Pyrolysis of Domestic Sewage Sludge: Effect of Process Parameters on Biochar Calorific Value

Abstract This research aims to look into a sustainable technique for the treatment, reuse and disposal of domestic sewage sludge (DSS). The purpose of the study was to examine the operating factors that influence the calorific value of the produced biochar from the pyrolysis of DSS. Based on the analysis of the full factorial design, the impacts of the pyrolysis conditions, specifically: temperature, heating rate, and isothermal time on the calorific value of biochar were evaluated. When the pyrolysis temperature was raised from 300 to 500 oC, the calorific value of biochar was decreased by 34%. A 14% decrease in the calorific content of the biochar was also noticed when the heating rate was increased from 5 to 35 oC/min. When the isothermal time was increased from 45 to 120 minutes, the calorific value of the biochar remained essentially unchanged. No interaction effects among process variables were found using the factorial design methodology. A first-order regression model was developed to predict the calorific value of biochar using the magnitude of the effects of the process factors and their interactions. The model predictions agreed very well with the obtained experimental results.