Production and Optimization of Bio-Oil from Municipal Wastewater Sludge by Thermal and Catalytic Pyrolysis Process

Limited resources and problems caused by fossil fuels consumption, have led researchers to pay attention to reproducible resources. In this study thermal and catalytic pyrolysis process were used to produce bio-oil from sewage sludge. In thermal pyrolysis, the effect of temperature, the heating rate and gas flow rate was investigated and optimum conditions for production of maximum amount of bio-oil with a production yield of 34.7% were determined equal to temperature 525 °C, heating rate of 20 °C/min and gas flow of 0.5 L/min. To improve the quality of bio-oil and reduce the number of oxygenated compounds, four catalysts HZSM-5 (SAR=40), Co/HZSM-5, Ni/HZSM-5 and Mo/HZSM-5 with weight ratios of 1:5 and 1:10 were used. Bio-oil produced by Mo/HZSM-5 catalyst with weight ratio of 1:5 and with factor groups of alkane/alkenes 27.72%, aromatic compounds 6.25 %, oxygenated compounds 5.82%, phenolic compounds 10.75% and high heat value 39.44 MJ/kg. Although the heating value of bio-oil produced from the catalytic pyrolysis of sewage sludge is lower than gasoline and bio-diesel, it is expected that by improving the quality of bio-oil, it will be used instead of fossil fuel in the future.