Temperature dependence of anaerobic TCE-dechlorination in a highly enriched Dehalococcoides-containing culture

Abstract

Temperature dependence of reductive trichloroethene (TCE) dechlorination was investigated in an enrichment culture (KB-1™), using lactate or propionate as electron donors at a temperature interval from 4 to 60 °C. Dechlorination was complete to ethene at temperatures between 10 and 30 °C (lactate-amended) and between 15 and 30 °C (propionate-amended). Dechlorination stalled at cis-1,2-dichloroethene ( cDCE) at 4 °C (lactate-amended), at and below 10 °C (propionate-amended), and at 40 °C with both electron donors. No dechlorination of TCE was observed at 50 and 60 °C. Concentrations of Dehalococcoides had increased or remained constant after 15 days of incubation at temperatures involving complete dechlorination to ethene. Temperature dependence of dechlorination rates was compared using zero order degradation kinetics and a Monod growth-rate model for multiple electron acceptor usage with competition. Maximum growth rates ( μ) and zero order degradation rates were highest for TCE dechlorination at 30 °C with lactate as substrate ( μ TCE of 7.00±0.14 days −1). In general, maximum growth rates and dechlorination rates of TCE were up to an order of magnitude higher than rates for utilization of cis-dichloroethene ( cDCE, μ c DCE up to 0.17±0.02 days −1) and vinyl chloride (VC, μ VC up to 0.52±0.09 days −1). Temperature dependence of maximum growth rates and degradation rates of cDCE and VC were similar and highest at 15–30 °C, with growth rates on cDCE being lower than on VC. This study demonstrates that bioaugmentation of chlorinated ethene sites may be more efficient at elevated temperatures.