreases, and when the concentration of the polymerization inhibitor exceeds 250 mg / L, The decline stops almost.
From this result, when there is a time from the incorporation and immobilization of the carrier to the use, it is preferable that the concentration of the polymerization inhibitor in the polymer material be 250 mg / L or less.

From the results of FIGS. 1 to 3, the upper limit of the concentration of the polymerization inhibitor in the polymer material for reducing the killing of microorganisms at the time of immobilization and thereafter is 300 mg / L or less,
It can be seen that the content is preferably 250 mg / L or less. Next, the relationship between the carrier strength and the concentration of the polymerization inhibitor contained in the polymer material will be described.

FIG. 4 shows the relationship between the relative compressive strength of the carrier and the concentration of the polymerization inhibitor in the polymer material. As the polymerization inhibitor in the polymer material, HQ, MEHQ,
It is an example of BHT. The relative compressive strength (D) is HQ10
When the compressive strength (E) of a carrier molded from a polymer material containing 0 mg / L is 100, HQ, MEHQ, B
HT is a relative comparison of the compressive strength (F) of a carrier molded from a polymer material having different content concentrations, and is expressed by the following (Formula 2).

[0021]

## EQU00002 ## Relative compressive strength (D) = (F / E) .times.100 (%) (Equation 2) As shown in FIG. 4, when the concentration of the polymerization inhibitor in the polymer material is increased, polymerization is inhibited. Although slightly different depending on the type of agent, the amount rapidly decreases when the amount exceeds 400 mg / L. For this reason, when the concentration of the polymerization inhibitor contained in the polymer material is viewed from the viewpoint of the strength of the carrier, the upper limit of the concentration of the polymerization inhibitor is preferably set to 400 mg / L.

From the results shown in FIG. 4, it can be seen that the upper limit of the concentration of the polymerization inhibitor in the polymer material for forming a microorganism carrier having a strong carrier strength is 400 mg / L or less, and 300 mg in consideration of the fluctuation due to the type of the polymerization inhibitor. / L or less. When the results of FIGS. 1 to 4 are comprehensively evaluated, as in the case of inclusive fixation, it is possible to reduce the death of microorganisms at the time of immobilization and thereafter, and to satisfy both of obtaining a microorganism carrier having a strong carrier strength. The upper limit of the concentration of the polymerization inhibitor in the polymer material is 300 mg / L or less, preferably,
It is 250 mg / L or less.

In addition, as in the case of adhesion fixing, microorganisms hardly die during immobilization, and the upper limit of the concentration of the polymerization inhibitor in the polymer material is 400 mg / L or less when emphasis is placed on increasing the strength of the carrier. Considering the fluctuation due to the type of the polymerization inhibitor and the like, it is 300 mg / L or less. next,
Considering the lower limit of the concentration of the polymerization inhibitor in the polymer material, from the viewpoint of killing microorganisms and the strength of the carrier, the polymerization inhibitor in the polymer material should be as small as possible, and should not be contained if possible. However, polymer materials that do not contain polymerization inhibitors at all will be polymerized and solidified before mixing microorganisms and / or activated sludge with the polymer material, and handling and transportation will be difficult if polymerization proceeds and fluidity is reduced. It becomes virtually impossible. Therefore, considering the ease of mixing the microorganism and / or the activated sludge with the polymer material and the ease of handling such as transportation, the lower limit of the concentration of the polymerization inhibitor in the polymer material is preferably 50 mg / L.

