Field-scale demonstration of induced biogeochemical reductive dechlorination at Dover Air Force Base, Dover, Delaware

Abstract

Biogeochemical reductive dechlorination (BiRD) is a new remediation approach for chlorinated aliphatic hydrocarbons (CAHs). The approach stimulates common sulfate-reducing soil bacteria, facilitating the geochemical conversion of native iron minerals into iron sulfides. Iron sulfides have the ability to chemically reduce many common CAH compounds including PCE, TCE, DCE, similar to zero valent iron (Fe 0 ). Results of a field test at Dover Air Force Base, Dover, Delaware, are given in this paper. BiRD was stimulated by direct injection of Epson salt (MgSO 4 ·7H 2 O) and sodium (L) lactate (NaC 3 H 5 O 3 ) in five injection wells. Sediment was sampled before and 8 months after injection. Significant iron sulfide minerals developed in the sandy aquifer matrix. From ground water analyses, treatment began a few weeks after injection with up to 95% reduction in PCE, TCE, and cDCE in less than 1 year. More complete CAH treatment is likely at a larger scale than this demonstration.

Stable carbon isotope analysis to distinguish biotic and abiotic degradation of 1,1,1-trichloroethane in groundwater sediments

“…sulfate and donor addition), as previously suggested for chlorinated ethenes by Kennedy et al (2006), or of direct abiotic degradation (FeS addition) may be a viable option e.g. prior to stimulation/bioaugmentation for enhanced reductive dechlorination of chlorinated ethenes.…”

Abiotic degradation of chlorinated ethanes and ethenes in water

“…BiRD is stimulated by addition sulphate and organic carbon. Iron, typically mineral, is usually naturally present in the aquifer but might be also supplemented (Kennedy et al 2006b). The advantages of BiRD are rapid dechlorination and no generation of less-chlorinated daughter products (Kennedy et al 2006a).…”

Impact of iron sulfide transformation on trichloroethylene degradation

“…Sulfur-and iron-reducing conditions typically encountered in permeable reactive barriers (PRBs), for example, favor the formation of iron sulfides, and FeS precipitation has been reported in PRB systems constructed with zero valent iron (ZVI) and in biowall systems constructed with plant mulch (Benner et al, 1999;Herbert et al, 2000;Phillips et al, 2000;Furukawa et al, 2002). FeS formation is also expected in landfills, enhanced bioremediation sites, and other sites where natural attenuation of groundwater contaminants is tracked in anoxic aquifers (e.g., KriegmanKing and Reinhard, 1994;Burton and Phillips, 2005;Burton et al, 2006;Kennedy et al, 2006a).…”