纳米颗粒对生物脱氮系统的联合胁迫效应与群体感应耦合调控作用研究

The rapid development of nanotechnology has led to an increasing accumulation of nanoparticles (NPs) in municipal biological wastewater treatment system, which will exert potential toxic effects on microbial community and activities of activated sludge, and depress nitrogen removal efficiency. However, the NP impacts on the production and emission of nitrogen oxides (NOx) as intermediates during the nitrogen removal process remain unclear. In addition, the different types of NPs can coexist in the influent and interact with each other, which probably amplify or mitigate the adverse effects of each type of NPs on the nitrogen removal performance of wastewater treatment system. However, current researches mainly focus on the impacts of single-NP-type contamination as the function of concentration and exposure time on wastewater treatment system. In this innovative proposal, the individual and combined effects of the representative NPs (nano-TiO2, nano-ZnO, or nano-CeO2) on the nitrogen transformation in biological nitrogen removal system, the system responses to NP stress, and the recovery of the suppressed system will be investigated. The special effort will be applied on the effects of NPs and their combined stresses on the formation and release of NOx. The spatial distributions, the forms, and the bioavailability of NPs in both liquid and solid phases of the system will be explored. The responses and the regulations of microbial community and extracellular polymeric substances to NP stresses will be inspected based on molecular ecotoxicology analysis. The coupled control capacity and the regulation mechanisms of quorum sensing on the system’s stress responses and performance recovery will be explored at the same time. In summary, the study will provide important theoretical support and practical operation guidelines for the appropriate prediction and evaluation of NP threats to biological nitrogen removal system, and help enhance the system’s treatment stability under NP contamination.

纳米颗粒（nanoparticles，NPs）在市政污水处理系统中的不断聚集可对系统污泥菌群结构与活性产生潜在毒性效应，造成系统脱氮性能下降，但其对脱氮过程中间产物氮氧化物的生成释放影响规律尚不明确。同时，不同类型NPs共存可对生物脱氮过程产生胁迫协同或拮抗效应，但现有研究仍侧重于单一类型NPs浓度与胁迫时间的作用影响上。故本项目拟开展典型NPs及其联合胁迫对污水生物脱氮系统的N循环转化影响以及系统的胁迫响应与性能恢复调控机制研究，重点阐释NPs对氮氧化物生成与释放水平动态变化的影响，掌握NPs在系统的空间分布形态与生物有效性，从分子生态毒理学角度解析污泥功能菌群及胞外聚合物对NPs的胁迫响应调节规律，并引入群体感应信息流对系统胁迫响应与性能恢复的耦合调控能力与作用机制研究，为正确预测与评价NPs对污水生物脱氮系统的潜在威胁、维护与提高NPs胁迫下系统的运行稳定性奠定重要的理论与实践基础。

纳米颗粒（NPs）因其独特的微小尺度效应而被广泛应用，从而进入污水生物处理系统并产生潜在生物毒性效应。本课题重点探讨了典型纳米金属氧化物（ZnO NPs、CeO2 NPs和TiO2 NPs）及其联合作用对生物脱氮系统氮循环转化的毒性影响、受胁迫系统性能自我恢复潜能，及群体感应对受胁迫系统氮循环物质代谢与抗胁迫应激响应的耦合调控能力。结果表明，ZnO NPs和CeO2 NPs一个SBR周期短期作用即对生物脱氮系统产生明显的剂量依赖胁迫影响，而测试浓度(1-50 mg/L)下的TiO2 NPs未对生物脱氮系统产生明显的短期胁迫影响。ZnO NPs主要干扰反硝化过程进而导致TN去除率和N2O排放通量降低，而CeO2 NPs具有抑制NH4+-N氧化活性的潜力并增加了N2O排放通量。长期胁迫过程中，10 mg/L ZnO NPs会同时影响系统NH4+-N和TN去除效率，10 mg/L CeO2 NPs仅影响了TN去除效率，而10 mg/L TiO2 NPs对NH4+-N和TN去除效率几乎没有影响。CeO2 NPs和TiO2 NPs主要刺激了异养反硝化过程中N2O的产生，而ZnO NPs主要体现了抑制效应。NPs诱导的糖代谢和氮代谢酶活性、氮代谢基因丰度和脱氮相关微生物峰度的下降是系统氮转化受抑制的主要原因。受TiO2 NPs胁迫的生物脱氮系统活性最终可完全恢复，受ZnO NPs胁迫的生物脱氮系统亚硝酸盐氧化活性不可恢复，而受CeO2 NPs胁迫的生物脱氮系统TN去除效果仅能部分恢复。CeO2 NPs和TiO2 NPs的加入均可增强ZnO NPs对生物脱氮系统的毒性效应。本研究成功建立了污泥系统中AHLs提取和检测方法。ZnO NPs毒性胁迫下内源信号分子C4-HSL、C6-HSL和C10-HSL浓度变化明显。外源投加C10-HSL显著促进受ZnO NPs胁迫系统的氨氧化速率、抑制反硝化性能，并通过提高抗氧化酶活性增强系统抗毒性能。本课题为正确预测与全面评价 NPs 对污水生物脱氮系统潜在威胁、建立我国 NPs 排放限额与环境风险管控标准提供了理论支撑，为促进受 NPs 胁迫污水处理系统有效应急管理调控策略与措施的确立提供了新思路。