固定化硫酸盐还原菌选择性去除U（Ⅵ）的性能

摘要

利用聚乙烯醇和海藻酸钠制备了硫酸盐还原菌微球，探讨了Zn2＋、Cu2＋、乙酸钠、草酸钠和柠檬酸钠对其还原U （Ⅵ）的影响，考察了其选择性去除U （Ⅵ）的工艺。实验结果表明，当Zn2＋或Cu2＋浓度低于100 mg/L时，U （Ⅵ）还原未受显著影响，但当其增至150 mg/L时，U （Ⅵ）还原被完全抑制。当单齿配体有机物（乙酸钠）存在时，U（Ⅵ）可被彻底还原；而多齿配体有机物（草酸钠和柠檬酸钠）存在时，会延缓甚至完全抑制U（Ⅵ）的还原。对于无机-U（Ⅵ）-重金属体系，可利用U（Ⅵ）和硫酸盐还原自由能的差异，适当降低COD/SO2-4比值直接选择性去除U （Ⅵ）；对于有机-U （Ⅵ）-重金属体系，可通过多齿配体有机物络合U（Ⅵ），同时利用硫化物选择性沉淀重金属，间接实现U（Ⅵ）的选择性去除。%T he sulfate-reducing bacteria immobilized in polyvinyl alcohol-sodium alginate beads were prepared .The impacts of Zn2+ ,Cu2+ ,acetate ,oxalate and citrate on the reduction of U (Ⅵ ) were investigated .Furthermore ,selective removal of U (Ⅵ ) or heavy metals was assessed .The results indicate that the existing of Zn2+ or Cu2+doesn’t affect U (Ⅵ) removal appreciably w hen their concentrations are less than 100 mg/L ,but they can inhibit U (Ⅵ) removal completely w hile their concentrations reach 150 mg/L .In the presence of monodentate ligand (acetate) ,U (Ⅵ) can be removed readily ,w hereas multidentate ligands (oxalate and citrate ) impose an inhibition on U (Ⅵ ) removal .In organic-free wastewater ,direct selective removal of U (Ⅵ ) can be achieved based on thermodynamic considerations and optimized by appropriately lowering COD/SO2 -4 .In wastewater containing multidentate organics ,U(Ⅵ) can be firstly complexed during precipitation of Zn2+ and Cu2+ , and then removed directively after degradation of organic ligands .