JPH05269488A - Removal of dimethylacetamide - Google Patents

Abstract

PURPOSE:To extremely enhance the value from an aspect of preservation of environmental sanitation by bringing a dimethylacetamide-containing solution into contact with bacterial cells of bacteria capable of metabolizing and decomposing dimethylacetamide and/or bacterial cell treated matter to decompose and remove dimethylacetamide. CONSTITUTION:A dimethylacetamide-containing waste solution is brought into contact with bacterial cells of bacteria capable of metabolizing and decomposing dimethylacetamide belonging to the genus Xanthobacter and/or bacterial cell treated matter thereof to decompose and remove dimethylacetamide. Since other substance is contained in the dimethylacetamide-containing waste solution in many cases, bacteria capable of decomposing the other substance can be used together with those bacteria in the treatment of the waste solution. After decomposition treatment, the treated solution of which the concn. of dimethylacetamide in the solution to be treated is reduced to tolerant concn. or less is discharged as it is or after bacterial cells and/or bacterial cell treated matter are removed if necessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for decomposing and removing dimethylacetamide in a liquid containing dimethylacetamide. More specifically, the present invention relates to a method for decomposing dimethylformamide in a liquid containing dimethylacetamide using bacteria. It is related to the method of disassembly and removal.

2. Description of the Related Art Wastewater from a factory that handles dimethylacetamide may contain dimethylacetamide. The waste liquid containing these dimethylacetamide is harmful and must be discharged after being detoxified for environmental hygiene. However, a method for efficiently decomposing and removing dimethylacetamide in a waste liquid containing dimethylacetamide has not been found so far. If it is possible to efficiently assimilate dimethylacetamide, which is stable and hardly decomposed, and find a microorganism that decomposes, it becomes possible to effectively detoxify the waste liquid containing dimethylacetamide using this microorganism.

[0002]

Means and Actions for Solving the Problems As a result of extensively searching the natural world, the present inventors have completed the present invention by finding a microorganism that assimilates dimethylacetamide actively and strongly decomposes it. That is, the present invention, by contacting a liquid containing dimethylacetamide, a bacterial cell of a bacterium belonging to the genus Xanthobacter that can assimilate dimethylacetamide, and / or a treated product of the bacterial cell of the bacterium, and A method for removing dimethylacetamide, which comprises decomposing and removing dimethylacetamide in a liquid.

The bacterium used in the present invention belongs to the genus Xanthobacter and efficiently assimilates dimethylacetamide,
There is no particular limitation as long as it is a strain having the ability to decompose. A typical example of these strains is Xanthobacter autotrophicus.
DSM 432 and Xanthobacter flavus (Xan
thobacter flavus) DSM 338 (= NCIB 1
0071). These strains are known, and DSM
(Deutsche Samnlung Von Mikroorganismen) and other preservation organizations. For more information on Xanthobacter, Xanthobacter autotrophicus and Xanthobacter flavus, see the Vergiz Manual.
Of systematic bacteriology (Bergey ^, s
Manualof Systematic Bacteriology) Volume 1, Editors Krieg and Holt, Williams and
Wilkins, 1984 ”.

A dimethylacetamide-containing agar plate medium and a dimethylacetamide-containing agar slant medium for growing the strain were prepared as follows. That is, (NH ₄ ) ₂ SO ₄ 3 g, KH ₂ PO ₄ 1.
_{4g, Na 2 HPO 4 2.1g,} MgSO 4 · 7H 2
O 0.2g, CaCl ₂ .2H ₂ O 30mg, Fe
_{C 6 H 5 O 7 · xH} 2 O 30mg, MnCl 2 · 4H
_{2 O 5mg, ZnSO 4 · 7H} 2 O 5mg, CuS
0.5 mg of O ₄ .5H ₂ O, 0.2 g of yeast extract and 5 g of dimethylacetamide were added to 1 L of pure water,
After adjusting the pH to 7.1, add 15 g of agar,
This was dissolved by heating, and then ² at 1 Kg / cm ² G.
Sterilized for 0 minutes. As the dimethylamine-containing liquid medium, the medium having the above composition without the addition of agar was used.

As one of the methods for detoxifying a solution containing dimethylacetamide (hereinafter also referred to as a processing solution) by the method of the present invention, various nutrient components are added to the solution to be processed, and the solution is added. As a medium, there is a method of culturing a bacterium belonging to the genus Xanthobacter and capable of assimilating and decomposing dimethylacetamide (hereinafter referred to as the present bacterium). The nutrient added to the liquid to be treated may be any substance that can be assimilated by the present bacterium to be used and is not particularly limited, and includes a carbon source, an inorganic component and other components.

