基于生物膜微区调控的单级自养脱氮工艺N2O减排研究

Nitrous Oxide (N2O), a potent greenhouse gas, is one of the intermediate products in biological nitrogen removal process. Recently, great attentions have been drawn to single-stage autotrophic nitrogen removal processes in the area of biological nitrogen removal. However, the complexity of wastewater and limited oxygen supply could lead to a variety of nitrogen metabolic pathways and metabolite products in the single-stage autotrophic nitrogen removal processes, and a further result of the N2O emission. In this study, single-stage autotrophic nitrogen removal biofilm reactors will be built up and fed with high ammonia nitrogen and low C/N ratio wastewater. Long-term reactor experiments, batch tests and chemical inhibition method will be used to probe N2O emission characteristics and its impact factors. The 15N isotope tracer technique will be used to track the transport of nitrogen and pathway for N2O production. FISH will be used to characterize the microbial communities in the biofilm. Using DO micro-electrode technology, the DO in the biofilm will be detected. Based on all above, the correlations between microbial communities, DO,and nitrogenous substance concentrations will be determined. Further, the transport of nitrogen and the mechanisms for N2O emission in single-stage autotrophic nitrogen removal biofilm processes will be elucidated. Finally, measures and techniques for the reduction and control of N2O emission will be proposed. This proposed project focus on the control of DO in the microzone and nitrogenous matter in the biofilm, which can provide scientific basis for the high nitrogen removal and the reduction of N2O emission in the single-stage autotrophic nitrogen removal biofilm processes and has great theoretical and practical values.

N2O是生物脱氮的中间产物，是一种强温室气体。单级自养脱氮研究在生物脱氮领域倍受关注，然而由于实际废水的复杂性和限制性供氧导致系统氮代谢途径和代谢产物的多样化，进而产生N2O排放问题。本项目拟以处理高氨氮低碳氮比废水的单级生物膜自养脱氮反应器为研究对象，进行反应器长期稳定运行和批式实验；采用化学抑制法和15N同位素示踪法，借助于FISH技术和微电极技术，探讨系统N2O的排放特性及其影响因素，解析生物膜微生物群落结构的空间分布与DO、含氮物质浓度的相关性，探索系统中氮的迁移转化与N2O产生途径，阐明单级生物膜自养脱氮系统N2O的排放机制，提出N2O减量化控制策略；通过对生物膜微区DO和含氮物质浓度的调控，实现目标微生物群在生物膜中的定向增殖与适配协调，为单级自养脱氮系统保持高效稳定脱氮效率，减少N2O的排放提供科学依据，具有重要的现实意义和学术价值。

N2O是生物脱氮的中间产物，是一种强温室气体。单级自养脱氮研究在生物脱氮领域倍受关注，然而由于实际废水的复杂性和限制性供氧导致系统氮代谢途径和代谢产物的多样化，进而产生了N2O排放问题。本课题以处理高氨氮低碳氮比废水的单级生物膜自养脱氮反应器为研究对象，建立了长期稳定运行的若干反应器，其N2O转化率介于1.2%~26.5%，并考察了反应器曝气方式、DO浓度、进水氨氮浓度、进水碳源类型等因素对系统N2O排放特征的影响与规律。对单级自养脱氮系统生物膜的宏观形貌进行了探讨，研究了系统生物膜的功能微生物分布，分析了微生物的多样性，并采用FISH技术表征了主要脱氮微生物种群在生物膜中的丰富度，获得生物膜内部微生物的组成和空间分布情况。在批式实验中应用了化学抑制法和15N同位素示踪法，借助于微电极技术，解析了生物膜微区DO与含氮物质浓度的相关性，探索了系统中氮的迁移转化与N2O产生途径，识别出AOB反硝化、异养反硝化和AOB亚硝化等是单级自养脱氮系统主要的N2O产生途径，并确定了典型工况下的N2O排放量和占比。通过课题研究，阐明了单级生物膜自养脱氮系统N2O的排放机制，提出了在不降低原有脱氮效率的基础上实现单级自养脱氮系统N2O减排的基本策略。研究成果为保持单级自养脱氮系统高效稳定的脱氮效率，减少N2O的排放提供了科学依据，具有重要的现实意义和学术价值。