调控异养硝化新菌种HITLi 7T强化去除低温微污染水源水中氨氮效能的机理研究

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.

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。

冬季水温降低，水体的自净能力减弱，导致给水厂对氨氮的处理难度增加。低温条件下给水厂现有的混凝、沉淀、过滤等常规工艺及普通生物活性炭工艺对氨氮基本没有去除能力，尽管在消毒工艺中，通过加大投氯量，以折点氯化的方式可去除水中过量的氨氮，但由于大量增加投氯量，不仅提高了制水成本，而且加大了消毒副产物的产生风险。 .为更好地解决在低温及缺少可生物利用碳源的条件下，水中氨氮去除效率低的难题，鉴于前期研究中发现的异养硝化菌Acinetobacter Harbinensis HITLi7T在低温下的应用潜力，本课题从基因组学、转录组学和蛋白组学三个角度阐明了菌株HITLi7T的适冷机理，并通过调整培养基中的微量元素组成能够实现其低温下快速生长和活性提高。通过基因注释，研究了HITLi7T在低温下的碳代谢特性以及碳氮共代谢机理；并应用数学模型，构建了其对有机碳、硝酸盐和氨氮的共代谢动力学模型，同时根据环境因子对模型进行了修正，明确了其对碳氮共代谢的化学计量关系。通过长期观测基于Acinetobacter Harbinensis HITLi7T构建的生物强化活性炭（BEAC）工艺对氨氮的去除效果和菌群的动态变化，证实了在水温不断变化条件下，异养硝化菌HITLi7T通过发挥其适冷特性，在长期运行时（506d）依然能够维持稳定状态，并与其他土著菌属共存，形成了较为稳定的微生物群落结构。同时通过活性炭预负载碳源、外加碳源和臭氧氧化工艺三种工艺调控的方式，从碳源调控角度强化了基于HITLi7T构建的BEAC工艺低温下对氨氮的去除效能。通过以上系统研究，明确了利用HITLi7T去除低温水中氨氮的关键理论与技术，对进一步完善低温水源水氨氮处理的新理论和新方法、保障冬季低温期水厂安全供水具有重要意义，该技术体系在我国尤其是北方地区具有广阔的应用前景。