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Updated: Jun 5, 2026
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Determination of the Settling Rate of Clay/Cyanobacterial Floccules
Published on: June 11, 2018
Development of a flocculation sub-model for a 3-D CFD model based on rectangular settling tanks.
M Gong1, S Xanthos, K Ramalingam
1Department of Civil Engineering, City College of City University of New York, 140th Street & Convent Avenue, New York, NY 10031, USA.
Summary
Researchers developed a 3D computational fluid dynamics (CFD) model to enhance final settling tank (FST) efficiency. The model optimizes flocculation and solids capture by analyzing baffle placement and loading rates, improving wastewater treatment performance.
Area of Science:
- Environmental Engineering
- Fluid Dynamics
- Wastewater Treatment
Background:
- Rectangular final settling tanks (FSTs) are crucial for wastewater treatment.
- Improving the efficiency of these tanks is essential for effective solids capture.
Purpose of the Study:
- To assess the performance of Gould II type FSTs and explore methods for efficiency improvement.
- To develop and validate a 3D computational fluid dynamics (CFD) model for FST optimization.
Main Methods:
- Development of a 3D CFD model using Fluent 6.3.26™.
- Incorporation of sub-models for settling, turbulence, flocculation, and rheology.
- Supplementation with field and bench-scale experiments to quantify model coefficients.
Main Results:
- The 3D CFD model can simulate various FST configurations, including baffle arrangements and loading rates.
- Flocculation, particularly near the inlet baffle, significantly impacts solids capture efficiency.
- An in-tank baffle can enhance flocculation by capturing smaller particles, improving overall performance.
Conclusions:
- The developed 3D CFD model provides a valuable tool for optimizing FST design and operation.
- Strategic placement of in-tank baffles can improve flocculation and solids capture.
- A modified equation for flocculation coefficients is proposed, reducing dependency on initial suspended solids concentration.
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