Li Jianmin, Liu Xiuhong, Gu Pengchao, Cui Bin, Yang Qing, Zeng Wei
Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing 100124, China.
Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing 100124, China.
Sci Total Environ. 2022 Dec 15;852:158282. doi: 10.1016/j.scitotenv.2022.158282. Epub 2022 Aug 27.
Although anaerobic ammonia oxidation (anammox) is a cost-effective nitrogen removal process, nitrous oxide (NO) production will greatly reduce the advantages of this process. It is important to identify the NO emission pathways and then reduce the NO production in anammox system. To date, very limited research has been done to investigate the NO production and NO emission pathways in anammox biofilter. In this study, NO production were investigated under different filtration rates in anammox biofilter for treating wastewater with low nitrogen concentrations, and NO emission pathways were analyzed with batch tests using NO microsensor and stable isotope mass spectrometry. The results showed NO production increased with the increase of filtration rates in anammox biofilter, where the NO emission factor increased from 0.012 % at 1.0 m/h to 0.496 % at 3.0 m/h. And the optimal operation condition was at filtration rate of 1.5 m/h, where NH-N and NO-N removal efficiencies reached 99 % and NO concentration was the lowest. qPCR showed that anammox bacteria, nitrifying bacteria and denitrifying bacteria were all present in anammox biofilter, with anammox bacteria in the highest abundance. And nitrifying bacteria and denitrifying bacteria provided the possibility of NO production. The batch tests and stable isotope mass spectrometry analysis indicated that nitrifier denitrification, hydroxylamine oxidation and endogenous heterotrophic denitrification were NO production pathways in aerobic zone and anoxic zone of anammox biofilter, respectively. In addition, batch tests under different conditions showed no oxygen environment could reduce NO production. Therefore, the production of NO in anammox system is a problem that cannot be ignored and should be paid more attention to.
尽管厌氧氨氧化是一种具有成本效益的脱氮工艺，但一氧化二氮（N₂O）的产生将大大降低该工艺的优势。识别N₂O排放途径并减少厌氧氨氧化系统中的N₂O产生非常重要。迄今为止，关于厌氧氨氧化生物滤池中N₂O产生及N₂O排放途径的研究非常有限。本研究对处理低氮浓度废水的厌氧氨氧化生物滤池在不同过滤速率下的N₂O产生情况进行了研究，并使用N₂O微传感器和稳定同位素质谱通过批次试验分析了N₂O排放途径。结果表明，厌氧氨氧化生物滤池中N₂O产生量随过滤速率的增加而增加，其中N₂O排放因子从1.0 m/h时的0.012%增加到3.0 m/h时的0.496%。最佳运行条件为过滤速率1.5 m/h，此时NH₃-N和NO₃-N去除效率达到99%，N₂O浓度最低。定量聚合酶链反应（qPCR）表明，厌氧氨氧化生物滤池中存在厌氧氨氧化菌、硝化细菌和反硝化细菌，其中厌氧氨氧化菌丰度最高。硝化细菌和反硝化细菌为N₂O产生提供了可能性。批次试验和稳定同位素质谱分析表明，硝化反硝化、羟胺氧化和内源性异养反硝化分别是厌氧氨氧化生物滤池好氧区和缺氧区的N₂O产生途径。此外，不同条件下的批次试验表明，无氧环境可减少N₂O产生。因此，厌氧氨氧化系统中N₂O的产生是一个不可忽视的问题，应予以更多关注。
