Push-Pull Tests for Evaluating the Aerobic Cometabolism of Chlorinated Aliphatic Hydrocarbons: Cost & Performance Report

Aerobic cometabolism is a promising technology for in situ remediation of chlorinated aliphatic hydrocarbons (CAH) at Department of Defense (DoD) sites. Low-cost methods are needed for generating the data required to design field-scale systems. This report describes a newly developed single-well technology for evaluating the feasibility of using in situ aerobic cometabolic processes to treat groundwater contaminated with chlorinated solvent mixtures. The Environmental Security Technology Certification Program (ESTCP) supported a 3-year field study to investigate single-well tests to evaluate the potential for aerobic cometabolism of CAHs. Tests were performed at McClellan Air Force Base (McAFB), California, using propane as the cometabolic substrate, and at Fort Lewis Logistics Center, Washington, using toluene as the cometabolic substrate. McAFB was selected as the demonstration site since it has significant CAH groundwater contamination, and it was the site of the ESTCP demonstration of cometabolic air sparging (CAS) with propane as a growth substrate. In the Fort Lewis demonstration, toluene was evaluated as a cometabolic growth substrate, and different surrogates and inhibitors were evaluated. The single-well test methods were developed and demonstrated to determine (1) the transport characteristics of nutrients, substrates, and CAHs and their transformation products; (2) the capability of indigenous microorganisms to utilize selected substrates and transform targeted contaminants and surrogate compounds; (3) the rates of substrate utilization and contaminant transformation.

The original document contains color images. Project No. ER-9921.