Competition for Hydrogen within a Chlorinated Solvent Dehalogenating Anaerobic Mixed Culture

Use of an appropriate hydrogen level is necessary to favor dehalogenation of chlorinated solvents, such as tetrachloroethene (PCE) and trichloroethene (TCE), over other hydrogen using processes. This study examined the competition between dehalogenators and other microorganisms occurring in a benzoa...

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Bibliographic Details
Published in:Environmental science & technology 1998-11, Vol.32 (22), p.3591-3597
Main Authors: Yang, Yanru, McCarty, Perry L
Format: Article
Language:English
Subjects:
Biodegradation of pollutants
Biological and medical sciences
Biotechnology
Chemical reactions
Chemistry
Earth sciences
Earth, ocean, space
Engineering and environment geology. Geothermics
Environment and pollution
ethene
Exact sciences and technology
Fundamental and applied biological sciences. Psychology
Hydrogen
Industrial applications and implications. Economical aspects
Methane
Microorganisms
Oxidation
Pollution, environment geology
Reduction
Remediation
Solvents
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Summary:Use of an appropriate hydrogen level is necessary to favor dehalogenation of chlorinated solvents, such as tetrachloroethene (PCE) and trichloroethene (TCE), over other hydrogen using processes. This study examined the competition between dehalogenators and other microorganisms occurring in a benzoate-acclimated dehalogenating methanogenic mixed culture. Results show that the dehalogenators competed best against methanogens and homoacetogens when the hydrogen level was maintained between 2 and 11 nM. The 2 nM hydrogen concentration represents the lower threshold value found here for cis-1,2-dichloroethene (cis-DCE) dehalogenation. The usefulness of this hydrogen range was further confirmed with both batch-fed and continuously-fed reactors. In batch studies, three times more ethene was produced from dehalogenation of cis-DCE using propionate than benzoate as electron donor, while benzoate produced three times more methane than propionate. A three times greater hydrogen utilization efficiency for dehalogenation was obtained with a CSTR than with batch reactors when benzoate was used as substrate because a constant hydrogen concentration in the appropriate range could be maintained with the CSTR. These results suggest different approaches that might be used to favor dehalogenators in competition with other microorganisms.
ISSN:0013-936X
1520-5851
DOI:10.1021/es980363n