磁性载体MBBR系统对纳米ZnO颗粒的胁迫响应

Responses of MBBR system with magnetic carrier to nano-ZnO partical stress

为探究磁性载体移动床生物膜反应器(MBBR)系统对不同浓度纳米ZnO胁迫的响应,构建2组MBBR开展纳米ZnO胁迫实验,通过对比普通与磁性载体MBBR中COD、NH_(4)^(+)-N去除性能、生物膜形貌、微生物群落及功能基因,分析磁性载体对纳米ZnO胁迫下MBBR中污染物去除性能及微生物的影响.结果表明:低浓度(5,10mg/L)纳米ZnO对COD、NH_(4)^(+)-N去除无显著影响;高浓度(30,50mg/L)纳米ZnO胁迫后,磁性载体MBBR的NH_(4)^(+)-N去除率分别降低10.57%和12.91%,低于普通载体的14.48%和16.94%.相比于NH_(4)^(+)-N,纳米ZnO胁迫对COD去除影响较小.此外,高浓度(30,50mg/L)纳米ZnO胁迫导致更多纳米ZnO颗粒团聚并吸附于磁性载体生物膜表面,继而改变了生物膜群落结构.在10mg/L的纳米ZnO胁迫下,磁性与普通载体生物膜中微单胞菌属(Micropruina)的相对丰度均有所提高,对该菌属生长起到促进作用.50mg/L纳米ZnO对Micropruina的生长产生明显的抑制,普通及磁性载体生物膜中其相对丰度分别降至0.20%和1.28%.KEGG代谢通路预测表明,高浓度的纳米ZnO改善了细胞膜转运蛋白和细胞活性等功能,降低了碳水化合物代谢、氨基酸代谢、能量代谢、辅助因子和维生素代谢、异种生物降解与代谢的功能.在纳米ZnO胁迫下,磁性载体较普通载体表现出更好的污染物去除性能,削弱了纳米ZnO对微生物的胁迫效应.

To investigate the response of the moving bed biofilm reactor(MBBR)with magnetic carriers to different concentrations of nano-ZnO stress,two sets of MBBRs were constructed to conduct nano-ZnO stress experiments.By comparing the performance of COD,NH_(4)^(+)-N removal,biofilm morphology,microbial community and functional genes of ordinary carriers with the magnetic carriers,the influence of magnetic carrier on pollutant removal performance and microorganisms in MBBR under nano-ZnO stress was analyzed.The results showed that low concentration(5,10mg/L)of nano-ZnO had no significant effect on COD and NH_(4)^(+)-N removal.After the stress of 30 and 50mg/L nano-ZnO,the NH_(4)^(+)-N removal of magnetic carrier MBBR decreased by 10.57% and 12.91%,respectively,lower than the 14.48% and 16.94% of ordinary carriers.Compared with NH_(4)^(+)-N,nano-ZnO stress had less effect on COD removal.In addition,more nano-ZnO particles were accumulated and adsorbed on the biofilm of magnetic carrier under high concentration(30,50mg/L)of nano-ZnO stress,thereby altering the community structure of biofilm.Under 10mg/L nano-ZnO stress,the relative abundance of Micropruina in both magnetic and ordinary carrier biofilms increased,promoting the growth of the genus.50mg/L nano-ZnO significantly inhibits the growth of Micropruina,and its relative abundance in ordinary and magnetic carrier biofilms decreased to 0.20% and 1.28%,respectively.The prediction of KEGG metabolic pathway indicated that high concentration of nano-ZnO improved the functions of cell membrane transporters and cell activity,while reduced the functions of carbohydrate metabolism,amino acid metabolism,energy metabolism,cofactor and vitamin metabolism,as well as heterologous degradation and metabolism.under the stress of nano-ZnO,magnetic carriers exhibit better pollutant removal performance than ordinary one,weakening the stress effect of nano-ZnO on microorganisms.