Comparison of Butyric Acid, Ethanol, Lactic Acid, and Propionic Acid as Hydrogen Donors for the Reductive Dechlorination of Tetrachloroethene

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• 作者：Donna E. Fennell ; James M. Gossett ; and Stephen H. Zinder
• 刊名：Environmental Science & Technology
• 出版年：1997
• 出版时间：March 1997
• 年：1997
• 卷：31
• 期：3
• 页码：918 - 926
• 全文大小：328K
• 年卷期：v.31,no.3(March 1997)
• ISSN：1520-5851

文摘

Previous studies indicated that dechlorinators can utilizeH₂ at lower concentrations than can methanogens.Thissuggests a strategy for selective enhancement ofdechlorination-managing H₂ delivery so as to impartacompetitive advantage to dechlorinators. FourH₂donors-butyric and propionic acids, which can only befermented when the H₂ partial pressure is lower than10^-3.5or 10^-4.4 atm, respectively, and ethanol andlactic acid,which are readily fermented at H₂ partial pressures2-3orders of magnitude higher-were administered toanaerobicmixed cultures. Comparison of the resultingenrichmentcultures during time-intensive, short-term tests showedsignificant differences in patterns of donor degradation,H₂ production and use, and distribution of reductionequivalentsbetween dechlorination and competing methanogenesis.Amendment with butyric and propionic acids resulted inlessmethanogenesis than did amendment with ethanol orlactic acid, which generated much higher H₂ levels.Ethanoldid not support complete dechlorination during short-term tests, but it was a viable donor over long-termtestingbecause a portion was converted to a pool of slowlydegraded propionic acid and because during long-termtests,cultures were routinely co-amended with pre-fermentedyeast extract, a source of slowly fermented volatile fattyacids.Understanding the fate of electron donors and theirfermentation products is an important component inunderstanding dechlorinating communities.