Analysis of the convective drying of residual sludge: From the experiment to the simulation

Abstract

The drying of residual sludge is a current environmental problem not sufficiently described in the literature, hence research investigations on this drying process are required. Sun drying sludge whilst covered is becoming increasingly attractive for small and medium sized wastewater treatment plants. The control of the quality of the dry product is becoming more and more necessary in order to ensure effectivity. Then new mathematical models should integer these requirements and consider the phenomena of shrinkage. This work gives a mathematical formulation of the different transfer phenomena (heat, mass), which describe the process. The model tries to be relatively simple but sufficiently complete in order to predict and analyze the distribution of temperature, and the moisture during the process. The developed nonlinear differential equations were solved by the classical fourth-order Runge-Kutta method. A validation of these results is achieved by the comparison of the numerical and experimental data.