• 한국대기환경학회지
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• 제18권3호
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• pp.223-230
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• 2002

Titania photocatalytic oxidation reactors were studied to investigate degradation efficiencies of hydrocarbons. In general, it is well known phenomena that thin layered titania oxidizes most of hydrocarbons to carbon dioxide and water under UV light. In this study, degradation efficiencies were measured due to changes in reactor structures, UV sources, the number of titania coatings, and various hydrocarbon chemicals. It was proven that gas degradation efficiencies are related to such factors as UV transmittance of coating substance, collision area of surface, and gas flow rate. For packing type annular reactor, about 98% degradation efficiency was achieved for achieved for propylene of 500 ppm level at a flow rate of 100 ml/min. Several gases were also tested for double-coated titania thin film under the condition of continuous flow of 100 ml/min and 365 nm UV source. It was shown that degradation efficiencies were decreasing in the order: $C_3$ $H_{6}$, n-C$_4$ $H_{10}$, $C_2$ $H_4$, $C_2$ $H_2$, $C_{6}$ $H_{6}$ and $C_2$ $H_{6}$./. 6/./.

• Journal of Microbiology
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• 제37권3호
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• pp.128-135
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• 1999

Among oil-degrading microorganisms isolated from oil-polluted industrial areas, one yeast strain showed high degradation activity of aliphatic hydrocarbons. From the analyses of 18S rRNA sequences, fatty acid, coenzyme Q system, G+C content of DNA, and biochemical characteristics, the strain was identified as Yarrowia lipolytica 180. Y. lipolytica 180 degraded 94% of aliphatic hydrocarbons in minimal salts medium containing 0.2% (v/v) of Arabian light crude oil within 3 days at 25$^{\circ}C$. Optimal growth conditions for temperature, pH, NaCl concentration, and crude oil concentration were 30$^{\circ}C$, pH 5-7, 1%, and 2% (v/v), respectively. Y. lipolytica 180 reduced surface tension when cultured on hydrocarbon substrates (1%, v/v), and the measured values of the surface tension were in the range of 51 to 57 dynes/cm. Both the cell free culture broth and cell debris of Y. lipolytica 180 were capable of emulsifying 2% (v/v) crude oil by itself. They were also capable of degrading crude oil (2%). The strain showed a cell surface hydrophobicity higher than 90%, which did not require hydrocarbon substrates for its induction. These results suggest that Y. lipolytica has high oil-degrading activity through its high emulsifying activity and cell hydrophobicity, and further indicate that the cell surface is responsible for the metabolism of aliphatic hydrocarbons.

• 한국미생물·생명공학회지
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• 제31권4호
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• pp.408-412
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• 2003

오염토양에 유류분해능을 가진 Nocardia sp. H17-1의 접종시 고려되어야 할 인자중 하나인 초기 오염농도에 의한 탄화수소분해능과 초기 접종농도에 의한 분해능 및 균주의 생육을 조사하였다. H17-1은 실험 50일 동안 초기 오염농도 10, 50, 100 g Arabian light oil/kg of soil에 대해 각각 78.5%, 94.3%, 53.2%의 탄화수소를 제거하였으며, 오염농도가 높을수록 분해속도 상수(k) 낮아졌다. $CO_2$의 생성량 또한 오염농도가 높을수록 증가하였으나, 100 g/kg-soil의 오염농도에서는 균의 생육이 저해를 받는 것으로 나타났다. H17-1의 초기 접종농도에 의한 영향은 균의 접종량에 따라 최종 남은 TPH의 양은 큰 차이를 나타내지 않았으나, 분해속도상수(k)는 균의 접종량이 늘어남에 따라 크게 증가되었으며, $CO_2$의 생성량 또한 균의 접종농도에 따라 증가하였다.

