TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method:The free fatty acids are separated from the plant and animal fatty acids, before they are combined with the fatty acids of step (b). The separation of fatty acids is carried out under vacuum with stripping steam of incoming feed stream. A degumming and filteration are used for the purification of raw materials. A combined process of bleaching, precipitating the polyethylene on clay particles with subsequent filtration is used for the removal of polyethylene from the raw materials. The hydrolytic cleavage is carried out at 10 bar using high pressure steam in pressure column and at the vapor pressure dependent temperature of the feed to be cleaved, preferably at least at 100 degrees C. The hydrolytic cleavage takes place continuously in pressure columns at an average retention time of 0.5-10 hours. The hydrolytic cleavage takes place batch wise in pressure reactors at an average retention time of 2-20 hours. The fatty acids are purified by an over head distillation under vacuum of 0.1-100 mbar using falling film evaporator, steam evaporator, flash evaporator or fractionating column. The low boiling fatty acids e.g. myristic acid and lauric acid are removed with the help of a pre-cut column. The fractionation of fatty acids is carried under vacuum of 0.1-50 mbar and at a maximum temperature of 265 degrees C. The esterification of the free fatty acids is carried out with acidic catalysts. The purification takes place by a saponification of the unreacted fatty acid in fatty acid alkyl ester with alkaline, where the purified fatty acids are treated with soap splitting acids. The purification is carried out by selective extraction with furfural. The free fatty acids and furfural are separated from corresponding phase by distillation and is led back for esterification. The resulting fatty acid alkyl ester is subjected to over head distillation. Preferred Components:The catalyst is a mineral acid, a Lewis acid, an enzyme or an organic cation exchanger and/or an alkyl or aryl sulfonic acid, preferably alkylbenzene sulfonic acid, e.g. dodecyl-sulfonic acid. The alkyl alcohol fatty acid ester obtained during the esterification is purified from non reacted fatty acids. The purification of fatty acids is carried out with a fractioned distillation under vacuum at 0.1-100 mbar and at the boiling temperature corresponding to the pressure. The overhead product is fatty acid alkyl ester with a purity of above 99.85% and the sump product does not react with obtained free fatty acids. EXAMPLE - No suitable example given.