低温饮用水处理物化-生化耦合除氨氮能力快速建立及机制研究

Biological removal of ammonia has been widely used for drinking water production, but after the water temperature decreases, it would take a long-term process (hereinafter referred to as "transition period") to establish efficient and stable removal capacity of ammonia, which will directly affect drinking water quality and safety. In this study, microscopic characteristics of pre-built physi-chemical-and-biological coupling system (referred to as "coupling system") will be discussed to reveal the mechanism of coupling system, focusing on the nitrogen transfer, nitrogen transform and in-situ bacteria-culturing during the transition period. Specific topics include: theoretical analysis and quantitative expression of the physi-chemical nitrogen transfer and biological nitrogen transform to explore the role of the coupling interaction between two mechanisms; establishment of system dynamics model and ammonia removal prediction model suitable for water pollution environment; build-up of optimal environment for the growth of hypothermia nitrifying bacteria on the basis of revealing coupling mechanism to achieve rapid formation of in situ nitrification bacteria biofilm; quick development of ammonia removal ability of coupling system through mutual promotion and strengthen between nitrogen transfer and nitrogen transform process. Expected results will provide theoretical support for ammonia removal during the transition period, which will be expecting engineering applications for the protection of drinking water quality and safety.

生物除氨氮工艺在饮用水生产中已得到广泛的应用，但在水温由高转低后，氨氮高效、稳定去除能力的建立需要一个长期的过程（以下简称“过渡期”），将直接影响饮用水水质安全。本研究以前期构建的物化-生化耦合除氨氮系统（简称“耦合系统”）的微观特性为研究对象，着重从氮转移、氮转换、菌种原位培养的角度探讨过渡期内耦合系统的除氨氮机制。具体内容包括：理论分析耦合系统中物化氮转移、生化氮转换的途径，对物化、生化两种作用进行定量表达，探索两种作用的相互影响机制；建立适合水体污染环境的生化系统与沸石物化系统耦合除氨氮的动力学模型及氨氮去除效果的预测模型；在揭示耦合机制的基础上，构筑低温硝化细菌的最适生长环境，原位快速形成以硝化细菌为主体的生物膜系统，通过氮转移与氮转换过程之间的相互促进、强化，实现耦合系统除氨氮能力的快速建立。预期成果将为过渡期内氨氮的去除提供理论支撑，对保障饮用水水质安全具有一定的工程应用前景。

我国水源水氨氮污染严峻，给饮用水安全带来了一定风险，尤其是在冬季低温期，饮用水处理工艺中常用的生物氧化法对氨氮的去除能力将会受限。事实上，当水温由高转低时，饮用水生物处理工艺系统在经过一段长期的、适应环境变化的过渡期后，才能形成较为稳定的除氨氮能力。但如何解决过渡期内饮用水氨氮污染问题是饮用水除氨工艺研究的盲点。因此，研究低温除氨氮能力的快速建立是当前非常重要和迫切的研究任务，具有深远意义。.本项目以前期构建的一套物化-生化耦合除氨氮系统（悬浮填料-沸石曝气生物滤池）为基础，研究了该系统的作用机制，考察了水环境变化、水体组分及运行参数等对该系统内氮转移、氮转换的影响，建立了生化系统与沸石物化系统耦合除氨氮的动力学模型及氨氮去除效果的预测模型，理论分析了耦合系统中物化氮转移、生化氮转换的途径；通过对天然水体中低温硝化细菌的识别，研究了微观生物菌群特征的变化反馈-宏观调控的作用机制，进而形成了“反冲洗菌液回流法诱导以低温硝化细菌为主体的生物膜系统快速形成”的技术。.研究结果表明，上层沸石对微生物的粘附、截留作用及其在贫营养环境下对氮源的缓冲调节作用益于硝化细菌的富集，特别是有利于新型低温硝化细菌Candidatus_Nitrotoga的富集和培养，下层悬浮填料的流化与挤压共存的特征也有利于上层沸石段更好地富集硝化细菌；高氨氮负荷更易增强硝化细菌的生态位，小粒径沸石对促进硝化细菌贮存、缩短系统过渡期是有利的；在低温水环境下，物化-生化耦合系统中亚硝化细菌菌属主要为Nitrospiraceae_Nitrospira和Candidatus_Nitrotoga。反冲洗菌液驯化、富集硝化细菌的优化条件为：原水氨氮负荷为2 mg/L左右，碳氮比约为4:1，pH为8左右，气水比1:1，水力停留时间1h，系统装填沸石优选粒径为1～3mm。.通过原位构筑该硝化细菌最适生长环境，反冲洗菌液强化物化-生化系统耦合除氨氮的技术实现了对氨氮去除效率的有效提高。此研究将为低温期水源水氨氮污染区域提供技术储备和理论支撑。