广谱抗菌剂三氯生对人类健康和环境安全的影响受到了越来越多的关注。城市污水处理厂是三氯生向环境迁移最重要的途径，但是现有工艺无法有效去除三氯生。因此，本研究以三氯生为目标污染物，在已获得大量实际污水处理厂AOA和AOB系统发育数据的基础上，利用DNA-SIP结合宏基因组学技术，在污水处理厂“原位”条件下，在实验室SBR系统和A/O脱氮系统中，分别针对除碳污泥、同时除碳脱氮污泥、硝化污泥（AOA>AOB，AOA≈AOB和AOA<AOB），在区分吸附和生物降解的基础上，研究污水处理厂背景浓度水平下三氯生的去除动力学和机理，分析AOA、AOB共代谢和异养菌基质代谢作用的贡献，探究AOA、AOB和异养菌系统发育（丰度和多样性）与生理代谢功能（代谢活性和途径、营养类型等）之间的关系，揭露活性污泥中AOA、AOB和异养菌在三氯生去除过程中的协同效应，为优化污水处理工艺、提高三氯生的去除效率提供理论依据。

Triclosan, as a broad-spectrum antibacterial agent, has received more and more concerns on its impact on human health and environment safety. Municipal wastewater treatment plants (WWTPs) are well demonstrated as the most significant way for triclosan to enter into the environment. However, triclosan could not be completely removed from wastewater by the existing sewage treatment processes. Therefore, in this project, the DNA stable-isotope probing (DNA-SIP) and meta-genomic techniques, as the promising methods recently developed will be employed to investigate the relationship between microbial identity and triclosan metabolic functions. Besides sorption, the co-metabolism by ammonia-oxidizing archaea (AOA) and (or) ammonia-oxidizing bacteria (AOB) and the growth metabolism by heterotrophic bacteria for triclosan degradation will be investigated..In our previous studies (NSFC. 51078007), the abundance and diversity of AOA and AOB have been well investigated in 50 full-scale WWTPs in 12 provinces in China. Three typical kinds of activated sludge will be chosen, i.e. AOA>AOB, AOA≈AOB and AOA<AOB. Then through in field label or microcosm incubation, 13C-labeled substrate DNA-SIP and meta-genomic techniques will be employed to reveal whether triclosan co-metabolism was driven by AOA and (or) AOB, the relative contributions of AOA and AOB to triclosan co-metabolism and the activity of AOA and AOB. Also, the contributions of heterotrophic bacteria for triclosan removal will be investigated. .In SBR systems, three kinds of activated sludge will be cultivated: carbon removal sludge, carbon and nitrogen removal sludge and nitrification sludge. Then, acclimatized sludge will be occupied to investigate the triclosan degradation by heterotrophic bacteria, the co-metabolism by AOA and (or) AOB and synergy among AOA, AOB and heterotrophic bacteria. In anoxic-oxic (A/O) system, two kinds of activated sludge will be cultivated. After the systems reach quasi-steady-state, triclosan will be added into the influent to investigate triclosan removal and its mechanism in continuous system. After the studies in batch and continuous system, DNA-SIP and meta-genomic techniques will be applied to investigate the microbial mechanisms of triclosan degradation in different kinds of activated sludge..On the whole, the contributions of the co-metabolism by AOA and AOB and the growth metabolism by heterotrophic bacteria for triclosan removal will be investigated. The relationships between the abundance and diversity of these microorganisms and the metabolic functions (metabolic activity, metabolic pathway and nutrition type) will be explored to reveal the synergy among AOA, AOB and heterotrophic bacteria for triclosan degradation in activated sludge. This project will provide microbial foundation for optimizing sewage treatment processes to improve the removal efficiency of triclosan.