Transformation of carbon tetrachloride under sulfate reducing conditions |
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Authors: | Jappe H de Best E Salminen Hans J Doddema Dick B Janssen Wim Harder |
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Institution: | (1) TNO Environmental Technology and Process Engineering Division, Department of Environmental Biotechnology, P.O. Box 342, 7300 AH Apeldoorn, The Netherlands;(2) Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands |
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Abstract: | The removal of carbon tetrachloride under sulfate reducing conditions was studied in an an aerobic packed-bed reactor. Carbon
tetrachloride, up to a concentration of 30 μM, was completely converted. Chloroform and dichloromethane were the main transformation
products, but part of the carbon tetrachloride was also completely dechlorinated to unknown products. Gram-positive sulfate-reducing
bacteria were involved in the reductive dechlorination of carbon tetrachloride to chloroform and dichloromethane since both
molybdate, an inhibitor of sulfate reduction, and vancomycin, an inhibitor of gram-positive bacteria completely inhibited
carbon tetrachloride transformation. Carbon tetrachloride transformation by these bacteria was a cometabolic process and depended
on the input of an electron donor and electron acceptor (sulfate). The rate of carbon tetrachloride transformation by sulfate
reducing bacteria depended on the type of electron donor present. A transformation rate of 5.1 nmol·ml-1·h-1 was found with ethanol as electron donor. At carbon tetrachloride concentrations higher than18 μM, sulfate reduction and
reductive dechlorination of carbon tetrachloride decreased and complete inhibition was observed at a carbon tetrachloride
concentration of 56.6 μM. It is not clear what type of microorganisms were involved in the observed partial complete dechlorination
of carbon tetrachloride. Sulfate reducing bacteria probably did not play a role since inhibition of these bacteria with molybdate
had no effect on the complete dechlorination of carbon tetrachloride.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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Keywords: | anaerobic biotransformation carbon tetrachloride electron donor sulfate reduction transformation products toxicity |
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