In Situ Bioremediation of Uranium with Emulsified Vegetable Oil as the Electron Donor

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• 作者：David B. Watson ; Wei-Min Wu ; Tonia Mehlhorn ; Guoping Tang ; Jennifer Earles ; Kenneth Lowe ; Thomas M. Gihring ; Gengxin Zhang ; Jana Phillips ; Maxim I. Boyanov ; Brian P. Spalding ; Christopher Schadt ; Kenneth M. Kemner ; Craig S. Criddle ; Philip M. Jardine ; Scott C. Brooks
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：June 18, 2013
• 年：2013
• 卷：47
• 期：12
• 页码：6440-6448
• 全文大小：500K
• 年卷期：v.47,no.12(June 18, 2013)
• ISSN：1520-5851

文摘

A field test with a one-time emulsified vegetable oil (EVO) injection was conducted to assess the capacity of EVO to sustain uranium bioreduction in a high-permeability gravel layer with groundwater concentrations of (mM) U, 0.0055; Ca, 2.98; NO₃^{鈥?/sup>, 0.11; HCO₃鈥?/sup>, 5.07; and SO₄2鈥?/sup>, 1.23. Comparison of bromide and EVO migration and distribution indicated that a majority of the injected EVO was retained in the subsurface from the injection wells to 50 m downgradient. Nitrate, uranium, and sulfate were sequentially removed from the groundwater within 1鈥? weeks, accompanied by an increase in acetate, Mn, Fe, and methane concentrations. Due to the slow release and degradation of EVO with time, reducing conditions were sustained for approximately one year, and daily U discharge to a creek, located approximately 50 m from the injection wells, decreased by 80% within 100 days. Total U discharge was reduced by 50% over the one-year period. Reduction of U(VI) to U(IV) was confirmed by synchrotron analysis of recovered aquifer solids. Oxidants (e.g., dissolved oxygen, nitrate) flowing in from upgradient appeared to reoxidize and remobilize uranium after the EVO was exhausted as evidenced by a transient increase of U concentration above ambient values. Occasional (e.g., annual) EVO injection into a permeable Ca and bicarbonate-containing aquifer can sustain uranium bioreduction/immobilization and decrease U migration/discharge.}