The following are applicable as the polymerization inhibitor in the present invention. Hydroquinone Butyl hydroxyl toluene Hydroquinone monomethyl ether Hydroquinone dimethyl ether Hydroquinone diethyl ether Thiodiphenylamine 4-Aminodiphenylamine Paraphenylenediamine diphenylamine Parabenzoquinone, etc. The following polymer materials correspond to the polymer material in the present invention. (Monomethacrylates) polyethylene glycol monomethacrylate polypropylene glycol monomethacrylate polypropylene glycol monomethacrylate methoxydiethylene glycol methacrylate methoxypolyethylene glycol methacrylate methacryloyloxyethyl hydrogen phthalate methacryloyloxyethyl hydrogen succinate 3chloro-2hydroxypropyl methacrylate stearyl methacrylate 2hydroxy methacrylate ethyl Methacrylate, etc. (monoacrylates) Nonylphenoxy polyethylene glycol acrylate Nonylphenoxy polypropylene glycol acrylate Silicon-modified acrylate Polypropylene glycol monoacrylate Phenoxyethyl acrylate Rate Phenoxydiethylene glycol acrylate Phenoxy polyethylene glycol acrylate Methoxy polyethylene glycol acrylate Acryloyloxyethyl hydrogen succinate Lauryl acrylate, etc. (dimethacrylates) 1,3 butylene glycol dimethacrylate 1,4 butanediol dimethacrylate ethylene glycol dimethacrylate diethylene glycol dimethacrylate triethylene Glycol dimethacrylate Polyethylene glycol dimethacrylate Butylene glycol dimethacrylate Hexanediol dimethacrylate Neopentyl glycol dimethacrylate Polypropylene glycol dimethacrylate 2hydroxy1,3 dimethacryloxypropane 2,2bis4methacrylo Xyethoxyphenylpropane 2,2bis-4methacryloxydiethoxyphenylpropane 2,2bis4methacryloxypolyethoxyphenylpropane, etc. (diacrylates) ethoxylated neopentyl glycol diacrylate propoxylated neopentyl glycol diacrylate polyethylene glycol diacrylate 1,6-hexanediol diacrylate neopentyl glycol diacrylate tripropylene glycol diacrylate polypropylene glycol diacrylate 2,2 bis-4 acryloxydiethoxyphenylpropane 2 hydroxy 1 acryloxy, 3 methacryloxy propane, etc. (trimethacrylates) trimethylol Propane trimethacrylate, etc. (triacrylates) Ethoxylated trimethylolpropa Triacrylate propoxylated trimethylolpropane triacrylate etc. (tetraacrylates) ethoxylated pentaerythritol tetraacrylate propoxylated pentaerythritol tetraacrylate ditrimethylolpropane tetraacrylate etc. (urethane acrylates) urethane acrylate urethane dimethyl acrylate urethane trimethyl acrylate etc. Epoxy acrylates) (Others) Polyvinyl alcohol Acrylamide Photocurable polyvinyl alcohol Photocurable polyethylene glycol Photocurable polyethylene glycol Polypropylene glycol prepolymer

[0025]

【Example】

 (Example 1) In Example 1, a carrier for inclusive immobilization was used.
Urethane acrylate with an HQ concentration of 200 mg / L
(Polymer material) using nitrifying bacteria (nitrifying bacteria concentration 5
× 10 ⁶(Cells / ml) immediately after comprehensive immobilization
The number of nitrifying bacteria in the body and the compressive strength were measured. Also attached
As a carrier for fixation and immobilization, an HQ concentration of 200 mg / L was used.
Mixing urethane acrylate with water and gelling
The compressive strength of the body was measured.

In Comparative Example 1, the same procedure as in Example 1 was carried out except that the HQ concentration of urethane acrylate (polymer material) was changed to 600 mg / L. Table 1 shows the results.
Shown in

[0027]

[Table 1] As can be seen from the results in Table 1, the degree of killing of the nitrifying bacteria in the entrapping immobilization carrier in Example 1 was 5 × 10 ⁶ (cells / ml) before immobilization, but immediately after immobilization. Was 5 × 10 ⁵ (cells / ml) and decreased only by one order.

