• Title, Summary, Keyword: 탈염소화

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Effect of Sulfate Reduction on the Hydrogen Competition among Dechlorination, Methane Production, and Sulfate Reduction (황산염 환원반응이 탈염소화, 메탄생성 및 황산염 환원 간 수소경쟁에 미치는 영향)

  • Lee, Il-Su;Bae, Jae-Ho
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.6
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    • pp.635-641
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    • 2005
  • Batch experiments were performed to evaluate the effect of sulfate reduction on methane production and reductive dechlorination, both compete for hydrogen with sulfate reduction. Dechlorination was inhibited by sulfate reduction at lower hydrogen concentration because their threshold values for hydrogen are similar (2 nM). Unlike methane production mainly inhibited transformation of cDCE to ethene, sulfate reduction inhibited the initial dechlorination step, PCE reduction into cDCE as well as cDCE dechlorination. The presence of sulfate eliminated methanogens as hydrogen competitor because of its high threshold value of 10 nM. When sulfate coexisted with PCE, dechlorination efficiency was not affected by the increase of seed concentration as both dechlorination and sulfate reduction were stimulated simultaneously by the increased seeding culture.

Characteristics of PCE Reductive Dechlorination using Benzoate as an Electron Donor (벤조산염을 전자공여체로 이용한 PCE의 환원성 탈염소화 특성)

  • Lee, Il-Su;Bae, Jae-Ho
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.3
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    • pp.292-299
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    • 2006
  • Batch experiments were performed to evaluate the effects of the electron donor dosage and the initial biomass on the reductive dechlorination of perchloroethene(PCE) with benzoate as an electron donor. When benzoate was added less than the theoretical requirement for dechlorination(electron donor/acceptor ratio=0.5 and 1), the dechlorination efficiency increased from 71% to 94.3% with the increase in benzoate dosage, but the fraction of electron equivalent utilized for dechlorination decreased from 92.7% to 79.6%. Methane production was observed when the hydrogen concentration was higher than the threshold value(10 nM) after PCE and trichloroethene (TCE) were reduced to cis-1,2-dichloroethene(cDCE). When benzoate was added more than the theoretical requirement, the residual hydrogen converted into methane after the completion of dechlorination. The increase in the seeding biomass shortened the lag time for dechlorination, but it did not affect the maximum dechlorination rate as it was mainly governed by the benzoate fermentation rate. When the seeding biomass concentration was high, active dechlorination during the early period increased dechlorination efficiency while decreasing methane production.

Biological Dechlorination of Chlorinated Ethylenes by Using Bioelectrochemical System (생물전기화학시스템을 이용한 염화에틸렌의 생물학적 탈염소화)

  • Yu, Jaecheul;Park, Younghyun;Seon, Jiyun;Hong, Seongsuk;Cho, Sunja;Lee, Taeho
    • Journal of Korean Society of Environmental Engineers
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    • v.34 no.5
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    • pp.304-311
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    • 2012
  • Chlorinated ethylenes such as perchloroethylene (PCE) and trichloroethylene (TCE) are widely used as industrial solvents and degreasing agents. Because of improper handling, these highly toxic chlorinated ethylenes have been often detected from contaminated soils and groundwater. Biological PCE dechlorination activities were tested in bacterial cultures inoculated with 10 different environmental samples from sediments, sludges, soils, and groundwater. Of these, the sediment using culture (SE 2) was selected and used for establishing an efficient PCE dechlorinating enrichment culture since it showed the highest activity of dechlorination. The cathode chamber of bioelectrochemical system (BES) was inoculated with the enrichment culture and the system with a cathode polarized at -500 mV (Vs Ag/AgCl) was operated under fed-batch mode. PCE was dechlorinated to ethylene via TCE, cis-dichloroethylene, and vinyl chloride. Microbial community analysis with polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) showed that the microbial community in the enrichment culture was significantly changed during the bio-electrochemical PCE dechlorination in the BES. The communities of suspended-growth bacteria and attached-growth bacteria on the cathode surface are also quite different from each other, indicating that there were some differences in their mechanisms receiving electrons from electrode for PCE dechlorination. Further detailed research to investigate electron transfer mechanism would make the bioelctrochemical dechlorination technique greatly useful for bioremediation of soil and groundwater contaminated with chlorinated ethylenes.

