Objective:

This project will conduct a quantitative demonstration of dense non-aqueous phase liquid (DNAPL) source zone bioremediation in a cost-effective manner with a known initial DNAPL mass and composition. More specifically, the project's objectives are to (1) provide a basis for critical analysis of the extant field data from ongoing tests to determine if source zone longevity is biologically impacted at these sites; (2) allow for the characterization of the microbial ecology in a NAPL source zone using molecular techniques for tracking and enumerating critical populations; (3) allow for the assessment of differences in source zone architecture on bioremediation potential; and (4) develop a basis for cost and effectiveness considerations at field scales.

Technology Description:

Operation of two parallel tanks with one serving as an independent uninoculated control will determine the impact of an actively dechlorinating culture on flux of contamination from the DNAPL to the aqueous phase. Furthermore, use of this experimental controlled release system (ECRS) for assessing the potential for DNAPL source zone bioremediation provides a means for avoiding many of the difficulties inherent in field-scale work. These difficulties include the adequate estimation of the mass and composition of DNAPL initially present and the high costs generally associated with experimental work at this scale.

Expected Benefits:

Assessing the potential of biological methods in source zone remediation in the subsurface suffers from the lack of suitable metrics or diagnostic tools for accurately quantifying success. DNAPL mass reduction stands as the goal of all strategies, and numerous physical-chemical methods such as surfactant flooding have been effective in removing significant portions of contaminant from the subsurface. However, rarely is a site sufficiently characterized such that there is certainty about the exact amount and location of free product in a heterogeneous aquifer. Therefore, the actual extent of mass reduction is only an estimate. The use of dissolution flux as a performance parameter can greatly aid in quantifying the impact of source zone bioremediation. A test platform such as the ECRS has the potential to demonstrate this effect at near-field scale. (Anticipated Project Completion - 2007)

Principal Investigator:
Dr. C. Herb Ward
Rice University
George R. Brown School of Engineering
P.O. Box 1892
6100 Main Street, MS 316
Houston, TX 77250-1892
Telephone: (717) 348-4086
Fax: (713) 348-5948
E-mail: wardch@rice.edu

DoD Liaison:
Dr. Andrea Leeson
SERDP and ESTCP Program Office
901 North Stuart Street, Suite 303
Arlington, VA 22203
Telephone: (703) 696-2118
Fax: (703) 696-2114
E-mail: Andrea.Leeson@osd.mil