Clarification of characteristics and development of reduction technology for greenhouse gas emissions derived from Johkasou.

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06556
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Civil and environmental engineering
• Research Institution: Toyo University
• Principal Investigator: Yamazaki Hiroshi 東洋大学, 理工学部, 准教授 (30573703)
• Co-Investigator(Kenkyū-buntansha): 蛯江 美孝 国立研究開発法人国立環境研究所, 資源循環・廃棄物研究センター, 主任研究員 (90391078)
• Research Collaborator: Inamura Shigeaki ; Kakishima Hayato
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 浄化槽 / 温室効果ガス / 季節影響 / 流量調整 / 汚泥可溶化

Outline of Final Research Achievements

According to the 2018 Japan Greenhouse Gas Inventory Report, GHGs emissions per capita derived from Johkasou were about 10 times for CH4 and about 5 times for N2O, respectively, compared to sewerage systems. In this study, we tried to clarify the characteristics of greenhouse gas emissions from Johkasou based on the investigation of each treatment unit throughout the year. It was revealed that sludge storage part is the important source in terms of CH4 emissions, and sludge solubilization caused by water temperature increase in spring leads higher N2O emissions. Therefore, GHGs emissions from Johkasou could be reduced to the same level of that of sewerage systems by increasing the amount of DO in the sludge storage part and stabilizing the treatment efficiencies of solubilized sludge.

Free Research Field

衛生工学

Academic Significance and Societal Importance of the Research Achievements

2018年の日本国温室効果ガスインベントリ報告書によると、浄化槽から排出される1人当たりのGHGs排出量は、下水道と比較して、CH4で約10倍、N2Oで約5倍となっている。本研究では、浄化槽を構成する各単位装置や季節的要因の調査を元に、GHGs排出特性の解明を試みた。その結果、浄化槽の特徴である余剰汚泥を貯留する汚泥貯留部からのCH4、貯留汚泥の可溶化に伴う好気処理部からのN2OがGHGs排出を増大させていることを明らかとした。そのため、汚泥貯留部へのDO量増加、汚泥貯留部から溶出する汚泥可溶化物の処理を安定させることで、浄化槽からのGHGs排出を下水道と同等にまで削減できると考えられた。