Enhanced Lipid Extraction from Microalgae Chlorella vulgaris Biomass: Experiments, Modelling, Optimization

Microalgae are a promising raw material source for the production of lipids. However, the existing technologies of lipid extraction from microalgae would benefit from their improvement. The objective of the present study was to determine optimal conditions for lipid extraction from Chlorella vulgaris (C. vulgaris) microalgae biomass. As a result of the conducted research, a method of cell walls disruption has been selected, and types and ratio of polar and non- polar solvents at the extraction stage have been experimentally identified. Also, the influence of extraction process conditions (temperature, type, and amount of extraction solvents added per unit of biomass) on the degree of lipid extraction from C. vulgaris IFR..- 111 microalgae biomass has been determined. The efficiency of microalgae cell walls disruption has been compared for the following disruption methods: microwave radiation, ` osmotic shock', ferromagnetic vortex layer treatment, enzyme solution treatment, and antibiotics treatment. A comparative analysis of the extraction solvents used for the extraction of lipids allowed to conclude that the use of a mixture of polar and non- polar extraction solvents almost quadruples the recovery of lipids (3.95 times as high) as compared to the extraction with non- polar solvent only. The optimum ratio of solvents of ethanol - petroleum ether 2:1 (vol.), and the temperature of 47 divided by 50 degrees C provides the maximum degree of lipid recovery - 28 %. A mathematical model of the lipid extraction process has been developed and optimal conditions for the extraction have been determined.