活性污泥中AOA、AOB和异养菌在三氯生去除过程中的协同作用机理

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.

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。

广谱抗菌剂三氯生(TCS)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TCS向环境迁移最重要的途径,但是现有工艺无法有效去除TCS。因此,本研究以TCS为目标污染物,首先考察TCS在未驯化活性污泥中的吸附和降解;其次,在实验室SBR和A/O工艺中,分别以除碳污泥、硝化污泥、同时除碳脱氮污泥、同步脱氮除磷污泥、短程反硝化污泥和短程硝化/厌氧氨氧化(PN/A)污泥为对象,考察TCS在不同污水生物脱氮系统中的去除及其对菌群结构和抗生素抗性基因的影响;最后,选择未驯化的脱氮污泥、SBR硝化污泥、A/O脱氮污泥和SBR短程反硝化污泥为对象,利用DNA-SIP结合高通量测序技术考察并鉴别不同污水生物脱氮系统中TCS去除途径及活性降解菌。主要结果如下:①污泥吸附TCS过程中官能团作用排序如下:疏水基团>巯基>胺基。②无论是硝化系统、A/O脱氮系统、短程反硝化系统还是PN/A系统,经过TCS长时间的驯化,系统中TCS的去除由吸附向降解转移。③硝化系统中主要的TCS代谢产物为2,4-二氯苯酚、2-氯对苯二酚和苯酚;A/O和短程反硝化系统中为2,4-二氯苯酚和苯酚。3个系统中TCS的降解途径可能为:首先TCS的C-O-C键断裂产生2,4-二氯苯酚,然后经过微生物氧化/还原脱氯作用转化为对苯二酚/苯酚,最后矿化为CO2或其它代谢终产物。④代表水平转移类基因的intI1和tnpA为优势移动元件基因;代表外排泵机制的mexB、mexD和mexF为优势的抗生素抗性基因;⑤未驯化的脱氮污泥、SBR硝化污泥、A/O脱氮污泥和SBR短程反硝化污泥系统中最主要的TCS降解途径均为异养菌的代谢作用,TCS的代谢能力依次为:未驯化的脱氮污泥(18.4%)<SBR短程反硝化污泥(48.87%)<A/O脱氮污泥(62.0%)<SBR硝化污泥(75.3%)。⑥实际生活污水生物脱氮系统中主要的活性TCS降解菌为Sphingobium;硝化系统中为Sphingomonas和Sphingobium,表面活性剂存在下硝化系统中为Amaricoccus;A/O系统中为Methylobacillus;短程反硝化系统中为Sphingomonas、Sphingosinicella、Thauera和Methylophilus。本研究为优化污水处理工艺、提高TCS的去除效率提供理论依据。