Investigation of Microwave-Induced Thin-Layer Drying for Municipal Sludge

Since the adverse factors such as deficient penetration and long reaction time have restricted the complete microwave-used drying of municipal sludge, the microwave-induced drying was considered which has advantages in such aspects. The investigation of the microwave-induced drying to uncover the mechanism has great meaning for its development and usage. The experiments indicated that temperature was the decisive factor affecting the drying rate. The microwave-induced sludge reached the highest drying rate at the moisture rate of 40%, with a 20% grade promotion compared with that of the original one. The molecular fracture caused by microwave radiation had obviously accelerated the drying process and the drying rate was rising in proportion to the microwave radiation dose. The diffusion coefficient of microwave-induced sludge was obviously enlarged more than 2 times grade. In this research, model Weibull proved to fit the experiment of thin-layer drying for municipal sludge best compared with the other ones.