As the carbon source, only dimethylformamide in the liquid to be treated may be used, but other carbon sources which can be assimilated by the bacterium used, for example, saccharides such as L-arabinose, D-glucose and D-galactose. , Sugar alcohols such as glycerol, organic acids such as acetic acid, and methylamines such as monomethylamine, dimethylamine and trimethylamine can be used in combination. As the nitrogen source, for example, inorganic nitrogen compounds such as ammonium salts, alkylamines, organic nitrogen-containing substances such as corn steep liquor, casein, peptone and meat extract are used. Since dimethylacetamide is a nitrogen compound, any bacterium can sufficiently grow and proliferate and assimilate and decompose dimethylacetamide without adding any other nitrogen source. Also, as the inorganic content,
For example, calcium salts, potassium salts, magnesium salts, phosphates, manganese salts, zinc salts, iron salts, copper salts, molybdenum salts, cobalt salts, boron compounds and iodine compounds are used. Further, when using a strain that requires a nutritional substance such as vitamins, the nutritional substance required by the strain is added.

The concentration of dimethylacetamide in the treatment liquid is not particularly limited as long as it can assimilate and decompose the used strain of the present invention, but is usually 1.5 wt% or less, preferably 1 wt% or less. Particularly preferred. Culture conditions may be such that the bacteria used can grow and proliferate, but generally, for example, the temperature is 10 to 37 ° C., preferably 1
5 to 37 ° C., pH is 6 to 9, preferably 6.5.
It is set to ~ 8.0. By aerobically culturing the bacterium under such conditions, the dimethylacetamide is decomposed, the dimethylacetamide in the liquid to be treated is reduced or eliminated, and the bacterium grows smoothly.

[0008] The cell concentration of the liquid to be treated during the decomposition treatment by culture cannot be generally specified, but the higher the cell concentration, the higher the dimethylacetamide decomposition rate. It is preferably 1/5 or more of the content (weight) (converted to dry cells). Further, the dissolved oxygen concentration during the decomposition treatment by culture is not particularly limited and is the same as the dissolved oxygen concentration in the usual culture of bacteria.
In order to obtain the desired dissolved oxygen concentration, the amount of aeration gas is adjusted, stirring is performed, oxygen gas or a mixed gas of oxygen and air is used as an aeration gas, and the pressure in the culture tank is increased. The usual means of is adopted. The treatment method may be batch, continuous or semi-continuous.

In addition to the method of detoxifying dimethylacetamide in the liquid to be treated by culturing the bacterium using the liquid to be treated as a medium as described above, the bacterial cells of the bacterium and the bacterium which have been cultured in advance can be used. Treated cells-for example, crushed cells of the bacterium and immobilized cells obtained by immobilizing the cells of the bacterium with a synthetic resin or the like- (these may be collectively referred to as cells below. ) Or the like can be brought into contact with the liquid to be treated. For example, (a) adding bacterial cells to the liquid to be treated
(B) Contacting the liquid to be treated with the activated sludge in which the above-mentioned bacterial cells, culture solution, crushed product of the bacterial cells, etc. are mixed, and (c) the liquid to be treated is placed in a column packed with immobilized bacterial cells. There are methods such as passing it. In the methods (a) and (b), the amount of bacterial cells used is not particularly limited, but in order to perform the treatment in a short time, it is usually 0.1 g or more per 1 l of the liquid to be treated in practice. (The same applies to the case of dry cells), preferably about 0.1 to 10 g. In the method of (c), the enzyme or the bacterial cell is immobilized by a usual method such as a carrier binding method, a cross-linking method and an entrapping method. In order to perform the treatment more efficiently, it is more preferable to use immobilized cells, in which case collagen, polymer gels such as carrageenan and polyurethane, microcapsules such as collodion and phospholipids or ultrafiltration membranes are used. A method of confining the body is performed. In any of (a), (b), and (c), the dimethylacetamide concentration, temperature, pH, etc. in the liquid to be treated are the same as in the case of the decomposition treatment by culture.

Since the waste liquid containing dimethylacetamide often contains other substances,
Microorganisms capable of decomposing other substances can be used in combination with the present bacteria in the treatment of such waste liquid, and this is preferable. After the decomposition treatment, the treatment liquid in which the concentration of dimethylacetamide in the treatment liquid was reduced to below the allowable concentration was
It is discharged as it is or after removing the cells and / or the treated product of the cells as necessary.