Analysis of Microbial Community During the Anaerobic Dechlorination of Tetrachloroethylene (PCE) in Stream of Gimpo and Inchon Areas (경기도 김포, 인천 서구지역 소하천의 PCE 탈염소화 군집의 선별 및 다양성 분석)

  • Kim, Byung-Hyuk;Baek, Kyung-Hwa;Cho, Dea-Hyun;Sung, Youl-Boong;Ahn, Chi-Yong;Oh, Hee-Mock;Koh, Sung-Cheol;Kim, Hee-Sik
    • Korean Journal of Microbiology
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    • v.45 no.2
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    • pp.140-147
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    • 2009
  • In this study, anaerobic enrichment cultivation was performed with the sediments from the Gimpo and Inchon areas. Lactate as an electron donor and PCE as an electron acceptor was injected into the serum bottle with an anaerobic medium. After the incubation of 8 weeks, the reductive dechlorination of PCE was observed in 7 sites among 16 sites (43%). Three enrichment cultures showed completely dechlorination of PCE to ethene, while four enrichment culture showed transformation of PCE to cis-DCE. The bacterial community structure was analyzed by PCR-DGGE. Dechlorinating bacteria were detected by species-specific primers. The dominant species in seven anaerobic enrichments were found to belong to the genus of Dehalococcoides sp. and Geobacter sp., and Dehalobacter sp.

The Effect of Electron Donor on Reductive Dechlorination of Chlorophenols (염소계페놀의 환원적 탈염소화에서의 전자공여체의 영향)

  • 박대원;김성주박정극
    • KSBB Journal
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    • v.11 no.2
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    • pp.211-217
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    • 1996
  • Batch experiments were conducted to investigate the effect of electron donor on reductive dechlorination of 2,4,5-trichlorophenol by a methanogenic consortium. The methanogenic consortium was obtained from the anaerobic digester of a municipal wastewater treatment plant. The batch reactor containing methanogenic consortium was spiked with 2,4,6-trichlorophenol at 10 mg/$\ell$. Acetate, ethanol, glucose of methanol, each was added as an electron donor for methanogenic consortium. During the course of the experiments liquid samples were taken from the batch reactor to measure dechlorination rate and find the dechlorination pathway of 2,4,6-trichlorophenol. After incubation 2,4,6-trichlorophenol was first dechlorinated to 2,4-dichlorophenol and then to 4-chlorophenol. Phenol was not detected in the batch reactor the highest rate of dechlorination of 2,4,6-trichlorophenol was observed when ethanol was used as an electron donor.

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Remediation of Soil Contaminated by Chlorinated Ethylene Using Combined Application of Two Different Dechlorinating Microbial Cultures and Iron Powder (두 종류의 탈염소화미생물 배양액과 철분 첨가에 의한 염화에틸렌 오염토양 복원)

  • Lee, Tae-Ho;Kim, Hyeong-Seok
    • Journal of the Korea Organic Resources Recycling Association
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    • v.11 no.2
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    • pp.55-65
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    • 2003
  • The combined effect of bioaugmentation of dechlorinating bacterial cultures and addition of iron powder($Fe^0$ on reductive dechlorination of tetrachloroethylene(PCE) and other chlorinated ethylenes in a artificially contaminated soil slurry(60micromoles PCE/kg soil). Two different anaerobic bacterial cultures, a pure bacterial culture of Desulfitobacterium sp. strain Y-51 capable of dechlorinating PCE to cis-1,2-dechloroethylene(cis-DCE) and the other enrichment culture PE-1 capable of dechlorinating PCE completely to ethylene, were used for the bioaugmentation test. Both treatments introduced with the strain Y-51 and PE-1 culture (3mg dry cell weight/kg soil) showed conversion of PCE to cis-DCE within 40days. The treatments added with $Fe^0$(0.1-1.0%) alone to the soil slurry resulted in extended PCE dechlorination to ethylene and ethane and the dechlorination rate depended on the amount of $Fe^0$ added. The combined use of the bacterial cultures with $Fe^0$(0.1-1.0%)) showed the higher PCE dechlorination rate than the separated application and the pattern of PCE dechlorination and end-product formation was different from those of the separated application. When 0.1% of $Fe^0$ was added with the cultures, the treatments with the strain Y-51 and $Fe^0$ resulted in cis-DCE accumulation from PCE dechlorination, but the treatment with the enrichment culture and $Fe^0$ showed the more extended dechlorination via cis-DCE. These results suggested that the combined application of and the bactrial culture, specially the complete dechlorinating enrichment culture, is practically effective for bioremediation of PCE contaminated soil.

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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.

