Case Number 112078 - Method to Produce Biodiesel from Trap Grease

Contact: Doug Nienaber
Phone: 513-558-3098

Description:  Dr. Mingming Lu and her lab have developed a new method of creating biodiesel from trap grease.

Trap grease, or brown grease, is waste grease which restaurants trap before it goes down the sewer. Brown grease, as compared to fryer grease, is a mixture of vegetable oil, animal fat, and other grease found in grease traps. Because of the nature and location where it is captured, trap grease can also contain other containments from the floor of an establishment including cleaning chemicals. These contaminants make brown grease unsuitable for reuse in many applications. In contrast, yellow grease, which is used frying oils from deep fryers, may be readily reused in a variety of applications, such as an animal feed additive and in the production of biodiesel. One primary difference between yellow and brown grease is that trap grease contains more moisture and much more impurities than the yellow grease. This limits its usefulness without additional processing including the use of potentially harmful solvents. In addition, any chemical solvent not currently in use to the biodiesel industry would require extensive changes to existing facilities.

A current method of creating biodiesel from trap grease is (1) add a solvent to the trap grease to reduce the glycerin and fatty acid content, (2) remove the solvent from the product of step 1, (3) perform acid and alkali catalysis on the product of step 2 and (4) perform transesterification on the product of step 3. The use of solvents causes an extra waste product and increase the cost and safety requirements. When compared to converting yellow grease, this is even more true, because a solvent isn't necessary. However UC has discovered a nonpolar solvent which doesn't need to be removed from the trap grease therefore eliminating step 2 and in the right amounts has the potential to eliminating step 3 above. Thus creating a useful, potentially economically viable, new process to convert trap grease into biodiesel. In addition since it uses methods already existing in biodiesel facilities, our new method could be adapted easily by current biodiesel manufacturers.