title: Microbial removal of uranium in uranium-bearing black shale.
abstract: The effects of several conditional factors on efficiency of U bioleaching using an iron-oxidizer, Acidithiobacillus ferrooxidans, from U-bearing black shale (349 mg kg-1 of U) were investigated. When batch-type reactors containing black shale were initially inoculated with the cells, lower pH, higher redox potential and higher amount of aqueous Fe3+ than those of non-inoculated reactor were observed until 200 h. Such development of condition, which was facilitated by microbial activity, can enhance the rate and extent of U leaching from the solid substrate. However, under the condition of enough nutrients and energy source (Fe2+) supplied, indigenous Fe-oxidizers in the non-inoculated black shale were activated over time. They exerted almost same influence on the leaching efficiency with the inoculated samples after 250 h. Low initial Fe2+ supply (5 g l-1) and no addition of inorganic nutrients resulted in nearly identical extent of U leaching with that of 9 g l-1 of initial Fe2+ and nutrients supply. The results indicate that, in a practical process of bioleaching, the expenses for Fe2+ and nutrients addition can be reduced.
authors.affiliation: Department of Civil, Geosystem, and Environmental Engineering, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Jong-Un
authors.initials: JU
authors.lastname: Lee
authors.forename: Sung-Min
authors.initials: SM
authors.lastname: Kim
authors.forename: Kyoung-Woong
authors.initials: KW
authors.lastname: Kim
authors.forename: In S
authors.initials: IS
authors.lastname: Kim
mesh_terms: D042763:Acidithiobacillus / Q000378:metabolism*; D001426:Bacterial Proteins / Q000032:analysis; D019015:Geologic Sediments / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism; D010084:Oxidation-Reduction; D012990:Soil Pollutants, Radioactive / Q000032:analysis / Q000378:metabolism*; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors; D014501:Uranium / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012990:Soil Pollutants, Radioactive; D014501:Uranium; D007501:Iron