Degradation of Tetrachloroethylene (PCE) by a Dechlorinating Enrichment Culture Fixed in an Anaerobic Reactor (탈염소화 미생물 부착 혐기성 고정막 반응기에 의한 테트라클로로에틸렌(PCE)의 분해)

  • Lee Tae Ho
    • Journal of Soil and Groundwater Environment
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    • v.9 no.3
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    • pp.49-55
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    • 2004
  • A soil enrichment LYF-1 culture from a contaminated site, which could reductively dechlorinate 900 $\mu$M (ca. 150 mg/L) of tetrachloroethylene (PCE) stoichimetrically into cis-1,2-dichloroethylene (cis-DCE), was established and characterized. The enrichment culture can use yeast extract, peptone, formate, acetate, lactate, pyruvate, citrate, succinate, glucose, sucrose, and ethanol as electron donors for dechlorination of PCE. Addition of NO$_2$$^{[-10]}$ and NO$_3$$^{[-10]}$ as alternative electron acceptors showed complete inhibition of PCE dechlorination, but S$_2$O$_3$$^{-2}$ , SO$_3$$^{-2}$ and SO$_4$$^{-2}$ had no significant effect on PCE dechlorination. The enrichment culture was attached to ceramic media in an anaerobic fixed-bed reactor. The fixed-bed reactor showed more than 99% of PCE degradation in the range of PCE loading rate of 0.13-0.78 $\mu$moles/L/hr. The major end product of PCE dechlorination was cis-DCE.

Analysis of Microbial Community During the Anaerobic Dechlorination of Perchloroethylene and Trichloroethylene (Perchloroethylene과 Trichloroethylene의 혐기적 탈염소화 및 미생물 군집 분석)

  • Lee Jae-Won;Kim Byung-Hyuk;Ahn Chi-Yong;Kim Hee-Sik;Yoon Byung-Dae;Oh Hee-Mock
    • Korean Journal of Microbiology
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    • v.41 no.4
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    • pp.281-286
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    • 2005
  • In this study, the anaerobic enrichment cultivation was performed with the sediments and the dredged soils from the cities of Ulsan, Masan, Yeosu, Gwangyang, Ansan and Seongnam. Acetate as an electron donor and PCE (perchloroethylene) or TCE (trichloroethylene) as an electron acceptor were injected into the serum bottle with an anaerobic medium. After the incubation of 12 weeks, the removal efficiency of PCE was highest at $70\%$ in the treatment with the sediment of Ulsan. Also, the bacterial community structure was analyzed by D-DGGE (double denatured gradient gel electrophoresis) through PCR-based 16S rDNA approaches. The dominant species id the anaerobic enrichment were found to belong to the genus of Desulfovibrio.

Evaluation of Microbial PCE Reductive Dechlorination Activity and Microbial Community Structure using PCE-Contaminated Groundwater in Korea (사염화에틸렌(PCE)으로 오염된 국내 4개 지역 지하수 내 생물학적 PCE 탈염소화 활성 및 미생물 군집의 비교)

  • Kim Young;Kim Jin-Wook;Ha Chul-Yoon;Kwon Soo-Yeol;Kim Jung-Kwan;Lee Han-Woong;Ha Joon-Soo;Park Hoo-Won;Ahn Young-Ho;Lee Jin-Woo
    • Journal of Soil and Groundwater Environment
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    • v.10 no.2
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    • pp.52-58
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    • 2005
  • In Korea, little attention has been paid to microbial perchloroethylene (PCE) and/or trichloroethylene (TCE) dechlorination activity and identification of microorganisms involved in PCE reductive dechlorination at a PCE-contaminated aquifer. We performed microcosm tests using the groundwater samples from 4 different contaminated sites (i.e. Changwon A, Changwon B, Bucheon and Yangsan) to assess PCE reductive dechlorination activity. We also adapted molecular techniques to screen what types of known reductive dechlorinators are present at the PCE-contaminated aquifers. In the Changwon A and Changwon B active microcosms where potential electron donors such as sodium propionate, sodium lactate, sodium butyrate, and sodium fumarate, were added, ethylene, an end-product of complete reductive dechlorination of PCE, was detected after a period of 90 days of incubation. In the Bucheon and Yangsan active microcosms, cis-1,2-dichloroethylene (c-DCE) was accumulated without the production of vinyl chloride (VC) and ethylene. Molecular techniques were used to evaluate the microbial community structures in the Changwon B and Yangsan aquifer. We found two sequence types that were closely related to a known PCE to ethylene dechlorinator, named uncultured bacterium clone DCE47, in the Changwon B site clone library. However, in the Yangsan site clone library, no sequence type was closely related to known PCE dechlorinators reported. It is plausible that microorganisms being capable of completely dechlorinating PCE to ethylene may be present in the Changwon B site aquifer. In this study we find that complete PCE reductive dechlorinators are present at some PCE-contaminated sites in Korea. In an engineering point of view this information makes it feasible to apply a biological reductive dechlorination process for remediating PCE- and/or TCE-contaminated aquifers in Korea.