Investigation of Sludge Drying Performances Using a Designed Microwave Thermogravimetric System

Sludge resource utilization has garnered significant attention in recent years as an effective strategy to mitigate environmental pollution and address energy crises. Drying treatment serves as the essential first step for achieving sludge harmlessness and resource utilization, necessitating a comprehensive understanding of the drying process to optimize its efficiency. A designed microwave drying thermogravimetric experimental system was used to investigate the effects of raw material weight and microwave power on sludge drying performances through analysis of transient temperature and weight variations during the drying process. The results showed that the effectiveness of microwave drying initially increased and subsequently decreased with increasing sludge weight, while specific energy exhibited an inverse trend. Both drying efficiency and energy utilization peaked at a 30 g sample mass, with cumulative weight losses reaching 81.8 wt.%. Sludge weight significantly influenced drying outcomes. Drying efficiency initially improved and then declined with increasing microwave power, whereas specific energy showed an initial decline followed by an improvement, achieving optimal performance at 500 W.