Wang Guohua, Liu Ying, Wang Jiali, Xiang Jinjing, Zeng Taotao, Li Shiyou, Song Jian, Zhang Zhiyue, Liu Jinxiang
Hunan Provincial Key Laboratory of Pollution Control and Resources Technology, University of South China, Hengyang, 421001, China.
Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang, 421001, China.
Environ Sci Pollut Res Int. 2023 Feb;30(9):23096-23109. doi: 10.1007/s11356-022-23902-z. Epub 2022 Nov 1.
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.
通过添加电子供体刺激本地微生物将水中的U(VI)还原为不溶性U(IV)，已被用作原位修复铀污染地下水的一种可行策略。然而，生物成因的U(IV)矿物在暴露于氧气后易发生氧化再迁移。为提高最终产物的稳定性，选择甘油磷酸酯（GP）在不同pH值（即7.0和5.0）下处理人工含铀地下水，并以甘油（GY）作为对照组。结果表明，GP处理组的铀去除率均高于GY处理组，且在GP处理组中生成了还原态的结晶U(IV)-磷酸盐和U(VI)-磷酸盐矿物（抗氧化再迁移）。虽然在pH 5.0时生物还原效率受到影响，但与GY相比，GP处理的最终产物稳定性显著提高。机理分析表明，GP可激活微生物群落的生物还原和生物矿化作用，GP处理组包括两个阶段。在早期阶段，生物还原和生物矿化均参与固定过程。随后，部分U(VI)沉淀物被微生物逐渐还原为U(IV)沉淀物。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，可能为长期稳定修复铀污染地下水提供一种更有效的策略。
