Mathematical modeling of thin-layer infrared drying of dewatered municipal sewage sludge (DWMSS)

In this paper, thin-layer infrared drying behavior of dewatered municipal sewage sludge was systematically investigated. Drying experiments were conducted at drying temperatures from 65 to 135 degrees C and the thickness of sludge cake from 2 to 10 mm. Twenty thin-layer drying kinetic models were selected to model the drying process, and model parameters were evaluated by nonlinear regression method, of which, two different nonlinear error functions (R-2, RSS) were examined to gauge the goodness-of-fit. The experimental results manifested that Hasibuan and Daud model is the best suitable model with highest R-2 values from 0.99951 to 0.99996 and lowest RSS values from 3.3 x 10(-4) to 0.00117 under our experimental conditions; drying rate increased with increase in drying temperature and decrease in the thickness of sludge cake; effective moisture diffusivity notably increased as drying temperature increased; activation energy for drying process was 34.9211 kJ/mol. (C) 2016 The Authors. Published by Elsevier B.V.