植物炭化回用强化湿地脱氮和调控N2O排放机理研究

Constructed wetlands (CWs) have been widely used in sewage treatment for their simple operation and low implementation costs. However, the nitrogen removal efficiency is low in the common CW due to lacking suitable environment for nitrification and denitrification, and the large amounts of harvested plant wastes and the greenhouse gas emissions (e.g. nitrous oxide (N2O)) are both limited the wide application of CW. In this research project, the harvested plant straw is carbonized and applied to build CW, and the influences of biochar on nitrogen removal, transformation and migration ways for nitogen, N2O emissions fluxes and pathways will be all investigated in biochar wetlands (BWs). Stable isotope probe technology (SIP) and 454 high throughput sequencing technology can be adopted to investigate the relationships between microbiological community and N2O emission. The tests and analyses of the nitrogenous metabolites quantities in liquid and gas phases and the key enzymes activities will be emploied to elucidate the micro-ecological mechanisms to regulate N2O emission in BW. According to the operation conditions and water quality characteristics, the approaches to establish BW will be optimized based on these above conclusions. The macro operation strategy for N2O emission reduction by using biochar as substrate in CW could be proposed, which will help to provide the scientific evidences to manage the harvested plants, strengthen nitrogen removal and reduce N2O emission in subsurface CW.

人工湿地因低能耗、易管理的优点被广泛用于污水处理，但因湿地中缺少硝化-反硝化的有利环境，致使脱氮效率不高。与此同时，收割后湿地植物的处理以及温室气体(如氧化亚氮(N2O))的排放问题均限制了人工湿地的应用。本课题拟将收割后的植物秸秆炭化并构建生物炭湿地，研究生物炭对湿地系统脱氮效果、氮的迁移转化、N2O的释放通量、N2O的产生途径的影响。利用稳定同位素(SIP)技术和454高通量测序技术，寻求微生物群落与N2O产排的相关性，结合系统液相和气相中含氮代谢产物及关键酶活性的分析，阐释生物炭对N2O产排的微生态调控机制。在此基础上，根据湿地运行条件与进水水质特征，优化生物炭湿地构建方式，提出利用生物炭实现N2O减量化控制的宏观运行策略，为处理湿地收割植物、强化潜流湿地脱氮并实现N2O减排提供科学依据。

本课题将收割后的植物秸秆炭化并构建生物炭湿地，研究了生物炭对湿地系统脱氮效果、氮的迁移转化、N2O的释放通量、N2O的产生途径的影响效果和机理。通过课题组三年的研究，完成了研究任务。利用热重分析方法，揭示了热解过程，构建了芦竹热解动力学；以复合Monod动力学模型为基础，探明了生物炭在去除氮素污染物中的作用途径；利用磷脂脂肪酸(PLFAs)技术和454高通量测序技术，探讨了微生物群落与N2O产排的相关性；结合液相和气相中含氮代谢产物及微生物胞外聚合物分析，阐释了生物炭对湿地微生物种群结构的微生态调控机制；以碳源类型、COD:N和生物炭投加量为控制条件，形成控制N2O排放的运行策略，该研究进展将有助于优化生物炭在人工湿地的利用过程，实现人工湿地减排。本课题研究成果已累计发表SCI论文4篇，课题负责人均为第一作者或通讯作者。课题负责人作为第一发明人获得发明专利1项。