人工菌群修复铀污染地下水的模拟

Simulating of Bioremediation Uranium-contaminated Groundwater by Designed Consortia

基于功能互补原则,采用“自下而上”的配菌法,将硝酸盐还原菌(NRB)、硫酸盐还原菌(SRB)及异化铁还原菌(FeRB)等比例混合,构建人工菌群并探讨其修复铀(U)污染地下水的效果与作用机制。模拟实验结果表明:在pH=7.2、25℃、U(Ⅵ)初始浓度为20.0 mg/L的铀污染地下水中,人工菌群对溶液中U(Ⅵ)的去除率比单菌提高了20%~35%。人工菌群的固铀过程分为三阶段:首先微生物将溶液中的U(Ⅵ)吸附固定于菌体表面,同时NRB将NO_(3)还原,为U(Ⅵ)的还原创造有利条件;然后SRB、FeRB同步还原U(Ⅵ)、SO^(2)_(4);最后FeRB等微生物促进非结晶态U(Ⅳ)转化为UO_(2),提高了还原产物的稳定性。

Nitrate-reducing bacteria(NRB),sulfate-reducing bacteria(SRB)and iron-reducing bacteria(FeRB)played key roles in bioremediation of uranium(U)-containing groundwater.They were mixed in equal proportion to construct designed consortia via the‘bottom-up’approach,comparing the efficiency uranium-fixing of pure bacteria and designed consortia,and exploring the mechanism of designed consortia reaction with underground uranium-containing wastewater.The simulating results showed that the removal efficiency of U(Ⅵ)in designed consortia was 20%—35%higher compared to the pure consortia with the pH=7.2,25℃and the 20 mg/L U(Ⅵ)of underground uranium-containing wastewater.The process of uranium-fixing by using designed bacteria could be divided into three stages.U(Ⅵ)in solution wasfirstly adsorbed located on the cells surface,and NO_(3) was reduced by NRB to create a favorable environment for U(Ⅵ)reduction;then U(Ⅵ)and SO^(2)_(4)were reduced simultaneously by SRB and FeRB;Finally some non-crystalline U(Ⅳ)were transformed into UO_(2) with aging by FeRB,et al,which improved the stability of the reduction product.