• 한국지하수토양환경학회지:지하수토양환경
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• 제11권5호
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• pp.35-42
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• 2006

본 논문에서는 황화철($FeS,\;FeS_{2}$) 유기 용매의 환원적 분해 반응과의 표면특성의 관계에 대해서 다음과 같은 결과를 얻었다. hexachloroethane(HCA)은 수소첨가반응, 탈염소제거반응과 탈수소탈염소화반응으로 pentachloroethane(PCA), tetrachloroethylene(PCE), trichloroethylene(TCE)와 cis-1,2-dichloroethylene(cis-1,2-DCE)로 분해되었다. FeS와 $FeS_{2}$를 반응 매개물로 HCA에 대한 반응에서 FeS는 $FeS_{2}$보다 분해반응 속도가 빠르게 나타났다. FeS와 $FeS_{2}$의 표면 특성 연구에서 각 광물질에 대한 친수성 표면 자리(Ns)를 정량적으로 계산하기 위해서 비표면적 값($107.0470m^{2}/g$와 $92.6374m^{2}/g$)과 표면 전위를 측정에 측정된 $PH_{ZPC}(FeS,\;PH_{ZPC}=7.42,\;FeS_{2},\;PH_{ZPC}=7.80)$ 값을 이용해서 계산한 결과 FeS와 $FeS_{2}$의 $N_{s}$값은 각각 $0.053\;site/nm^{2},\;0.205\;site/nm^{2}$으로 나타났다. 그리고 0.2 g/L Fe광물질에 대한 실질적인 친수성 표면 농도는 각각 $3.303{\times}10^{-6}\;mol/L$와 $1.102{\times}10^{-5}\;mol/L$ 나타났다. $FeS_{2}$는 FeS에 비해 훨씬 친수성 표면임을 실험 결과 확인하였다. FeS와 $FeS_{2}$의 두 광물질 중에서 유기 용매의 환원 반응 속도는 FeS가 훨씬 빠르게 나타났다.

• 한국환경보건학회지
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• 제36권4호
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• pp.323-336
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• 2010

We evaluated the properties of a fixed-bed column reactor for high-concentration tetrachloroethylene (PCE) removal. The anaerobic bacterium Clostridium bifermentans DPH-1 was able to dechlorinate PCE to cis-1,2-dichloroethylene (cDCE) via trichloroethylene (TCE) at high rates in the monoculture biofilm of an upflow fixed-bed column reactor. The first-order reaction rate of C. bifermentans DPH-1 was relatively high at $0.006\;mg\;protein^{-1}{\cdot}l{\cdot}h^{-1}$, and comparable to rates obtained by others. When we gradually raised the influent PCE concentration from $30\;{\mu}M$ to $905\;{\mu}M$, the degree of PCE dechlorination rose to over 99% during the operation period of 2,000 h. In order to maintain efficiency of transformation of PCE in this reactor system, more than 6 h hydraulic retention time (HRT) is required. The maximum volumetric dechlorination rate of PCE was determined to be $1,100\;{\mu}mol{\cdot}d^{-1}l$ of reactor $volume^{-1}$, which is relatively high compared to rates reported previously. The results of this study indicate that the PCE removal performance of this fixed-bed reactor immobilized mono-culture is comparable to that of a fixed-bed reactor mixture culture system. Furthermore, our system has the major advantage of a rapid (5 days) start-up time for the reactor. The flow characteristics of this reactor are intermediate between those of the plug-flow and complete-mix systems. Biotransformation of PCE into innocuous compounds is desirable; however, unfortunately cDCE, which is itself toxic, was the main product of PCE dechlorination in this reactor system. In order to establish a system for complete detoxification of PCE, co-immobilization of C. bifermentans DPH-1 with other bacteria that degrade cDCE aerobically or anaerobically to ethene or ethane may be effective.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2007년도 추계학술발표회
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• pp.185-185
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• 2007

