Investigation of high pressure steaming (HPS) as a thermal treatment for lipid extraction from Chlorella vulgaris

Biofuels from algae are considered a technically viable energy source that overcomes several of the problems present in previous generations of biofuels. In this research high pressure steaming (HPS) was studied as a hydrothermal pre-treatment for extraction of lipids from Chlorella vulgaris, and analysis by response surface methodology allowed finding operational points in terms of target temperature and algae concentration for high lipid and glucose yields. Within the range covered by these experiments the best conditions for high bio-crude yield are temperatures higher than 174 °C and low biomass concentrations (<5 g/L). For high glucose yield there are two suitable operational ranges, either low temperatures (<105 °C) and low biomass concentrations (<4 g/L); or low temperatures (<105 °C) and high biomass concentrations (<110 g/L). High pressure steaming is a good hydrothermal treatment for lipid recovery and does not significantly change the fatty acids profile for the range of temperatures studied.