Evaluation of unique autothermal thermophilic digestion process showing no nitrification and denitrification

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02875
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 38020:Applied microbiology-related
• Research Institution: Kyushu University
• Principal Investigator: SAKAI KENJI 九州大学, 農学研究院, 教授 (50205704)
• Co-Investigator(Kenkyū-buntansha): 田代 幸寛 九州大学, 農学研究院, 准教授 (90448481)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 自家熱型高温好気消化（ATAD)法 / 複合微生物工学 / 液肥 / し尿処理 / SDGs / 総括酸素移動容量係数（KLa） / 剪断力 / 細菌群集構造変化

Outline of Final Research Achievements

A unique autothermal thermophilic aerobic digestion (ATAD), showing distinctive bacterial community transitions and producing high-nitrogen content and pathogen-free organic liquid fertilizer was investigated. Investigation of a lab-scale gas-inducing system suggested that shear stress and oxygen supply system would affected the ATAD performances. Among 28 gene categories obtained by shotgun metagenomic analyses, abundance of four gene categories changed. A decrease in the phage-related gene category and the presence of bacteriolysis factors in secondary metabolism may explain the drastic change in bacterial community structure. A potential increase in the gene category in sporulation would be correlated with the deterioration of growth conditions and stabilization processes. In addition, unusually stable accumulation of ammonia throughout the process can be explained by the presence/absence of related metabolic genes belonging to the respective predominant bacterial families.

Free Research Field

環境微生物学

Academic Significance and Societal Importance of the Research Achievements

本研究の結果、し尿から衛生的で高窒素含量の有機液肥を製造する際の制御因子とそのユニークさの理由が明らかになった。学術的には複合微生物工学を呼称できる好例と考える。これにより、プロセスのパフォーマンス最大化と使用エネルギー・コストの最小化を目指すことができ、畜産し尿処理-リサイクル法としての開発、国内外の適地への導入促進を行う技術的素地ができた。普及により、資源循環型農業生産が広がり、持続社会の創成、SDGsの推進に大いに貢献することを期待したい。