The equations governing the consolidation of flocculated suspension in a ideal continuous thickener are solved numerically (using Maple 9) using the assumption that the flocculated suspension possesses a compressive yield stress P-y(phi) that is a solely a function of the local volume fraction, Kaolinite was chosen as a representative substance since the volume fractions of kaolinite suspensions corresponding to the gel point, phi(g), had been determined under different electrolyte concentrations and pH together with the compressive yield stresses, P-y(phi). The numerical results show that the maximum volume fraction at bottom of the thickener phi(u). is a relatively sensitive function of the electrolyte concentration and pH. Hence, the separation efficiency of the thickener can be altered by changing the feed chemistry. (c) 2007 Elsevier B.V. All rights reserved.