Com. post-refining fatty acids, used frying oils and techn. animal fats were analyzed for d., viscosity, melting temp., acidic, sapon. and I nos. and chem. compn., then purified by dewatering with glycerol and removing solid impurities by filtration, deacidified by esterification with MeOH in presence of p-toluenosulfonic acid catalyst and addn. by treatment with KOH in glycerol, and finally, transesterified with MeOH to fatty acid Me esters. Properties of the Me esters met the std. requirements for biofuels except for content of solid impurities, acidic no., and viscosity in some cases.