Mathematical Modeling of Thin Layer Drying of Sewage Sludge

Abstract

Drying characteristics of sewage sludge were investigated using hot air with a temperature range of 60~140°C and an air velocity range of 0.50~2.50m/s at a convective dryer. Several mathematical models available in the literatures were fitted to the experimental data by multiple non-linear regression analysis. Three statistical parameters: coefficient of determination (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), root mean square error (RMSE) and mean relative deviation modulus (P) were used to evaluate the fitting performance. Results show the Page model gave the better predictions than others. The effective diffusivity of moisture transfer during drying process varied between 0.552×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /s and 1.801 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /s while the activation energy for moisture diffusion in sewage sludge was found to be 16.26kJ/mol.