title: Uranium bioremediation in continuously fed upflow sand columns inoculated with anaerobic granules.
abstract: Reductive precipitation of soluble hexavalent uranium (U(VI)) to insoluble tetravalent uranium (U(IV)) containing minerals is one of the more promising approaches to uranium remediation. The objective of this study was to evaluate the long-term performance of methanogenic granules for the continuous treatment of U(VI). For this purpose, three sand-packed columns inoculated with anaerobic biofilm were operated with or without ethanol and one column was exposed to nitrate co-contamination. The columns were operated for 373 days and efficiently removed U (24 mg L(-1)) in excess of 99.8%. No long-term benefit of ethanol addition was observed, suggesting that endogenous substrates in the biofilm were sufficient to drive the reduction reactions. Nitrate addition was found to inhibit U(VI) reduction and cause re-oxidation of some U(IV) deposited in the column. Taken as a whole, the results indicate that methanogenic biofilms can be reliably applied in bioreactor technology for sustained U removal from groundwater.
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, PO Box 210011, Tucson, Arizona 85721, USA.
authors.forename: Aida
authors.initials: A
authors.lastname: Tapia-Rodriguez
authors.forename: Virginia
authors.initials: V
authors.lastname: Tordable-Martinez
authors.forename: Wenjie
authors.initials: W
authors.lastname: Sun
authors.forename: James A
authors.initials: JA
authors.lastname: Field
authors.forename: Reyes
authors.initials: R
authors.lastname: Sierra-Alvarez
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism*; D001673:Biodegradation, Environmental; D018533:Biomass; D000431:Ethanol / Q000378:metabolism; D008697:Methane / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D012822:Silicon Dioxide; D014501:Uranium / Q000378:metabolism*; D014875:Water Pollutants, Radioactive / Q000378:metabolism*
chemical_list: D009566:Nitrates; D014875:Water Pollutants, Radioactive; D000431:Ethanol; D014501:Uranium; D012822:Silicon Dioxide; D008697:Methane