2023 Fiscal Year Final Research Report

Development of nitrogen removal technology in a single sewage treatment plant aeration tank with accelerated aerobic denitrification reaction

Research Project

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Project/Area Number	20H02290
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 22060:Environmental systems for civil engineering-related
Research Institution	Ichinoseki National College of Technology (2021-2023) Nagaoka National College of Technology (2020)
Principal Investigator	Araki Nobuo 一関工業高等専門学校, その他部局等, 校長 (30193072)
Co-Investigator(Kenkyū-buntansha)	川上周司長岡工業高等専門学校, 環境都市工学科, 准教授 (00610461) 青木仁孝国立研究開発法人国立環境研究所, 地域環境保全領域, 研究員 (80775809) 押木守北海道大学, 工学研究院, 准教授 (90540865) 渡利高大長岡技術科学大学, 工学研究科, 助教 (90800540)
Project Period (FY)	2020-04-01 – 2024-03-31
Keywords	好気性脱窒細菌 / 従属栄養硝化脱窒反応 / 都市下水処理
Outline of Final Research Achievements	In this study, the effect of DO concentration on aerobic denitrification bacteria was investigated. Since the DO concentration cannot be controlled by the shaking culture method reported previously, an apparatus to maintain a constant dissolved oxygen concentration was constructed in this study and aerobic denitrification tests were conducted under different DO concentration conditions. Aerobic denitrification proceeded simultaneously with nitrification under all aerobic conditions. The results of the bacterial flora analysis based on rRNA genes showed that bacteria of the genera Paracoccus and Pseudomonas predominated as the DO concentration increased, revealing a competitive relationship in a complex microbial system. A tracer test using stable isotope 15N-labelled nitric acid on the sludge confirmed the formation of N2, confirming an aerobic denitrification reaction.
Free Research Field	排水処理工学
Academic Significance and Societal Importance of the Research Achievements	これまで報告されていた好気性脱窒反応の多くは振盪培養法によってDOを制御しており、細菌群が対数増殖期に入ると十分なDOを確保できず、嫌気的な脱窒反応も混在していたことが予想され、多くの研究者の疑念を払拭できずにいた。本研究では、DOを維持する装置を作成し、5mg/Lといった高いDO条件下でも好気性脱窒反応を確認した。またDO濃度の違いにより優占する細菌群が異なることも示した。このことは実現場で起きている好気性脱窒のメカニズム解明を後押しする重要な知見であり、今後好気性脱窒反応を卓越させた脱窒処理技術の開発に大きく寄与するものと思われる。