Statistical optimization of pretreatment of municipal solid waste by response surface methodology for fermentable sugar production

Abstract

This research aims to use low‐cost and easily available chemicals for chemical pretreatment to achieve a high yield of fermentable sugars using biodegradable municipal solid waste as a substrate. Biodegradable municipal solid waste was pretreated with locally available toilet cleaner (acidic in nature) and washing detergent (basic in nature) and to achieve maximum yield of reducing sugars, two variables; chemical concentration and time were selected for optimization using a central composite design. In Central composite design 13 runs for toilet cleaner (acidic in nature) and washing detergent (basic in nature) pretreatment models were created while ranges for two variables were selected as 1, 2, 3 days for time and 1%, 3%, 5% for chemical concentration. In the toilet cleaner (acidic in nature) pretreatment, optimum conditions were 5% (vol/vol) of toilet cleaner (acidic in nature) for 3 days. At optimal conditions, the model for toilet cleaner (acidic in nature) pretreatment released 167.755 g/L of reducing sugars and 2.684 MJ/L energy while the model for washing detergent (basic in nature) pretreatment released 159.141 g/L of reducing sugars and 2.546 MJ/L energy. An enzyme cocktail hydrolyzed the toilet cleaner (acidic in nature) pretreated sample, and the highest value of fermentable sugar was achieved at 36 h of 237.83 ± 11.028 g/L. Thus, the chemical pretreatment using toilet cleaner and washing detergent has a great potential for fermentable sugar production and effectively be used in industrial and household digesters for the conversion of waste into useful products.