Sustained bacterial reduction of Co{sup III}EDTA{sup {minus}} in the presence of competing geochemical oxidation during dynamic flow
- Oak Ridge National Lab., TN (United States). Environmental Sciences Div.
Radionuclides and metals can be mobilized by chelating agents typically present in low-level radioactive liquid wastes. [{sup 60}Co]EDTA in the form {sup 60}Co{sup III}EDTA{sup {minus}} represents a highly stable and mobile form of this radionuclide. By contract, the reduced form of this metal-ligand complex, {sup 60}Co{sup II}EDTA{sup 2{minus}}, is much less stable and less mobile. There is an increasing awareness that dissimilatory metal-reducing bacteria (DMRB) can be used to mediate redox transformations of metals and radionuclides whose stability and mobility are governed by their oxidation state. The authors conducted a series of column experiments to provide an improved understanding of Co{sup III}EDTA{sup {minus}} reduction by the facultative anaerobe Shewanella alga BrY (BrY). Experiments were conducted under growth conditions using lactate a carbon and energy source. They were able to demonstrate the sustained reduction of Co{sup III}EDTA{sup {minus}} in column flow experiments with the desired result that a less stable, less mobile product was formed. The amount of reduction varied directly with the fluid residence time in the columns. In the presence of a suitable mineral sorbent [Fe(OH){sub 3}], Co-EDTA transport was delayed as a direct consequence of the bacterial reduction reaction. Even in the presence of a strong mineral oxidant the net reduction of Co{sup III}EDTA{sup {minus}} dominated the fate and transport of this species.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 696774
- Journal Information:
- Environmental Science and Technology, Vol. 33, Issue 17; Other Information: PBD: 1 Sep 1999
- Country of Publication:
- United States
- Language:
- English
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