Experimental characterization of isothermal drying of dewatered sewage sludge particle

Three types of dewatered sludge with different particle sizes were dried at constant temperature of 65°C, 85°C, 105°C and 125°C, respectively. The results showed that reducing sludge particle size or increasing the drying temperature had good effect on improving the drying rate of sludge. The drying rate of digested sludge was the highest, followed by biological aerated filter sludge and excess sludge. SEM analysis indicated that there were significant differences in the micro-morphologies of three types of sludge. Digested sludge had very rough surface and loose structure, while excess sludge had smooth surface and dense structure and biological aerated filter sludge had rough surface and less dense structure. There was a positive correlation between the surface roughness of sludge and the drying rate.