Organic Carbon Supply Influences Uranium Bioremediation
Addition of organic carbon compounds to uranium-contaminated environments stimulates the activity of microorganisms resulting in the removal of uranium from groundwater. Researchers at LBNL have shown that competing biogeochemical reactions driven by the rate of organic carbon supply strongly influence uranium mobility during biostimulation and must be carefully optimized to ensure the sustainability of the remediation technique. At low organic carbon supply rates, desorption of uranium from sediments increases soluble uranium concentrations while higher rates stimulate conditions necessary for removal of soluble uranium via microbial bioreduction in laboratory column experiments. Further increases in organic carbon supply rate lead to formation of uranium-carbonate complexes that may drive uranium reoxidation thereby increasing soluble uranium concentrations. The results illustrate that uranium bioremediation processes are more complicated than previously thought and organic carbon supply rates will need to be optimized to balance several competing biogeochemical processes to ensure uranium immobilization over long time frames.
Environ. Sci. Technol., 2008, 42(23): 8901-8907.