Prediction of Quality Properties for Biodiesel Production by Oleaginous Yeast Cultivated in Pure and Raw Glycerol

Abstract

Biofuels such as biodiesel are a renewable and environmentally safe alternative to fossil fuels. Besides their production is growing rapidly, leading as a consequence, to large amounts of glycerol, the main co- product generated during the process. There is an increased interest in exploring alternatives for the production of lipids to produce biofuel and also to use glycerol surplus. Oleaginous microorganisms are able to accumulate 20 % or more of their biomass in lipids, mainly in the form of triacylglycerol (TAG), which can be used to produce biodiesel by transesterification process. The properties of various individual fatty esters that comprise biodiesel determine the overall fuel properties. Structural features that influence the physical and fuel properties are chain length, degree of unsaturation and branching of the chain. In this work we studied the production of lipids by Candida sp. LEB-M3 cultivated in pure and raw glycerol. Various methods for the prediction as a function of fatty acids were presented and standards used to verify the quality and applicability of this microbial oil as a raw material for biodiesel production. The fatty acid profile showed predominance of oleic acid (C18:1), 57.35 % for cultivation in pure glycerol, and linoleicacid (C18:2), 46.0 % in raw glycerol. Predicted values were (pure - raw): cetane number (56 - 53), heat of combustion (37 - 39 KJ/g), oxidative stability (8.5 - 8 h), kinematic viscosity (3.82 - 3.79 mm2/s), density (807 - 872 Kg/m3) and iodine index (74 - 115.5 gI2/100g). The results indicate that lipid produced by Candida sp. LEB-M3 using raw glycerol is a potential and appropriate source of raw material for biodiesel production according to main current standards.