title: Nitrous oxide emission in low-oxygen simultaneous nitrification and denitrification process: sources and mechanisms.
abstract: 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±0.1 mgN/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.
authors.affiliation: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
authors.forename: Wenlin
authors.initials: W
authors.lastname: Jia
authors.forename: Shuang
authors.initials: S
authors.lastname: Liang
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Huu Hao
authors.initials: HH
authors.lastname: Ngo
authors.forename: Wenshan
authors.initials: W
authors.lastname: Guo
authors.forename: Yujie
authors.initials: Y
authors.lastname: Yan
authors.forename: Yina
authors.initials: Y
authors.lastname: Zou
mesh_terms: D001419:Bacteria / Q000235:genetics; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology; D058645:Denaturing Gradient Gel Electrophoresis; D058440:Denitrification / Q000187:drug effects*; D005798:Genes, Bacterial / Q000235:genetics; D052836:Heterotrophic Processes / Q000187:drug effects; D008969:Molecular Sequence Data; D058465:Nitrification / Q000187:drug effects*; D009584:Nitrogen / Q000302:isolation & purification; D009609:Nitrous Oxide / Q000032:analysis*; D010100:Oxygen / Q000494:pharmacology*; D010802:Phylogeny
chemical_list: D009609:Nitrous Oxide; D009584:Nitrogen; D010100:Oxygen