纳米氧化镍长期暴露对活性污泥物化特性及微生物代谢的影响

Long-term effects of nickel oxide nanoparticles on the physicochemical properties and microbial metabolism of activated sludge

为揭示纳米氧化镍(NiO NPs)在复杂环境体系中的生物毒性效应,以活性污泥为研究对象,探讨了NiO NPs(0~200mg/L)长期暴露对序批式生物反应器运行效能、污泥性能以及微生物代谢作用的影响.结果表明,低浓度(0~50mg/L)NiO NPs对活性污泥运行效能影响不显著,高浓度(100~200mg/L)NiO NPs对氨氮和COD去除有明显抑制作用,分别降低了8%和20%.随着NiO NPs的浓度增加,硝化过程关键功能酶氨单加氧酶(AMO)和羟胺氧化酶(HAO)活性分别降低55.71%和62.09%,乳酸脱氢酶(LDH)释放量增加了113.06%.同时,NiO NPs对活性污泥絮凝性产生负面影响,污泥平均粒度增加,絮体形状松散,絮凝性略有降低.胞外聚合物(EPS)整体呈下降趋势,高浓度下蛋白质(N-H,C=O)和多糖(C-O,C-C,C-O-C,C-O-H)相关官能团的强度减弱,三维荧光蛋白特征峰强度大幅降低.但死亡微生物的生物分解和应激反应促进了EPS中微生物代谢和酪氨酸蛋白类物质生成.此外,活性污泥中微生物群落的多样性和稳定性均受到NiO NPs的影响.PICRUSt2预测显示,微生物的代谢和遗传信息处理相关的代谢通路均受到NiO NPs的显著抑制.因此,NiO NPs通过改变微生物群落结构和代谢通路影响活性污泥硝化作用和有机物的去除.

In order to reveal the biotoxicity of nickel oxide nanoparticles(NiO NPs)in complex environmental systems,this study used activated sludge as the research target and investigated the long-term effects of NiO NPs(0~200mg/L)on the operational efficacy,sludge performance,and microbial metabolism of sequencing batch reactors.Results indicated that low concentrations(0~50mg/L)of NiO NPs did not have significant effects on activated sludge operational efficacy,and high concentrations(100~200mg/L)of NiO NPs significantly inhibited the removal of ammonia nitrogen and COD by 8%and 20%,respectively.With the increase of the concentration of NiO NPs,the activities of key functional enzymes ammonia monooxygenase(AMO)and hydroxylamine oxidase(HAO)in the nitrification process decreased by 55.71%and 62.09%,respectively,and the release amounts of lactate dehydrogenase(LDH)increased by 113.06%.Meanwhile,NiO NPs negatively affected activated sludge flocculation,with an increase in average sludge particle size,loose floc shape,and a slight decrease in flocculation.Extracellular polymeric substances(EPS)showed an overall decreasing trend,the intensities of protein-related(N-H,C=O)and polysaccharide-related(C—O,C—C,C—O—C,C-O-H)functional groups weakened at high concentrations,and the intensities of the proteins characteristic peak of three-dimensional fluorescent decreased substantially.However,biodegradation of dead microorganisms and stress response promoted microbial metabolism and tyrosine protein-like substance production in EPS.In addition,the diversity and stability of microbial communities in activated sludge were both affected by NiO NPs.PICRUSt2prediction showed that metabolic pathways related to metabolisms and genetic information processing were both significantly inhibited by NiO NPs.Therefore,NiO NPsaffected nitrification and organic matter removal of activated sludge by altering microbial community structure and metabolic pathways.