A comparison of isothermal with nonisothermal drying kinetics of municipal sewage sludge

Thermal drying behavior of the municipal sewage sludge in nitrogen atmosphere was explored using a thermal analysis technique under isothermal and nonisothermal drying conditions. The Midilli model, , was the best suitable for predicting both the isothermal and nonisothermal drying behavior of the sewage sludge with the highest R (2). The isothermal drying apparent activation energies of the first falling rate period and the second falling rate period were 18.03 and 11.87 kJ mol(-1), respectively. The nonisothermal drying apparent activation energies of sewage sludge were from 33.61 to 47.37 kJ mol(-1) in the first falling rate period and from 20.47 to 33.43 kJ mol(-1) in the second falling rate period, respectively. In two falling rate periods, the dominant mechanism functions for the isothermal drying were identical, . The dominant mechanism functions for the first falling rate period and the second falling rate period in the nonisothermal drying were described by and , respectively.