Bio-oil production from residual biomass of microalgae after lipid extraction: The case of Dunaliella Sp

Microalgae are known as the potential feedstock for production of bio based fuels due to their high lipid contents. Residual microalgae biomass after conversion of lipids into biodiesel can be converted into bio-oils in order to achieve complete exploitation of microalgae biomass in a microalgae biorefinery. Hydrothermal liquefaction (HTL) is a promising way for converting high-moisture biomass waste into high-energy crude oil. Therefore, this study intended to produce bio-oil from residual biomass of microalgae Dunaliella Sp. after lipid extraction by utilizing HTL as a biorefinery concept. HTL results showed that the average bio-oil yield was 11.81 w/w%, which was obtained at 350 degrees C, a residence time of 60 min and pressure of 200 bar. The results of CHNS analysis showed that crude oil produced by the HTL process in this study contains 4.82% nitrogen, 68.53% carbon, 1% hydrogen, 21.9% sulfur, which are within the permitted ranges.