Extraction of fats, oil and grease from grease trap waste for biodiesel production

Abstract

Fats, oil and grease, the main composition of GTW, is the major cause of sewer pipe blockage that can lead to a costly treatment for councils as well as the households themselves. To prevent this, grease traps are required to be installed in most of commercial food services such as restaurants and food processing factories. As a result, a large amount of grease trap waste is being collected and need to be treated at the end of life that can cause many problems for most of the environmental services. This study investigated a potential solvent extraction method to extract FOG from the very low quality GTW. GTW was collected from an environmental service in Adelaide region, while hexane (HEX), diethyl ether (DEE) and co-solvent hexane - diethyl ether (HEX-DEE) are utilised as solvent to extract FOG and used it as a feedstock for biodiesel production. The results showed that the extraction yield was increased significantly while utilising the solvent as the following order: DEE > HEX-DEE > HEX. A 96% extraction yield was obtained under the optimum operating condition of 1:1 DEE-GTW ratio (v/w), 30oC, 300 rpm and 360 min. In addition, HEX-DEE co-solvent was observed more efficiency in terms of emulsion reduction. All of the solvents are recycled and can be used two to three times for FOG extraction with more than 88% extraction yield.