Mathematical Modeling of Thin Layer Drying of Sewage Sludge

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 (R²), 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^-6 m²/s and 1.801 × 10^-6 m²/s while the activation energy for moisture diffusion in sewage sludge was found to be 16.26kJ/mol.