Comparison of butyric acid, ethanol, lactic acid, and propionic acid as hydrogen donors for the reductive dechlorination of tetrachloroethene

Article Abstract:

Dechlorinators enjoy an advantage over methanogens with the delivery of hydrogen via donors that are fermented only under low hydrogen partial pressures in competing for the evolved H2. This approach for selective enhancement of dechlorination is based on previous findings that dechlorinators can utilize H2 at lower concentrations than can methanogens. Electron donors were added to an anaerobic dechlorinating culture and the resulting patterns of H2 production/comnsumption and the distribution of H2 use between competing processes of dechlorination and methanogenesis were examined.

Analysis, Electron donor-acceptor complexes

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Modeling the production of and competition for hydrogen in a dechlorinating culture

Article Abstract:

Model simulations of mechanisms involved in dechlorinating reveals that important considerations to ensure optimal dechlorination include quality of hydrogen donor and quantity. Fermentation of electron donors and competition for freed H2 between hydrogenotrophic tetrachloroethene dechlorinators and methanogens is modeled and results show that excessive levels of rapidly fermented high H2-level-generating donors results in the eventual failure of dechlorination instead of competition being overcome.

Research and Development in the Physical, Engineering, and Life Sciences, Other Commercial and Service Industry Machinery Manufacturing, Ecological Sciences, Service industry machinery, not elsewhere classified, Chlorinators & Related Equip, Methods, Bioremediation, Environmental sciences, Waste management, Methanobacteriaceae, Methanogens, Chlorine compounds

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Comparative kinetics of hydrogen utilization for reductive dechlorination of tetrachloroethene and methanogenesis in an anaerobic enrichment culture

Article Abstract:

The kinetics of hydrogen (H2) utilization by methanogens and dechlorinators were measured by measurement of their respective half-velocity constants (Ks) at 35 degrees Centigrade under agitated conditions. The half-velocity constant for methanogenesis was 960+/-180 and 100+/-50 nM for dechlorination. An analysis of the effect of formate/H2 lyase activity on Ks(H2) revealed that only methanogenesis is affected but not dechlorination.

Hydrogen, Perchloroethylene

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