Development of a stable anaerobic treatment process for organic wastewater using extracellular electron transfer

2024 Fiscal Year Final Research Report

• Project/Area Number: 22K05926
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 41050:Environmental agriculture-related
• Research Institution: Yamagata University
• Principal Investigator: Kaku Nobuo 山形大学, 農学部, 教授 (80359570)
• Project Period (FY): 2022-04-01 – 2025-03-31
• Keywords: 細胞外電子伝達 / 廃水処理 / 嫌気発酵 / メタン生成 / 微生物燃料電池

Outline of Final Research Achievements

In this study, we aimed to develop a technology to prevent the collapse of the methanogenic fermentation process caused by the accumulation of volatile fatty acids (VFAs), by utilizing electric syntrophy, which transfers the reducing power generated from VFA degradation to remote microorganisms via conductive solids, and microbial fuel cells (MFCs), which recover the reducing power through electrodes and convert it into electricity.
A comparison of tolerance to VFA accumulation between an anaerobic digester and a two-chamber microbial fuel cell (MFC) revealed that the MFC exhibited higher tolerance. Subsequently, we attempted to establish electric syntrophy between the anodic and cathodic microorganisms of the MFC. As a result, we successfully constructed an MFC system in which the reducing power generated from the degradation of acetic acid and propionic acid at the anode was transferred to the cathode and consumed through methanogenesis.

Free Research Field

環境微生物学

Academic Significance and Societal Importance of the Research Achievements

本研究は、VFAの蓄積により不安定化しやすい食品廃水や畜産排水などの難分解性廃水に対し、安定的かつ省エネルギーな処理技術の開発に資する基礎的知見を提供するものである。MFCがVFAに高い耐性を示すこと、また外部電力なしでメタン生成と連携可能であることを実証し、新たなバイオリアクター設計の可能性を示した。さらに、既存の嫌気性処理の課題を克服する方策としても有望である。本成果は、持続可能な資源循環型社会の構築や、地域分散型エネルギーシステムの確立、低炭素社会の実現に貢献する意義を有する。