Master of Science in Civil Engineering (MSCE)
Civil and Environmental Engineering
The research goals presented here were to evaluate the solvent concentrations over which Dehalogenimonas lykanthroporepellens strain BL-DC-9T and Dehalogenimonas sp. IP3-3 are able to reductively dechlorinate 1,2-dichloroethane (1,2-DCA), 1,2-dichloropropane (1,2-DCP), and 1,1,2-trichloroethane (1,1,2-TCA). Both of these novel bacteria were isolated from contaminated groundwater at the PetroProcessors of Louisiana, Inc. Superfund site located near Baton Rouge. Both cluster in the phylum Chloroflexi, related to, but distinct from, the widely studied, reductively dechlorinating “Dehalococcoides” strains .
Although previous research demonstrated that strains BL-DC-9T and IP3-3 are able to reductively dechlorinate a variety of polyhalogenated alkanes, the solvent concentration at which the strains are able to dehalogenate the solvents has not been rigorously evaluated until now. The ability of strains to dechlorinate solvents at high concentrations has important implications for remediation of areas where chlorinated solvents remain in the subsurface as dense, non-aqueous phase liquids (DNAPL’s). The concentration range over which strains can reductively dehalogenate chlorinated solvents also has important implications with respect to approaches suitable for growing inocula for use in bioaugmentation.
In the research described here, track study experiments and concentration range experiments were setup simultaneously for each species and compound. The track study involved weekly sampling of replicate bottles spiked with an initial contaminant concentration of 2 mM, a concentration previously known to be degraded by these organisms. The concentration range study was set up to take place over the course of 8 weeks, with sampling at t=0 and after 8 weeks of incubation with replicate bottles containing a wide range of initial contaminant concentrations ranging from 0.5 to 15 mM. All experiments were conducted at 30C.
Both species were shown to dechlorinate 1,2-DCA, 1,2-DCP, and 1,1,2-TCA at initial concentrations at least as high as 8.7 mM, 4.0 mM, and 3.5 mM, respectively. When compared to the concentrations of these contaminants in the area from which these bacteria were isolated, the organisms were shown to be capable of dehalogenating concentrations at least as high as those present. These results have important implications for the remediation of the PPI Superfund site and many other locations around the world.
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Maness, Andrew D., "Reductive Dechlorination of High Concentrations of 1,2-Dichloroethane, 1,2-Dichloropropane, and 1,1,2-Trichloroethane by Dehalogenimonas sp." (2012). LSU Master's Theses. 1672.