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DISTRIBUTION OF DEHALOCCOIDES AT DOD CHLORINATED SOLVENT SITES-DO YOU NEED TO BIOAUGMENT?
Citation:
Kampbell*, D H., J T. Wilson*, AND X. Lu. DISTRIBUTION OF DEHALOCCOIDES AT DOD CHLORINATED SOLVENT SITES-DO YOU NEED TO BIOAUGMENT?
Impact/Purpose:
To inform the public.
Description:
Dehaloccoides is the only organism that has been shown to completely dechlorinate TCE, cis-DCE, and vinyl chloride to ethene or ethane (Maymo-Gatell et al., 2001; He et al., 2003a; He et al., 2003b). Dehaloccoides is a naturally occurring organism, with a world-wide distribution (Hendrickson et al., 2002). The presence of Dehaloccoides in an aquifer can be confirmed by analyzing a water sample for DNA from Dehaloccoides using the polymerase chain reaction (Fennell et al., 2001; Hendrickson et al., 2002). There is considerable discussion among the ground water remediation community on the need to bioaugment sites with strains of Dehaloccoides sp. to stimulate biological reductive dechlorination (Nyer et al., 2003; Major et al., 2003; Lendvay et al., 2003). Opinions on the value of bioaugmentation often depend on the personal experience of the ground water scientist or engineer involved.
To determine whether bioaugmentation with Dehaloccoides strains was generally needed for success at sites where biological reductive dechlorination was an important mechanism, existing remediation efforts were sampled that had not been augmented with Dehaloccoides. At three sites soybean oil was injected to stimulate dechlorination, at one site molasses was injected, and at one site plant mulch was installed in a passive reactive barrier. Two of the sites were passive reactive barriers constructed with zero valence iron. Iron zero releases hydrogen as it reacts with water. These iron walls should also stimulate biological reductive dechlorination. Two sites with physical treatment systems were included as negative controls. The presence of adequate populations of Dehaloccoides in ground water at a site that had not been augmented with Dehaloccoides would indicate that bioaugmentation was not necessary at the site.