Numerical Simulation of Batch Settling Process

Abstract

The batch settling process was simulated numerically using a dynamic model for zone settling and compression. The simulation can provide the height variation of the supernatant-suspension interface with time as well as the vertical solids profile at different times. The simulation results were compared with experimental batch settling data in the literature for various types of suspended materials with different initial suspended solids concentrations. Generally good agreement between the simulations and experimental measurements was obtained. The method presented here has several advantages for the simulation of the batch settling process compared with the methods found in the literature; it is simple, requires only four parameters, and provides good results for both zone and compression settling. Also presented is a technique for quantifying all four required parameters, in particular, the two describing the compression characteristics of a suspension from batch settling tests. These compression parameters are needed to estimate the depth requirement of steady-state gravity thickeners. This method also will be useful for environmental engineering processes that use batch settling for solids-liquid separation, such as sequencing batch reactors.