VEGETABLE OIL INJECTION FOR IN SITU REMEDIATION OF TCE: PHYSICAL/CHEMICAL EFFECTS

Chlorinated ethenes are among the most widely detected groundwater contaminants. The addition of vegetable oil (VegOil) into the groundwater to enhance the biodegradation of chlorinated ethenes via reductive dechlorination may have advantages over alternative carbon substrates due to its low cost and the potential for slow release over time. The physical and chemical interaction of VegOil with chlorinated ethenes (both dissolved and non-aqueous phase liquids) was experimentally evaluated in batch and flow tests. If the VegOil mixes with trapped residual DNAPLs in the subsurface, the viscosity of the NAPL will be higher than the pure DNAPL and the interfacial tension will generally be lower. Therefore net effects on NAPL mobility are uncertain. Significant partitioning of the chlorinated ethenes into VegOil occurred which can serve to help attenuate contaminant plumes. Results indicate that VegOil addition should be beneficial for risk management at sites contaminated with chlorinated ethenes due to its physical/chemical effects, in addition to the potential for enhanced biodegradation.