Final Report: Biofuel Production From Grease Trap WasteEPA Contract Number: EPD14019
Title: Biofuel Production From Grease Trap Waste
Investigators: Hums, Megan E
Small Business: Environmental Fuel Research, LLC
EPA Contact: Manager, SBIR Program
Project Period: May 1, 2014 through April 30, 2015
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2014) RFA Text | Recipients Lists
Research Category: SBIR - Waste to Energy Systems , Small Business Innovation Research (SBIR)
This project evaluates the potential of producing a drop-in diesel substitute by extracting degraded lipids (fats, oils and greases) from a waste material. Grease Trap Waste (GTW) is a high-lipid waste that is removed from food service wastewater to prevent sewer blockages and is currently treated as a liability. GTW is an untapped source of hydrocarbons that can be converted into valuable fuels while simultaneously reducing the burden of high-intensity waste treatment. Environmental Fuel Research, LLC, is expanding on prior research from Drexel University that demonstrated conversion of the acidic, degraded lipids in GTW into Fatty Acid Methyl Esters (FAME), a class of chemicals commonly known as "biodiesel." The research in the project addressed several key technical challenges to commercialization of GTW to biodiesel processes: the highly variable composition of GTW, the difficulties in converting degraded lipids to FAME and the need to remove impurities—particularly sulfur compounds—from crude FAME to meet fuel quality specifications. The commercial feasibility of a GTW-to-biodiesel process was evaluated by both techno-economic modeling and environmental impacts through life cycle assessment. However, the results are highly sensitive to the variability in quantity of GTW, its composition and to the energy requirements of several process stages.
This project evaluates convertying the high-lipid portion of GTW into biofuiels while reducing the management intensity of the remaining waste. For example, GTW can be separated into four fractions: (1) brown grease lipids, (2) floating solids, (3) secondary wastewater and (4) sediments. The secondary wastewater is the largest fraction and can be disposed of much more cheaply than GTW. Lipids extracted from GTW—also called brown grease—can be converted into FAME using technologies such as a bubble column reactor developed by the Drexel researchers, but the variability in lipid yield and composition leads to several process uncertainties addressed in this project. A critical challenge to the extraction and conversion processes is the highly variable composition of the waste grease that leads to variable yields of biodiesel and variable energy and chemical requirements. This project included a longitudinal study of varibility in GTW composition and quantity that guided the analysis of alternative process designs for separating lipids from waste greases. The project also included research demonstrating process steps needed to purify FAME produced from GTW into biodiesel that meets fuel quality standards. A key outcome of the proposed project is the evalutaiton of the economic and environmental sustainability of material conversion of waste greases to value-added biofuels within the wastewater management system.
Environmental Fuel Research, LLC, is a small research start-up company coordinating a strong team of collaborators for this project, including an academic research team at Drexel University; a government laboratory with extensive equipment and experience in biofuels at the USDA Eastern Regional Research Center; and one of the largest companies collecting GTW in the Philadelphia/New York metropolitan area, Russell Reid Waste Management. In addition, new contacts were developed at local wastewater treatment facilities and other biofuel companies during this project.
During this SBIR Phase I project, Environmental Fuel Research, LLC has:
- Demonstrated the technical feasibility of producing ASTM-quality biodiesel from (GTW): GTW-Biodiesel from gallon-scale research reactors has sulfur content of 100-400 PPM, and sulfur content was redued to 6-30 PPM by vacuum distillation. The purified biodiesel is transparent and pale yellow and has fuel properties similar to biodiesel from other sources.
- Evaluated the economic feasibility of several scenarios for GTW-biodiesel processing: a process that converts 120,000 gallons of GTW per day into 2,300 gallons of biodiesel, 100,000 gallsons of industrial wastewater, and other waste streams has an estimated $3 million capital cost, yearly positive cash flow of more than $550,000 and a payback period of less than 6 years. Evaluation of alternative process scenarios show that the largest economic impact comes from reducing the cost of waste disposal by removing wastewater from GTW. The economic impacts of converting brown grease to biodiesel are highly sensitive to raw material costs and required capital investment that will be optimized in future process development.
- Applied life cycle assessment to estimate the environmental impacts of GTW-biodiesel relative to traditional biodiesel and petroleum diesel: The greenhouse gas emissions and cumulative energy demand of the GTW-biodiesel process is dominated by waste treatment, primarly due to the large amount of wastewater. However, in a comparative analysis to current GTW management, the net greenhouse gas emissions for GTW-biodiesel are about 30 g-CO2eq/MJ-fuel and the energy demand is about 0.44 MJ-fossil/MJ-fuel, both of which are similar to soybean biodiesel and less than one-third of petroleum diesel.
- Monitored the variability of GTW composition and its effect on biodiesel production: The longitudinal study of GTW in this project showed lipid content of GTW varies between 0.2-12 percent, but after gravity settling at ambient temperatures, the floating solid layer contains 10-40 percent lipids. The secondary wastewater from ambient settling accounts for 60-80 percent of the volume of the GTW and had COD of 3,000-15,000 mg/L and total solids of 1,500-12,000 mg/L, which are similar to industrial wastewater.
Based on these results, Environmental Fuel Research, LLC, intends to continue research into GTW-biodiesel process development and establishing partnerships to improve the likelihood of commercialization success.