Comparative Kinetics of Hydrogen Utilization for Reductive Dechlorination of Tetrachloroethene and Methanogenesis in an Anaerobic Enrichment Culture
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- 作者：Concordia R. Smatlak ; James M. Gossett ; and Stephen H. Zinder
- 刊名：Environmental Science & Technology
- 出版年：1996
- 出版时间：September 1996
- 年：1996
- 卷：30
- 期：9
- 页码：2850 - 2858
- 全文大小：649K
- 年卷期：v.30,no.9(September 1996)
- ISSN：1520-5851
文摘
Anaerobic microorganisms that reductively dechlorinate tetrachloroethene (PCE) must often competewith methanogens for H2. This study comparedthekinetics of H2 utilization between the two typesoforganisms at 35 
C under conditions of continuousagitation. Limiting levels of H2 wereadministeredto 160-mL serum bottles seeded with a PCE/butyric acidenrichment culture; H2, methane, and vinylchloridewere tracked over time using headspace samples.Measured half-velocity constants with respect toH2-Ks(H2) values ± 95% CI-formethanogenesis anddechlorination were 960 ± 180 and 100 ± 50 nM,respectively. Mass-transfer equations were usedto calculate aqueous H2 concentrations at thehalf-velocity point from headspace measurements. Thepossible effect on Ks(H2)values arising from interconversion between H2 and formate through anactiveformate/H2 lyase system was examined bycomparingresults from formate-fed and H2-fed bottles.Onlymethanogens in the culture were apparently capableof using formate; hence, the measured methanogenicKs(H2) was dependent on whichelectron donor wasadministered. The nearly 10-fold difference inKs(H2) between methanogens and dechlorinatorssuggeststhat the deliberate choice of an electron donorwhose fermentation results in a slow, steady, and low-level release of H2 over time could maximizedechlorination potential while minimizing methanogeniccompetition for H2.
C under conditions of continuousagitation. Limiting levels of H2 wereadministeredto 160-mL serum bottles seeded with a PCE/butyric acidenrichment culture; H2, methane, and vinylchloridewere tracked over time using headspace samples.Measured half-velocity constants with respect toH2-Ks(H2) values ± 95% CI-formethanogenesis anddechlorination were 960 ± 180 and 100 ± 50 nM,respectively. Mass-transfer equations were usedto calculate aqueous H2 concentrations at thehalf-velocity point from headspace measurements. Thepossible effect on Ks(H2)values arising from interconversion between H2 and formate through anactiveformate/H2 lyase system was examined bycomparingresults from formate-fed and H2-fed bottles.Onlymethanogens in the culture were apparently capableof using formate; hence, the measured methanogenicKs(H2) was dependent on whichelectron donor wasadministered. The nearly 10-fold difference inKs(H2) between methanogens and dechlorinatorssuggeststhat the deliberate choice of an electron donorwhose fermentation results in a slow, steady, and low-level release of H2 over time could maximizedechlorination potential while minimizing methanogeniccompetition for H2.