Production of biodiesel from freshwater microalgae and evaluation of fuel properties based on fatty acid methyl ester profile

Eleven freshwater microalgal strains of Chlorella sorokiniana BTA4015; Chlorella sp. BTA4032, C. variabilis BTA4036; Chlorella sp. BTA4071; C. variabilis BTA4109; C. variabilis BTA4121; Chlorella sp. BTA4146; Chlamydomonas asymmetrica BTA4028; C. asymmetrica BTA4154; Scenedesmus armatus BTA4076 and Scenedesmus regularis BTA4112 were isolated from northeast India and identified through internal transcribed spacer 2 region sequence alignment. Algal strains cultured in 20 L carboys in outdoor condition in tap water enriched with NPK showed doubling time ranged between 1.5-6.8 d, lipid content (4.5 - 9.1% dry wt), biomass productivity (6 -26 mg L (1) d (1)) and lipid productivity (0.31 - 1.99 mg L (1) d (1)). The biodiesel properties of iodine value, saponification value, cetane number, high heating value, oxidation stability, allylic and bis-allylic position equivalent, kinematic viscosity, cold filter plugging point, cloud point, pour point and C18: 3 were calculated from fatty acid profile. Equally weighted parameters for biodiesel component using Preference Ranking Organization Method for Enrichment Evaluation and Graphical Analysis for Interactive Assistance analysis ranked Chlorella variabilis BTA4109 & BTA4036, C. sorokiniana BTA4015 the most suitable strains meeting the EN14214 biodiesel standard. The biomass productivity for the three strains recorded 20.83, 26.04 and 6.83 mg L (1) d (1) whereas the lipid productivity recorded 0.95, 1.89 and 0.32 mg L (1) d (1) respectively.