Concentration of organic matter in municipal wastewater by membrane processes with extremely intensive membrane cleaning: sewage systems can be transformed into energy generating infrastructures

2020 Fiscal Year Final Research Report

• Project/Area Number: 20K20351
• Project/Area Number (Other): 18H05333 (2018-2019)
• Research Category: Grant-in-Aid for Challenging Research (Pioneering)
• Allocation Type: Multi-year Fund (2020); Single-year Grants (2018-2019)
• Review Section: Medium-sized Section 22:Civil engineering and related fields
• Research Institution: Hokkaido University
• Principal Investigator: Kimura Katsuki 北海道大学, 工学研究院, 教授 (10292054)
• Co-Investigator(Kenkyū-buntansha): 渡部 靖憲 北海道大学, 工学研究院, 教授 (20292055)
• Project Period (FY): 2018-06-29 – 2021-03-31
• Keywords: 有機物回収 / 膜処理 / 下水 / 直接膜ろ過 / セラミック平膜

Outline of Final Research Achievements

Organic matter in municipal wastewater can be recovered and concentrated by using direct membrane filtration (DMF) adequately, which leads to net-generation of energy from wastewater. Flat-sheet ceramic membranes are physically and chemically robust, and therefore intensive membrane cleanings that cannot be used with polymeric membranes can be used. In this study, DMF of municipal wastewater by flat-sheet ceramic membranes was investigated. With the aid of intensive physical and chemical cleaning, long-term operations under high membrane fluxes were possible. In addition, switching the feed from of the influent of the primary sedimentation basin to the effluent, very short-period aeration, alternative use of acid and oxidant in chemically enhanced backwash were found to be effective for mitigation of membrane fouling in DMF.

Free Research Field

環境工学

Academic Significance and Societal Importance of the Research Achievements

下水DMFを一定流量で長期間行うデータは現時点において関連研究例で希少であり、本技術の実用性を示すことができた。本研究では嫌気性消化に供されるスラリー体積を1/50-1/150にできることを実証したため加温が現実的になった。DMFでは嫌気性MBR等の競合技術と比較して回収エネルギーを大幅に増加させられることが示された。DMFで回収される有機物からのバイオガス発生ポテンシャルが高いことを実測により確認し、これをベースにDMFを基盤とする下水処理のエネルギー収支を推算した。DMFを用いた場合、現状で下水処理に用いられるエネルギーに相当するエネルギーを創出できる可能性が示された。