A Field Application of Hydrogen-Releasing Compound (HRC^TM) for the Enhanced Bioremediation of Methyl Tertiary Butyl Ether (MTBE)

Uranium reduction and microbial community development in response to stimulation with different electron donors

“…Previously, many attempts to choose the most effective agent have been focused on trying to stimulate a particular species or community of bacteria that are known to be effective uranium-reducers, even though in some cases the agent is only effective for a short period of time Anderson et al 2003). This study demonstrates that more complex organic amendments which have been successfully used for the bioremediation of other contaminants (Hazen et al 2005;Haas et al 2001;Borden 2007;Long and Borden 2006;Lindow et al 2005) produce diverse bacterial communities, and that overall production of microbial biomass may be an equally important predictor of effectiveness in U(VI) retention as the stimulation of specific bacterial species. This opens up a number of new possibilities when choosing options for uranium bioremediation, in turn leading to more effective, sustainable, and costeffect methods of cleaning up remaining waste sites.…”

“…There was a substantial lag prior to uranium removal with these amendments, but once uranium removal was initiated, these amendments were very effective. The observed lag may be related to the fact that EOS and HRC are complex mixtures of multiple organics, some of which may be broken down by a series of microorganisms (Haas et al 2001;Long et al 2006). There were substantial differences in the composition of the microbial community between the EOS-or HRC-amended sediments and those amended with acetate or lactate, including a diverse collection of Firmicutes and the sulfate-reducing bacteria Desulfotomaculum, and Desulfosporosinus, all of which contain species known to reduce U(VI) (Junier et al 2010;Suzuki et al 2004;Wall and Krumholz 2006).…”

“…Neither edible oil nor HRC had been previously used to stimulate uranium reduction, but they have been used to stimulate Cr(VI) reduction (Hazen et al 2005;Faybishenko et al 2008), MTBE degradation (Haas et al 2001), PCE dechlorination and degradation (Borden 2007;Long and Borden 2006), and acid mine drainage remediation (Lindow et al 2005). …”

“…There is virtually no information on uranium reduction and community structure for commercial electron donors such as HRC TM or edible oil (vegetable oil), which are slow-releasing electron donor sources that appear to have many advantages for in situ anaerobic bioremediation (Borden 2007;Haas et al 2001). Neither edible oil nor HRC had been previously used to stimulate uranium reduction, but they have been used to stimulate Cr(VI) reduction (Hazen et al 2005;Faybishenko et al 2008), MTBE degradation (Haas et al 2001), PCE dechlorination and degradation (Borden 2007;Long and Borden 2006), and acid mine drainage remediation (Lindow et al 2005).…”

Evaluation of a laboratory-scale bioreactive in situ sediment cap for the treatment of organic contaminants

“…When lactate was removed from the influent at 13.3 pore volumes, however, a mixture of chlorinated ethenes was observed in the effluent, indicating the importance of exogenous reducing equivalents to the sand column. Delivery of external electron donor is a common technique used to stimulate and enhance reductive dechlorination in groundwater aquifers (Anderson et al, 2003; Haas and Trego, 2001; Lendvay et al, 2003; Scow and Hicks, 2005) and may be necessary for bioreactive caps employing anaerobic biotransformations. Contaminant mass entering the cap also dictated performance, as noted above, since incomplete dechlorination was observed when additional cis -DCE was supplemented into the influent (0 to 3.4 pv) while complete dechlorination was observed when the cap was only treating sediment effluent (5 to 10 pv).…”