Conversion of Paper and Food-rich Municipal Solid Waste Streams to Ethanol through Bioprocessing

This article provides a method to convert landfill-designated municipal solid waste (MSW, paper-rich and food-rich) to bioproducts through integrated bioprocessing, also a way of improving the MSW diversion rate to reduce environmental stress. Compositional analysis, bacterial community profiling, homogenization, enzymatic hydrolysis, and yeast fermentation were performed on the collected MSW samples. Results show that these two types of MSW streams are potential feedstock sources for biorefineries based on their abundance, carbohydrate composition, and bioconversion yield. Addition of selected enzyme cocktails to the homogenized substrates resulted in coproduction of C6/C5 sugars and organic acids in the hydrolysates. Maximum 81% glucose and 100% xylose yields were achieved in the paper-rich MSW-derived hydrolysate (PDH). A glucose yield of 96.7% was obtained in the food-rich MSW-derived hydrolysate (FDH). Sugars in PDH and FDH were readily fermentable without detoxification and solid separation. Preliminary fermentation attained 17.7 g/L ethanol from the PDH (69.4% theoretical yield) and 8.9 g/L ethanol from FDH (70.3% theoretical yield), respectively, both comparable with the Avicel-derived hydrolysate (67.6% theoretical yield) used as the control.