ABSTRACT
Food waste (FW) is the discarded/leftover food, which shares around 40% area of the total municipal solid waste. With the increase in population, FW is estimated to double by the next 25 years. FW management is primarily done by composting or anaerobic digestion, which solely involved biochemical techniques. Low conversion efficiency, difficulty in maintaining operating conditions, sensitive to operating conditions, high operational and maintenance costs, and huge capital investment make the biochemical technique very challenging. Due to the fossil fuel crisis in the past decades, there has been significant development of alternate energy sources such as biomass, hydropower, geothermal, wind, solar, and nuclear energy. The major focused end products are bio-ethanol, bio-diesel, lipid-derived bio-fuel, biogas, etc., to replace fossil fuels. Conversely, thermal techniques like incineration, gasification, pyrolysis, hydrothermal, etc. proved their worth to retrieve energy from the FW. Incineration resulted in the generation of furans, which creates air pollution. Pyrolysis technique reduces the FW volume up to 90% and generates varieties of end-products such as bio-oil, biochar, and syngas, which can be further used as energy sources. However, the slow heating rate and production of low-quality end-products are still the major drawbacks of the thermal conversion of FW through pyrolysis. Advanced pyrolysis techniques such as plasma pyrolysis and microwave pyrolysis and aid-in techniques such as co-pyrolysis and catalytic pyrolysis were considered to improve the process efficiency. Finally, the process efficiency was assessed through the quality and quantity of end-products in terms of energy yield and energy efficiency.
