JP2985282B2 - Method and apparatus for treating low-concentration organic matter-containing wastewater - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for treating wastewater containing low-concentration organic substances, and more particularly, to a method and an apparatus for treating wastewater using entrapping immobilized microorganisms.

[Conventional technology]

Recently, with the advancement of industrial technology, wastewater containing low-concentration organic substances has been discharged. Particularly, in a semiconductor manufacturing plant, cleaning is performed using extremely pure water (ultra pure water), and the wastewater used has high purity, and it is advantageous to collect and reuse the wastewater.

Such wastewater contains a trace amount of the solvent used in the process, and has conventionally been decomposed by ultraviolet irradiation. However, recently, biological treatments with lower initial cost and running cost than ultraviolet irradiation have been studied.

The amount of organic matter contained in such wastewater is several mg /, and the treatment target is in the unit of μg /.

Sudo et al., "Wastewater treatment by microbial immobilization method", Industrial Water Research Committee, p. 151 (1988) reported that activated carbon was treated with fluidized bed using microorganisms attached to activated carbon.
C3610 μg / is treated up to 443 μg / TOC of treated water. In this case, the TOC removal rate is 88%, and it is necessary to further improve the removal rate.

When this type of wastewater is treated with naturally occurring microorganisms or activated carbon to which activated sludge is attached, bacteria,
The cause is that the metabolites of the fungus flow out and the removal rate does not increase. Metabolites of bacteria include polysaccharides having a molecular weight of 100,000 or more and endotoxin substances.

[Problems to be solved by the invention]

The present invention solves the drawbacks of the prior art, significantly improves the TOC removal rate, and treats wastewater containing low-concentration organic substances, which can reduce contamination of microorganisms and metabolites of microorganisms into treated water as much as possible. The purpose is to provide.

[Means for solving the problem]

The present invention provides the above object by using an entrapping immobilization material having a pore having a molecular weight fraction of 67,000 or less and entrapping and immobilizing a yeast having a high enzyme activity such as dehydrogenase activity that decomposes the TOC component. Is achieved.

That is, in the method for treating low-concentration organic matter-containing wastewater according to the present invention, the organic matter-containing wastewater having a TOC concentration of 10 mg / or less was immobilized by entrapping yeast at a concentration of 10 ² to 10 ⁵ cells / cm ³ -carrier inside the immobilization carrier. It is characterized by treating with immobilized yeast. The method of the present invention can be carried out in a fluidized bed type or a fixed bed type.A processing device for carrying out the method of the present invention comprises an aeration tank in which immobilized yeast is fluidized by a diffuser provided at the bottom. An immobilized yeast separation net for separating treated water and immobilized yeast is provided inside, and an aeration device is installed on the treated water discharge side of the separation net, and immobilized in a treatment tank. A fixed bed filled with yeast is provided, and a device for removing immobilized yeast is provided inside the fixed bed.

Examples of yeasts that can be used in the present invention include Saccharomycetaceae, Sporobolomycetaceae, and Cryptococcus (Cryptococcus).
ococcaceae), and in particular, Saccharomyces sp., Saccharomycodes sp., Trichosporone (T
richosporon sp.), Candita sp., Kloeckera sp., Rhodotorula sp.
hodotorula sp.) is preferred. These yeasts are
It has high enzymatic activity such as dehydrogenase activity that degrades the C component.

In the present invention, the yeast as described above is used after being comprehensively fixed with an immobilizing material. As an immobilizing material, the molecular weight cut off is 6
Gels such as polyurethane, polyvinyl alcohol, polyethylene glycol, and polyacrylamide, which have pores of 7,000 or less and do not elute TOC components from the material, can be used. The molecular weight cut off of the gel is related to the type of polymer material constituting the gel, its molecular weight and particularly to the gel concentration. For polyethylene glycol gels, polyacrylamide gels and polyvinyl alcohol gels, the gel concentration is 9 to 9%.
At 18%, bovine serum albumin, myoglobin and the like permeate into the gel, and a fraction having a molecular weight cut off of 67,000 or less is obtained.

