EFFECT of MICROWAVE and CONVEYOR DRYING on the DRYING CHARACTERISTICS, MODELING, and THERMAL PROPERTIES of MUNICIPAL WASTEWATER SLUDGE

Abstract

Wastewater treatment plant sludges are high moisture content sludges that during their storage and transport can cause various different problems. Therefore, a significant process is to dry these sludges. Based on drying times and energy consumption, microwave and conveyor drying methods for drying wastewater treatment plant sludge were examined in this study. Sludge weights of 20 g, 40 g and 60 g were used in the drying experiments carried out using two separate dryers. Microwave drying trials were performed at 360 W, 600 W and 800 W power, conveyor drying trials at temperatures of 60 ± 1 oC, 70 ± 1 oC and 90 ± 1 oC, at a fixed belt speed of 0,2 m/min. Energy consumption increased with the rise in microwave power as a consequence of the experiments. At 800 W and 60 g, the least energy consumption is measured as 0,015 kWh. In conveyor drying, on the other hand, drying time decreased with the rise in drying temperature, and energy consumption decreased. At 90 oC and 20 g, the least energy consumption was measured as 4,1 kWh. In terms of time and energy, the most appropriate of both drying systems was determined at 800 W. Furthermore, as a result of the statistical analysis, the most suitable model among five drying models was determined according to the ?2, es, and r criteria as Logarithmic and Henderson and Pabis.