HR: 0800h
AN: H31B-0377    [Abstracts]
TI: Remediation of Dense Non-Aqueous Phase Liquids Using Biostimulation and Bioaugmentation
AU: Hood, E
EM: ehood@geosyntec.com
AF: GeoSyntec, 130 Research Lane, Suite 2, Guelph, ON N1G 5G3 Canada
AU: * Major, D
EM: dmajor@geosyntec.com
AF: GeoSyntec, 130 Research Lane, Suite 2, Guelph, ON N1G 5G3 Canada
AU: Edwards, E
EM: edwards@chem-eng.utoronto.ca
AF: University of Toronto, Department of Chemical Engineering 200 College St., Toronto, ON M5S 3E5 Canada
AU: Sleep, B
EM: sleep@enviro.civ.utoronto.ca
AF: University of Toronto, Department of Civil Engineering 35 St. George Street, Toronto, ON M5S 1A4 Canada
AU: Quinn, J
EM: Jacqueline.W.Quinn@nasa.gov
AF: NASA, Mail Stop YA-C3-C (O&C 3115), Kennedy Space Center, FL 32899 United States
AB: Launch Complex 34 (LC-34) at the Kennedy Space Center is the site of historic releases of trichloroethene (TCE) which is present in the subsurface as a dense, non-aqueous phase liquid (DNAPL). Under intrinsic condition at LC-34, TCE biodegrades via anaerobic reductive dechlorination resulting in the accumulation of cis-1,2-dichloroethene (cis-1,2-DCE), suggesting that complete biodegradation to ethene is limited by either: 1) the absence of dehalorespiring microorganisms or 2) the absence of soluble organic carbon substrates for microbial metabolism and growth. Anaerobic reductive dechlorination, the most common biodegradation process for chlorinated solvents, is a well-understood degradation mechanism for TCE and less-chlorinated alkenes (i.e., cis-1,2-DCE and vinyl chloride) that can result in complete dechlorination to ethene, a non-toxic degradation product. Typically, enhanced bioremediation treatment involves the amendment of groundwater with an organic substrate (e.g., alcohols, organic acids) as an electron donor (biostimulation) although at sites where the activity of microorganisms capable of mediating complete dechlorination is low the addition of the microbial inoculum containing the requisite dechlorinating microorganisms (bioaugmentation) may be necessary. In May 2002, an enhanced bioremediation pilot study of the performance of biostimulation and bioaugmentation was initiated at LC-34 with the concurrent collection of performance data by the USEPA Superfund Innovative Technology Evaluation (SITE) program for the purpose of technology validation. The primary purpose of this study was to determine if ethanol amendment and the addition of microorganisms capable of mediating complete conversion of TCE to ethene would increase the rate of VOC degradation, thereby minimizing the migration of chloroethenes in groundwater and increasing the rate of DNAPL dissolution. An indigenous Dehalococcoides microorganism present in groundwater was demonstrated to be capable of TCE biodegradation, resulting in complete conversion to ethene. The activity of the indigenous dechlorinating microorganisms was significantly enhanced by the addition of ethanol. Surprisingly, ethanol addition did not stimulate methanogenesis, likely as a result of the relatively high chloroethene concentrations remaining in groundwater (primarily cis-1,2-DCE and vinyl chloride) and/or the absence of an indigenous methanogenic population. Biostimulation resulted in rapid biodegradation of TCE to cis-DCE and VC, with limited conversion to ethene (concentrations as high as 5 mg/L). Additional conversion past VC to ethene was observed following bioaugmentation. Ongoing efforts are underway to further evaluate the impacts of bioaugmentation on both dechlorinating activity and microbial population diversity.
DE: 1831 Groundwater quality
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting