污水生物处理系统中纳米颗粒污染物的影响

Impacts of nanoparticle pollutants on biological wastewater treatment systems

重点探讨了水处理系统中纳米颗粒(NPs)污染物的分布和归趋特点,及其对系统中微生物菌群结构与功能、有机物与氮磷去除效率的影响.结果显示:反应器可拦截进水中90%以上NPs;NPs短期内对水处理系统有机物去除效率无明显抑制,当50 mg/L的纳米TiO2和ZnO作用70 d可使得污水总氮去除率从80.3%,81.5%降至24.4%和70.8%,纳米ZnO甚至可使除磷效率完全丧失.NPs还会造成反应器内硝化细菌浓度和比重的下降,如50 mg/L TiO2作用70d可使反应器内氨氧化菌和亚硝酸盐氧化菌含量分别由8%,6%降至1%和3%,但对聚磷菌种群的相关显著影响尚未发现.NPs的生物毒性作用机制主要包括氧化胁迫、细胞膜破坏与酶活性抑制等,如50 mg/L的纳米TiO2可分别对活性污泥中的氨单加氧酶和亚硝酸盐氧化还原酶活性产生80%和55%的抑制率.

The distributions and fates of nanoparticles （NPs）pollutants in the biological wastewater treatment systems and the impacts of NPs on the structures and functions of microbial community, the removal of organic matter,nitrogen and phosphorus were investigated.The results show that more than 90%of NPs can be intercepted in the bioreactor.When the wastewater treatment system is exposed to the influent with 50 mg/L of nano-TiO2 and nano-ZnO for 70 d,the removal efficiencies of total nitrogen decrease from 80.3%and 81.5%to 24.4%and 70.8%,respectively.Nano-ZnO can even cause a complete loss of phosphorus removal ability.The presence of NPs can cause a de-crease in density and abundance of nitrifying bacteria,but this decrease of phosphorus accumulating organisms in the microbial community of a bioreactor is not observed.When exposed to 50 mg/L nano-TiO2 for 70 d,the ammonia-oxidizing bacteria and nitrite-oxidizing bacteria decreased from 8%and 6% to 1% and 3%,respectively.Mechanisms of NPs biotoxicity include oxidative stress,cell damage,and enzyme inhibition.When 50 mg/L nano-TiO2 is exerted on the activated sludge,the activity inhibition rates of ammonia monooxygenase and nitrite oxidoreductase are 80% and 55%, respectively.