[0011]

EXAMPLES The present invention will be described in more detail by way of examples.
Reveal The present invention is limited to these examples.
Not a thing. Example 1 (NH_Four)₂SO_Four 3g, KH₂P
O_Four 1.4g, Na ₂HPO_Four 2.1 g, MgSO
_Four・ 7H₂O 0.2g, CaCl₂・ 2H₂O 30
mg, FeC₆H_FiveO₇・ XH₂O 30mg, MnC
l₂・ 4H₂O5mg, ZnSO_Four・ 7H₂O 5m
g, CuSO_Four・ 5H₂O 0.5 mg and yeast exhaust
0.2 g of sucrose was added and the pH was adjusted to 7.1.
The base medium is used, and a predetermined amount of dimethylacetoa is added to this base medium.
Medium was added to make the medium. That of these media
Xanthobacter autotrophicus (Xanth
Bacterium autotrophicus) DSM 432 and xanthan
Xanthobacter flavus DSM
 Inoculated with 338, cultured at 30 ℃ for 7 days,
The assimilation and degradability of acetamide were investigated. From Table 1,
Efficiently removes even treatment solutions containing high concentrations of tylacetamide.
I know that it can be harmed.

[0012]

[Table 1] Table 1 Dimethylacetamide-assimilating strain Dimethylacetamide concentration (wt%) 0.2 0.3 0.5 1.0 1.5 2.0 3.0 5.0 DSM 432 ++ ++ ++ ++ ++ ++ ++ + -DSM 338 ++ ++ ++ ++ ++ ++-- ++: Utilizes actively. +: Utilize. -: Not assimilated.

Example 2 (NH) per 1 L of pure water_Four)₂SO_Four 3g, KH₂P
O_Four 1.4g, Na ₂HPO_Four 2.1 g, MgSO
_Four・ 7H₂O 0.2g, CaCl₂・ 2H₂O 30
mg, FeC₆H_FiveO₇・ XH₂O 30mg, MnC
l₂・ 4H₂O5mg, ZnSO_Four・ 7H₂O 5m
g, CuSO_Four・ 5H₂O 0.5mg, yeast extract
0.2 g and 5 g of dimethylacetamide are added,
200 mL of medium adjusted to pH 7.0 was added to a 1 L triangular flask.
It was put in a scoot and sterilized at 120 ° C. for 20 minutes. This medium
In addition, xanthates obtained by pre-culturing in the same medium
Pre-cultivation of Bacter Autotrophicus DSM 432.
Nutrient solution (cell concentration OD₆₁₀ 1.4) as 1 vol%
Inoculation was carried out as described above and the cells were cultured at 30 ° C. for 30 hours. Got
The pH of the cultivated culture solution was 8.0,
About 1.2 g was contained per liter of culture solution. Also, culture
Dimethylacetamide was not detected in the supernatant.
The generation time was about 4.5 hours.

Example 3 (NH) per 1 L of pure water_Four)₂SO_Four 3g, KH₂P
O_Four 1.4g, Na ₂HPO_Four 2.1 g, MgSO
_Four・ 7H₂O 0.2g, CaCl₂・ 2H₂O 30
mg, FeC₆H_FiveO₇・ XH₂O 30mg, MnC
l₂・ 4H₂O5mg, ZnSO_Four・ 7H₂O 5m
g, CuSO_Four・ 5H₂O 0.5mg, yeast extract
0.2 g and 5 g of dimethylacetamide are added,
200 mL of medium adjusted to pH 7.0 was added to a 1 L triangular flask.
It was put in a scoot and sterilized at 120 ° C. for 20 minutes. This medium
In addition, xanthates obtained by pre-culturing in the same medium
Bacteria flavus DSM 338 preculture liquid (bacteria
Concentration O. D.₆₁₀ 1.2) to be 1 vol%
The cells were inoculated and cultured at 30 ° C for 30 hours. The obtained culture solution
Has a pH of 7.5 and cultures the bacterial cells of the bacterium 1
It contained about 1.1 g per L. In addition, from the culture supernatant
Dimethylacetamide was not detected. Generation
The time was about 5.3 hours.

Example 4 In the same manner as in Example 2, Xanthobacter autotrophicus DSM 432 was cultured and decomposed with dimethylacetamide. The obtained culture solution has a pH of 8.0.
And about 1.2 g of the bacterium of the present bacterium was contained per 1 L of the culture solution. In addition, dimethylacetamide was not detected in the culture supernatant. The generation time was about 4.8 hours.

