JP2967950B2 - PCB disassembly method - Google Patents

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 polychlorinated biphenyl (hereinafter referred to as "PCB") efficiently.

[0002]

2. Description of the Related Art At present, PCB is not used due to its harmfulness, but PCB is chemically and physically stable, and is a fluid at room temperature, so it is easy to handle. It has been used in large amounts as an insulating material or as a component of pressure-sensitive paper, etc., and even now, there has been a problem of disposal of products using these PCBs, and they are often found in soil, wastewater or sludge. Although PCBs have been detected in them and have become a social problem, attempts to decompose and detoxify PCBs have been very difficult due to the stability of the PCBs.

[0003] In such a situation, studies have been made to decompose and render the PCB harmless. For example, a method in which the PCB is irradiated with ultraviolet rays to decompose the PCB (No. 6).
Proceedings of the JSCE Autumn Meeting p.313, Michio Hirose et al., "Removal of PCB in Wastewater" and Tokyo Metropolitan Industrial Technology Center Research Report No. 4 (1974) p.91, Toru Nishiwaki, et al. Decomposition of PCB components ") and those in which microorganisms are mixed and cultured in a PCB-containing medium to decompose PCB (JP-A-64-6864)
No. 281) is known.

[0004]

However, in these prior arts, the decomposition rate of PCB is low, and
It was not practical. Therefore, an object of the present invention is to provide a practical PCB decomposition method for decomposing a PCB with high efficiency and rendering it harmless.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies and as a result, have found a practical method of disassembling a PCB and completed the present invention.
That is, the present invention provides (1) a method for decomposing a PCB, which comprises irradiating the PCB with ultraviolet rays and then treating the PCB with a microorganism belonging to the genus Pseudomonas;
(2) Treatment with a microorganism belonging to the genus Pseudomonas is performed by Pseudomonas sp.
And a method for decomposing PCB according to claim 1, which is carried out in a mixed culture system of Pseudomonas sp. KKS102.

Hereinafter, the present invention will be described in more detail. The PCB decomposition method of the present invention can be applied to a wide range of PCBs such as tetrachloride and pentachloride, and is not particularly limited to the type of PCB. In addition, any object to be decomposed can be applied to soil, wastewater, insulating materials such as transformers, and PCBs in pressure-sensitive paper.

When irradiating ultraviolet rays in the present invention, if the form of the PCB-containing substance is an aqueous liquid such as wastewater, it is possible to irradiate the ultraviolet rays in the form of an aqueous liquid. When PCBs in insulating materials such as transformers and pressure-sensitive paper are decomposed, the PCBs are oil-soluble. Therefore, the PCBs are extracted with a suitable organic solvent such as n-hexane and the solvent is removed by evaporation. -It is preferable to irradiate ultraviolet rays in a form dissolved in a suitable organic solvent such as isopropanol.

In the embodiment, a high-pressure mercury lamp (UM102 manufactured by Ushio Inc.) was used as an ultraviolet lamp.
In this case, irradiation for about 2 hours is sufficient. This indicates a feature of the present invention that the PCB can be decomposed effectively even if the PCB is not decomposed completely by ultraviolet rays, but can be decomposed by a subsequent microbial treatment.

[0009] The partially decomposed product of PCB after ultraviolet irradiation is subjected to the following microorganism treatment step. The microorganism used in this step is preferably a microorganism belonging to the genus Pseudomonas, and particularly, a microorganism belonging to the genus Pseudomonas.
s) sp.KKL101 (Microtechnical Laboratories No. 9355) and Pseudomonas sp.KKS102 (Microtechnical Laboratories No. 9354)
Is preferable.

[0010] Among the above microorganisms, Pseud monas (Pseud
omonas) sp. KKS102 will mineralize PCB (CO ₂ decomposes to) have the genes for, in particular have a decomposing capability of a conventional pentachloride degradation was impossible PCB doing. Also, Pseudomonas sp.
KKL101 does not have direct PCB resolution, but has the ability to produce and secrete the growth factors and biosurfactants of the Pseudomonas sp. KKS102. This biosurfactant is a kind of surfactant and has a property of emulsifying and suspending an oil-soluble substance such as PCB in water.

Therefore, when a mixed culture system of these microorganisms is used, the solution in which the PCB component is dissolved in the above-mentioned organic solvent is directly added to an aqueous nutrient medium without using other emulsifiers. , Efficiently P
Decomposition of the CB component can be performed. This culture is usually 30
Perform for 1-2 weeks with shaking at <RTIgt; According to the PCB decomposing method of the present invention, as is apparent from the following examples, the decomposition rate of PCB is much higher than in the case of conventional ultraviolet irradiation alone and microorganism treatment alone.

This is probably because the efficiency of PCB degradation by ultraviolet irradiation and microorganisms differs depending on the position of chlorine substitution in the PCB, and it is difficult to remove chlorine at all substitution positions by ultraviolet irradiation. Thus, it is easy to remove chlorine at the substitution position (ortho position) that inhibits decomposition by the microorganism of the genus Pseudomonas, which is thought to have facilitated the decomposition of PCB by the microorganism.

[0013]

The present invention provides an extremely effective method for decomposing PCBs, and decomposes PCBs in products using PCBs, which cannot be disposed of due to the harmfulness of PCBs at present. And greatly contribute to solving environmental problems caused by PCB contamination.

[0014]

EXAMPLES (1) PCB Samples As a PCB sample to be subjected to decomposition, commercially available PCB mixtures Kaneklor KC400 and Kaneklor KC500 (Kanechlor; registered trademark, Kanegabuchi Chemical Industry Co., Ltd.) were used.

