Development of advanced dewatering process of sludge for its conversion to solid fuel

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05190
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 27010:Transport phenomena and unit operations-related
• Research Institution: Meijo University
• Principal Investigator: Katagiri Nobuyuki 名城大学, 理工学部, 准教授 (00345919)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 汚泥 / 圧搾脱水 / 浸透圧脱水 / 固形燃料化 / 破砕操作 / 超高圧圧搾 / フロック崩壊 / 微生物細胞

Outline of Final Research Achievements

We attempted a dewatering operation using the osmotic pressure of activated sludge with high moisture content, which is discharged in large quantities from a sewage treatment facility, and elucidated its dewatering effect. A filter cake with a moisture content of approximately 80 wt% prepared by filtration of activated sludge was immersed in a high-concentration salt solution. The intracellular water was discharged owing to the osmotic pressure difference between the inside and outside of the microbial cells constituting the activated sludge, whereby a low moisture-content dewatered cake was obtained. The higher the osmotic pressure, the greater was the dewatering effect. With an osmotic pressure of approximately 22 MPa, the moisture content of the cake decreased to approximately 60 wt% within a few minutes. The sludge cake dehydrated by osmotic pressure had an extremely low moisture content, suggesting the possibility of use as a solid fuel.

Free Research Field

水処理工学

Academic Significance and Societal Importance of the Research Achievements

難脱水性有機汚泥の高効率な脱水法の開発は、汚泥の減量化や脱水汚泥の資源としての有効利用の見地から現在急務とされている課題である。省エネルギー的な脱水操作として機械的固液分離が導入されているが、現在の技術ではその脱水度は充分なものではなく、その後に熱的操作を必要としている。本研究では、汚泥を構成する微生物細胞の内と外の浸透圧差を利用する浸透圧脱水法を確立し、汚泥の含水率を迅速に60％程度まで減少させることに成功しており、従来技術の70～80％を遙かに凌駕する成果が得られている。高い脱水速度と高い脱水度の両者を同時に満足し、汚泥の固形燃料化に繋がる省エネルギー的な脱水プロセスとして有用である。