污水处理中硝化菌低温压力响应机制与优化调控研究

Ammonia is a important pollutant in surface water, and in the "twelfth five year plan" China has set stringent limiatations on its discharge. However, the low removal efficiency of ammonia at low temperature has been a major limiting factor in nitrification system. The existing enhancement technologies for ammonia removal at low temperature generally suffer from high cost and poor efficiency. In this project, we shall investigate the changes of the major stress response indexes such as nitrobacteria community structure, antioxidative enzyme system (catalase, superoxide dismutase, etc.), nitrification activity (such as gene expression of nitrogen monooxygense and dehydrogenase activity, Hydroxylamine oxidoreductase activity, and oxygen uptake rate). We aim to elucidate the mechanism of nitrifier responsing to low-temperature stress from three aspects: bacteria community, cell stress defense system and degradation activity. Both sharp change (1-5℃/day)and gradual change (5-15℃/month shall be investigated. The dynamic changes of response indexes under enhancement shall also be studies. Based on these researches and the rules of in exchange, a new low-temperature enhancement control technology shall be developed.

当前，氨氮已成为影响地表水水环境质量的首要指标，国家明确将氨氮纳入"十二五"节能减排约束性指标。低温下氨氮生物硝化处理效率大幅下降，严重制约氨氮冬季达标排放与污水处理提标升级改造，而现有低温调控技术缺乏理论指导，存在成本高、效率低等问题。针对这些问题，本项目重点研究低温下硝化菌种群结构、抗氧化物酶系统（过氧化物酶、过氧化氢酶、超氧化物歧化酶等）、硝化活力指标（脱氢酶、氨单加氧酶基因（amoA）表达、羟胺氧化酶、耗氧呼吸速率等）与氨氮硝化效果（降解动力学）等压力响应表征指标的动态变化，意图从硝化菌种群结构及低温下细胞防御与氨氮降解活力三个方面，研究硝化菌对骤变（1-5℃/天）与渐变（5-15℃/月）低温冲击下的压力响应机制；并模拟现有低温氨氮强化措施，考察强化措施下响应指标的动态变化规律；在此基础上，低温响应机制与强化措施下响应指标变化规律相结合，指导研发低温下硝化处理系统新型调控技术。

针对当前低温下氨氮生物硝化处理效率大幅下降，严重制约氨氮冬季达标排放的问题，本项目以硝化污泥和异养硝化好氧反硝化菌HN-02为研究对象，重点研究了低温下硝化菌种群结构、抗氧化物酶系统（过氧化物酶、过氧化氢酶、超氧化物歧化酶等）、硝化活力指标（ATP、耗氧呼吸速率、脱氢酶等）与氨氮硝化效果等压力响应表征指标的动态变化；得到了HN-02和硝化污泥中的抗氧化酶体系中的SOD活性、能量代谢体系中的ATP含量均对低温冲击表现出明显相关性，并与脱氮效果密切相关；同时，在菌群结构方面，偏爱低温、变温的Nitrosospira相比偏爱中温、恒温环境的Nitrosomonas为占优势的AOB，偏爱中温、恒温环境的Nitrospira为占优势的NOB，这最终导致氨氧化活性相比亚硝氮氧化活性更敏感，但恢复性更高；此外，中温驯化有助于提高硝化菌群的耐低温性能与长期胁迫下恢复性能。基于上述低温压力响应机制，研发了硝化菌群活性调控技术、快速富集技术及污泥快速增殖技术，实现工程应用2项，发表SCI论文2篇，申请发明专利1件。