Enhanced isolation of lipids from microalgal biomass with high water content for biodiesel production.

• Three-phase portioning process (TPP) was used in lipid extraction from microalgae biomass. • Three-phase portioning process could extract lipid from high water content and non-broken microalgae biomass. • Various parameters were studied to improve TPP performance. • Ethyl acetate/DKP ratio, and temperature, incubation time were crucial for efficient extraction. • TPP was found to extract around 15.9% of total lipid transformable to methyl esters. In present study, lipids were extracted from unbroken microalga Chlorella vulgaris with high water content (50% microalgal solution) through three-phase partitioning (TPP). The method was found to extract around 15.9% of total lipid transformable to methyl esters (LTMEs) from unbroken microalgal cells which is two times of Bligh and Dyer method. We investigated the effects of various parameters on TPP performance and were optimised through response surface methodology. The results indicated that incubation duration, temperature and extraction time were positively correlated with LTME extraction efficiency. The optimum temperature was 60 °C, incubation duration was 120 min, extraction time was 60 min, ratio of solvent to DKP was 1:1. The FAME yield was calculated as 12.05% and major fatty acids together accounted for 71.33% which indicated the great potential of the proposed lipid extraction procedure for microalga-based biodiesel production. [ABSTRACT FROM AUTHOR]