Experimental Investigation of the Influence of Baffle Position on the Flow Field, Sediment Concentration, and Efficiency of Rectangular Primary Sedimentation Tanks

Sedimentation due to gravitation is applied extensively in water and wastewater treatment to remove suspended solids. Suitable baffle configurations may help form favorable flow fields and increase the efficiency of a primary sedimentation tank. Experimental tests were performed to determine the best position for a baffle in a rectangular primary sedimentation tank. The experimental measurements consisted of three parts. First, the velocity fields were measured using an acoustic Doppler velocimeter. The concentration at different vertical and horizontal points was then evaluated. Finally, the removal efficiency of the sedimentation tank was measured. The results of the present study indicate that a uniform flow field in the settling zone is enhanced when the baffle position provides a small volume of circulation regions. In this case, the maximum concentration of the suspended sediments inside the settling zone and the highest removal efficiency are achieved. © 2013 American Society of Civil Engineers.