SIMULATION OF THE CAKE FORMATION AND GROWTH IN SEDIMENTATION AND FILTRATION

This paper presents a numerical study of the cake formation and growth in sedimentation or filtration in which the flow of discrete particles is three-dimensional and the flow of continuous liquid one-dimensional. The motion of particles is controlled by various forces, including particle-particle interactions due to collision and the van der Waals forces between particles, and particlefluid interactions such as buoyancy, drag and lift forces. The validity of the method is tested by comparing the simulated and measured results. It is shown this simulation technique can generate detailed information at both microscopic and macroscopic levels. The cake thickness, average cake solidosity, filtrate volume, filtrate flow rate (for constant pressure filtration) or pressure drop across the filter unit (for constant rate filtration) as a function of filtrate time have been quantified under different flow and operational conditions. The effects of variables such as particle size, Hamaker constant, fluid density and fluid viscosity on cake properties are examined through a series of controlled numerical experiments.