1D Numerical Modeling of sediment Pattern in settling Basins

Settling basins are one of the most important structures is commonly used for deposition of sediment particles in water and wastewater systems, in order to prevent the damage of sediment particles. The purpose of this study is to provide a one-dimensional numerical model for simulating flow and sediment in a rectangular sedimentation tanks. The governing equations are depth averaged equations of flow and sediment transport. In order to the numerical solution, the finite difference method has been used. The model can be used for non-uniform flow and non-uniform particles and could predict important information such as removal efficiency, thickness, and distribution of particle size of sludge. Comparison of the results of the proposed numerical model with the results of other researchers stated the acceptable accuracy of the proposed model, so that in all cases the error rate was less than 3%. The results of the sensitivity analysis showed that more than 50 percent of suspended sediment deposited at the first 5 meters of the basin; therefore, the increase in the dimensions of the rectangular reservoir is not the best way to improve the performance of the pond. In fact, increasing the removal efficiency can be achieved by reducing the depth of the settling basin, increasing the cross-sectional area of flow and reducing the surface loading rate.