• 한국환경농학회지
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• 제34권4호
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• pp.268-273
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• 2015

본 연구는 유류로 오염된 토양의 정화를 위한 생물자극법에서 퇴비의 시용효과를 알아보기 위해 실시되었다. TPH로 오염된 토양에 퇴비를 수준별로 처리 한 후 TPH 함량 변화를 관찰 한 결과, 퇴비 처리량이 증가 할수록 토양 내 TPH 함량이 감소하는 경향이 나타났다. TPH 분해율을 알아보고자 퇴비 처리수준에 따른 TPH 함량 변화를 1차와 2차 kinetics 모델에 적용하여 결정계수(R²)를 비교 한 결과 second order kinetic 모델의 결정계수 값이 잘 적용되었다. 퇴비를 처리하였을 때 seond-order kinetic 모델의 reaction rate constant 값은 퇴비를 30 Mg/ha 이상 처리하였을 때 무처리 보다 4배 정도 높게 나타났으며, 퇴비 처리 수준이 높아질수록 그 값은 증가하는 경향을 보였다. 퇴비의 처리량을 증가시킴에 따라 토양 내 미생물의 수는 증가하는 경향을 나타냈다. 또한 퇴비의 처리량은 토양 내 미생물 수와 TPH 함량의 변화와 밀접한 관계가 있음을 보여주었다. 따라서 TPH로 오염된 토양 내 적합한 양의 퇴비 처리는 토양 내 미생물 수를 증가시켜 TPH 함량의 감소를 가속화시킬 수 있을 것으로 판단된다.

• Journal of Microbiology and Biotechnology
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• 제11권4호
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• pp.607-613
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• 2001

The biodegradation rates of diesel oil by a selected diesel-degrading bacterium, Pseudomonas stutzeri strain Y2G1, and microbial consortia composed of combinations of 5 selected diesel-degrading bacterial were determined in liquid and soil systems. The diesel degradation rate by strain Y2G1 linearly increased $(R^2=0.98)$ as the diesel concentration increased up to 12%, and a degradation rate as high as 5.64 g/l/day was obtained. The diesel degradation by strain Y2G1 was significantly affected by several environmental factors, and the optimal conditions for pH, temperature, and moisture content were at pH8, $25^{\circ}C$, and 10%, respectively. In the batch soil microcosm tests, inoculation, especially in the form of a consortium, and the addition of nutrients both significantly enhanced the diesel degradation by a factor of 1.5 and 4, respectively. Aeration of the soil columns effectively accelerated the diesel degradation, and the initial degradation rate was obviously stimulated with the addition of inorganic nutrients. Based on these results, it was concluded that the major rate-limiting factors in the tested diesel-contaminated soil were the presence of inorganic nutrients, oxygen, and diesel-degrading microorganisms. To resolve these limiting parameters, bioremediation strategies were specifically designed for the tested soil, and the successful mitigation of the limiting parameters resulted in an enhancement of the bioremediation efficiency by a factor of 11.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.1135-1139
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• 2005

Psychrotrophic phenanthrene-degrading bacteria were identified in the sediment samples collected from Lake Baikal, Russia. Among 70 phenanthrene-degrading isolates, the seven that had the highest phenanthrene-degradation rates were identified by 16S rDNA sequencing. Isolate P25, identified as the Gram-positive rod-shaped organism Rhodococcus erythropolis, had the highest growth and degradation rate at $15^{\circ}C$. It could remove $26.0\%$ of 100 mg $1^{-1}$ phenanthrene in 20 days at $15^{\circ}C$, and degradation was less at $5^{\circ}C\;and\;25^{\circ}C$. The addition of surfactants to enhance degradation was tested. Brij 30 and Triton X-100 inhibited degradation at all surfactant concentrations tested, but Tween 80 stimulated phenanthrene degradation, especially at low concentrations. When $20{\times}$ CMC (critical micelle concentration) of Tween 80 was added, $38.0\%$ of 100 mg $1^{-1}$ phenanthrene was degraded in 12 days at $15^{\circ}C$. This psychrotrophic phenanthrene-degrading bacterium is a candidate for use in bioremediation of polycyclic hydrocarbon contamination in low temperature environments.

