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Enzymatic nitrous oxide emissions from wastewater treatment

Guo, Gang, Wang, Yayi, Hao, Tianwei, Wu, Di, Chen, Guang-Hao
Frontiers of environmental science & engineering 2018 v.12 no.1 pp. 10
denitrification, environmental factors, enzymes, greenhouse effect, greenhouse gas emissions, greenhouse gases, nitrification, nitrogen, nitrous oxide, wastewater treatment
Nitrous oxide (N₂O), a potent greenhouse gas, is emitted during nitrogen removal in wastewater treatment, significantly contributing to greenhouse effect. Nitrogen removal generally involves nitrification and denitrification catalyzed by specific enzymes. N₂O production and consumption vary considerably in response to specific enzyme-catalyzed nitrogen imbalances, but the mechanisms are not yet completely understood. Studying the regulation of related enzymes’ activity is essential to minimize N₂O emissions during wastewater treatment. This paper aims to review the poorly understood related enzymes that most commonly involved in producing and consuming N₂O in terms of their nature, structure and catalytic mechanisms. The pathways of N₂O emission during wastewater treatment are briefly introduced. The key environmental factors influencing N₂O emission through regulatory enzymes are summarized and the enzyme-based mechanisms are revealed. Several enzymebased techniques for mitigating N₂O emissions directly or indirectly are proposed. Finally, areas for further research on N₂O release during wastewater treatment are discussed.