Example 5 1.5 L of the basal medium of Example 1 was placed in a 3 L jar fermenter and sterilized at 120 ° C. for 20 minutes, and then 15 g of dimethylacetamide was aseptically added to obtain a medium.
Xanthobacter autotrophicus DSM 43 obtained by previously culturing this medium in a medium similar to this
2 of the preculture liquid (cell concentration OD ₆₁₀ 1.2) was added to 1
The cells were inoculated to a Vol% level and cultured at 30 ° C. for 24 hours. The bacterial cell concentration of the culture solution was 0. D. ₆₁₀ , 5.0 ~
When it reached 6.0, dimethylacetamide was added to 0.6
A continuous treatment of an aqueous solution containing wt% was started. The continuous treatment was performed while supplying the liquid to be treated to the treatment tank so that the average residence time was 10 hours, and withdrawing an equal amount of the treatment liquid from the treatment tank. For the pH adjustment during the continuous treatment, a 5N sulfuric acid aqueous solution was used. As a result, dimethylacetamide was not detected in the treated liquid. The amount of bacterial cells of this bacterium contained in the treatment liquid was about 1.4 g per 1 L of the treatment liquid, and the COD value of the supernatant obtained by removing the bacteria from the treatment liquid was 190 pp.
m, TOC value was 200 ppm. In this decomposition treatment, the dissolved oxygen concentration of the treatment liquid is about 2 to 4 ppm.
Was kept at.

Example 6 1.5 L of the basal medium of Example 1 was placed in a 3 L jar fermenter and sterilized at 120 ° C. for 20 minutes, and then 15 g of dimethylacetamide was aseptically added to obtain a medium.
This medium was inoculated with a pre-cultured solution of Xanthobacter flavus DSM 338 (bacterial cell concentration OD ₆₁₀ 1.0) obtained by pre-culturing in the same medium as 1% by volume. And cultured at 30 ° C. for 24 hours. The bacterial cell concentration of the culture solution was 0. D. _{At 610} , when it reached 3.0 to 4.5, continuous treatment of an aqueous solution containing 0.6 wt% of dimethylacetamide was started. Average residence time for continuous processing is 1
The liquid to be treated was supplied to the treatment tank at 0 hour, and an equal amount of the treatment liquid was withdrawn from the treatment tank. For the pH adjustment during the continuous treatment, a 5N sulfuric acid aqueous solution was used. Dimethylacetamide was not detected in the treated liquid. In addition, the amount of bacterial cells of this bacterium contained in the treatment liquid is 1
It is about 1.3 g per L, and the COD value of the supernatant obtained by removing the bacterial cells from the treated liquid is 190 ppm and the TOC value is 210 p.
It was pm. In this decomposition treatment, the concentration of dissolved oxygen in the treatment liquid was maintained at about 2 to 4 ppm.

Example 7 In the same manner as in Example 5, the dimethylacetamide aqueous solution was continuously treated with an average residence time of 10 hours. The separated bacterial cells collected by centrifugation of the treated solution were frozen and stored at -20 ° C. 0.2 g of the above-mentioned frozen bacterial cells as a dry weight was added to 1 L of the liquid to be treated obtained by adding dimethylacetamide to 0.6 wt%, and the dimethylacetamide was decomposed at 30 ° C. Dimethylacetamide in the liquid to be treated decreased almost linearly with the passage of time, and was not detected 8 hours after the start of the reaction. The treatment rate of dimethylacetamide per gram of cells is about 6 g / h
It was r.

Example 8 Factory waste liquid 1 containing 0.6 wt% of dimethylacetamide
The pH of L was adjusted to 7.0, 0.5 g of the frozen microbial cells obtained in the same manner as in Example 7 was added as dry cell weight, and dimethylacetamide was decomposed at 30 ° C. 8 hours after the start of the reaction, dimethylacetamide was not detected at all. In each of the above embodiments,
The amount of dimethylacetamide in the liquid was analyzed by gas chromatography. Model: Shimazu 7AGC column: Unisole 30T 5% Uniport HP 80/100 Glass column (3 mm × 2 m) Column temperature: 70 ° C. Flow rate: (standard state) 30 mL / min

[0020]

EFFECTS OF THE INVENTION According to the present invention, dimethylacetamide, which is a harmful substance that is stable and difficult to decompose, is efficiently decomposed.
Since it is possible to remove the harmful waste liquid containing dimethylacetamide, it is possible to efficiently detoxify the harmful waste liquid, which is extremely valuable for environmental hygiene.

Claims (1)

[Claims] 1. A liquid containing dimethylacetamide and assimilating dimethylacetamide belonging to the genus Xanthobacter,
A method for removing dimethylformamide, which comprises decomposing and removing dimethylformamide in the liquid by contacting the degradable bacterial cell and / or a treated product of the bacterial cell.