纳米铁系材料与反硝化细菌复合去除地下水硝酸盐氮研究

Reducing nitrate in groundwater by denitrifying bacteria combined with nanoiron-based materials

采用不同液相还原法制备了纳米Fe、纳米Fe/Ni和油酸钠包覆型纳米Fe粒子,并将其与反硝化细菌复合应用于地下水中硝酸盐氮的去除研究中.分别考察了不同纳米铁系材料与反硝化细菌复合体系去除硝酸盐氮的反应速率及对脱氮产物生成的影响.同时,从核糖核酸(RNA)水平考察了不同纳米铁系材料对反硝化细菌的影响.结果表明,纳米Fe/Ni复合体系脱氮速率最快,6d内对硝酸盐氮的去除率可达到100%,最终产物主要为氨氮,占体系总氮的69%;而纳米Fe和油酸钠包覆型纳米Fe复合体系9d可将硝酸盐氮100%去除,氨氮的转化率分别为52%和16%.另外,从反应前后反硝化细菌总RNA浓度的变化情况看,纳米Fe/Ni复合体系、纳米Fe复合体系和油酸钠包覆型纳米Fe复合体系的反硝化细菌总RNA浓度分别降低了93%、40%和34%,可见3种纳米铁系材料对反硝化细菌毒性大小顺序为:纳米Fe/Ni>纳米Fe>油酸钠包覆型纳米Fe.

Three nanoiron-based particles,Fe,Fe/Ni and sodium oleate-coated Fe,were synthesized by liquid-phase reduction methods and then integrated with denitrifying bacteria to remove nitrate from groundwater.Batch experiments were carried out to examine the removal rate of nitrate and the final nitrogen transfomation products in these particle-bacteria systems.Also,the total RNA content in these systems was measured to evaluate the toxicity of nanoiron-based particles on the integrated bacteria.The results showed that almost 100% removal of nitrate was reached within 6 days in the Fe/Ni nanoparticle-bacteria system,and the ratio of ammonium to TN was 69% in the final products.Both nano-scale Fe and sodium oleate-coated Fe particlebacteria systems took 9 days to complete 100% removal of nitrate,producing 52% and 16% ammonium,respectively.The total RNA of the integrated bacteria decreased in content by 93%,40% and 34% in the Fe/Ni,Fe and sodium oleate-coated Fe nanoparticle-bacteria systems respectively,which suggested the toxicity of these nanoparticles to denitrifying bacteria should be in the sequence：nano-scale Fe/Ni nano-scale Fe sodium oleate-coated Fe.