• Journal of Microbiology and Biotechnology
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• 제17권11호
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• pp.1772-1781
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• 2007

Activated sludge was sequentially adapted to benzene, toluene, and o-xylene (BTX) to study the effects on the change of microbial community. Sludge adapted to BTX separately degraded each by various rates in the following order; toluene>o-xylene>benzene. Degradation rates were increased after exposure to repeated spikes of substrates. Eleven different kinds of sludge were prepared by the combination of BTX sequential adaptations. Clustering analyses (Jaccard, Dice, Pearson, and cosine product coefficient and dimensional analysis of MDS and PCA for DGGE patterns) revealed that acclimated sludge had different features from nonacclimated sludge and could be grouped together according to their prior treatment. Benzene- and xylene-adapted sludge communities showed similar profiles. The sludge profile was affected from the point of the final adaptation substrate regardless of the adaptation sequence followed. In the sludge adapted to 50 ppm toluene, Nitrosomonas sp. and bacterium were dominant, but these bands were not dominant in benzene and benzene after toluene adaptations. Instead, Flexibacter sp. was dominant in these cultures. Dechloromonas sp. was dominant in the culture adapted to 50 ppm benzene. Thauera sp. was the main band in the sludge adapted to 50 ppm xylene, but became vaguer as the xylene concentration was increased. Rather, Flexibacter sp. dominated in the sludge adapted to 100 ppm xylene, although not in the culture adapted to 250 ppm xylene. Two bacterial species dominated in the sludge adapted to 250 ppm xylene, and they also existed in the sludge adapted to 250 ppm xylene after toluene and benzene.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.386-389
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• 2003

Pseudomonas savastanoi BCNU 106은 o-xylene 뿐만 아니라 m-, p-xylene을 분해할 수 있는 능력을 나타내었고, 비교적 높은 농도인 10 mM toluene, 2 mM o-xylene, 10 mM m-xylene, 10 mM p-xylene에서 높은 분해율을 보여주었다. Pseudomonas savastanoi BCNU 106의 resting cell을 이용하여 o-xylene의 중간대사산물을 GC-MS를 통하여 조사하였다. 주로 2-methylbenzyl alcohol, 2-methylbenzoic acid 등이 발견되었다.

• Bulletin of the Korean Chemical Society
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• 제12권6호
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• pp.625-628
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• 1991

Using uniform flat plate-like samples of ZSM-5 zeolites, diffusion coefficients were measured volumetrically for the diffusion of xylene, ethyltoluene and diethylbenzene by direct measurement of sorption rate. Toluene disproportionation over H(100)-, K(72)-and Cs(82)-ZSM-5 at 773 K and toluene methylation, toluene ethylation and ethylbenzene ethylation over Cs(75)-ZSM-5 at 623 K were carried out. The selective formation of para xylene during the toluene disproportionation, presumably due to the increased tortuosity over Cs-ZSM-5, could be explained by smaller diffusion coefficient in Cs-ZSM-5 than in K-and H-ZSM-5. The para selectivity increased in the order; toluene methylation < toluene ethylation < ethylbenzene ethylation. As the chain length of the alkyl substituent in dialkylbenzenes is increased, the para selectivity of the products was improved. It may be attributed to the differences in the ratios of diffusion coefficient of para products to that of ortho ones. Diffusion coefficient of m-xylene was about 1 order of magnitude smaller than that of o-xylene.

• 한국산업보건학회지
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• 제1권1호
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• pp.16-28
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• 1991