On the other hand, the degree of killing of the nitrifying bacteria in the entrapping immobilization carrier in Comparative Example 1 was 4 immediately after immobilization.
× 10 ³ (cells / ml), which was greatly reduced to 3 orders. The compressive strength of Example 1 was 4.0 (kg / cm ² ), while that of Comparative Example 1 was 2.2 (kg / cm ² ), which was about 1/2.
Reduced to Example 2 In Example 2, nitrifying bacteria (nitrifying bacteria concentration 5 × 10 ⁶ (cells / cell) were used as a carrier for entrapping immobilization using polyethylene glycol acrylate (polymer material) having an MEHQ concentration of 150 mg / L. of the nitrifying bacteria in the carrier immediately after entrapping and immobilizing the same, and the compressive strength were measured.
The compressive strength of the carrier when water was mixed with polyethylene glycol acrylate having a Q concentration of 150 mg / L and gelled was measured.

In Comparative Example 2, the MEHQ concentration of polyethylene glycol acrylate (polymer material) was 600 m
The operation was performed in the same manner as in Example 2 except that the amount was changed to g / L. Table 2 shows the results.

[0030]

[Table 2] As can be seen from the results in Table 2, the degree of killing of the nitrifying bacteria in the entrapping immobilization carrier in Example 2 was 5 × 10 ⁶ (cells / ml) before immobilization, but immediately after immobilization. Was 6 × 10 ⁵ (cells / ml) and decreased only by one order.

On the other hand, the degree of killing of the nitrifying bacteria in the entrapping immobilization carrier in Comparative Example 2 was 2 immediately after immobilization.
× 10 ³ (cells / ml), which was greatly reduced to 3 orders. The compressive strength of Example 2 was 4.5 (kg / cm ² ), whereas that of Comparative Example 2 was 3.0 (kg / cm ² ), which was a great decrease.

[0032]

As described above, according to the method for immobilizing microorganisms and the microorganism carrier of the present invention, it is possible to reduce the killing of microorganisms during entrapment immobilization and maintain the activity high, thereby shortening the acclimatization period. can do. In addition, since the strength of the carrier for the inclusive fixation and the attachment and fixation can be increased, the life of the carrier can be dramatically improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the relationship between the gel time of a polymer material and the concentration of a polymerization inhibitor in the polymer material.

FIG. 2 shows the residual activity of microorganisms in a carrier immediately after entrapping and immobilization, elapsed time, and HQ in a polymer material.
Explanatory diagram showing the relationship with concentration

[FIG. 3] FIG. 3 is a graph showing the residual activity of microorganisms in a carrier three weeks after the entrapment and immobilization of a carrier in relation to the concentration of a polymerization inhibitor in a polymer material during the entrapment and immobilization. Figure

FIG. 4 is an explanatory diagram showing the relationship between the relative compressive strength of a carrier and the concentration of a polymerization inhibitor in a polymer material.

Claims (4)

[Claims] 1. A microorganism and / or activated sludge, a monomer,
In the method for immobilizing microorganisms, wherein the raw material liquid obtained by mixing a polymer material such as a prepolymer and an oligomer is gelled to thereby immobilize the microorganisms and / or activated sludge in the polymer material, The method for immobilizing microorganisms, wherein the concentration of the polymerization inhibitor contained in the obtained polymer material is 300 mg / L or less, preferably 50 to 250 mg / L. 2. A method for immobilizing microorganisms, wherein microorganisms and / or activated sludge are adhered and immobilized on a gelled carrier by mixing water with a polymer material such as a monomer, a prepolymer or an oligomer. A method for immobilizing microorganisms, wherein the concentration of the polymerization inhibitor contained in the polymer material used is 400 mg / L or less, preferably 50 to 300 mg / L. 3. A monomer having a polymerization inhibitor content of 300 mg / L or less, preferably 50 to 250 mg / L.
The method is characterized in that the microorganisms and / or activated sludge are entrapped and fixed in the polymer material by gelling a raw material liquid obtained by mixing a polymer material such as a prepolymer or an oligomer with microorganisms and / or activated sludge. Microbial carrier. 4. A monomer having a polymerization inhibitor content of 400 mg / L or less, preferably 50 to 300 mg / L.
A microbial carrier characterized by adhering microorganisms and / or activated sludge to a gelled carrier obtained by mixing water with a polymer material such as a prepolymer or oligomer.