American Society of Civil Engineers

Numerical Modeling of Type I Circular Sedimentation Tank

by Jian Huang, (Graduate student, Faculty of Engineering, Univ. of Regina, Regina, SK, Canada, S4S 0A2.) and Yee-Chung Jin, (Professor, Faculty of Engineering, Univ. of Regina, Regina, SK, Canada, S4S 0A2.)

Journal of Environmental Engineering, Vol. 137, No. 3, March 2011, pp. 196-204, (doi:

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Document type: Journal Paper
Abstract: A numerical model for Type I circular sedimentation tanks (center feed) has been developed to provide useful information for circular tank operation. The unsteady flow process in circular sedimentation tanks is divided by numerous time intervals in which flow and sediment transport are considered to be steady. The other feature for this model is that particle size distribution of raw water is nonuniform. A numerical experiment based on the proposed model is carried out, and the results were compared with results from other models. The comparison shows that this model can provide more information, such as variations of water elevation, overall removal efficiency, bottom sludge thickness, and particle size distribution at outlet. In addition, this model had the advantage of optimizing the tank dimensions based on the sludge raking frequency and preferred removal efficiency. After simplification of the model, this model is practical in determining the overall removal efficiency and dimension of the tank based on different inflow situations for tank design.

ASCE Subject Headings:
Sediment transport
Sedimentation tanks

Author Keywords:
Depth-averaged model
Nonuniform sediment
Removal efficiency
Sediment transport
Sedimentation tank
Sludge thickness