title: Biological reduction of uranium--from the laboratory to the field.
abstract: The chemical and biological processes underlying in situ bioremediation of uranium-contaminated groundwater have been studied in the laboratory and in the field. This article focuses on the long-term stability of uraninite (UO(2)) in the underground. A large tailings pond, 'Dänkritz 1' in Germany, was selected for this investigation. A single-pass flow-through experiment was run in a 100-liter column: bioremediation for 1year followed by infiltration of tap water (2.5years) saturated with oxygen, sufficient to oxidize the precipitated uraninite in two months. Instead, only 1wt.% uraninite was released over 2.4years at concentrations typically less than 20μg/L. Uraninite was protected against oxidation by the mineral mackinawite (FeS(0.9)), a considerable amount of which had formed, together with uraninite. A confined field test was conducted adjacent to the tailings pond, which after bio-stimulation showed similarly encouraging results as in the laboratory. Taking Dänkritz 1 as an example we show that in situ bioremediation can be a viable option for long-term site remediation, if the process is designed based on sufficient laboratory and field data. The boundary conditions for the site in Germany are discussed.
authors.affiliation: WISUTEC Wismut Umwelttechnik GmbH, Chemnitz, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Dullies
authors.forename: Werner
authors.initials: W
authors.lastname: Lutze
authors.forename: Weiliang
authors.initials: W
authors.lastname: Gong
authors.forename: H Eric
authors.initials: HE
authors.lastname: Nuttall
mesh_terms: D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D005296:Ferrous Compounds / Q000737:chemistry; D014501:Uranium / Q000032:analysis / Q000378:metabolism*; D014865:Waste Disposal, Fluid; D014871:Water Microbiology; D014875:Water Pollutants, Radioactive / Q000032:analysis / Q000378:metabolism*
chemical_list: D005296:Ferrous Compounds; D014875:Water Pollutants, Radioactive; D014501:Uranium; C022597:ferrous sulfide