Effects of ultrasonic treatment on pyrolysis characteristics and reaction kinetics of municipal sludge

Key words:  ultrasonic treatment  municipal sludge  pyrolysis  thermogravimetric experiment  reaction dynamics

Abstract:

The effect of ultrasonic treatment process on pyrolysis reaction kinetics of municipal sludge was studied. On the basis of the Coats-Redfern integral method and relative error intercept screening principle, the pyrolysis kinetics was analyzed, the most probable mechanism function and kinetic parameters of ultrasonic treatment sludge were determined. The effect of ultrasonic pretreatment on the sludge pyrolysis characteristics was investigated. The results show that the sludge pyrolysis mechanism is becoming from three-dimensional diffusion to random nucleation and subsequent growth in the pyrolysis temperature range of 300-440 ℃. The apparent activation energy in this temperature zone is increased from 18.29 kJ·mol-1 to 26.32 kJ·mol-1, and pre-exponential factor is increased from 24.78 min-1 to 2761.62 min-1. The average activation energy of pyrolysis total reaction is decreased from 15.21 kJ·mol-1 to 14.65 kJ·mol-1.The pyrolysis reaction can be carried out more easily for the sludge after ultrasonic pretreatment.