Thermal drying of residual sludge

The drying of residual sludge is a current environmental problem not well described in scientific literature. Thus research investigations on this dewatering process are necessary according to the industrial demand. This paper proposes, from laboratory convective drying experiments, a macroscopic approach in terms of kinetics curve and drying potential. This criterion which groups a set of external conditions into an unique parameter (T, RH, v) allows an easy classification of different operating strategies-then it can be the first step for design investigations. Moreover this study allowed us to compare the behaviour of tao very different kinds of sludge. It also described a crust phenomenon in the case of activated sludge and a large permeability of the PVC drying cake according to water transport. (C) 2000 Elsevier Science Ltd. All rights reserved.