固体缓释碳源协同短程硝化反硝化生物膜脱氮调控及运行机制研究

At present, the influent carbon source concentration of China’s urban sewage treatment plants is generally low, resulting in the difficulty in the continuous and stable reaching the standard of the effluent total nitrogen (TN). Solid slow-release carbon source is often used as denitrification carbon source and biological filler by combination of partial nitrification-denitrification biofilm based on nitrite pathway, which is one of the effective ways to solve the shortage of carbon source and efficient removal of total nitrogen in WWTP. However, the optimization regulation, nitrogen transformation and operation mechanism of the process still need to be further studied. Therefore, this project intends to apply a sequencing batch biofilm reactor to achieve the optimal operating conditions of slow-release carbon source synergistic partial nitrification biofilm through regulating system parameters, and the inhibition mechanism of nitrite oxidizing bacteria (NOB) will be also analyzed. Next, the key components and physicochemical characteristics of extracellular polymer substances (EPS) during the formation process of slow-release carbon source synergistic partial nitrification biofilm will be analyzed. Moreover, the characteristics of biofilm formation will be explored. Additionally, the characteristics and bioavailability of dissolved organic nitrogen (DON) in the slow-release carbon source synergistic partial nitrification biofilm will be analyzed by using chemical analysis and spectroscopic approach. In the end, the key functional genes and dominant population evolution of biofilm will be investigated by using modern molecular biology to confirm the microbial mechanism. This research result of the project is of guiding significance for promoting the development and application of new biotechnology.

目前，我国城镇污水厂进水碳源浓度普遍偏低，致使出水总氮难以持续稳定达标。利用固体缓释碳源作为反硝化碳源和生物填料，构建基于亚硝酸盐途径的短程硝化反硝化生物膜脱氮工艺，是解决污水厂碳源不足和总氮高效去除的有效途径之一。但该工艺的优化调控、氮污染物形态转化和运行机制等问题仍需进一步深入研究。基于此，本项目拟采用序批式生物膜反应器，通过调控系统参数，建立固体缓释碳源协同短程硝化生物膜的最佳运行条件，明确亚硝酸盐氧化菌（NOB）抑制机制；分析生物膜形成过程中微生物胞外聚合物（EPS）关键组分和物化特性，探索其形成特性；采用化学分析与光谱表征相结合的手段，分析短程硝化系统中溶解性有机氮（DON）生成特性和生物有效性，明确其化学结构和分子构成；在此基础上，通过分子生物学技术明确短程硝化生物膜脱氮关键功能基因和优势种群演变，揭示其微生物作用机制。本项目的研究成果对推动新型生物技术发展和应用具有指导意义。

针对污水处理厂进水碳源低、碳源投加不易控制和总氮难以稳定达标的技术难题，本项目构建了基于亚硝酸盐途径的缓释碳源反硝化耦合短流程生物脱氮系统，并解析了氮化合物形态转化及相关的微生物作用机制。主要研究结论如下：（1）缓释碳源耦合短程硝化工艺稳定运行阶段氨氮去除率95%以上，亚硝酸盐积累率（NAR）达到94%，总无机氮去除率85%以上；（2）构建了缓释碳源耦合短程硝化-厌氧氨氧化（PNA）脱氮系统，进一步降低运行能耗和缓释碳源投加量，氨氮和总无机氮去除率分别高达99.7±0.2%和98.4±1.0%；（3）PBS缓释碳源投加前后，PNA系统的溶解性有机氮（DON）出水由1.0降低到0.6 mg/L，出水DON/TDN比例由2.8%增加到41.2%，高分辨质谱表明木质素和蛋白质是最丰富的DON分子，具有大分子量、不饱和性和芳香结构的DON在投加缓释碳源后优先被分解和利用；（4）缓释碳源的投加未影响PNA系统中Candidatus_Jettenia（17.7%）的主导地位，并提高了Denitratisoma（2.2%）、Thauera（3.3%）等反硝化菌丰度；代谢组学检测出225个差异代谢物，主要集中在嘧啶代谢，氨基酸代谢、芳香族化合物降解和维生素代谢等代谢途径。本项目的研究成果对推动低碳氮比废水的处理和应用以及理解该工艺的氮化合物形态转化机制，提供理论支持和技术参考。