Pretreatment of eliminating FFA is needed to make biodiesel from animal fat recovered from leather wastes because its acid value is high. This study was carried out to investigate the influence of 4 different pretreatment methods, which are heterogeneous catalyst method, ion exchange resin method, low pressure.high temperature method, and alkali method on the eliminating FFA and fatty acid composition. The results showed that the rate of eliminating FFA increased in the order of alkali method > catalyst method > low pressure high temperature method > ion exchange method. In the case of pretreatment of alkali method using NaOH, the rate of eliminating FFA appeared more than 86% regardless of acid value. Therefore, it was considered that alkali method using NaOH was the most effective in the view of economical and productive aspects, taking it into account that the acid value of animal fat recovered from fleshing scrap generated during leather making processes was 7 to 8.

Flesh wasters from tannery create major environmental problems. Despite their considerable fat content, these waster do not find important usage. Their disposal is also troublesome and costly. We have investigated the possible use of this fat as the production of biodiesel(fatty acid methyl esters) by transesterification using with fossil fuels. The fat released the waste by boiling water under the optimal condition (i.e., temperature, 120℃; decompression, 200mbar) and used to dry without refining for the production of fatty acid methyl esters. Under the optimal condition, the experimental value of biodiesel yield was about 96%. The result of the chemical and GC analysis showed fatty acid composition and characteristics of biodiesel. Evaluation of the product indicated that it was suitable for use as a biodiesel fuel. In result of this experiment oil extract from fleshing process can be transformed into an environmentally affination fuel, to provide economical and ecological profits.