Evaluation of Microbial Reductive Dechlorination in Treated Source ZonesEPA Grant Number: U916150
Title: Evaluation of Microbial Reductive Dechlorination in Treated Source Zones
Investigators: Amos, Benjamin K.
Institution: Duke University
EPA Project Officer: Jones, Brandon
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $139,878
RFA: STAR Graduate Fellowships (2003) Recipients Lists
Research Category: Fellowship - Environmental Engineering , Academic Fellowships , Engineering and Environmental Chemistry
The overall objective of this research project is to explore the microbial reductive dechlorination process as a viable polishing step for the removal of residual dense nonaqueous phase liquids (DNAPLs) after the initial physical-chemical treatment. Chlorinated solvents are major groundwater contaminants and are of particular concern because they form DNAPLs, which are long-term, continuous sources of contamination. Removal of source zones is critical before lasting treatment of the dissolved contaminants in the plume can be achieved. Considerable research has focused on the development and demonstration of physical-chemical technologies (e.g., surfactant flushing) for DNAPL mass recovery from contaminated source zones. Although promising, no approach removes 100 percent of the source zone contaminant mass, resulting in continued and persistent contaminant elution and plume formation after treatment. The specific objective of this research project is to determinate dechlorination rates and product formation patterns under saturated conditions and in the presence of free-phase perchloroethylene using pure and mixed bacterial cultures.
After the initial screening, the most promising cultures will be tested to promote complete contaminant removal in one-dimensional aquifer columns following physical-chemical treatment. Two-dimensional aquifer flow cells will be constructed to further evaluate the feasibility of the sequential approach for source zone remediation. Culture-independent molecular approaches will be used to monitor the distribution of the key populations in the aquifer columns and flow cells. The research outlined above is relevant because it will provide convincing evidence to the remediation community that microbial reductive dechlorination is a suitable posttreatment strategy for the removal of residual DNAPL from contaminated source zones.
The results of this research project could increase the effectiveness of current remediation strategies by combining both physical and biological remediation technologies, aiding in the evaluation, reduction, and management of risk at chloroethene-contaminated sites, and reducing the remediation cost.