间歇增氧型垂直流人工湿地中氮的迁移转化规律及微生物机制研究

Oxygen supply insufficiency is usually the main cause for low nitrogen removal efficiency in subsurface flow constructed wetlands (SFCWs) . Recent studies focus on different plants, substrate as well as feeding modes, which always leads to limited removal efficiency. Continuous aeration increases both organics removal efficiency and conversion rate of ammonium nitrogen into nitrate, however, it results in the faster depletion of influent carbon source and the lack of effective anoxic zone; both of them inhibit the subsequent denitrification step. Intermittent-aerated SFCWs will be built to assess its performance in decentralized rural sewage treatment. Nitrogen transformation and microbial mechanisms will be studied. Cyclic DO distribution in aerated and non-aerated SFCWs will be illustrated in this study. Stable isotopes 15N will be used to study the nitrogen transformations in intermittent-aerated SFCWs and the distributions of nitrogen input will be identified. Molecular biology techniques such as 16S rDNA clone library, reverse transcription-polymerase chain reaction and quantitative PCR, will be used to investigate the community composition and abundance of microbes in the SFCWs system. The mechanisms of nitrogen removal will be revealed based on the correlation between the DO supply and variation of microbial abundance, community composition, and system functions. The proposed project will provide theoretical guidances for the design and operation of intermittent-aerated SFCWs and maximize its nitrogen removal efficiency.

基质内溶解氧不足是导致人工湿地污水处理系统生物脱氮效率低、长期运行效果不佳的关键限制因子。目前脱氮强化研究多集中在植物、填料、进水方式等方面，其脱氮效果提升有限。连续曝气运行方式可有效促进氨氮转化，但由于富氧环境的存在导致总氮去除受到限制。如何提高人工湿地基质溶氧、实现氨氮及总氮同步高效去除已成为当前研究的热点。本项目通过构建间歇增氧型垂直流人工湿地系统，研究间歇供氧对污染物去除及微生物群落的影响。通过绘制周期内溶解氧分布规律，分析溶解氧周期变化与污染物周期变化规律之间的动态响应关系；利用稳定同位素15N示踪技术，建立人工湿地污染物生物地球化学循环模型，明确间歇增氧型垂直流人工湿地系统中氮的迁移转化规律；采用现代分子生物学技术，研究间歇增氧条件下垂直潜流人工湿地中微生物的群落结构、数量、活性对增氧型湿地的响应机制，为实现人工湿地脱氮功能的可持续稳定发挥提供有力的技术支撑。

基质内溶解氧不足是导致人工湿地污水处理系统生物脱氮效率低、长期运行效果不佳的关键限制因子。本文选择建筑废料作为人工湿地基质，构建间歇增氧型垂直潜流人工湿地小试系统处理模拟生活污水，取得主要结果如下：.（1）不同基质会影响人工湿地处理污水性能，从大到小依次为粉煤灰砖>红砖>砾石，说明粉煤灰砖是人工湿地中强化脱氮除磷的潜在优良基质，其次是红砖。.（2）通过近2年连续监测，间歇曝气可以显著改善人工湿地污染物质净化效果。COD、NH4+-N和TN的去除率分别高达94.71%、 99.11%和 93.91%。间歇曝气湿地系统中TP质量去除率也提升了许多。.（3）间歇曝气显著地改变了人工湿地中的氮磷迁移转化路径。曝气湿地中硝化/反硝化作用是主要氮去除途径所占的比例为36.79-55.44%；而非曝气系统主要的除氮途径是基质蓄积（8.47-48.64%）。不到16%的氮被植物吸收，N2O排放贡献了0.08-0.39%。间歇曝气也利于植物生长，进而植物对磷的吸收增长了0.57-1.45倍。基质蓄积仍是主要的除磷途径，占23.92-59.47%。曝气系统中微生物吸收的磷约占30.93%，非曝气系统中仅为14.84-26.47%。.（4）通过微生物分析发现，间歇曝气增加了湿地中与氮磷去除有关的功能菌，揭示了微生物与水质净化效果的内在关系。.以上研究结果为深入了解间歇增氧建筑废料人工湿地中氮磷迁移转化机制，提升人工湿地对分散式生活污水中的污染物同步去除能力给予了理论依据和技术支持，具有现实性的意义。