Sunday, May 3, 2009
3-37
Biological Conversion of Municipal Solid Waste to Ethanol
Mirvat A. Ebrik, Jian Shi, Bin Yang, and Charles E. Wyman. Center for Environmental Research and Technology, Bourns College of Engineering, University of California, Riverside, 1084 Columbia Avenue, Riverside, CA 92521
Municipal solid waste (MSW) is an attractive cellulosic resource for sustainable production of transportation fuels and chemicals because of its abundance, the need to find uses for this problematic waste, and its low and perhaps negative cost. However, significant heterogeneity and possible toxic contaminants are barriers to biological conversion to ethanol and other products. In this study, we obtained six fractions of sorted MSW from a waste processing facility in Fontana , California : 1) final alternative daily cover (ADC Final), 2) ADC green, 3) woody waste, 4) grass waste, 5) cardboard, and 6) mixed paper. Application of dilute sulfuric acid pretreatment followed by enzymatic hydrolysis gave the highest sugar yields in the cardboard and ADC final fractions for enzyme loadings of 100 mg enzyme protein/g sugars in the solids prior to pretreatment. However, treatment with our protein detoxification technology before adding enzymes improved sugar yields at low enzyme loading of 10 mg enzyme protein/g sugars in raw materials. For example, pretreatment with 1% dilute sulfuric acid for 40 min followed by BSA supplemented enzymatic hydrolysis at an enzyme loading of 10mg enzyme protein/g glucan recovered 72% of the potential glucan and 76% of potential xylan in solution from ADC final. These results will be incorporated into an economic model to estimate the economic feasibility of converting MSW to ethanol and identify opportunities for improving the economics.