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Rheological behavior of sewage sludge with high solid content.
1Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China E-mail: li.huan@sz.tsinghua.edu.cn; Joint Research Center of Urban Resource Recycling Technology of Graduate School at Shenzhen, Tsinghua University and Shenzhen Green Eco-Manufacturer High-Tech Co. Ltd, Shenzhen 518055, China.
Summary
This study reveals high-solids sludge exhibits complex rheological properties, including thixotropy. A new model accurately describes sludge viscosity based on solids content and shear rate.
Area of Science:
- Environmental Engineering
- Fluid Mechanics
- Materials Science
Background:
- Sludge rheological properties are critical for efficient transport and treatment in pipes, tanks, and reactors.
- Limited data exists on the rheological behavior of high-solids sludge, hindering process optimization.
- Understanding these properties is essential for designing and managing sludge handling systems.
Purpose of the Study:
- To systematically investigate the rheological properties of high-solids sludge.
- To develop a novel rheological model for high-solids sludge.
- To analyze the influence of total solids content, shear rate, organic content, and temperature on sludge viscosity.
Main Methods:
- Experimental investigation of sludge rheological properties across varying total solids (TS) content.
- Development and validation of a new complex rheological model combining exponential and power-law functions.
- Analysis of the impact of sludge organic content and temperature on viscosity.
Main Results:
- Low-solids sludge (TS 2-15%) behaved as a pseudoplastic fluid.
- High-solids sludge (TS 7-15%) exhibited thixotropic properties.
- Sludge viscosity increased exponentially with TS and decreased with shear rate, accurately described by the new model.
- Organic content significantly increased viscosity, while temperature decreased it in high-solids sludge.
Conclusions:
- A new complex rheological model effectively characterizes high-solids sludge behavior.
- Sludge rheology is highly sensitive to TS, organic content, and temperature, particularly in high-solids concentrations.
- Findings provide crucial insights for optimizing the hydraulic transport and processing of high-solids sludge.
