In situ Microbial Community Control of the Stability of Bio-Reduced Uranium
In aerobic aquifers typical of many Department of Energy (DOE) legacy waste sites, uranium is present in the oxidized U(VI) form which is soluble and thus mobile compared to U(IV). Previous work at the Old Rifle Uranium Mill Tailings Remedial Action (UMTRA) site demonstrated that biostimulation by acetate injection promoted growth of Geobacteraceae and stimulated the microbial reduction of U(VI) to less soluble U(IV) (1, 4). Despite the potential for oxidative dissolution of bio-reduced U(IV), field experiments at the Old Rifle site show that although the rate of U(VI) reduction decreases following the on-set of sulfate reduction, U(VI) reduction continues even following the cessation of acetate injection (1, 4). However, U(VI) reduction is reversible and the basis for the observed maintenance of U(VI) reduction post-stimulation is a critical but as yet unresolved issue for the application of biostimulation as a treatment technology. The continued U(VI) reduction and the maintenance of reduced U(IV) may result from many factors including U(VI) reduction by sulfate reducing bacteria (SRB), generation of H2S or FeS0.9 which serves as an oxygen sink, or the preferential sorption of U(VI) by microbial cells or biopolymers. The overall goal of the project is to develop an understanding of the mechanisms for the maintenance of bio-reduced uranium in an aerobic aquifer under field conditions following the cessation of electron donor addition.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA; University of Tennessee, Knoxville, TN
- Sponsoring Organization:
- USDOE - Office of Science (SC)
- OSTI ID:
- 896016
- Report Number(s):
- ERSD-1024837-2006
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
59 BASIC BIOLOGICAL SCIENCES
ACETATES
AQUIFERS
BINDING ENERGY
DISSOLUTION
ELECTRONS
FEED MATERIALS PLANTS
MAINTENANCE
OXYGEN
REMEDIAL ACTION
SORPTION
STABILITY
SULFATE-REDUCING BACTERIA
SULFATES
TAILINGS
URANIUM
URANIUM 228
VALENCE
WASTES