Drying Kinetics and Characteristics of Sewage Sludge/Rice Straw Mixture

This study aimed at investigating thin-layer drying characteristics of sludge mixed with different rice straw contents (1, 2, 3, and 5% wb). The experimental results showed that adding 1, 2, and 3% (wb) rice straw to sludge is helpful to improve the drying rate of sludge as the surface area and cracks increase but the drying rate of the sludge mixed with 5% (wb) rice straw decreases with a reduction in thermal conductivity. When the content of rice straw is 2% (wb), the increased amplitude of drying rate is the highest, 14.6, 14.8, 16.0, and 17.6% at 100, 120, 140, and 160 degrees C, respectively. The model proposed by this study showed better prediction compared with the other models and satisfactorily described the drying characteristics of sludge/rice straw mixture as well and is applicable under the given experimental conditions. The values of R-2, root mean square error (RMSE), and (2) varied from 0.99935 to 0.99992, 0.00295 to 0.00830, and 0.00001 to 0.00007, respectively.