Thus, in the present invention, a yeast that secretes a large amount of an enzyme such as dehydrogenase having a molecular weight of 100,000 or more that decomposes organic substances such as methanol in wastewater has a molecular weight cutoff of 67,000.
By immobilizing with an entrapping immobilizing material having the following pores, the amount of extracellular enzymes, for example, dehydrogenase, held in the immobilization carrier is increased, and the decomposition of organic substances is promoted. In this case, the catalytic reaction of the enzyme is the main reaction, and a slight growth reaction of yeast supplementing the enzyme occurs. At that time, TOC components such as polysaccharides and endotoxin produced by yeast have a large molecular weight and do not flow out of the carrier, and the yeast cells themselves do not flow out of the carrier, so that the TOC of the treated water is improved.

Next, an apparatus for performing the method of the present invention will be described. FIGS. 1 and 2 show an embodiment of a treatment apparatus for wastewater containing low-concentration organic substances according to the present invention.

FIG. 1 is a system diagram of a fluidized bed type processing apparatus of the present invention. This device is mainly composed of an aeration tank 1, an aeration device 5, and an immobilized yeast separation net 6. The aeration tank 1 is provided with a treated water discharge pipe 4 together with a waste water introduction pipe 3. The aeration tank 1 is further provided with a diffuser 5 for supplying air into the tank, and the diffuser 5 is connected to a not-shown air supply pump or the like. An immobilized yeast separation network 6 is attached to the vicinity of the treated water discharge pipe 4 on the side of the aeration tank 1 so that the immobilized yeast 7 does not flow out to the treated water discharge pipe 4. Further, an aeration device 8 is provided on the treated water discharge side of the immobilized yeast separation network 6 so that microorganisms are not deposited near the treated water discharge portion.

The apparatus shown in FIG. 2 is a fixed-bed processing apparatus, which mainly includes a processing tank 11 and an immobilized yeast take-out tube 15. The treatment tank 11 is provided with a treated water discharge pipe 4 together with the wastewater introduction pipe 3. On the side of the processing tank 11,
An immobilized yeast take-out tube 15 is connected, and when the amount of yeast in the immobilized yeast exceeds a certain amount due to the growth of yeast, an immobilized yeast layer with a large amount of yeast is taken out and new immobilized yeast is replenished.

In the present invention, the amount of yeast in the immobilized yeast is 10 ² to 1
0 ⁵ cells / cm ^3- Must be a carrier, 10 ² cells / cm ³
cm ³ - is less than the carrier, TOC removal rate is slow, 10 ⁵ cells / cm ³
-If the carrier is exceeded, the yeast is likely to be exposed on the surface of the carrier, and the quality of the treated water deteriorates because the yeast and metabolites flow out into the treated water.

In the present invention, wastewater having a TOC concentration of 10 mg / or less is targeted, but when the present invention is applied to wastewater having a higher TOC concentration, the growth of bacteria inside the pellet is large, and the bacteria may be easily exposed outside the pellet. There is not suitable.

〔Example〕

Next, the present invention will be described in detail based on examples, but the present invention is not limited thereto.

Example 1 A treatment experiment was performed using wastewater of 10 mg / TOC discharged from Company T. Trichospor
on cutanium) were immobilized at various concentrations ranging from 10 to 10 ⁷ cells / cm ³ -carrier. Immobilization is acrylamide 18%,
N, N'-methylenebisacrylamide 1%, N, N, N ', N'
-Gelation was performed using 0.5% of tetramethylethylenediamine and 0.25% of potassium persulfate, and the mixture was formed into a 3 mm square cube.

