Influence of Reactive Transport on the Reduction of U(VI) in the Presence of Fe(III) and Nitrate (Liu NABIR-Fe/U, PNNL Scope #42331)
EMSL Project ID
4592
Abstract
To examine in sediment-containing experimental systems (packed columns) the reduction of U(VI) by metal-reducing bacteria in a simulated groundwater medium.Work authorization text added 08/11/05:
The coupling of biogeochemical and transport processes is important to the bioremediation of metals and radionuclides in the field, but experimental research systems with transport and biologically-mediated redox reactions is severely lacking. We propose to examine the reduction of U(VI) in the presence of Fe(III)-containing minerals under conditions representative of biostimulation. This research will establish: (1) mechanisms by which the fluxes of electron acceptors, electron donors, and other species can be controlled to maximize the transfer of reductive equivalents to the aqueous solid phases, (2) process models that describe the transport and reaction of U(VI) and iron species under conditions relevant to bioremediation, and (3) the potential for long-term immobilization of uranium in bioreduced sediments. This research will be conducted using DOE subsurface sediments collected from the Hanford site and the Oak Ridge FRC, and synthetic porous materials with specific bioavailable iron mineral phases and contents. The facultative dissimilatory metal reducing bacterium Shewanella putrefaciens (strain CN32) will be adopted as a test organism. Experimental research will be focused on three main areas: (1) the importance of the abiotic reduction of U(VI) by Fe(II); (2) the influence of the transport process on Fe(II) production and U(VI) immobilization; and (3) the reductive capacity of biologically-reduced sediments (with respect to re-oxidation by convective fluxes of O2 and NO3-). The research will provide scientifically-based information that will be useful in the design and assessment of bioremediation strategies for U(VI) as well as other metals and radionuclides.* Contact Chongxuan Liu, project manager, for additional information. Assumptions - The DOE client (Office of Biological and Environmental Research) expects us to conduct fundamental research to further our knowledge in areas of importance to DOE's mission, and to disseminate this knowledge through publications in peer-reviewed journals and presentations of results at scientific meetings. Products/Deliverables: - Publications in scientific journals - Presentations at scientific meetings and symposia.
Project Details
Project type
Exploratory Research
Start Date
2003-08-15
End Date
2004-12-03
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members