• 한국환경과학회지
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• 제16권10호
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• pp.1147-1155
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• 2007

The applicability of in situ biobarrier or microbial filter technology for the remediation of groundwater contaminated with chlorinated solvent was investigated through column study. In this study, the effect of packing materials on the reductive dechlorination of PCE was investigated using Canadian peat, Pahokee peat, peat moss and vermicompost (or worm casting) as a biobarrier medium. Optimal conditions previously determined from a batch microcosm study was applied in this column study. Lactate/benzoate was amended as electron donors to stimulate reductive dechlorination of PCE. Hydraulic conductivity was approximately $6{\times}10^{-5}-8{\times}10^{-5}\;cm/sec$ and no difference was found among the packing materials. The transport and dispersion coefficients determined from the curve-fitting of the breakthrough curves of $Br^-$ using CXTFIT 2.1 showed no difference between single-region and two-region models. The reductive dechlorination of PCE was efficiently occurred in all columns. Among the columns, especially the column packed with vermicompost exhibited the highest reductive dechlorination efficiency. The results of this study showed the promising potential of in situ biobarrier technology using peat and vermicompost for the remediation of groundwater contaminated with chlorinated solvents.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.391-394
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• 2003

The applicability of in situ microbial filter or biobarrier technology for the remediation of soil and groundwater contaminated with chlorinated solvents was investigated. The efficiency and rates of reductive dechlorination of chlorinated solvents are known to be highly dependent on hydrogen concentration. In this study, the effect of electron donors on the reductive dechlorination of PCE was investigated using vermicompost (worm casting) and peat as permeable reactive barrier medium The effect of organic acids (lactate, butyrate and benzoate), yeast extract and vitamin $B_{l2}$ on the reductive dechlorination was investigated. Compared to the control (no electron donor added), addition of electron donors stimulated the dechlorinated rate. Among the electron donor treatments, lactate/benzoate amendment exhibited the highest dechlorination rate. Since vermicompost and peat are inexpensive and biodegradable and have high sorption capacity, they could be successfully used as biobarrier media, especially when electron donors (for example, lactate/benzoate) are added.d.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.131-134
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• 2005

Anaerobic reductive dechlorination of tetrachloroethylene(PCE) to ethylene was investigated by performing laboratory experiments using semi-continuous flow two-in-series soil columns. The columns were packed with soils obtained from TCE-contaminated site in Korea. Site ground water containing lactate(as electron donor and/or carbon source) and PCE was pumped into the soil columns. During the first operation with a period of 50 days, injected mass ratio of lactate and PCE was 620:1 and incomplete reductive dechlorination of PCE to cis-DCE was observed in the columns. However, complete dechlorination of PCE to ethylene was observed when the mass ratio increased to 5,050:1 in the second operation, suggesting that the electron donor might be limited during the first operation period. During the degradation of cis-DCE to ethylene, the concentration of hydrogen was $22{\sim}29mM$. These positive results indicate that the TCE-contaminated groundwater investigated in this study could be remediated through biological anaerobic reductive dechlorination processes.

• Environmental Engineering Research
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• 제13권4호
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• pp.177-183
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• 2008

Ex-situ reductive dechlorination of carbon tetrachloride (CT) by iron sulfide in a batch reactor was characterized in this study. Reactor scaled-up by 3.5 L was used to investigate the effect of reductant concentration on removal efficiency and process optimization for ex-situ degradation. The experiment was conducted by using both liquid-phase and gas-phase volume at pH 8.5 in anaerobic condition. For 1 mM of initial CT concentration, the removal of the target compound was 98.9% at 6.0 g/L iron sulfide. Process optimization for ex-situ treatment was performed by checking the effect of transition metal and mixing time on synthesizing iron sulfide solution, and by determining of the regeneration time. The effect of Co(II) as transition metal was shown that the reaction rate was slightly improved but the improvement was not that outstanding. The result of determination on the regeneration time indicated that regenerating reductant capacity after $1^{st}$ treatment of target compound was needed. Due to the high removal rates of CT, ex-situ reductive dechlorination in batch reactor can be used for basic treatment for the chlorinated compounds.

• 한국환경과학회지
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• 제3권1호
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• pp.65-76
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• 1994

자연호소의 혐기성 저질을 특정한 chlorophenol(CP)에 적응시킨 후 다른 구조물 가진 CP에 대한 탈염소 특성을 검토하였다. CP에 노출되지 않는 혐기성 저질에서는 mono-CP의 경우 ortho > meta > para-염소의 손으로 di-CP의 경우는 ortho > par > meta- 염소의 순서로 짧은 지체기를 거친 후 탈염소가 발생하였다. Mono-CP 중 2-CP에 적응된 저질은 4-CP와 3,4DCP를 제외하고, 3-CP에 적응시킨 저질은 4-CP를 제외한 모든 시험물질에 대하여 지체기 없이 탈염소 특성을 나타내었다. DCP에 적응된 모든 저질은 2-CP, 2,3,-, 2,4-, and 3,4-DCP를 지체기 없이 탈염소가 발생하지 않았다. 이 결과에서 볼 때 mono-와 di-CP를 탈염소시키는 혐기성 미생물의 종류가 다양함을 알 수 있다.

