我国地表水普遍存在氨氮超标问题，当冬季水源水温低至1～6℃时，折点加氯去除氨氮会带来消毒副产物超标等问题，并增加水厂运行费用。采用新菌种HITLi7T为解决低水温期氨氮处理的问题提供了新途径。已有研究表明，用HITLi7T处理6～8℃进水氨氮为3.6mg/L的地下水时，其去除率在90%以上，但处理1～2℃进水氨氮为1.7mg/L的地表水源水时，受低温及可生物利用碳源影响，其去除率仅为21%。目前对于如何提高HITLi7T低温下的生长速率、基于C、N共代谢和菌种稳定性去除氨氮的机制与途径仍不清楚。本项目将通过分子生物学方法研究低温下提高新菌种HITLi7T的生长速率和活性的调控方法；明确新菌种的C、N、O计量关系及C、N共代谢机理，建立C、N共代谢模型；结合生态学原理和生物学方法，多角度分析新菌种的长期稳定机理；强化低温水源水中氨氮去除的工艺控制；进而完善低温水源水氨氮处理的新理论和新方法。

In China, ammonium concentration in surface water is normally over the standard. In winter, the water temperature drops to 1-6 °C. At that time, ammonium removal by break-point chlorination causes the over-standard of disinfection by-product, and rises the running cost for drinking water treatment plant. The application of the novel strain HITLi7T proposed a new approach for solving the problem of ammonium removal at low water temperature period. The previous studies showed that the strain HITLi7Tremoved above 90% of ammonium from ground water at 6-8 °C when the initial ammonium concentration was 3.6 mg/L. However, it only removed 21% of ammonium from the surface water at 1-2 °C when the initial ammonium concentration was 1.7 mg/L, because it was influenced by low temperature and lacking of biodegradable organic carbon. In present, it is still not clear for the mechanism and approach of improving the growth rate of the novel strain HITLi7T at low temperature, enhancing the ammonium removal efficiency on the base of C, N co-metabolism and microbial stability. In this project, the molecular biological methods will be used to study the management methods for improving the growth rate and activity of the novel strain HITLi7T at low temperature. The stoichiometric equation of C, N and O will be calculated. The C and N co-metabolism mechanism will be investigated.The C and N co-metabolism model will be built. The principal of long-term stability of the novel strain will be studied with ecological principal and molecular biological technology. The process management will be proposed for enhancing the ammonium removal from source water. The research will supplement the novel theory and approach about ammonium removal from source water at low temperature.