Nitrous oxide emission in low-oxygen simultaneous nitrification and denitrification process: Sources and mechanisms

• Published in: Bioresource technology 2013-05, Vol.136, p.444-451
• Main Authors: Jia, Wenlin, Liang, Shuang, Zhang, Jian, Ngo, Huu Hao, Guo, Wenshan, Yan, Yujie, Zou, Yina
• Format: Article
• Language: English
• Subjects: Accounting; Bacteria; Bacteria - genetics; Biological and medical sciences; Biological Oxygen Demand Analysis; Bioreactors - microbiology; Carbon; Communities; Denaturing Gradient Gel Electrophoresis; Denitrification - drug effects; Emission; Fundamental and applied biological sciences. Psychology; Genes, Bacterial - genetics; Heterotrophic denitrification; Heterotrophic Processes - drug effects; Low-oxygen SND; Microbial community; Molecular Sequence Data; Nitrification; Nitrification - drug effects; Nitrifier denitrification; Nitrogen - isolation & purification; Nitrous oxide; Nitrous Oxide - analysis; Nitrous oxides; Oxygen - pharmacology; Phylogeny; Pollution sources
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2013.02.117

•The sources and mechanisms of N2O emission in low-oxygen SND process were studied.•Nitrifier denitrification turned out to be the dominant N2O emission source.•Nitrifier denitrification was enhanced due to enrichment of denitrification AOB.•Heterotrophic denitrification was limited by oxygen and the lack of carbon source. This study attempts to elucidate the emission sources and mechanisms of nitrous oxide (N2O) during simultaneous nitrification and denitrification (SND) process under oxygen-limiting condition. The results indicated that N2O emitted during low-oxygen SND process was 0.8±0.1mgN/gMLSS, accounting for 7.7% of the nitrogen input. This was much higher than the reported results from conventional nitrification and denitrification processes. Batch experiments revealed that nitrifier denitrification was attributed as the dominant source of N2O production. This could be well explained by the change of ammonia-oxidizing bacteria (AOB) community caused by the low-oxygen condition. It was observed that during the low-oxygen SND process, AOB species capable of denitrification, i.e., Nitrosomonas europaea and Nitrosomonas-like, were enriched whilst the composition of denitrifiers was only slightly affected. N2O emission by heterotrophic denitrification was considered to be limited by the presence of oxygen and unavailability of carbon source.