Numerical simulation of a sedimentation basin. 2. Design application

A numerical model of a rectangular settling tank is used to study the importance of selective variables on the settling process while demonstrating the capabilities of the computer simulation. The computer model follows the spatial and temporal development of the influent particle size distribution toward the outlet of the tank based on the fundamental mechanisms which govern particle motion and growth. It is shown that both the removal efficiency of a flocculating suspension and the effluent particle size distribution are influenced strongly by the mass concentration in the inflow, the influent particle size distribution, the floc size-density relationship, and the collision efficiencies of the particles. It is suggested that future experimental work should focus on obtaining information on the size-density relationship, the reentrainment of the deposits, and the collision efficiencies of floes.