Bio-oil from microwave assisted pyrolysis of food waste-optimization using response surface methodology

Municipal solid waste (MSW) contains on an average 40% food waste and needs to be managed in an environment friendly manner. Food wastes have high energy content and offer a good potential feed stock for pyrolysis. Microwave assisted pyrolysis of food waste at different microwave power levels has been carried out in the present study. Maximum bio-oil yield of 30.24 wt.% is obtained under the optimized pyrolysis conditions of 400 degrees C temperature, 30 min residence time and 50 mL min(-1) of nitrogen flow rate at the microwave power of 450 W. The regression model with 95% confidence level resulted in the high value of R-2 = 95.4% with R-2 adjusted = 91.2% indicates a very good or excellent fit of the data to the model. Main functional groups as detected by the Fourier transform infrared (FTIR) analysis are alcohols, alkenes, aromatic compounds, primary and secondary amines, carboxylic acid, esters and phenols. Oxygenated and non oxygenated compounds, nitrogenated compounds and other compounds such as phosphine, methyl-, propane, 2-fluoro-, (2-hydroxyethyl) trimethylsilyl methyl sulfide, and 1,3-bis(2-hydroxymethyl)urea have been identified by the gas chromatography/mass spectrometry (GC-MS) analysis. The heating value of the bio-oil was 23.94 MJ kg(-1 ).