Abstract

Tanneries generate a large amount of solid wastes. Lime fleshings, one of those solid wastes, are a very important fat source although normally they are not used and are disposed off representing a high cost for tanners. A process to recover fat from such fleshings was developed, introducing a new value-adding route through the use of fat for biodiesel production. Biodiesel obtained from this fat material was characterized by parameters according to EN 14214 standard, showing good accordance in almost all of the evaluated specifications. However, we still needed to adjust the process in order to improve parameters, like moisture and ester content, that are close to the limits. An economic evaluation of the fat recovery and usage as raw material for biodiesel production was done, showing an economic potential when compared to vegetable oils. It was demonstrated that a fat selling price of 350 €/ton, with some margin for reduction, is possible. This price is better than the normal price of vegetable oils, which lies between 500 and 700 €/ton.