20세기에 들어 산업, 군사 및 다양한 목적으로 비인화성 용매인 PCE와 TCE의 사용량이 증대하였다. 주의를 필요로 하는 물질임에도 불구하고 부주의한 사용과 보관으로 인해 토양, 퇴적토, 지하수에 심각하게 오염되었다. High-chlorinated ethenes은 호기성 박테리아의 oxygenation에 의해 분해되지 않는다. PEC및 TCE의 완전한 탈염소화는 혐기성조건에서만 관찰되어지며, 지난 10연년간의 연구에 의해서 탈염소화 혐기성 미생물의 수의 보고는 증가되었다. 혐기성 조건에서 탈염소화 미생물에 의해 PCE와 TCE는 less-chlorinated ethenes 또는 무해한 ethene으로 전환이 가능하다. 본 연구는 lactate를 electron donor로 이용해 PCE에서 ethene까지 완전히 탈염소화하는 혐기성 배양을 수행했다. PCE로 오염된 퇴적토 시료로부터 혐기성 미생물 배양을 성공했다. PCE가 ethene까지 완전히 분해되는 것이 관찰되었다. 추가적으로 혐기성 미생물 배양액에서 1,2-cis-dichloroethene (cis-DCE)와 vinyl chloride (VC)의 축적이 일어남을 관찰하였다. 혐기성 미생물 배양액에서 Dehalococcoides 16S rRNA gene sequences에 특이적으로 반응하는 primer를 이용한 DGGE를 통해 미생물 군집을 분석하였다. 결론적으로, 우리의 연구에서 PCE를 감소시키는 배양액을 배양했으며, 이 배양엑에는 Dehalococcoides sp. 존재하는 것을 확인하였다.

• 미생물학회지
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• 제45권2호
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• pp.140-147
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• 2009

경기도 김포 지역과 인천 서구 지역공단 주변에 위치한 소하천의 저니(sediment)에서 난분해성 염소화합물인 PCE (tetrachloroethylene)의 혐기성 탈염소화 능력이 있는 군집을 선별하고, 탈염소화에 관여하는 미생물을 탐색하였다. 혐기성 탈염소화 능력을 조사하기 위해 전자공여체로 lactate를 사용하여 혐기성 회분식 실험을 실시하였으며, 탈염소화 능력을 가진 군집을 선별하였다. 선발된 미생물군집은 분자생물학적 기법인 16S rRNA gene의 Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) 기법과 탈염소화 미생물을 선택적으로 탐색할 수 있는 species-specific primer를 이용하여 분석하였다. 총 16개의 시료 중에서 접종 8주 만에 3개의 시료에서 ethene까지 탈염소화시켰으며, 4개의 시료에서 cis-1,2-dichloroethene (cis-DCE)까지 탈염소화시켰다. 또한, 16S rRNA gene을 이용한 PCR-DGGE와 탈염소화 species-specific primer를 이용하여 분석한 결과, PCE 탈염소화 시료 내에는 Dehalococcoides sp.와 Geobacter sp.가 주로 존재하였으며, Dehalobacter sp.도 일부 시료에서 검출되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권6호
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• pp.101-113
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• 2016

To properly manage and remediate groundwater contaminated with chlorinated hydrocarbons such as trichloroethylene (TCE), it is necessary to assess natural attenuation processes of contaminants in the aquifer along with investigation of contamination history and aquifer characterization. This study evaluated natural attenuation processes of TCE at an industrial site in Korea by delineating hydrogeochemical characteristics along the flow path of contaminated groundwater, by calculating reaction rate constants for TCE and its degradation products, and by using geochemical and reactive transport modeling. The monitoring data showed that TCE tended to be transformed to cis-1,2-dichloroethene (cis-1,2-DCE) and further to vinyl chloride (VC) via microbial reductive dechlorination, although the degree was not too significant. According to our modeling results, the temporal and spatial distribution of the TCE plume suggested the dominant role of biodegradation in attenuation processes. This study can provide a useful method for assessing natural attenuation processes in the aquifer contaminated with chlorinated hydrocarbons and can be applied to other sites with similar hydrological, microbiological, and geochemical settings.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.158-161
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• 2004

Chlorinated aliphatic hydrocarbons (CAHs) especially perchlorethylene (PCE) and trichlooethylene (TCE) are common groundwater contaminants in Korea. PCE and TCE were often reductively dechiorinated in an aquifer. Several isolates dechlorinate PCE to TCE or cis-1,2 dichloroethylene (c-DCE) were obtained from contaminated and pristine sites in USA and Europe. However in Korea, no information on indigenous microorganism being involved in reductive dechlorination of PCE and TCE is available and different dechlorinating microorganisms might be reside in Korea, since geochemical, and hydrogeological conditions are different, compared to those in the other sites. So we evaluate that: 1) if reductive dechlorinating microorganisms are present in PCE-contaminated site in Korea, 2) if so, what kinds of microorganisms are present; 3) to what extent PCE is reductively dechlorinated. As a results in some PCE-contaminated aquifers in Korea other dechlorinating microorganisms but Dehalococcoides ethenogenes may be responsible for PCE dechlorination. More detailed molecular works are required to evaluate that different dechlorinating microorganisms would reside in Korea.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권5호
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• pp.309-312
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• 2003

