磷回收介导的碳源调控-生物膜脱氮除磷系统的耐低温机制

The recovery of phosphorous (P) from wastewaters as the global phosphorous resource conservation strategy had stepped into a new historical era. Converting the conventional Bionutrients removal reactors (BNR) into BNR -Phosphorous Recovery reactors (BNR - PR ) is one of the most important trends in developing municipal wastewater treatment plants. For the seek of performing effective phosphorous recovery from the low-P-containing wastewaters and the effective removal of nitrogen simultaneously under low temperatures, the project would exploit an alternating anaerobic/aerobic biofilter system. The prospecting purposes of the project include: .① To investigate the supplementary carbon source amendment strategies and their impact on the durable intracellular carbon source storage by the microbial communities in the biofilm, thus the intrinsic pattern of effective carbon and energy source storage induced by the phosphorous recovery process can be discovered. .② To ascertain the inter-connection between the cold resilient characteristics of the biofilm microbial communities and their intracellular carbon source storage, aiming at uncovering the mixotrophic growth potential for a fraction of nitrifiers inhabiting in the biofilm. In addition, the project planned to discover the potential functions of the predominant microbial communities and their metabolic pathways for carbon, nitrogen and phosphorous. .③ To uncover the excreting of EPS (Tightly Bound-EPS, Loosely Bound-EPS and Slime EPS) by the biofilm microbial communities during the system’s subjections to low temperatures. Thus the potential survival and competition strategies developed by the biofilm microbial communities can be excavated. .The achievements of the project will enhance our understanding of the advantages of the biofilm nitrogen removal and phosphorous accumulation process, and the understanding of the way to improve the robustness of the biofilm BNR systems under the low temperature operational conditions. In addition, the achievements of the project will advance the future research & development on resource recovery from low-P-containing wastewaters.

废水磷回收作为全球磷资源战略已步入新的历史阶段，将传统的生物脱氮除磷工艺（BNR）改为生物脱氮/蓄磷-磷回收工艺是污水厂未来发展的重要方向。为从低磷废水中有效回收磷，同时强化低温脱氮效果，项目利用厌氧好氧交替生物滤池进行生物脱氮与蓄磷，并且研究：.①厌氧磷回收过程中，补充碳源性质对菌群合成持久型内源碳的影响、揭示碳源调控耦合磷回收对生物膜菌群合成内源性碳源及能源的驱动机制。.②菌群的耐低温特性与内源碳贮存的关系；探索生物膜硝化菌的低温兼养生长特性；探明生物膜群落组成与潜在功能，以及相关碳、氮、磷的去除途径，构建碳源调控耦合磷回收型脱氮除磷新工艺的理论基础。.③碳源调控下生物膜菌群形成胞外多聚物的响应机制，揭示生物膜功能菌群耐受低温时采取的竞争策略。.项目成果对理解附着生长生物脱氮/蓄磷-磷回收工艺的优势、提高低温生物膜脱氮除磷系统稳健性、研发低磷废水资源回收的新工艺提供理论参考。

为缓解未来磷资源不足的危机，将传统的生物脱氮除磷工艺（BNR）转化为生物脱氮/蓄磷-磷回收工艺是污水厂未来发展的重要方向之一。本项目基于厌氧/好氧交替生物滤池工艺，为强化磷回收，周期性引入补充碳源，将普通生物脱氮工艺升级为生物脱氮/蓄磷-碳源调控磷回收工艺。项目分析了补充碳源对系统运行的影响，探究了系统低温稳定运行的机制： .① BBNR-CPR 可长期在低温（5-15℃）以及低 C/N 比（<7）条件下保持高效脱氮、除磷、回收磷的效率：氨氮与总氮平均去除率分别达到90%、72%，磷平均回收率为35%。氮、磷的去除负荷分别为0.12±0.01 N· m-3·d-1 和 0.05 kg P· m-3·d-1。.② 高度富集了多个自养/异养硝化混合生长菌群：其中之一可在 4℃具有同时硝化与反硝化活性（最大氨氮降解速率为 12gN· m-3·d-1，总氮平均去除率为 58%）。具有一定研究及推广价值的耐低温自养/异养硝化混合生长菌群。.③ 补充碳源的性质对BBNR-CPR的菌群组成的作用：碱法机械破解污泥可直接释放富含氨基酸的污泥基碳源，部分游离性氨基酸 （e.g.天冬氨酸，谷氨酸，精氨酸、甘氨酸等）可被BBNR菌群直接吸收与贮存；并对施用菌群的组成产生显著影响。.④ 菌群的耐低温特性与胞内、外碳源贮存的关系：低温运行可促进新型推定的聚磷菌（Thauera spp.和Candidatus Accumulibacter spp.）的高度富集；低温下实施厌氧磷回收操作，可通过提升补充碳源浓度，促进硝化菌与反硝化聚磷菌在低温下的富集；胞外聚合物（extracellular polymersubstance，EPS）与PHA是补充碳源在生物膜内两种主要贮存形式；蓄磷周期内生物膜PHA的贮存量不断下降，而胞外多聚物EPS在生物膜内的贮存量呈周期性先升后降的规律； .⑤ 碳源调控下生物膜菌群的自适应响应机制：对生物膜样本的基因组与转录组生信数据分析后发现，运行温度降低后混合生长菌群中各功能物种合成甘氨酸（glycine）和胞外聚合物基因大幅增加，且几乎所有物种都高表达分子伴侣、冷休克蛋白和PHA合成的相关基因。.项目成果对理解附着生长生物脱氮/蓄磷-磷回收工艺的优势、为未来研发低磷废水资源回收的新工艺提供理论依据。