Uranium (VI) Reduction by Denitrifying Biomass

Authors: Wu, Wei-Min¹; Gu, Baohua²; Fields, Matthew³; Gentile, Margaret¹; Ku, Yee-Kyoung⁴; Yan, Hui⁴; Tiquias, Sonia³; Yan, Tingfen⁴; Nyman, Jennifer¹; Zhou, Jizhong⁴; Jardine, Phillip⁴; Criddle, Craig¹

Source: Bioremediation Journal, Volume 9, Number 1, January-March 2005 , pp. 49-61(13)

Publisher: Taylor and Francis Ltd

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Abstract:

Groundwater near the S3 ponds at the US Department of Energy's Y-12 site in Oak Ridge, Tennessee, is contaminated by high levels of nitrate (up to 160 mM) and U(VI) ( sim

0.3 mM). To minimize nitrate inhibition, the authors proposed extraction of contaminated groundwater, nitrate removal in a denitrifying fluidized bed bioreactor (FBR), and return of nitrate-free effluent to the aquifer to stimulate in situ microbial reduction of U(VI). In the presence of carbonate, U(VI) sorption to biomass was negligible, but in its absence, sorption was significant. Biomass reduced U(VI) to U(IV), exhibiting slow first-order removal with respect to U(VI). Addition of electron donor increased rates. Addition of an inhibitor of sulfate reduction (molybdate) slowed the rate and inhibited sulfate reduction. Denitrifying beta

- Proteobacteria dominated clone libraries of SSU rRNA and dsr A gene sequences. Approximately 10% were low-G+C microorganisms that had 90% to 92% sequence identity with Sporomusa, Acetonema , and Propionispora . The dsr A sequences were dominated by a single clone with sim

80% nucleotide identity to dsr A of Desulfovibrio vulgaris sub sp. oxamicus . The authors conclude that some members of this denitrifyng community reduce uranium, and that sulfate-reducing bacteria likely contribute to this capability.

Keywords: denitrification; fluidized bed reactor; microorganisms; uranium reduction

Document Type: Research article

DOI: http://dx.doi.org/10.1080/10889860590929628

Affiliations: 1: Department of Civil and Environmental Engineering, Stanford University, Stanford, California, 94305-4020, USA 2: Environmental Science Division, Oak Ridge National Laboratory, P.O. Box 2008, MS-6036, Oak Ridge, Tennessee, 37831, USA 3: Department of Natural Sciences, University of Michigan–Dearborn, 4901 Evergreen Road, 115F SB, Dearborn, Michigan, 48128-1491, USA 4: Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee, 37831-6038, USA

Publication date: 2005-01-01

Uranium (VI) Reduction by Denitrifying Biomass

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