The effect of baffle angle on primary sedimentation tank efficiency

Abstract

Sedimentation due to gravitation is extensively applied in water and wastewater treatments to remove suspended solids. To improve settling efficiency, the settling surface area should be increased which will consequently reduce the size of circulation zones in the tank. There are many ways to decrease the size of the circulation zone. In this study, the presence of a baffle with different angles and its effect on the hydrodynamics of the flow field is investigated in a primary sedimentation tank by the application of a computational model. Additionally, laboratory experiments are conducted and the measured velocity fields determined by Acoustic Doppler Velocimeter (ADV). Experimental and computational results show that a baffle angle of 90° provides the specific favorable flow field. Finally, the hydraulic efficiency of a sedimentation tank with different baffle angles is compared by using the Flow Through Curves (FTCs) method.