On the Pyrolysis of Sewage Sludge: The Influence of Pyrolysis Temperature on Biochar, Liquid and Gas Fractions

Pyrolytic conversion of sewage sludge to biochar, oil and gas is an environmentally and economically acceptable way comparable to conventional options for sewage sludge disposal. The aim of this paper is to investigate the influence of pyrolysis temperature on production of biochar fraction for agronomic application, oil and gas fractions for energy utilization. Sewage sludge samples collected from an urban sewage treatment plant were pyrolysed in a bench–scale quartz tubular furnace over the temperature range of 300-700°C.The results indicated that the biochar fraction yield decreased, the yields of liquid (oil and water) fraction and gas fraction increased by evaluating the pyrolysis temperature. Concentration of heavy metals and nutrient elements present in biochar varied with pyrolysis temperature, the heating value of oil from liquid fraction fluctuated between 26938.3 and 30757.9kJ/kg, the heating value of gas fraction increased from 4012kJ/Nm3 to 12077 kJ/Nm3 with the increasing pyrolysis temperature.