Investigating the Biostimulating Effects of ESO Addition to a TCE Contaminated Site

Abstract

Remediation of chlorinated ethene contaminated sites presents a problem for the environmental industry. Many innovative technologies exist to remove these chemicals from the subsurface; however, most of these technologies require extensive time and incur significant cost. A technology called bioremediation utilizes microorganisms to break down contaminants such as perchloroethene (PCE), trichloroethene (TCE), dichloroethene (DCE), and vinyl chloride (VC) to non-toxic compounds in a process called reductive dechlorination.

Microorganisms that are capable of dechlorination usually require reducing conditions as well as bioavailable hydrogen and carbon sources. Emulsified vegetable oil has emerged as a cost-effective source of degradable organic matter to facilitate reductive dechlorination in the subsurface. Through Æ Ã -oxidation, microorganisms can break down the long chain fatty acids in vegetable oil into smaller fatty acids such as acetate, propionate, and butyrate. The fermentation of the oil provides reduced conditions as well as a slow release of hydrogen and carbon into the subsurface.

This study consisted of an evaluation the effectiveness of emulsified vegetable oil in stimulating reductive dechlorination using sixteen laboratory microcosms constructed from soil and groundwater from an aquifer contaminated with TCE located at the Naval Weapons Station in Charleston, South Carolina. Each microcosm was monitored for chloroethenes, volatile fatty acids, long chain fatty acids, and total carbon on a weekly basis. Results show successful fermentation of fatty acids and reduced conditions favorable for dechlorination.