10 cm ^{3 of} the immobilized yeast thus obtained and 190 ml of wastewater from Company T were placed in a Sakaguchi flask and cultured with shaking. After 30 minutes of culturing, the immobilized yeast was separated by a net and treated water was allowed to flow out. At this time, the TOC value of the treated water was measured, and the results are shown in FIG. As is clear from FIG. 3, the TOC was 1 mg / or less in the range of 10 ² to 10 ⁵ cells / cm ³ −carrier, and a removal rate of 90% or more was achieved. If the amount of yeast was too large, the yeast was likely to be exposed on the gel surface during immobilization, and metabolites such as yeast and polysaccharides increased in the treated water, resulting in a deterioration in the TOC value. Conversely, when the amount of yeast is small, the decomposition rate of organic matter in wastewater is low, and the TOC removal rate is low.

Example 2 The processing apparatus shown in FIG.
10 ³ cel prepared in Example 1 using a bench plant of
The aeration tank 1 was filled with 6% by volume of ls / cm ³ -immobilized yeast on a carrier and treated with T company wastewater having a TOC concentration of 10 mg /. As a result, treated water of 200 μg / TOC was obtained with a residence time of 30 minutes.

Comparative Example 1 In Example 2, activated carbon was used instead of immobilized yeast.
When the same yeast was attached and the same yeast was attached thereto, 6 cells of 10 ³ cells / ml were introduced, and the continuous operation was performed. As a result, the TOC concentration of the treated water obtained in a residence time of 30 minutes was 1.2 mg /.

Comparative Example 2 In Comparative Example 1, one activated sludge of 1000 mg / instead of yeast was charged, and the continuous operation was performed. As a result, the TOC concentration of the treated water obtained in a residence time of 30 minutes was 2.5 mg /.

Example 3 10 ³ cells / cm ³ prepared in Example 1 using a bench plant having a capacity of 200 in the processing tank 11 of the processing apparatus shown in FIG.
-30% by volume of the carrier immobilized yeast was filled, and the TOC concentration was 1 mg /
When the wastewater of Company N was treated, treated water having a TOC concentration of 85 μg / was obtained in a residence time of 20 minutes.

When the amount of yeast in the immobilized yeast exceeds 10 ⁵ cells / cm ³ -carrier, the water quality deteriorates, so the amount of immobilized yeast with a large amount of yeast is collected from the immobilized yeast take-out tube 15 and replenished with new immobilized yeast. did.

〔The invention's effect〕

According to the method and apparatus of the present invention, organic matter in wastewater can be efficiently and easily decomposed in a fluidized bed type or a fixed bed type, and contamination of microorganisms and metabolites of microorganisms in treated water can be extremely reduced. TOC removal rate can be easily achieved and high treated water quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram of a processing apparatus showing one embodiment of the present invention, FIG. 2 is a schematic system diagram of a processing apparatus showing another embodiment of the present invention, and FIG. 4 is a graph showing the relationship between the temperature and the TOC concentration of treated water. DESCRIPTION OF SYMBOLS 1 ... aeration tank, 4 ... treated water discharge pipe, 5 ... diffuser,
6 ... immobilized yeast separation net, 7 ... immobilized yeast, 8 ... aeration device, 11 ... treatment tank, 15 ... immobilized yeast take-out tube

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI C12N 11/00 C12N 11/00 (56) References JP-A-62-273099 (JP, A) JP-A-60-14996 (JP) , A) Fully open 1988-115493 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) C02F 3/34 C02F 3/00-3/12 C12N 11/00-11/18

Claims (2)

(57) [Claims] 1. An organic matter-containing wastewater having a TOC concentration of 10 mg / or less is treated using immobilized yeast in which yeast is immobilized at a concentration of 10 ² to 10 ⁵ cells / cm ³ -carrier in an immobilized carrier. A method for treating low-concentration organic matter-containing wastewater, comprising: 2. An apparatus for carrying out the method according to claim 1, wherein an aeration device provided at a bottom portion separates the treated water and the immobilized yeast into an aeration tank through which the immobilized yeast flows. An apparatus for treating wastewater containing low-concentration organic substances, comprising an immobilized yeast separation net.