Time-dependent batch settling of flocculated suspensions

The equations governing the settling and consolidation of flocculated fully networked suspensions under the influence of gravity, based on the assumption that the network possesses a compressive yield stress P(oslash;) that is a function of local volume fraction (oslash;) only, are discussed. They are nonlinear partial differential equations with two moving boundaries, one at the top of the bed and the other marking the position of the consolidation region. A novel technique is used to solve these numerically. The time evolution of the volume fraction in the sedimenting column and the two moving boundaries are computed, and their dependence on the physical properties of the system are discussed. Analytic results for the steady state and the small time behavior are given