基于Fe^(0)的地下水混养反硝化脱氮效能与机制

Fe^(0) SUPPORTED MIXOTROPHIC DENITRIFICATION FOR GROUNDWATER TREATMENTS: PERFORMANCE AND POTENTIAL MECHANISM

以含硝态氮(NO~--N)的模拟地下水为研究对象,采用零价铁(Fe^(0))与生物耦合实现混养反硝化高效脱氮。结果表明:在C/N为2.78~3.08时,1号反应器(仅添加活性污泥)平均TN和NO~--N去除率分别为39.6%和40.1%,而2号反应器(添加活性污泥+Fe^(0))中平均TN和NO~--N去除率分别为80.7%和81.4%。2号反应器单批次物质转化结果表明,1个反应周期内包含2个阶段:0~12 h混养反硝化阶段及12~24 h自养反硝化阶段,且脱氮过程集中在前12 h;零级动力学结果表明,0~12 h的反硝化速率为2.38 mg/(L·h),是12~24 h反硝化速率的9.5倍;通过理论计算可知,4~12 h自养及异养脱氮贡献比例较稳定,两者比值约为4∶6,12~24 h自养反硝化作用贡献占比为100%。SEM和XRD分析结果表明,Fe^(0)表面有明显的微生物腐蚀现象,FeOOH和含铁有机复合物是主要的腐蚀产物。微生物群落结构分析表明,Fe^(0)可有效提高菌落多样性与丰富性,且动胶菌属(Zoogloea)作为优势菌属在反硝化过程中起主导作用。

To achieve high-efficiency denitrification of groundwater containing NO-N, Fe^(0) was added to strengthen biological mixotrophic denitrification. The results showed that when C/N was 2.78~3.08, the average TN and NO-N removal efficiency of reactor 1 were 39.6% and 40.1%, and they were 80.7% and 81.4% in reactor 2 adding Fe^(0). The results of substance transformation in a single batch of reactor 2 showed that one reaction cycle was composed of two stages: mixotrophic denitrification stage in 0~12 h and autotrophic denitrification stage in 12~24 h, and the denitrification process mainly occurred in stage of 0~12 h;the zero-order kinetics fitting results revealed that the denitrification rate was 2.38 mg/(L·h) in 0~12 h, 9.5 times of that in 12~24 h;in 4~12 h, the contribution ratio of autotrophic and heterotrophic denitrification was stable(about 4∶6), and contribution ratio of autotrophic denitrification was 100% in 12~24 h. Moreover, SEM and XRD analysis showed that there was significant microbial corrosion on the surface of Fe^(0), and the major products were FeOOH and bioorganic-Fe complexes. Microbial community structure analysis result indicated that Fe^(0) could effectively improve the diversity and richness of microbial community, and Zoogloea played a leading role in the denitrification process as the predominant genus.