The effectiveness of whey as an electron donor that stimulates bioremediation and enhances dissolution of trichloroethene (TCE) dense nonaqueous phase liquid (DNAPL) was investigated. Laboratory experiments were conducted to evaluate increased mass transfer of TCE from the DNAPL to the aqueous phase in abiotic batch microcosms amended with several concentrations of whey, and in abiotic columns using high-and low-concentration whey mixtures. The effective solubility of TCE was a factor of 6 higher in microcosms amended with 10% w/w whey compared to 1% w/w whey or nanopure water. Increased aqueous-phase concentrations of TCE were a function of both the concentration of whey and time. In the columns, a factor of 5 increase in TCE concentrations was observed in the effluent during amendment with 10% w/w whey compared to potable water and 1% w/w whey. A field study involving three whey injections was performed at a site that had been actively undergoing bioremediation in a residual source area using lactate for 5 years. Results of the field test show a factor of 3 increase in total molar concentrations of chloroethenes and ethene following injection of 10% w/w whey compared to 5% lactate. In addition, complete dechlorination of TCE to ethene continued.

Idaho National Laboratory's Test Area North is the site of a trichloroethene (TCE) plume resulting from waste injections. Previous investigations revealed that TCE was being attenuated relative to two codisposed internal tracers, tritium and tetrachloroethene, with a half-life of 9 to 21 years. Biological attenuation mechanisms were investigated using a novel suite of assays, including enzyme activity probes designed for the soluble methane monooxygenase (sMMO) enzyme. Samples were analyzed for chlorinated solvents, tritium, redox parameters, primary substrates, degradation products, bacterial community methanotrophic potential, and bacterial DNA. The enzyme probe assays, methanotrophic enrichments and isolations, and DNA analysis documented the presence and activity of indigenous methanotrophs expressing the sMMO enzyme. Three-dimensional groundwater data showed plume-wide aerobic conditions, with low levels of methane and detections of carbon monoxide, a by-product of TCE cometabolism. The TCE half-life attributed to aerobic cometabolism is 13 years relative to tritium, based on the tracer-corrected method. Similarly, a half-life of 8 years was estimated for cisdichloroethene (DCE). Although these rates are slower than most anaerobic degradation processes, they can be significant for large plumes. This investigation is believed to be the first documentation of intrinsic aerobic TCE and DCE cometabolism in an aquifer by indigenous methanotrophs.

Environmental Laboratory, involves a trichloroethene (TCE) residual source area in a deep, fractured basalt aquifer that has been undergoing enhanced bioremediation since January 1999.Complete dechlorination from TCE to ethene was documented within nine months of operation, and sodium lactate injections were shown to enhance TCE mass transfer from the residual source.Since that time, optimization of injection strategies has maintained efficient dechlorination while demonstrating accelerated cleanup at a lower cost by changing to a whey powder amendment that solubilizes DNAPL.

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