Production of biodiesel from brown grease

Among the renewable energy sources is biodiesel. This fuel is usually produced by catalytic transesterification of vegetable oils and animal fats under heating and pressure. Brown grease is a mixture of oils, fats, solids and detergents from food industry wastes that is captured in grease traps. Brown grease is classified as waste and must be treated and disposed of appropriately. It contains oils and fats that can be converted into biodiesel. However, the high concentration of free fatty acids in brown grease does not enable the use of conventional biodiesel production schemes. This study proposes a new scheme for biodiesel production from brown grease. In addition, conditions for the effective separation of a fat phase from brown grease were tested, and the composition of a fatty phase was determined for several grease traps. Esterification and transesterification of brown grease lipids were carried out with methanol, where the Lewis acids BF₃ and AlCl₃ were used as catalysts and the reaction was activated by ultrasound. The results show that biodiesel can be obtained from brown grease by esterification and transesterification within several minutes under ultrasonic activation at room temperature. These results open prospects for the development of efficient, low-cost and environmentally friendly biodiesel production.