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Comparative study of methanol, butyrate, and hydrogen as electron donors for long‐term dechlorination of tetrachloroethene in mixed anerobic cultures

Comparative study of methanol, butyrate, and hydrogen as electron donors for long‐term... This study examined the ability of different electron donors (i.e., hydrogen, methanol, butyrate, and yeast extract) to sustain long‐term (500 days) reductive dechlorination of tetrachloroethene (PCE) in anerobic fill‐and‐draw bioreactors operated at 3:1 donor:PCE ratio (defined on a total‐oxidation basis for the donor). Initially (i.e., until approximately day 80), the H2‐fed bioreactor showed the best ability to completely dechlorinate the dosed PCE (0.5 mmol/L) to ethene whereas, in the presence of methanol, butyric acid or no electron donor added (but low‐level yeast extract), dechlorination was limited by the fermentation of the organic substrates and in turn by H2 availability. As the study progressed, the H2‐fed reactor experienced a diminishing ability to dechlorinate, while more stable dechlorinating activity was maintained in the reactors that were fed organic donors. The initial diminished ability of the H2‐fed reactor to dechlorinate (after about 100 days), could be partially explained in terms of increased competition for H2 between dechlorinators and methanogens, whereas other factors such as growth‐factor limitation and/or accumulation of toxic and/or inhibitory metabolites were shown to play a role for longer incubation periods (over 500 days). In spite of decreasing activity with time, the H2‐fed reactor proved to be the most effective in PCE dechlorination: after about 500 days, more than 65% of the added PCE was dechlorinated to ethene in the H2‐fed reactor, versus 36%, 22%, and <1% in the methanol‐fed, butyrate‐fed, and control reactors, respectively. © 2005 Wiley Periodicals, Inc. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Biotechnology and Bioengineering Wiley

Comparative study of methanol, butyrate, and hydrogen as electron donors for long‐term dechlorination of tetrachloroethene in mixed anerobic cultures

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References (27)

Publisher
Wiley
Copyright
Copyright © 2005 Wiley Periodicals, Inc., A Wiley Company
ISSN
0006-3592
eISSN
1097-0290
DOI
10.1002/bit.20569
pmid
16007584
Publisher site
See Article on Publisher Site

Abstract

This study examined the ability of different electron donors (i.e., hydrogen, methanol, butyrate, and yeast extract) to sustain long‐term (500 days) reductive dechlorination of tetrachloroethene (PCE) in anerobic fill‐and‐draw bioreactors operated at 3:1 donor:PCE ratio (defined on a total‐oxidation basis for the donor). Initially (i.e., until approximately day 80), the H2‐fed bioreactor showed the best ability to completely dechlorinate the dosed PCE (0.5 mmol/L) to ethene whereas, in the presence of methanol, butyric acid or no electron donor added (but low‐level yeast extract), dechlorination was limited by the fermentation of the organic substrates and in turn by H2 availability. As the study progressed, the H2‐fed reactor experienced a diminishing ability to dechlorinate, while more stable dechlorinating activity was maintained in the reactors that were fed organic donors. The initial diminished ability of the H2‐fed reactor to dechlorinate (after about 100 days), could be partially explained in terms of increased competition for H2 between dechlorinators and methanogens, whereas other factors such as growth‐factor limitation and/or accumulation of toxic and/or inhibitory metabolites were shown to play a role for longer incubation periods (over 500 days). In spite of decreasing activity with time, the H2‐fed reactor proved to be the most effective in PCE dechlorination: after about 500 days, more than 65% of the added PCE was dechlorinated to ethene in the H2‐fed reactor, versus 36%, 22%, and <1% in the methanol‐fed, butyrate‐fed, and control reactors, respectively. © 2005 Wiley Periodicals, Inc.

Journal

Biotechnology and BioengineeringWiley

Published: Sep 20, 2005

Keywords: competition; electron donors; ethene; long‐term dechlorination; PCE

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