Mechanisms of NO and N2O production by enriched nitrifying sludge in a sequencing batch reactor: Effects of hydroxylamine. (15th August 2022)

• Record Type: Journal Article
• Authors: Zhao, Junkai; Zhao, Jianqiang; Yang, Wenjuan; Hu, Bo; Huang, Ting; Xie, Shuting; Lei, Shuhan; Hou, Wei
• Is Part Of: Journal of environmental management. Volume 316(2022)
• Publication Date: 2022-08-15
• Subjects: Hydroxylamine -- Nitric oxide -- Nitrous oxide -- Nitrifying sludge; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2022.115237
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: NO and N2 O as important greenhouse gases andtheir production mechanisms during nitrification are not completely understood. This study aimed to analyze the effect of hydroxylamine (NH2 OH) on NO and N2 O produced by nitrifying bacteria from activated sludge in a sequencing batch reactor (SBR). Experimental results showed that when nitrite (NO2 − ) accumulated during aerobic ammonia (NH4 + ) oxidation, N2 O was the main product. The total amount of NO and N2 O produced by NH2 OH oxidation was positively correlated with dissolved oxygen (DO) levels. The imbalance of NH4 + oxidation caused by NH2 OH addition was more conducive to the generation of NO and N2 O under high DO conditions. When NH2 OH was added into the reactor with NO2 − as the substrate, the production of NO and N2 O under high DO levels was mainly related to NH2 OH oxidation. Under low DO conditions, NO and N2 O from the biotic/abiotic hybrid pathways were more significant in the reactor of the coexistence of NO2 − and NH2 OH, which could be mainly caused by the pathways of nitrifier denitrification and abiotic reaction. Besides, limited amount of NO and N2 O was generated by heterotrophic denitrification pathway during autotrophic nitrification. The implications for the above results are important for understanding the production of NO and N2 O under NH2 OH stress in nitrifying sludge reactor. Graphical abstract: Image 1 Highlights: When NO2 − accumulated during aerobic NH4 + oxidation, N2 O was the main product. Total amount of NO and N2 O produced by NH2 OH oxidation was positively correlated with DO. Imbalance of NH4 + oxidation due to NH2 OH dosing was helpful to NO and N2 O production. NO and N2 O from the hybrid pathway of NH2 OH and NO2 − were more obvious under low DO.