Bioremediation of Chlorinated Ethenes in Fractured Bedrock and Associated Changes in Dechlorinating and Nondechlorinating Microbial Populations

Citations Over TimeTop 10% of 2014 papers

Abstract

The use of enhanced in situ anaerobic bioremediation (EISB) and bioaugmentation in fractured bedrock is limited compared to its use in granular media. We evaluated EISB for the treatment of trichloroethene (TCE)-impacted groundwater in fractured carbonate rock at a site in Southern Ontario, Canada, with cool average groundwater temperature (∼ 13 °C). Borehole-connectivity, contaminant concentrations, and groundwater properties were investigated. Changes in dechlorinating and nondechlorinating populations (fermenters, acetogens, methanogens, and sulfate reducers) were assessed via quantitative PCR (qPCR). During biostimulation with ethanol, concentrations of TCE daughter products cis-dichloroethene (cDCE) and vinyl chloride (VC) decreased in association with an enrichment of vcrA (VC reductive dehalogenase)-carrying Dehalococcoides, whereas ethene production was only moderate. Following bioaugmentation with the mixed dechlorinating culture KB-1, greater concentrations of chloride-a product of dechlorination-was observed in most wells; in addition, ethene production increased significantly in monitoring well locations that had strong hydraulic connectivity to the groundwater recirculation system, while Dehalococcoides and vcrA concentrations did not appreciably vary. Interestingly, increases of 3-4 orders of magnitude of an ethanol-fermenting Bacteroidetes population also present in KB-1 were correlated to improved conversion to ethene, an observation which suggests there could be a causal relationship-for example, better syntrophy and/or synergy among bacterial populations.

Related Papers

• → Bioreactive Barriers: A Comparison of Bioaugmentation and Biostimulation for Chlorinated Solvent Remediation(2003)318 cited
• → PCB dechlorination enhancement in Anacostia River sediment microcosms(2009)73 cited
• → Selective Enrichment Yields Robust Ethene-Producing Dechlorinating Cultures from Microcosms Stalled at cis-Dichloroethene(2014)43 cited
• → Effects of bioaugmentation on enhanced reductive dechlorination of 1,1,1-trichloroethane in groundwater: a comparison of three sites(2013)15 cited
• → Dehalococcoides abundance and alternate electron acceptor effects on large, flow-through trichloroethene dechlorinating columns(2015)10 cited