Improvement of Suspended Solids Removal Efficiency in Sedimentation Tanks by Increasing Settling Area Using Computational Fluid Dynamics

Abstract

In the renovation design of sedimentation tanks for the wastewater treatment plant, the small settling velocity particles should be removed to improve total suspended solids (SS) removal efficiency. Theoretically speaking, when the flow rate is constant, the increased settling area in the sedimentation tank results in high removal efficiency of small settling velocity particles. Alternatively, the SS removal efficiency increases in lamella settling tank as installing inclined plates. However, the actual effect of increased settling area due to different tank configuration to improve the removal efficiency of small settling velocity particles was not fully investigated. In this study, the computational fluid dynamics model was applied to simulate the effect of increased settling area on SS removal efficiency in three types of configuration when flow rate was remained unchanged. The simulation results show that the highest SS removal efficiency was observed in the tank with increased settling area by extending the length of the tank, in which the increased settling area contributed 69% to improve the removal efficiency of small settling velocity particles. These results have an important role in optimizing the design to enhance the SS removal efficiency of the settling tank.