A study on comparison of standard charcoal tube method, infrared gas analyzer, and detector tube method were conducted. Measurements were performed simultaneously at same sampling points in an air chamber containing benzene, toluene and xylene vapors. Charcoal tube samles were collected at sampling flowrates of 0.05, 0.2, 0.5, and 1.0 1pm. Results are as follows : 1. Coefficients of variation of results with charcoal tube method for bezene, toluene and xylene mixture vapor were 14.34 % in benzene(0.28-11.12 ppm), 9.20 % in toluene (2.68-135.09 ppm) and 10.21 % in xylene (2.56-82.64 ppm), respectively. 2. Results of infrared gas analyzer in mixture air were non-specific on benzene and toluene. Ratio of results of infrared gas analyzer to those of charcoal tube on benzene, toluene and xylene were 696.4 %, 30.3 % and 36.6 %, respectively. 3. Ratio of responses of detector tubes to those of charcoal tube were 49.4 % in benzene, 22.1 % in toluene and 223.9 % in xylene. Xylene detector tube were interfered by toluene greately. 4. Collection efficiencies of charcoal tubes at low concentraton(benzene : 1 ppm, toluene : 10 ppm, xylene : 10 ppm) were stable on various flowrate from 0.05 to 1.0 1pm, but at high concentrations the efficiency decreased at high flowrate above 0.5 1pm. 5. Within the saturation capacity of charcoal, collection effiency decreased at 0.5-1.0 1pm. Smpling feowrates of 0.05-0.20 1pm were appropriate for sampling organic vapors.

• 한국환경과학회지
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• 제7권3호
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• pp.393-400
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• 1998

A microorganism, Klebsiella gr. 47, capable of degrading BTX(benzene, toluene and xylene) was isolated from oil-contaminated soil and its characteristics of BTX degradation were investigated. When benzene and toluene were fed to Klebstella gr. 47 simulataneously, they showed competitive ingibition. The degradation rate of xylene was enhanced as much as 3 times when xylene was fed with benzene or toluene. Degradation rate of benzene and toluene was also enhanced by cocultured with Alcaligenes xylosoxidans. When benzene-adapted microorganism was used, each BTX compound was degraded efficiently within 5 hours.

• KSBB Journal
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• 제16권1호
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• pp.61-65
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• 2001

BTX를 배출하는 지역에서 얻어진 슬러지를 적절한 배지에 3개월 간 적응시킨 결과, benzene과 toluene을 빠르게 분해하는 MY컨소시엄와 p-, m-, o-xylene을 빠르게 분해하는 MA컨소시엄을 획득하였다. 균주의 동정결과 MA 및 MA컨소시엄의 주된 균주는 Rhodococcus ruber DSM 43338T과 Rhodococcus sp.로 밝혀졌다. BTX 단일성분의 분해속도 측정결과 benzene > toluene > o-xylene > p-xylene > m-xylene의 순으로 분해가 일어났다. MY 및 MY컨소시엄으 동시배양을 이용한 2-5종의 복합 BTX의 분해실험결과 대부분의 경우 108시간내에 완전히 분해되었으며, 각 혼합물의 조성에 따라 촉진 및 방해작용을 나타내었다. 분 연구에서 획득한 2종의 미생물컨소시엄은 BTX의 생물학적 처리에 매우 유용하게 사용될 수 있을 것으로 사료된다.

• 한국산업보건학회지
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• 제21권1호
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• pp.49-54
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• 2011

In order to develop the methods for exposure assessment and find susceptibility markers for the workers who are exposed to low doses of toluene, xylene and other chemical in petroleum industries, we investigated the application of P-450 expression in human lymphocytes utilizing mouse monoclonal anti-rat CYP2B1/2, the levels of toluene and xylene in air and their metabolite levels in urine with the levels of expressed CYP2B1/2 proteins. The general characteristics such as age, smoking and drinking habit were no significant difference between the control and exposed workers, but the working durations and working hours were significantly different. Workers in exposed group were exposed to the mean of 2.1 ppm (range, 0.00-4.54) of toluene and 0.3 ppm (rang, 0.00-1.23) of xylene. The mean concentration of urinary hippuric acid was low and less than 1/5 of the biological exposure index recommended by the Ministry of Employment and Labor Korea. Methyl hippuric acid in urine was not detected in control and exposed workers. Also, there were no significant differences in the levels of the urinary metabolites between the control and exposed group. When chemiluminescence dot blottings were carried out utilizing mouse monoclonal antibody against CYP2B1/2, the strong density dots corresponding to a mouse monoclonal antibody was observed in the human lymphocytes from the exposed workers. These results suggested that the chemiluminescence dot blot assay for CYP of lymphocytes should be valuable for identifying CYP expression as biomarkers in the workers exposed to toluene and xylene.