The transformation capacity (T$\_$c/) of Methylosinus trichosporium OB3b in the degradation of ethylene chlorides was determined by measuring the decrease of soluble methane monooxygenase (sMMO) activity of resting cells in batch experiments. All measurements of sMMO activity were taken in the presence of 20 mM formate to avoid the deficiency of reducing power, and within 2 hrs to avoid the effect of natural inactivation from instability of the resting cells. The constant T$\_$c/ values of 0.58 ${\pm}$ 0.132 and 0.80 ${\pm}$ 0.17 ${\mu}$mol/mg cell were obtained for trichloroethylene (TCE) and 1,2-dichloroethylene (cis and trans-1,2-DCE), respectively, regardless of their concentrations. The transformation capacity measured by this method can be used to predict the amount of cells that should be stimulated in in-situ bioremediation.

• 대한환경공학회지
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• 제28권3호
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• pp.292-299
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• 2006

전자공여체로 벤조산염을 이용한 perchloroethene(PCE)의 환원성 탈염소화 과정에서 전자공여체의 첨가량 및 초기 미생물 식종량이 탈염소화에 미치는 영향을 평가하기 위하여 회분식 실험을 수행하였다. 벤조산염이 탈염소화를 위한 양론비 이하(전자공여체/수용체 비=0.5와 1)로 첨가된 경우 탈염소화 효율은 벤조산염 첨가량이 증가함에 따라 71%에서 94.3%로 증가하였으나, 탈염소화에 이용된 전자공여체의 분율은 92.7%에서 79.6%로 감소하였다. 메탄생성은 PCE와 trichloroethene(TCE)가 모두 cis-1,2-dichloroethene(cDCE)으로 전환된 후 문턱농도(threshold value, 10 nM) 이상으로 수소농도가 유지되는 동안 진행되었다. 벤조산염이 양론비 이상으로 첨가된 경우 탈염소화 완료 후 잔존하는 수소는 메탄생성량을 증가시켰다. 식종 미생물량의 증가는 지체기를 감소시켰지만 최대 탈염소화 속도는 벤조산염 분해 속도에 의해 결정되어 식종 미생물량에 큰 영향을 받지 않았다. 식종 미생물 농도가 높은 경우 초기 활발한 탈염소화로 인하여 메탄생성량은 감소하고, 탈염소화 효율은 증가하였다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권1호
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• pp.40-46
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• 2005

Clostridium bifermentans strain DPH-1 has already been found to dechlorinate perchloroethylene (PCE) to cis-dichloroethylene (cis-DCE) via trichloroethylene (TCE). In this study, our investigation on different culture conditions of this DPH-1 strain was extended to find a more efficient and cost effective growth medium composition for this DPH-1 strain in bioremediation practices. Temperature dependency of strain DPH-1 showed that the growth starting time and PCE degradation at $15^{\circ}C$ was very slow compared to that of $30^{\circ}C$, but complete PCE degradation occurred in both cases. For the proper utilization of strain DPH-1 in more cost effective bioremediation practices, a simpler composition of an effective media was studied. One component of the culture medium, yeast extract, had been substituted by molasses, which served as a good source of electron donor. The DPH-1 strain in the medium containing molasses, in the presence of $K_{2}HPO_4\;and\;KH_{2}PO_4$, showed identical bacterial multiplication (0.135 mg protein $mL^{-1}h^{-1}$) and PCE degradation rates ($0.38\;{\mu}M/h$) to those of the yeast extract containing medium.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.77-80
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• 2001

Groundwater, contaminated predominantly with aromatic compounds and chlorinated ethylene, could be biologically treated in a fluidized-bed reactor with immobilized cells. The decomposition efficiency for the aromatics was over 90% at the retention time of 2.5 h. The chlorinated ethylenes, especially trichloroethylene (TCE) and cis-dichloroethylene (DCE), could be decomposed only insufficiently. No anaerobic methane formation was observed for this groundwater even at a very low dissolved oxygen (DO) concentration of 0.75 mg/L. The variation of DO concentration resulted in an optimal value of 1.5 mg/L. The recycle of air waste could increase the utilization of oxygen. The amount of low boiling pollutants stripped out remained constant with the recycle, while for the higher boiling pollutants the stripping slightly increased. Using air instead of oxygen increases the flow rate of air waste, which is connected to a higher stripping of pollutants. In this investigation, the pollutant concentration in the air waste remained constant. The stripping of main pollutants did not exceed 0.3 %.