土著菌群介导下多机制协同治理铀污染水体

Multi Mechanism Synergistic Treatment of Uranium-contaminating Water Body Mediated by Indigenous Bacteria

为提高铀污染地表水的修复效率,本实验以甘油磷酸钠为外加磷源,研究了土著菌群介导下铀污染地表水的微生物协同修复机制。结果表明,仅用60 h,铀的去除率即可达到96.3%,且随着时间的延长铀的去除率增高、解吸率降低。固铀过程可分为2个阶段:第1阶段,可溶性U(Ⅵ)附着在细胞表面,为U(Ⅵ)矿化物的形成提供初始成核位点;第2阶段,U(Ⅵ)-磷酸盐矿物在细胞内外以变钾铀云母K(UO_(2))(PO_(4))·3H_(2)O的形式出现,U(Ⅵ)也被还原成U(Ⅳ),固铀产物为结晶态的UO_(2),稳定性明显提高。该菌群的组成为unclassified_f_Enterobacteriaceae(53.15%)、lysinibacillus(42.05%)、dysgonomonas(2.79%)、citrobacter(1.13%)、petrimonas(0.88%)。本研究对于促进U(Ⅵ)的固定化与产物的稳定性具有重要意义,对于铀废水的原位修复更具有实际意义。

The uranium-containing wastewater produced in the process of uranium mining and nuclear energy utilization poses a serious potential threat to the ecological environment and human health.It is an urgent environmental problem to be solved.Microbial remediation has the advantages of simple operation design,low cost,high feasibility,and little environmental interference.There are four mechanisms of interaction between microorganisms and U(Ⅵ):biosorption,biomineralization,bioreduction and bioaccumulation.In order to study the multiple remediation mechanism of uranium-contaminating water body mediated by indigenous bacteria,in this study,β-sodium glycerophosphate(GP)was used as the sole carbon and phosphorus source to induce the conversion of free U(Ⅵ)in solution to solid-phase precipitation under the degradation of indigenous phosphorus-dissolving bacteria.The objective is to investigate whether there are multiple mechanisms at play in the biomineralization of phosphate that occurs in the presence of added exogenous organophosphorus.The results of the solution parameters show that the removal of uranium reaches 90.68%at 36 h and 98.34%at 228 h.The stability analysis of the product shows that the desorption rate of uranium is 80.28%at 40 h and 30.23%at 228 h.The occurrence of biosorption,mineralization,reduction,and accumulation is verified by SEM-EDS,FT-IR,XRD,XPS,and TEM,respectively.At the early stage it is found that soluble U(Ⅵ)first attaches to the cell surface.It combines with hydroxyl,phosphate group and amide through electrostatic action and complexation to provide initial nucleation sites for the formation of U(Ⅵ)biominerals.Subsequently,XPS and XRD results jointly demonstrate that the solid uranium product is UO_(2) in the crystalline state.And U(Ⅵ)-phosphate mineral appeares in the form of Metaankoleite K(UO_(2))(PO_(4))·3H_(2)O.The crystallinity of U(Ⅵ)-phosphate minerals becomes better with increasing reaction time.The appearance of fibrous and granular structural deposits around,on the surface and in the body of the bacteria is also found by TEM.Metaankoleite K(UO_(2))(PO_(4))·3H_(2)O is also found inside the cells.The composition of this flora is unclassified_f_Enterobacteriaceae(53.15%),lysinibacillus(42.05%),dysgonomonas(2.79%),citrobacter(1.13%)and petrimonas(0.88%).Unclassified_f_Enterobacteriaceae plays a major role in the whole system.It has the functions of biosorption,biomineralization,bioreduction and bioaccumulation.The above results indicate that in complex and diverse outdoor environments,not only one type of microorganism is involved.It is more practical to study the remediation of uranium-containing wastewater by indigenous bacteria.Moreover,the indigenous bacteria may have the result of multiple mechanisms in the process of uranium remediation.