FAME and bio-oil properties and carbon yield coefficients of Chlorella sorokiniana cultivated heterotrophically with industrial effluents

The fatty acid (FA) distribution of bi-oil derived from Chlorella sorokiniana and FAME basic prop-erties were examined. C. sorokiniana was cultivated heterotrophically in two very different growth media: a) glycerol and inorganic salts (GLIN) and b) glycerol and anaerobic digestate (GLAD), as well as in two different modes: a) semi-batch (GLIN) and b) batch (GLAD). The culti-vation took place in 42 L bioreactors and from the biomass collected the bio-oil was extracted, converted to the corresponding fatty acid methyl esters (FAME) and subsequently their distribu-tion was determined in a gas chromatograph. The protein and lipid content were also determined and were used for the estimation of the carbon yield coefficients, which are equal to 0.13 and 0.25 for the GLIN and GLAD treatments respectively. The fatty acid distribution covered chain lengths from C10 to C26. The great proportion of the FA were of medium chain FA C16-C18 con-stituting about 85% and 53% of the total fatty acids of the GLIN and GLAD treatments respec-tively. Also, the distribution of saturated, monounsaturated and polyunsaturated FA differed. The basic properties of the biodiesel such as the density, the kinematic viscosity, the acid value, the cetane number, the iodine value and the heating value are within acceptable ranges and differ-ences in the properties of the two treatments are due to differences in FA distribution.

Automated summary

This study examined the distribution of fatty acids in bi-oil derived from Chlorella sorokiniana and analyzed its basic properties. The results showed that the medium chain fatty acids C16-C18 were the predominant components in the bi-oil. The properties of the biodiesel were within acceptable ranges and varied due to differences in fatty acid distribution.