Experimental Study and Modeling of Drying Kinetics and Evaluation of Thermal Diffusivity of Sewage Sludge

Abstract

This article discusses the use of solar dryers as a method for stabilizing and reducing the volume of residual sludge produced by wastewater treatment facilities. The study focused on the convective drying behavior of sewage sludge produced by the wastewater treatment plant of Meknes City under convective solar drying. The study aimed to investigate the drying kinetics of sewage sludge and emphasize the effect of temperature and water content on the evolution of the drying rate. The measured water content values showed a decrease as drying time increased. The results revealed the presence of phase II, which characterizes the decreasing rate drying period, and the absence of phase I, which describes the constant rate drying period.The study developed an empirical model to describe the kinetic behavior of convective solar drying of Moroccan domestic sludge. The model can be used to predict the shape of a drying curve under other aerothermal conditions. Additionally, the study analyzed the thermal diffusivity and activation energy of sewage sludge using an experimental macroscopic method based on Fick's diffusion model and the Arrhenius equation. The measured diffusion coefficient values range from 0,71 10-9 m2.s-1 to 1,47 10-9 m2.s-1, and the value of activation energy was evaluated at 17.54 kJ/mol.