Abstract：
Stimulating indigenous microbes to reduce aqueous U(VI) to insoluble U(IV) by adding an electron donor has been applied as an applicable strategy to remediate uranium-contaminated groundwater in situ. However, biogenic U(IV) minerals are susceptible to oxidative remobilization after exposure to oxygen. To enhance the stability of the end product, glycerol phosphate (GP) was selected to treat artificial uranium-containing groundwater at different pH values (i.e., 7.0 and 5.0) with glycerol (GY) as the control group. The results revealed that removal ratios of uranium with GP were all higher than those with GY, and reduced crystalline U(IV)-phosphate and U(VI)-phosphate minerals (recalcitrant to oxidative remobilization) were generated in the GP groups. Although bioreduction efficiency was influenced at pH 5.0, the stability of the end product with GP was elevated significantly compared with that with GY. Mechanism analysis demonstrated that GP could activate bioreduction and biomineralization of the microbial community, and two stages were included in the GP groups. In the early stage, bioreduction and biomineralization were both involved in the immobilization process. Subsequently, part of the U(VI) precipitate was gradually reduced to U(IV) precipitate by microorganisms. This work implied that the formation of U-phosphate minerals via bioreduction coupled with biomineralization potentially offers a more effective strategy for remediating uranium-contaminated groundwater with long-term stability.
摘要：
通过添加电子供体刺激本地微生物将水性U（VI）还原为不溶性U（IV）已被用作原位修复铀污染的地下水的适用策略。然而,生物U（IV）矿物质在暴露于氧气后容易氧化再动员。为了增强最终产品的稳定性，选择甘油磷酸盐（GP）来处理不同pH值的人造含铀地下水（即，7.0和5.0），以甘油（GY）为对照组。结果表明，GP对铀的去除率均高于GY，在GP组中产生了还原的结晶U（IV）-磷酸盐和U（VI）-磷酸盐矿物质（对氧化再固定有抑制作用）。尽管在pH5.0时生物还原效率受到影响，但与GY相比，GP的最终产物的稳定性显着提高。机理分析表明，GP可以激活微生物群落的生物还原和生物矿化，GP组包括两个阶段。在早期阶段,生物还原和生物矿化都参与了固定化过程。随后，部分U(VI)沉淀被微生物逐渐还原成U(IV)沉淀。这项工作表明，通过生物还原与生物矿化相结合形成U-磷酸盐矿物可能为长期稳定地修复受铀污染的地下水提供了更有效的策略。