• KSBB Journal
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• 제22권3호
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• pp.134-138
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• 2007

미생물이 환원된 전극을 전자공여체로 이용하고, 염소화페놀을 전자수용체로 이용하는 새로운 혐기성 호흡의 생물전기화학공정을 통해 2,6-DCP을 탈염소시킬 수 있는지를 조사하였다. 이를 위해 전류의 유무에 따른 농도변이와 전극 표면을 주사전자현미경으로 관찰한 결과, 전류가 흐르는 경우에만 염소화페놀이 완전히 제거됨을 보였으며, 전극표면에 생물막이 형성된 것을 통해서 전극이 전자공여체 역할을 함으로서 탈염소시킬 수 있음을 증명하였다. 또한, 본 연구의 생물전기화학공정을 통해서 고농도의 염소화페놀 적용도 가능한지를 조사하고 Monod식을 이용하여 최대 탈염소화 속도를 산정하였는데 본 실험의 최대초기농도인 $457mg/{\ell}$까지 분해가 가능하였으며, 최대탈염소화 속도는 $5.95mg/{\ell}$-h($cm^2$ (electrode surface area))이었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제11권2호
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• pp.22-37
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• 2006

생물벽체(biobarrier) 또는 원위치 미생물 필터(in situ microbial filter) 기술을 이용한 염소계 유기용매로 오염된 지하수의 복원 가능성을 회분식 실험을 통하여 살펴보았다. PCE의 환원성 탈염소화의 효율과 속도는 수소 농도에 의존하는 것으로 알려져 있다. 본 연구에서는 분변토와 토탄을 생물벽체로 이용한 PCE의 환원성 탈염소화시 전자공여체의 영향을 살펴보았다. 유기산(lactate, butyrate benzoate)과 yeast extract, 비타민 $B_{12}$가 PCE의 환원성 탈염소화에 미치는 영향을 조사하였다. 생물벽체 담체 비존재시, 전자공여체를 투여하지 않은 control 실험에 비해, 전자공여체의 첨가는 PCE의 탈염소화 속도를 촉진하였다. 전자공여체를 투여한 실험 중에서 lactate 또는 lactate/benzoate를 수소 공여체(hydrogen donor)로 첨가된 경우, 탈염소화 속도가 가장 빨랐다($k_1=0.0260{\sim}0.0266\;day^{-1}$). 분변토를 생물벽체로 사용한 경우, lactate/benzoate 첨가시 탈염소화 속도가 가장 빨랐으며, 겉보기 1차 분해속도상수($k_1$)는 $0.0849day^{-1}$였다. 반면, Pahokee peat을 생물벽체로 사용하였을 경우, butyrate 또는 lactate의 첨가시 탈염소화 속도가 가장 빨랐으며 $k_1$ 값은 각각 0.1092, $0.1067\;day^{-1}$로 나타났다. 본 연구결과로부터 분변토 또는 토탄을 원위치 생물벽체로 사용하여 염소계 유기용매로 오염된 지하수 처리의 잠재적인 응용 가능성을 알 수 있었다.

• Journal of Microbiology
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• 제44권1호
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• pp.23-28
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• 2006

We investigated the effects of halogenated aromatic compounds (HACs) including naturally occurring ones (L-thyroxine, 3-chloro-L-tyrosine, 5-chloroindole, 2-chlorophenol, 4-chlorophenol and chlorobenzene) on polychlorinated biphenyl (PCB) dechlorination in sediment cultures. A PCB-dechlorinating enrichment culture of sediment microorganisms from the St. Lawrence River was used as an initial inoculum. When the culture was inoculated into Aroclor 1248 sediments amended with each of the six HACs, the extent of dechlorination was not enhanced by amendment with HACs. The dechlorination patterns in the HAC-amended sediments were nearly identical to that of the HAC-free sediments except the 3-chloro-L-tyrosine-amended ones where no dechlorination activity was observed. When these sediment cultures were transferred into fresh sediments with the same HACs, the dechlorination specificities remained the same as those of the initial inoculations. Thus, in the present study, the substrate range of the highly selected enrichment culture could not be broadened by the HACs. It appears that HACs affect PCB dechlorination mainly through population selection rather than enzyme induction of single population.

• 대한환경공학회지
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• 제31권2호
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• pp.125-131
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• 2009

영가철과 혐기성 미생물을 이용한 환원적 탈염화반응을 통한 다이옥신 처리 능력을 평가하기 위해, 자유에너지 선형관계(linear free energy relationship)를 이용하여 다이옥신의 탈염화에 의한 농도 및 독성변화 예측 모델을 최초로 정립하였다. 수용액상에 존재하는 다이옥신류의 깁스자유에너지는 기존 문헌의 열역학적 계산결과를 범밀도함수이론(density functional theory)을 이용한 계산 수준으로 보정하였으며, 보정된 깁스자유에너지와 실험을 통해 얻은 탈염화 반응속도 상수와의 선형관계를 통해 다이옥신의 탈염화 반응 256개에 대한 반응속도상수를 예측하였다. 본 모델을 통해 탈염화에 의해 변화하는 다이옥신 류 76종에 대한 시간 별 농도를 계산할 수 있다. 8염화다이옥신(Octachlorinated dibenzo-p-dioxin, OCDD)이 완전히탈염화되어 dibenzo-p-dioxin (DD)로 탈염화되기까지는 100년 이상의 반응시간이 필요하였으며, 독성등가값(toxic equivalent quantity, TEQ)의 경우 탈염화가 진행되면서 초기농도의 10배 이상까지 증가하는 것으로 밝혀졌다. 이를 통해, 다이옥신의 처리를 위해서는 좀 더 빠른 탈염화 반응속도를 갖는 다른 전자공여 시스템을 사용하거나, 환원적 탈염화-라디칼 산화와 같은 복합 연계처리가 필요함을 알 수 있다. 본 논문을 통해 제시된 예측 기법은 다이옥신뿐 아니라 다른 할로겐화 화합물의 탈염화 예측과 여러 전자공여 시스템에 대한 평가에 적용이 가능하다.

• 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.