Sustained bacterial reduction of Co{sup III}EDTA{sup {minus}} in the presence of competing geochemical oxidation during dynamic flow

Journal Article · Wed Sep 01 04:00:00 EDT 1999 · Environmental Science and Technology

DOI:https://doi.org/10.1021/es990245f· OSTI ID:696774

Brooks, S C; Carroll, S L; Jardine, P M ^[1]

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1. 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, Journal Name: Environmental Science and Technology Journal Issue: 17 Vol. 33; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
BIODEGRADATION
COBALT 60
EDTA
ENVIRONMENTAL TRANSPORT
GEOCHEMISTRY
LOW-LEVEL RADIOACTIVE WASTES
REDOX REACTIONS
REMEDIAL ACTION