This Small Business Innovation Research (SBIR) Phase I project will address fat, oil, and grease ("brown grease") reclaimed out of the wastewater collected from restaurant grease interceptors. These contain free fatty acids ("FFA"), glycerides and a significant amount of sulfur compounds (soaps, detergents, etc.). Thus, crude biodiesel produced from sewer brown grease may have a total sulfur concentration greater than 10,000 ppm?well above the 15 ppm limit specified in the biodiesel ASTM standard. It is proposed to examine novel and economical strategies for reducing sulfur in crude biodiesel to meet its ASTM standard: (1) metal sorbent adsorption: using a metal sorbent for selective removal of sulfur out of biodiesel, (2) oxidation-adsorption: oxidizing sulfides to sulfoxides and sulfones, which could be facilely scavenged by clay or silica; and (3) the combination of these two methods for deep sulfur reduction. The broader/commercial impacts of this research are effective remediation of waste grease streams. It is estimated that each year, over 4 billion pounds of brown grease are buried at the landfill sites or dumped at wastewater treatment plants which could equate to 500 million gallons of biodiesel. Effective remediation of waste grease streams could produce a value-added supply of biomass for energy conversion with an annual market value over $2 billion. Converting sewer brown grease into biodiesel will not only reduce environmental pollutions, but also create jobs and reduce reliance on foreign oils. The use of low-sulfur biodiesel from sewer brown grease will reduce SOx and greenhouse gas emissions.
