Rheological, Thermal, and Physicochemical Characterization of Animal Fat Wastes for use in Biodiesel Production

The rheological, thermal and physicochemical properties of animal fat wastes (tallow, lard, choice white grease, and yellow grease) are important parameters for an efficient design of equipment and to optimize the processing procedures of biodiesel production. In this study, the physicochemical properties of animal fat waste samples and the correlation of these properties to their thermal and rheological behaviors were elucidated. Pure lard was equally investigated to monitor the effects of impurities on the rheological and thermal properties of the animal fat wastes. It was established that the presence of impurities had effects on the rheological and thermal properties of fats. Additionally, due to the high level of free fatty acid (FFA) present in the wastes, transesterification cannot be applied directly. It will be necessary to reduce the FFA level by using acid pretreatment or enzyme catalyzed transesterification.