CANON工艺铁诱导生物膜形成与适应机制及其性能强化机理研究

Completely autotrophic nitrogen removal over nitrite (CANON) process combining shortcut nitrification and anaerobic ammonium oxidation (Anammox) in one reactor has the advantages of economical efficiency, high operation efficiency and low energy cost. Nowadays, this process has been paid more attention to international society and been widely used to treat the wastewater with higher ammonia nitrogen and lower C/N ratio. However, the operation of CANON process is restricted by its disadvantages of long-term startup period, low biomass yield and more sensitive to operation conditions. Especially, the innovative biofilm CANON process has the weaknesses including bacteria imbalance, longer biofilm formation time and limited nitrogen removal performance. In this project, the sequencing batch reactors and continuous flow reactors will be used to study the structure, formation and adaption mode with process characteristics of biofilm under various operation conditions with different valence chelating and free irons. The formation and adaption mode of biofilm induced by different irons and its interaction relationship with nitrogen removal performance were explored by analyzing the functional bacteria, migration and transformation characteristics of iron elements with their existing forms and distribution in biofilm. And the adaptation mechanisms of biofilm and functional microorganisms to iron with different valences and the mechanisms of nitrogen removal in CANON systems will be revealed. According to the discovery, the performance enhancement strategies for nitrogen removal based on the adjustment of iron valences will be put forward, which providing the technical support for high-efficient operation and industrialization of biofilm CANON process.

结合短程硝化和厌氧氨氧化(Anammox)的新型全自养脱氮工艺（CANON）因其经济、高效和低耗的优点日益受到国际社会的广泛关注，常用于高氨氮低C/N废水的处理。然而，CANON工艺具有启动周期长、生物产率低、运行性能易受运行条件制约等缺点，尤其是新型生物膜CANON工艺更是存在菌群不平衡、生物膜形成时间长、脱氮性能需进一步强化等问题。项目在序批式和连续流CANON反应器中研究不同种类和水平螯合态及游离态铁对工艺生物膜形成及适应模式、结构特征和过程特性的影响，通过分析系统功能菌群、探索铁元素的迁移转化规律及其在生物膜中的存在形态及分布特征，阐明不同价态铁元素诱导生物膜形成与适应模式及其与脱氮性能的定量关系，揭示CANON工艺系统生物膜及功能菌群对不同价态铁的适应机制及脱氮机理，并提出基于铁元素价态调控的工艺脱氮性能强化策略，为生物膜CANON系统高效运行和工业化应用提供技术支撑。

项目在连续流CANON反应器中研究不同种类和水平铁离子对工艺生物膜形成及适应模式、结构特征和过程特性的影响，揭示了不同价态铁诱导CANON生物膜工艺的脱氮途径及机理，获得的主要结论包括：1）低DO条件下能够有效富集CANON工艺功能菌Anammox混培物，Candidatus Brocadia和Nitrosomonas分别为优势厌氧氨氧化菌（AnAOB）属和优势氨氧化菌（AOB）。2）在低DO胁迫下生物膜在颗粒污泥系统有效形成生物膜，生物膜紧密结合型胞外聚合物（TB-EPS）的蛋白（PN）/多糖（PS）值0.048，有利于生物膜的形成。3）CANON系统中，Planctomycetes、Proteobacteria和Chloroflexi为污泥和生物膜中的优势门，在弹性载体生物膜中Candidatus Jettenia和Candidatus Brocadia的相对丰度（RA）和厌氧氨氧化相关的功能基因RA明显高于BFBC和BFCC生物膜。4）低浓度的Fe(II)和Fe(III)（2.3 mg/L）促进自养脱氮能力，且Fe(II)的促进效果优于Fe(III)。高浓度的Fe(II)和Fe(III)（8.3 mg/L）抑制自养脱氮能力，且Fe(III)的抑制效果强于Fe(II)。5)活性炭（AC）-活性炭海绵（ACS）CANON生物膜系统中，5 mg/L Fe(III)和5 mg/L Fe(II)促进CANON性能，且强化效果大于2.3 mg/L Fe(II)。进水Fe(II)与EDTA1:1络合的反应器较进水Fe（II）未完全络合的反应器在成功启动以后能够更长期保持稳定运行。6）相比于活性炭，ACS生物膜中所测PN和PS含量较高，表明该载体生物膜形成更好。Candidatus Jettenia和Candidatus Brocadia是CANON生物膜中主要的AnAOB，Nitrosomonas和Nitrospira分别是主要的AOB和NOB属。5 mg/L Fe(III)降低了CANON污泥中的AnAOB，但是明显提升了AC生物膜中Candidatus Jettenia和Candidatus Brocadia。ACS生物膜中AnAOB属Candidatus Jettenia相比对照反应器提升了3.52倍，AOB属没有观察到明显变化。