Uranium sequestration in sediment at an iron-rich contaminated site at Oak Ridge, Tennessee via bioreduction followed by reoxidation

Ping-Song Li, Wei-Min Wu, Debra Phillips, David Watson, Shelly Kelly, Tonia Mehlhorn, Jennifer Earles, Hu-Chun Tao, Tong Zhang, Craig Criddle

Research output: Contribution to journalArticle

3 Citations (Scopus)
16 Downloads (Pure)

Abstract

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.
Original languageEnglish
Pages (from-to)156-167
Number of pages11
JournalJournal of Environmental Sciences
Volume85
DOIs
Publication statusPublished - 02 Jul 2019

Fingerprint Dive into the research topics of 'Uranium sequestration in sediment at an iron-rich contaminated site at Oak Ridge, Tennessee via bioreduction followed by reoxidation'. Together they form a unique fingerprint.

  • Impacts

    Reducing transport of radionuclides into the environment

    Debra Phillips (Participant)

    Impact: Environmental Impact, Health Impact

    Cite this