• Title/Summary/Keyword: Reductive

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Anaerobic Reductive Dechlorination of Tetrachloroethylene (PCE) in Two-in-series Semi-continuous Soil Columns (반연속 흐름 2단 토양 컬럼에서의 사염화 에틸렌(PCE)의 혐기성 환원탈염소화)

  • Ahn, Young-Ho;Choi, Jeong-Dong;Kim, Young;Kwon, Soo-Youl;Park, Hoo-Won
    • Journal of Soil and Groundwater Environment
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    • v.11 no.2
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    • pp.68-76
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    • 2006

  • 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. Dechlorination rate of PCE to cis-DCE was $0.62{\sim}1.94\;{\mu}mol$ PCE/L pore volume/d and $2.76\;{\mu}mol$ cis-DCE/ L pore volume/d for that for cis-DCE to ethylene, resulting that net dechlorination rate in the system was 1.43 umol PCE/L pore volume/d. During the degradation of cis-DCE to ethylene, the concentration of hydrogen in column groundwater was $22{\sim}29\;mM$ and $10{\sim}64\;mM$ for the degradation of PCE to cis-DCE. These positive results indicate that the TCE-contaminated groundwater investigated in this study could be remediated through in-situ biological anaerobic reductive dechlorination processes.

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Effect of Electron Donor on the Reductive Dechlorination of PCE in Groundwater Using Biobarrier: Batch Experiment (생물벽체를 이용한 지하수내 PCE의 환원성 탈염소화시 전자공여체의 영향: 회분식 실험)

  • HwangBo, Hyun-Wook;Shin, Won-Sik;Kim, Young-Hun;Song, Dong-Ik
    • Journal of Soil and Groundwater Environment
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    • v.11 no.2
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    • pp.22-37
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    • 2006

  • The applicability of biobarrier or in situ microbial filter technology for the remediation of groundwater contaminated with chlorinated solvent was investigated through batch microcosm study. The efficiency and rates of reductive dechlorination of tetrachloroethylene (PCE) 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 (or worm casting) and peat as a biobarrier medium. The effect of organic acids (lactate, butyrate and benzoate), yeast extract and vitamin $B_{12}$ on the reductive dechlorination was investigated. In the absence of biobarrier medium (adsorbent), addition of electron donors stimulated the dechlorination rate of PCE compared to the control experiment (i.e., no electron donor added). Among the treatments, addition of lactate or lactate/benzoate as hydrogen donor exhibited the highest dechlorination rate ($k_1=0.0260{\sim}0.0266\;day^{-1}$). In case of using vermicompost as a biobarrier medium, amendment of lactate/benzoate exhibited the highest dechlorination rate following with a pseudo-first-order degradation rate constant of $k_1=0.0849\;day^{-1}$. In contrast, when Pahokee peat was used as a biobarrier medium, either butyrate or lactate addition exhibited the highest dechlorination rate with $k_1$ values of 0.1092 and $0.1067\;day^{-1}$, respectively. The results of this study showed the potential applicability of in situ biobarrier technology using vermicompost or peat as a barrier material for the remediation of groundwater contaminated with chlorinated solvent.

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