Evaluation of biostimulation using CENSUS qPCR quantification of Dehalococcoides and vinyl chloride reductase genes
The study site was a shallow aquifer impacted by chlorinated solvents. Historical groundwater monitoring indicated an accumulation of cis-dichloroethene (DCE). A baseline sampling event including CENSUS qPCR quantification of Dehalococcoides and vinyl chloride reductase genes was conducted to assess the potential for complete reductive dechlorination of TCE to ethene under existing site conditions and evaluate the need for electron donor injection.
- Dehalococcoides and vinyl chloride reductase genes were detected in baseline samples but at concentrations below the threshold concentration of 1.00E+04 Dehalococcoides cells/mL recommended by Lu et al. (2006) for generally effective rates of reductive dechlorination.
- Groundwater total organic carbon (TOC) and volatile fatty acid (VFA) concentrations were low suggesting Dehalococcoides populations and therefore reductive dechlorination were limited by a lack of suitable electron donors.
Remedy Performance Monitoring
A commercial electron donor was injected in the source area to stimulate growth of halorespiring bacteria and promote complete reductive dechlorination. CENSUS® qPCR quantification of Dehalococcoides and functional genes (tceA, bvcA, vcrA) was performed to monitor remedy performance.