• Journal of Microbiology
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• 제42권2호
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• pp.94-98
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• 2004

Phenanthrene is a three-ring polycyclic aromatic hydrocarbon and commonly found as a pollutant in various environments. Degradation of phenanthrene by white rot fungus Trametes versicolor 951022 and its laccase, isolated in Korea, was investigated. After 36 h of incubation, about 46％ and 65％ of 100 mg/l of phenanthrene added in shaken and static fungal cultures were removed, respectively. Phenanthrene degradation was maximal at pH 6 and the optimal temperature for phenanthrene removal was 30$^{\circ}C$. Although the removal percentage of phenanthrene was highest (76.7％) at 10 mg/1 of phenanthrene concentration, the transformation rate was maximal (0.82 mg/h) at 100 mg/L of phenanthrene concentration in the fungal culture. When the purified laccase of T. versicolor 951022 reacted with phenanthrene, phenanthrene was not transformed. The addition of redox mediator, 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) or 1-hydroxybenzotriazole (HBT) to the reac-tion mixture increased oxidation of phenanthrene by laccase about 40％ and 30％, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.415-417
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• 2009

A low temperature decal (LTD) transfer method is tried to fabricated hydrocarbon (HC) membrane based MEA. Sandwiched structures of outer ionomer/catalyst/carbon coating/substrate, which had been developed for Nafion membrane, are used for transfer of catalyst to the HC membrane. Performances of the HC MEA before and after 500hr continuous operation are compared and it is found that a severe delamination occurs at the interface between the HC membrane and the catalyst layer, which is the main reason of the low performance and its degradation. The delamination is due probably to the different nature of HC membrane to the Nafion ionomer. A substitutional method, therefore, is suggested to overcome this. In such a way, the outer ionomer process is removed and the low transfer rate of catalyst by skipping the ionomer process is compensated with optimization of other process variables such as transfer time or temperature. The resulting performance is superior to the original LTD method, which can be explained in terms of low resistive components both in ohmic and kinetic.

• Journal of Microbiology and Biotechnology
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• 제19권4호
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• pp.339-345
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• 2009

We evaluated the activity and abundance of the crude-oil-degrading bacterium Nocardia sp. H17-1 during bioremediation of oil-contaminated soil, using real-time PCR. The total petroleum hydrocarbon(TPH) degradation rate constants(k) of the soils treated with and without H17-1 were $0.103\;d^{-1}$ and $0.028\;d^{-1}$ respectively. The degradation rate constant was 3.6 times higher in the soil with H17-1 than in the soil without H17-1. In order to detect and quantify the Nocardia sp. H17-1 in soil samples, we quantified the genes encoding 16S ribosomal RNA(16S rRNA), alkane monooxygenase(alkB4), and catechol 2,3-dioxygenase(23CAT) with real-time PCR using SYBR green. The amounts of H17-1 16S rRNA and alkB4 detected increased rapidly up to 1,000-folds for the first 10 days, and then continued to increase only slightly or leveled off. However, the abundance of the 23CAT gene detected in H17-1-treated soil, where H17-1 had neither the 23CAT gene for the degradation of aromatic hydrocarbons nor the catechol 2,3-dioxygenase activity, did not differ significantly from that of the untreated soil($\alpha$=0.05,p>0.22). These results indicated that H17-1 is a potential candidate for the bioaugmentation of alkane-contaminated soil. Overall, we evaluated the abundance and metabolic activity of the bioremediation strain H17-1 using real-time PCR, independent of cultivation.

• 생명과학회지
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• 제21권11호
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• pp.1511-1517
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• 2011

페난스렌은 다환방향족 탄화수소의 일종으로서 미량으로도 인체에 강한 해를 미칠 수 있는 주요 환경오염 물질이다. 미생물을 이용한 페난스렌 제거 목적으로 중국 쑤저우(Suzhou) 지역의 유류 오염토양에서 페난스렌을 강력하게 분해하는 세균을 분리하였다. 16S rDNA 염기서열 결정에 의하여 이 세균은 Sphingobacterium sp. SW-09로 동정되었으며 PCR 증폭을 통하여 페난스렌 분해 유전자인 nahH를 가지고 있음이 확인되었다. 이전의 연구에서 포천일대의 군부대에서 분리된 강력한 페난스렌 분해세균인 Staphylococcus sp. KW-07과 이번에 분리된 Sphingobacterium sp. SW-09을 이용하여 이들의 페난스렌 분해능을 비교분석하였다. 그 결과, 쑤저우 지역에서 분리된 Sphingobacterium sp. SW-09이 최소배지와 실제토양에서 모두 Staphylococcus sp. KW-07보다 강하게 페난스렌을 분해하는 것으로 나타났다. 결과적으로 이번에 분리된 Sphingobacterium sp. SW-09을 사용하여 유류 오염토양의 환경정화에 사용할 수 있을 것으로 판단된다.