基于载体吸附的亚硝化-Anammox工艺城市污水脱氮性能优化与N2O减排机制研究

The low energy consumption, stable and efficient nitrogen removal of urban sewage is the research hotspot of wastewater treatment. The partial nitrification (PN) -Anammox process owns obvious advantages in terms of energy saving, however its nitrogen removal efficiency is lowered by the low ammonia concentration in urban sewage. Adding zeolite to the PN-Anammox reactor as the biofilm carrier can realize a stable and low energy consumption nitrogen removal through ammonia adsorption and microbial bio-regeneration of the biofilm carrier. Nevertheless, some problems as low nitrogen removal efficiency and high emission of greenhouse gas N2O still exist. This study takes the PN-Anammox reactors added with ammonia adsorption materials as the research object, optimizes the ammonia adsorption materials and analyzes the relationship between biofilm growth and microbial bio-regeneration, in order to successfully start a reactor with low energy consumption, stable and high nitrogen removal capacity. And then, this study strengthens the nitrogen removal efficiency and determines the key factors influencing N2O reduction, in order to fulfill a significant reduction of N2O emission as well as a low energy consumption, stable and efficient nitrogen removal of urban sewage. At last, this study explores the characteristics of functional microorganisms, N2O generation mechanism, and the synergistic reactions exist between physicochemical adsorption and bio-regeneration process of nitrogen removal, so as to produce an operation control strategy of PN-Anammox process with low energy consumption, low carbon footprint, stable and efficient nitrogen removal of urban sewage.

城市污水低能耗、稳定高效脱氮是污水处理领域的研究热点。亚硝化-Anammox生物脱氮工艺在节能降耗方面优势明显，但城市污水的低氨氮浓度限制了该工艺的脱氮效率。向亚硝化-Anammox系统中添加氨氮吸附材料沸石用作生物膜载体，通过生物膜载体氨氮吸附和生物再生作用，可实现城市污水的低能耗脱氮，但存在脱氮效率不高、N2O排放量大等问题。本项目以添加氨氮吸附载体的亚硝化-Anammox反应装置为对象，通过氨氮吸附载体优选、膜生长与生物再生效果关系分析，成功启动具有低能耗、稳定高效脱氮能力的反应器；通过工艺脱氮性能优化与N2O减排关键影响因素分析，力求在实现亚硝化-Anammox工艺城市污水低能耗、稳定高效脱氮的基础上显著削减N2O排放，结合功能微生物特性、N2O产生机理及物化吸附-生物再生协同脱氮作用机制解析，制定出可实现低能耗、低碳排放、稳定高效脱氮的PN-Anammox工艺运行调控策略。

城市污水低氨氮浓度是限制亚硝化-Anammox工艺脱氮能力的主要瓶颈，城市污水脱氮过程中温室气体N2O排放问题也不容忽视。本研究设计了一种基于氨氮吸附载体强化的亚硝化-Anammox工艺，力求实现城市污水处理脱氮性能与N2O减排的协同优化。.研究结果表明，以添加沸石为氨氮吸附载体的PN-Anammox反应器在脱氮方面较添加大孔树脂和蛭石的反应器更具优势，因此在本研究中，沸石被选作为氨氮吸附载体。通过将滴滤式的运行模式改良为两段独立式的运行模式，提升了PN-Anammox反应器的脱氮能力，150天时，系统的脱氮能力处于80%左右。随着反应器运行时间的延长，在第360天时，系统的脱氮能力降低至65%，这主要归因于Anammox细菌非常弱的氨氮解析和去除能力，系统中起脱氮作用的应该是系统中共存的反硝化菌，而不是厌氧氨氧化菌，推断这主要是源自于低氨氮条件下自养菌缓慢的生长速率。微生物高通量测序结果验证了反应器内存在Thauera和Dechloromonas等属的异养反硝化细菌，对厌氧氨氧化脱氮过程产生不良影响。与此同时，PN反应器内存在的Nitrospira会将亚硝酸盐进一步转化为硝酸盐，流入Anammox反应器的硝酸盐会促进反应器中异养反硝化细菌的生长和繁殖，这也是导致系统脱氮效率降低的原因之一。以沸石为吸附载体的PN-Anammox反应器PN段N2O排放量（N2O/TN）最大为3.35%，亚硝酸盐是影响PN段N2O排放的直接因素；Anammox段溶解态N2O的浓度最大值为0.44mg/L，氨氮和亚硝酸盐是影响Anammox反应器内N2O产生的直接因素，溶解氧DO是PN-Anammox工艺进行N2O排放调控的主要参数。以沸石作为氨氮吸附载体可促进好氧颗粒污泥快速成型，在18天内实现快速颗粒化，且平均脱氮效率高于85%，解决了AGS造粒时间长，启动期脱氮效果差等问题。