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Groundwater contaminated with 1000-2500 µg/L chlorinated ethenes (trichloroethene [TCE], dichloroethene [DCE], vinyl chloride [VC]) was treated by in situ bioaugmentation with a specialized microorganism, Burkholderia cepacia ENV435. The strain was selected for its limited adhesion to aquifer solids and its ability to degrade chlorinated ethenes in the absence of inducing cosubstrates. Approximately 550 L of the toluene ortho-monooxygenaseproducing ENV435 culture (∼100 g/L) was injected along with oxygen (20 mg/L) into a semi-confined silty-sand aquifer (test plot). An equal volume of basal salts medium was simultaneously injected into an adjacent control plot. The plots each measured 4.6 m wide by 12 m long, were spaced 9.2 m apart, and contained 18 multilevel monitoring wells. Groundwater ENV435 concentrations exceeded 1 × 10 8 cfu/mL 7 days after injection, and the strain traveled the 12 m from injection to recovery well with an average linear velocity of 0.37 to 0.54 m/day. By comparison, a bromide tracer passed through the same formation at a rate of 0.53 to 0.68 m/day. In one trial, the total mass of TCE, DCE, and VC in the treated area was reduced by as much as 78% within 2 days after injecting the organisms.

Xpert Design & Diagnostics, LLC (XDD), & Conestoga‐Rovers and Associates (CRA) conducted a biosparging field trial at a Superfund site in New Jersey. The biosparging field trial proved that biosparging with oxygen was very effective in promoting the biological destruction of benzene. The approximately 265‐day period of oxygen injection successfully reduced benzene concentrations by several orders of magnitude, or even to non‐detect values, at least 40 feet from the point of injection. Through co‐precipitation of arsenic with oxidized iron, biosparging also effectively reduced total concentrations of arsenic and iron in groundwater. Based on the results of the biosparging field trial, the final remedy for the site has been amended to include the use of biosparging technology as an alternative to groundwater pumping and aboveground treatment in select locations. © 2001 John Wiley & Sons,Inc.