Uranium and Technetium Bio-Immobilization in Intermediate-Scale Physical Models of an In Situ Bio-Barrier
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- 作者：Mandy M. Michalsen ; Bernard A. Goodman ; Shelly D. Kelly ; Kenneth M. Kemner ; James P. McKinley ; Joseph W. Stucki ; Jonathan D. Istok
- 刊名：Environmental Science & Technology
- 出版年：2006
- 出版时间：November 15, 2006
- 年：2006
- 卷：40
- 期：22
- 页码：7048 - 7053
- 全文大小：336K
- 年卷期：v.40,no.22(November 15, 2006)
- ISSN：1520-5851
文摘
We investigated the long-term effects of ethanol additionon U and Tc mobility in groundwater flowing throughintermediate-scale columns packed with uncontaminatedsediments. The columns were operated above-ground at acontaminated field site to serve as physical models ofan in situ bio-barrier for U and Tc removal from groundwater.Groundwater containing 4 
M U and 520 pM Tc waspumped through the columns for 20 months. One columnreceived additions of ethanol to stimulate activity of indigenousmicroorganisms; a second column received no ethanoland served as a control. U(VI) and Tc(VII) removal wassustained for 20 months (~189 pore volumes) in the stimulatedcolumn under sulfate- and Fe(III)-reducing conditions.Less apparent microbial activity and only minor removalof U(VI) and Tc(VII) were observed in the control. Sequentialsediment extractions and XANES spectra confirmed thatU(IV) was present in the stimulated column, although U(IV)was also detected in the control; extremely low concentrations precluded detection of Tc(IV) in any sample. Theseresults provide additional evidence that bio-immobilizationmay be effective for removing U and Tc from groundwater.However, long-term effectiveness of bio-immobilization maybe limited by hydraulic conductivity reductions or depletionof bioavailable Fe(III).
M U and 520 pM Tc waspumped through the columns for 20 months. One columnreceived additions of ethanol to stimulate activity of indigenousmicroorganisms; a second column received no ethanoland served as a control. U(VI) and Tc(VII) removal wassustained for 20 months (~189 pore volumes) in the stimulatedcolumn under sulfate- and Fe(III)-reducing conditions.Less apparent microbial activity and only minor removalof U(VI) and Tc(VII) were observed in the control. Sequentialsediment extractions and XANES spectra confirmed thatU(IV) was present in the stimulated column, although U(IV)was also detected in the control; extremely low concentrations precluded detection of Tc(IV) in any sample. Theseresults provide additional evidence that bio-immobilizationmay be effective for removing U and Tc from groundwater.However, long-term effectiveness of bio-immobilization maybe limited by hydraulic conductivity reductions or depletionof bioavailable Fe(III).