Elucidating N2O production mechanisms by ammonia-oxidizing bacteria based on nitrogen atoms and electron flows

2016 Fiscal Year Final Research Report

• Project/Area Number: 26701009
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Partial Multi-year Fund
• Research Field: Environmental engineering and reduction of environmental burden
• Research Institution: Tokyo University of Agriculture and Technology
• Principal Investigator: Terada Akihiko 東京農工大学, 工学(系)研究科(研究院), 准教授 (30434327)
• Research Collaborator: KOBA Keisuke 京都大学, 生態学研究センター, 教授 (90311745) ; SUWA Yuichi 中央大学, 理工学部, 教授 (90154632) ; HORI Tomoyuki 国立研究開発法人産業技術総合研究所, 環境管理研究部門, 主任研究員 (20509533)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 亜酸化窒素 / アンモニア酸化細菌 / 部分硝化 / 15Nトレーサー / 省エネ型排水処理 / 窒素除去 / ハイブリッド反応 / ヒドロキシルアミン

Outline of Final Research Achievements

Mitigation of nitrous oxide (N2O), known as a highly-potent greenhouse gas and ozone-depleting substance, is demanded. This study elucidated production pathways of N2O emitted during partial nitrification (PN) as a promising technology to removal nitrogen from wastewater in a cost-effective way. To unveil intricate N2O production pathways during PN, mainly mediated by ammonia-oxidizing bacteria, a 15N tracer method was employed, capable of measuring N2O isotopologues. The application of the method to batch tests for PN demonstrated that N-nitrosation hybrid reaction, coupling hydroxylamine with nitrite, mainly occurred in a PN bioreactor. This hybrid reaction was likely to occur also via an abiotic reaction, which has been incorporated into a new N2O production model. Furthermore, the experiment on dissolved oxygen (DO) effect on N2O production and pathways underpinned that proportions of N2O production pathways vary depending on DO concentrations.

Free Research Field

環境バイオテクノロジー