| 1 | Uranium sequestration in sediment at an iron-rich contaminated site at Oak Ridge, Tennessee via.bioreduction followed by reoxidation显示文摘This study evaluated uranium sequestration performance in iron-rich (30 g/kg) sediment via bioreduction followed by reoxidation.Field tests (1383 days) at Oak Ridge,Tennessee demonstrated that uranium contents in sediments increased after bioreduced sediments were re-exposed to nitrate and oxygen in contaminated groundwater.Bioreduction of contaminated sediments (1200 mg/kg U) with ethanol in microcosm reduced aqueous U from 0.37 to 0.023 mg/L.Aliquots of the bioreduced sediment were reoxidized with O2,H2O2,and NaNO3,respectively,over 285 days,resulting in aqueous U of 0.024,1.58 and 14.4 mg/L at pH 6.30,6.63 and 7.62,respectively.The source-and the three reoxidized sediments showed different desorption and adsorption behaviors of U,but all fit a Freundlich model.The adsorption capacities increased sharply at pH 4.5 to 5.5,plateaued at pH 5.5 to 7.0,then decreased sharply as pH increased from 7.0 to 8.0.The O2-reoxidized sediment retained a lower desorption efficiency at pH over 6.0.The NO3--reoxidized sediment exhibited higher adsorption capacity at pH 5.5 to 6.0.The pH-dependent adsorption onto Fe(Ⅲ) oxides and formation of U coated particles and precipitates resulted in U sequestration,and bioreduction followed by reoxidation can enhance the U sequestration in sediment. | Peng-Song Li Wei-Min Wu Debra H.Phillips David B.Watson Shelly Kelly Bing Li Tonia Mehlhorn Kenneth Lowe Jennifer Earles Hu-Chun Tao Tong Zhang Craig S.Criddle | 2019 | Journal of Environmental Sciences2019，31，11： | 1 |
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