TY - JOUR
T1 - In situ bioreduction of uranium (VI) to submicromolar levels and reoxidation by dissolved oxygen
AU - Wu, Wei Min
AU - Carley, Jack
AU - Luo, Jian
AU - Ginder-Vogel, Matthew A.
AU - Cardenas, Erick
AU - Leigh, Mary Beth
AU - Hwang, Chiachi
AU - Kelly, Shelly D.
AU - Ruan, Chuanmin
AU - Wu, Liyou
AU - Van Nostrand, Joy
AU - Gentry, Terry
AU - Lowe, Kenneth
AU - Mehlhorn, Tonia
AU - Carroll, Sue
AU - Luo, Wensui
AU - Fields, Matthew W.
AU - Gu, Baohua
AU - Watson, David
AU - Kemner, Kenneth M.
AU - Marsh, Terence
AU - Tiedje, James
AU - Zhou, Jizhong
AU - Fendorf, Scott
AU - Kitanidis, Peter K.
AU - Jardine, Philip M.
AU - Criddle, Craig S.
PY - 2007/8/15
Y1 - 2007/8/15
N2 - Groundwater within Area 3 of the U.S. Oepartment of Energy (OOE) Environmental Remediation Sciences Program (ERSP) Field Research Center at Oak Ridge, TN (ORFRC) contains up to 135 μM uranium as U(VI). Through a series of experiments at a pilot scale test facility, we explored the lower limits of groundwater U(VI) that can be achieved by in-situ biostimulation and the effects of dissolved oxygen on immobilized uranium. Weekly 2 day additions of ethanol over a 2-year period stimulated growth of denitrifying, Fe(III)-reducing, and sulfate-reducing bacteria, and immobilization of uranium as U(IV), with dissolved uranium concentrations decreasing to low levels. Following sulfite addition to remove dissolved oxygen, aqueous U(VI) concentrations fell below the U.S. Environmental Protection Agengy maximum contaminant limit (MCL) for drinking water (<30μg L-1 or 0.126 μM). Under anaerobic conditions, these low concentrations were stable, even in the absence of added ethanol. However, when sulfite additions stopped, and dissolved oxygen (4.0-5.5 mg L_1) entered the injection well, spatially variable changes in aqueous U(VI) occurred over a 60 day period, with concentrations increasing rapidly from <0.13 to 2.0 μM at a multilevel sampling (MLS) well located close to the injection well, but changing little at an MLS well located further away. Resumption of ethanol addition restored reduction of Fe(III), sulfate, and U(VI) within 36 h. After 2 years of ethanol addition. X-ray absorption near-edge structure spectroscopy (XANES) analyses indicated that U(IV) comprised 60-80% of the total uranium in sediment samples. At the completion of the project(day 1260), U concentrations in MLS wells were less than 0.1 μM. The microbial community at MLS wells with low U(VI) contained bacteria that are known to reduce uranium, including Desulfovibrio spp. and Geobacter spp., in both sediment and groundwater. The dominant Fe(III)-reducing species were Geothrix spp.
AB - Groundwater within Area 3 of the U.S. Oepartment of Energy (OOE) Environmental Remediation Sciences Program (ERSP) Field Research Center at Oak Ridge, TN (ORFRC) contains up to 135 μM uranium as U(VI). Through a series of experiments at a pilot scale test facility, we explored the lower limits of groundwater U(VI) that can be achieved by in-situ biostimulation and the effects of dissolved oxygen on immobilized uranium. Weekly 2 day additions of ethanol over a 2-year period stimulated growth of denitrifying, Fe(III)-reducing, and sulfate-reducing bacteria, and immobilization of uranium as U(IV), with dissolved uranium concentrations decreasing to low levels. Following sulfite addition to remove dissolved oxygen, aqueous U(VI) concentrations fell below the U.S. Environmental Protection Agengy maximum contaminant limit (MCL) for drinking water (<30μg L-1 or 0.126 μM). Under anaerobic conditions, these low concentrations were stable, even in the absence of added ethanol. However, when sulfite additions stopped, and dissolved oxygen (4.0-5.5 mg L_1) entered the injection well, spatially variable changes in aqueous U(VI) occurred over a 60 day period, with concentrations increasing rapidly from <0.13 to 2.0 μM at a multilevel sampling (MLS) well located close to the injection well, but changing little at an MLS well located further away. Resumption of ethanol addition restored reduction of Fe(III), sulfate, and U(VI) within 36 h. After 2 years of ethanol addition. X-ray absorption near-edge structure spectroscopy (XANES) analyses indicated that U(IV) comprised 60-80% of the total uranium in sediment samples. At the completion of the project(day 1260), U concentrations in MLS wells were less than 0.1 μM. The microbial community at MLS wells with low U(VI) contained bacteria that are known to reduce uranium, including Desulfovibrio spp. and Geobacter spp., in both sediment and groundwater. The dominant Fe(III)-reducing species were Geothrix spp.
UR - http://www.scopus.com/inward/record.url?scp=34548092119&partnerID=8YFLogxK
U2 - 10.1021/es062657b
DO - 10.1021/es062657b
M3 - Article
C2 - 17874778
AN - SCOPUS:34548092119
SN - 0013-936X
VL - 41
SP - 5716
EP - 5723
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 16
ER -