基于r-K策略菌群选择的硝化动力学模拟及其优化调控

The optimization of activated sludge process is mainly for improving short term effluent quality and reducing operation cost, without considering the bacterial population structure, which is important for the long term stable operation of activated sludge process. The molecular techniques for biological assays can be used to identify the bacterial species within activated sludge. However the results from these techniques are usually case-specific and cannot be used for qualitative evaluation. In this project, the r-K selection theory from ecology will be used to quantify the activated sludge bacterial population structure systematically. The r and K strategist bacterial have different substrate consumption kinetics. The r- strategist bacterial is strong competitor at high substrate concentration and can be used for rapid substrate reduction. The K- strategist bacterial is favoured at low substrate concentration and can be used for refining the effluent quality. Therefore by optimizing the r-K strategist bacterial population structure, the shocking load management and effluent refinement can be achieved. Currently, it is not clear on the mechanism of r-K strategist bacterial population selection. In this project, the r-K strategist nitrifier (AOB and NOB) selection mechanism during nitrification process will be studied to develop a kinetic model that can be used for the optimization of nitrification process the nitrifier population structures. The results will not be limited to nitrification process and can be used in other activated sludge processes that involve bacterial selections.

活性污泥系统优化常以提高短期出水水质和降低运行费用为目标，一般不涉及菌群结构,而合理的菌群结构对污水生物处理的长期稳定运行至关重要。分子生物学手段可对活性污泥中的菌群进行鉴定，但是其鉴定结果一般比较多样、具体，不能作为定量化手段。本项目拟通过生态学中的r-K选择理论，来系统地界定活性污泥菌群结构。r、K策略菌具有不同的底物降解特性：在底物浓度较高时，r-策略细菌具有竞争优势，可快速降解底物;底物浓度较低时，K-策略细菌具有优势，能进一步降低污染物浓度。因此通过优化r-K策略菌的结构，可应对冲击负荷和降低出水污染物浓度。而目前又缺乏对活性污泥r-K策略菌竞争机制的研究。本项目拟通过对硝化过程中r-K策略硝化菌（AOB和NOB）选择机制的研究，并建立动力学模型，对硝化系统进行调控，做到在满足硝化效果的同时，又能对硝化菌群结构进行优化。研究成果也可扩展到活性污泥系统中其它菌群结构优化。

有关硝化动力学和硝化细菌的分子生物学研究表明了r-K策略硝化菌在硝化系统中的广泛存在。通过保持r-K策略硝化菌的多样性，可以提高硝化效果的稳定性。但是缺乏针对性的r-K策略优化调控手段。本课题将通过r-K策略硝化细菌结构选择机制的研究，通过数学模拟，来达到对硝化过程和硝化菌群结构优化调控的目的。.本项目的研究目标共三项：（1）明确硝化过程中硝化菌r-K策略选择机制；（2）建立基于硝化菌r-K策略选择的硝化动力学数学模型；（3）利用硝化菌r-K策略选择机制，优化调控硝化过程，使其在满足硝化效果同时，又能对硝化菌群结构进行长期优化。.数学模拟的结果表明维持较高的混合液氨氮浓度对实现短程硝化有帮助，初步证明了数学模拟的结论。通过提高混合液氨氮浓度，可以富集r-AOB, 在低浓度氨氮废水中，实现了稳定的短程硝化，从而为应用最近发展的厌氧氨氧化技术创造了条件。建议在低温下开展短程硝化实验，进一步验证数学模拟的结论，并且利用分子生物学手段，研究短程硝化过程中AOB和NOB的变化规律。实验测得AOB的溶解氧亲和力要比NOB 低,在这种条件下,AOB的最大比生长速率高于NOB是实现短程硝化的重要条件; 两级硝化数学模拟的结果表明,在AOB的溶解氧亲和力低于NOB条件下,低溶解氧和高泥龄都不利于短程硝化实现,而较高溶解氧和低泥龄组合有利于短程硝化实现。本研究结果表明AOB种类随SRT和体积NH4 +浓度的变化而变化。然而，对于AOB物种转变的直接证据，需要使用分子生物技术工具进一步研究细菌群落分析。.明确了硝化过程中r-K策略硝化菌AOB和NOB的竞争选择机制；建立然基于r-K策略AOB和NOB的竞争选择的硝化动力学数学模型；.利用r-K策略选择机制，提出了优化调控硝化过程的方法，使其在满足硝化效果的同时，又能对硝化菌菌群结构进行长期优化。