Conversion of Grease Wastes from the Wastewater Management Systems into Biodiesel
US Environmental Protection Agency
Dr. Richard Cairncross, Associate Professor, Chemical & Biological Engineering
Dr. Sabrina Spatari, Assistant Professor, Civil, Environmental, and Architectural Engineering
Energy Systems, Analytics and Control
Two high-lipid waste streams from the wastewater management system are underutilized despite their potential for conversion into valuable fuels: (1) grease trap waste and (2) sewage scum. Grease trap waste is dirty, low-value material produced by the food service industry that is high in lipids. The quantity of grease trap waste in the USA is sufficient to produce half a billion gallons of biodiesel, about half the current domestic biodiesel capacity and ten times the potential production from waste fryer oil. Grease to biodiesel processes benefit grease collectors through reduced disposal costs and benefit consumers through improved environmental impacts. With prior support from the US Environmental Protection Agency and current collaboration efforts with researchers from the USDA Eastern Regional Research Center, we are conducting longitudinal studies of grease trap waste composition and process efficiencies for reaction and separation into techno-economic and life cycle models to evaluate the economic feasibility and environmental impact of grease to biodiesel processes. Because brown grease and crude biodiesel produced from brown grease contain sulfur far in excess of the specifications for biodiesel, we are actively exploring wiped-film evaporation and other purification techniques that have demonstrated significant reductions in sulfur content.