(2) UV irradiation Kanechlor KC400 and Kanechlor KC500 are
Aliquots of 100 mg each were taken, dissolved in a small amount of 2-isopropanol and placed in separate beakers. NaOH was dropped 13.76 mg to Kanechlor KC400 and 12.56 mg to Kanechlor KC500, and 2-isopropanol 50
ml was added to dissolve completely.

Next, 200 ml of the sample in these beakers was added.
Transfer to a volumetric flask, and add 2-isopropanol.
The volume was adjusted to 00 ml to prepare standard solutions of canechlor kc500 in 500 ppm alkaline 2-isopropanol. These standard solutions are separately put into the reaction liquid layer of the ultraviolet irradiation device, and then passed through a high-pressure mercury lamp (UM102, manufactured by Ushio Inc.). The liquid temperature was maintained at 25 ° C. by passing cooling water, and each standard solution was irradiated with ultraviolet rays for 2 hours while stirring with a stirrer.

(3) Microbial treatment (preculture) Pseudomonas sp. KKL101 (No. 9355) is dissolved in LB medium (10 g of bactotryptone, 5 g of bacto yeast extract and 5 g of salt) in 1 liter of water. Medium,
The same applies hereinafter) to 10 ml of a medium supplemented with 0.5% glucose, and cultured overnight. 1 ml of the culture was added to a DLG medium (3.3 g bactotryptone, 1.7 g bacto yeast extract, 5 g salt)
And 100 ml of a medium in which 5 g of glucose was dissolved in 1 L of water) and cultured overnight with shaking. Next, the culture supernatant was filtered and 5 ml thereof was collected.

On the other hand, Pseudomonas sp.
KKS102 (Micro Koken No. 9354) was inoculated into 10 ml of LB medium supplemented with 0.5% of glucose, and cultured for 24 hours. 0.5 ml of this culture was inoculated into 50 ml of DLG medium, and shaking culture was performed overnight. Then after centrifugation collector bacteria, phosphate buffer cells _{(Na 2 HPO 4 · 12H 2} O 2.19g, NaH 2 PO 4 · 12H 2 O0.61
g, 8 g of NaCl / 1 L of distilled water), and the cells were suspended in 20 ml of the above phosphate buffer, and 4 ml of the cells were collected. (Decomposition of PCB) To the fractions collected above, 80 ml of a PCB sample solution, 10 ml of a WPN solution, 1 ml of a W salt solution, and 100 mg of biphenyl were added. Composition of WPN solution (per liter of water ) KH ₂ PO ₄ 17 g Na ₂ HPO ₄ .12H ₂ O 98 g (NH ₄ ) ₂ SO ₄ 1 g Composition of W salt solution (per liter of water ) MgSO ₄ .7H ₂ O _{10.0g MgO 1.075g FeSO 4 · 7H 2} O 0.95g CaCO 3 0.2 g ZnSO 4 · 7H 2 O 0.144g MgSO 4 · 4H 2 O 0.112g CuSO 4 · 7H 2 O 0.028g CuSO 4 · 5H 2 O 0.025g H ₃ BO ₃ 0.006g conc.HCl 5.13ml This is shake-cultured for 5 weeks in a 500ml Sakaguchi flask kept at 30 ° C. 6 ml of acetic acid was added to the supernatant collected by centrifugation,
The sample adjusted to pH 4 to 5 was used as an analysis sample.

As the PCB sample solution, in addition to Kanechlor KC400 (500 ppm) and Kanechlor KC500 (500 ppm) irradiated with ultraviolet light in the above (2), for comparison, Kanechlor KC400 not irradiated with ultraviolet light was also used. Crawl KC50
0 was used. (Analysis) The above analysis sample was analyzed (coefficient method) according to JIS K0093.

The gas chromatography used for this analysis and the operating conditions are as follows. Gas chromatograph Hitachi 263-30 Detector type ⁶³ Ni ECD detector temperature 300 ° C Separator tube filling OV-17 (2%), Chromosolve W (80-100) Separator tube temperature 240 ° C Separator tube 2mmΦ × 1.8m Carrier Gas pressure N ₂ 1.8 ^kg / _{m The} analysis results are shown in the following table.

[0021]

[Table 1]

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toma Toshihole 2-4-1 Nishi Atsugigaoka, Chofu-shi, Tokyo Tokyo Electric Power Company R & D Center (72) Inventor Masataka Nomura 2-chome, Nishi-Atsugigaoka, Chofu-shi, Tokyo No. 4-1 Tokyo Electric Power Company Technical Research Institute (56) References JP-A-1-68281 (JP, A) JP-A-62-84780 (JP, A) JP-A-63-56280 (JP, A) ( 58) Field surveyed (Int. Cl. ⁶ , DB name) A62D 3/00

Claims (2)

(57) [Claims] 1. A method for decomposing polychlorinated biphenyl (PCB), which comprises irradiating polychlorinated biphenyl (PCB) with ultraviolet rays and treating it with a microorganism belonging to the genus Pseudomonas. 2. The method according to claim 1, wherein the treatment with a microorganism belonging to the genus Pseudomonas comprises the step of treating the microorganism with the genus Pseudomonas.
sp.KKL101 and Pseudomonas sp.KKS1
2. The method for decomposing polychlorinated biphenyl (PCB) according to claim 1, which is performed in a mixed culture system of No. 02.