• 미생물학회지
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• 제34권3호
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• pp.96-100
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• 1998

연안 저서시료에 의한 benzene과 toluene, meta-xylene(BTX)의 혐기성 분해를 촉진시키기 위해 전자수용체 및 접종 시료의 적응에 따른 분해 정도를 조사하였다. 비적응 시료에 의해 BTX 는 10주 정도의 적응기 후에 분해되기 시작하여 16주 경과 후 benzene은 37~61%, toluene은 57~61% 분해되었다. 접종 시료별 혐기성 분해도는 유해물질의 유입이 많은 지역에서 채취한 시료가 우수한 분해력을 보였다. 그러나 6개월 가량 적응시킨 결과, 접종 시료별 BTX의 분해 차이는 나타나지 않았으며 적응기가 발생하지 않은 채 빨리 분해시켰다. BTX 단일 화합물을 첨가하였을 경우, 메탄생성 조건에서도 분해도가 다른 조건에 비해 다소 느리게 일어났으며, BTX 혼합체에서는 탈질화 조건에서 분해력이 다소 떨어졌다. BTX의 성분별 분해 정도는 m-xylene이 가장 빨랐으며, benzene의 분해가 가장 느렸다. 오랜 기간 BTX에 적응된 시료에 의해서도 m-xylene의 분해가 빨랐으나 benzene의 분해도 신속히 일어나 toluene과 비슷한 분해율을 나타냈다. 이러한 BTX의 혐기성 분해에 따라 독성이 감소하였다.

• 대한화학회지
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• 제44권4호
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• pp.343-349
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• 2000

PC/Monitor의 구성 전자부품으로부터 방출되는 휘발성 유기화합물(Volatile Organic Com-pounds,VOCs)를 분석하였다. Mpnitor를 구성하는 전자부품으로부터 연속으로 방출되는 VOCs의 경향을 시료챔버에 직접 연결되어있는 잔류가스 분석기(Residual Gas Analyzer,RG A)로 분석하였으며, 이들 전자부품에서 방출되는 VOCs의 성분을 RGA와 GC-MS로 분석하였다. 정성분석된 VOCs 중 소량으로 방출되거라도 불쾌한냄새와 건강상의 장해를 초래할 수 있는 toluene. xylene, cyclohexanone 및 benzofuran에 대하여 GC-MS로 정량분석하였다. 이러한 분석결과, 전자부품중 PCB(CEM-1)을제외하고 나머지 부품들은 가열시작 후 30분에서 1시간동안 toluene, xylene, cyclohexanone 및 phenol이 다량으로 연속 방출되는 경향을 나타내었으며, 거의 모든 전자부품에서 toluene, xylene, phenol, cyclohexanone 및 benzofuran 등의 물질들이측정시간 범위내에서 가장 빈번하게 방출되었다. 부품들 중 Trans가 가장 높은 VOCs의 방출농도를 보였으며, 전자부품으로부터 정량분석된 VOCs중에는 xylene의 방출농도가 550~2482 ${\mu}g/m^2$로 가장 크게 나타났다.

• Journal of Microbiology
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• 제38권1호
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• pp.31-35
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• 2000

A suitable packing material for biofiltration of monoaromatic solvent vapors was selected among various types of packing materials such as peat, bark chips, vermiculite, and Hydroballs. A previously isolated strain, Pseudomonas pseudoalcaligenes BTXO2, which could utilize toluene, m-and p-xylene as carbon and energy sources was used as a biofilter inoculum. Four glass biofilters (6 cm dia. x 60 cm) were individually packed with each of the packing materials and solvent vapors were passed through the columns. During three weeks of peat biofilter operation, average removal efficiencies of toluene, m-and p-xylene were 90.4%, 95.3%, and 82.1%, respectively. With the other packings, the efficiencies were in the range of 10.1 to 58.6％ which were significantly lower than those of the peat biofilter. The peat biofilter was continually operated for approximately nine months and the biofilter sustained its degradation activity during the operation period with minimal maintenance. At steady state, average removal rates of toluene, m- and p-xylene vapors were estimated as 14.2, 5.5, and 8.1 g m$\^$-3/ packing h$\^$-1/, respectively.