Greg Davis President Microbial Insights, Inc.

Greg Davis has been with Microbial Insights since 1996 and has served as President since 2001. Under Mr. Davis's direction, Microbial Insights has become renowned for the commercialization of cutting edge non-culture based analyses typically available only through academia. Research efforts have focused not only on the continual development of molecular biological tools but also on coupling these tools with innovative in situ sampling techniques to facilitate effective site characterization and management decisions within the remediation industry. Mr. Davis holds a B.S. degree in Environmental Science with a concentration in microbiology from the University of Tennessee. Mr. Davis regularly contributes to the discipline of environmental microbiology through publications and presentations on the application of molecular biological tools and their role in understanding natural and enhanced bioremediation of both chlorinated solvents and petroleum hydrocarbons.

Presentation Description
Integrated Approach to PCE-impacted Site Characterization, Site Management and Enhanced Bioremediation
Tetrachloroethene (PCE) and trichloroethene (TCE) impacted sites pose significant challenges even when site characterization activities suggest that biodegradation is occurring under monitored natural attenuation (MNA) conditions. Although site-specific, regulatory, and economic factors play roles in the decision making process, evaluation of remedial alternatives should be science-driven and follow a tiered approach from small scale (less expensive) studies to screen bioremediation options (MNA, biostimulation, and bioaugmentation) to more in depth testing when a proposed corrective action has been identified. The case study was performed at a PCE-impacted site at which reductive dechlorination of PCE and TCE had led to accumulation of cis-dichlorethene (cis-DCE) concentrations ranging from approximately 10 to 100 mg/L. In situ microcosms with Bio-Trap® samplers and quantitative polymerase chain reaction (qPCR) enumeration of Dehalococcoides spp. were used to evaluate MNA, biostimulation with HRC®, and biostimulation with HRC-S as treatment measures. Dehalococcoides populations in HRC-S amended Bio-Traps deployed in impacted wells were on the order of 103 - 104 cells/bead but were below detection limits in most unamended and HRC amended Bio-Traps. Thus the in situ Bio-Trap study identified biostimulation with HRC-S as the candidate corrective action and directed site activities toward a focused pilot study. After the pilot HRC-S injection, Dehalococcoides populations increased to 106 - 107 cells/bead and concentrations of cis-DCE and vinyl chloride decreased with concurrent ethene production. Based on these results, a full scale HRC-S injection was designed and implemented at the site. As with the pilot study, full scale HRC-S injection promoted growth of Dehalococcoides spp. and stimulated reductive dechlorination of the daughter products cis-DCE and vinyl chloride.