Techno-economic analysis of bioethanol production from microwave pretreated kitchen waste

Cost-effective production of bioethanol from waste material is becoming the need of the hour to combat the exhaustive nature of fossil fuel. In this study, bioethanol was produced from microwave-pretreated kitchen waste at high dry material consistency. Pretreatment was performed for 30 min at a constant power of 90 W. Liquefaction/saccharification was done with in-house produced amylase from Bacillus licheniformis MTCC 1483. The liquefaction step was optimized using response surface modeling. Three factors, viz. pH, concentration of dry substrate and amylase, were optimized by using reducing sugar and ethanol yield as response. The optimum conditions of input parameters obtained were pH 7.5, dry material 40% (w/v) and amylase 15 IU g−1. The process developed in the present study leads to 0.129 g ml−1, i.e., 0.32 g per g biomass ethanol production. The novelty of the manuscript lies in the fact that no acid/alkali hydrolysis was carried out for the release of reducing sugar. Instead, microwave treatment was carried out at low power for longer time so as to release maximum sugar. The cost incurred in bioethanol production was also estimated by taking cost of chemicals, instruments and operating cost in account. The total cost of bioethanol produced in the present study was calculated as 0.143 $/l of ethanol. A 8.32-fold decrease in price of ethanol produced in the present study was observed when compared to the market selling price of ethanol. This makes the developed process economically and industrially feasible.