硝态氮氨化菌群富集及其与部分反硝化协同的机制研究

Nitrite accumulation technology is the bottleneck to the popularization and application of Anaerobic ammonium oxidation (Anammox) technology for its unstable supplement of NO2- in domestic waste water treatment. Therefore, the development of novel NO2- supply technology and process are of great significance. Based on the newly found phenomenon, dissimilatory nitrate reduction to ammonia (DNRA), this research selected three candidate systems (heterotrophic denitrification, Anammox, and autotrophic denitrification) to acclimate DNRA dominated process. The environmental factors influencing DNRA and Partial-DNRA coupled with Partial-DEN systems were systematically studied, and the cooperative mechanism for DNRA and DEN microorganism was uncovered by using isotopic tracer method and molecular biological technology. The dynamic correlation of environmental parameter, nitrogen transformation pathway, and microorganism succession process were helped to illustrate the competition-cooperation mechanism in systems. The innovation of this research are: 1) In the first time to propose Partial-DNRA as a way to accumulate nitrite for anammox in domestic waste water treatment. 2) Evaluating factors influencing DNRA with DEN and illustrating cooperative mechanism in system. 3) Building a pragmatic control strategy for Partial-DNRA coupled with Partial-DEN process which can ensure Anammox performed smoothly.

亚硝酸盐稳定供给是厌氧氨氧化技术(Anammox)在城市污水处理中推广应用的瓶颈，对新型亚硝酸盐供给技术的研究具有重要意义。本研究基于新近在污水处理领域发现的硝态氮氨化（DNRA）现象，从异养反硝化、Anammox、自养反硝化三种系统中进行DNRA过程驯化与富集，研究影响DNRA过程及Partial-DNRA和部分反硝化（Partial-DEN）过程协同的因素。采用同位素示踪及分子生物学手段，分析氮素在体系中的转移路径及微生物代谢机制，建立DNRA过程与环境参数的动态响应体系，从而提出Partial-DNRA与Partial-DEN过程协同的控制策略。研究创新点：1）首次提出经Partial-DNRA累积亚硝酸盐为Anammox提供底物的方法；2）开展DNRA与DEN过程协同竞争的环境条件与功能菌代谢机制研究；3）建立Partial-DNRA和Partial-DEN过程协同的控制策略。

DNRA是自然界中硝酸盐还原途径的一种，而在污水处理体系中少见报道。其将硝酸盐还原为NH4+与主流的污水生物脱氮目标相悖，但将其引入到厌氧氨氧化体系中后，产物NO3-能再度被利用最终以氮气形式去除，可达到系统深度脱氮的目标。本项目通过在异养反硝化，自养反硝化，厌氧氨氧化三种体系中改变电子供体种类（有机物，硫物质，铁物质）及电子供体与硝酸盐氮的比例进行DNRA过程的驯化和富集研究，明确了在污水处理系统中富集DNRA过程的运行条件为较高的无机电子供体和有限的硝酸盐电子受体体系，硫化物体系更容易驯化富集呼吸型DNRA；确立了环境参数（ORP，pH）与硝酸盐还原途径的动态响应机制，环境中较低的氧化还原电位是发生DNRA过程的充分条件；阐明了DEN与DNRA过程的协同竞争模式，两者共同竞争NO2-，进行过程歧化。通过分子生物学手段进行了微生物群落演替规律及特征的分析，初步确定了各系统中具有DNRA功能的微生物种类有Geobacter，Desulfomicrobium，Ignavibacterium，Hydrogenophaga。通过在厌氧氨氧化体系中DNRA-SOAD-ANAMMOX三者的耦合，实现了氮的深度去除。该项目属于国内较早研究DNRA在污水处理领域应用的研究，填补了在无机还原体系中实现DNRA的技术空白，丰富了人们对DNRA功能菌群种类及特征的认识。该研究成果将提高DNRA过程在污水处理领域中的重要性，拓展厌氧氨氧化工艺在污水处理中的应用领域，并进一步达到污水深度脱氮的目标。