ASI: Hydrothermal extraction and characterization of bio-crude oils from wet chlorella sorokiniana and dunaliella tertiolecta

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Abstract

In this research, the potential of geothermal water as an alternative water source was tested for the production of algal bio-fuels. Two algal species, Chlorella Sorokiniana and Dunaliella Tertiolecta were cultivated in a photo-bioreactor with tap water and geothermal water. The freshly harvested wet algae samples were used to produce bio-crude oil samples in a high pressure reactor under a hydrothermal liquefaction (HTL) condition (300°C, 90 bar and solid loading of 9 wt %). Supernatant water obtained after harvesting was used in the HTL experiments. A thermogravimetric analyzer was used to determine the moisture and ash content of the algal biomass. It was observed that the bio-crude oil yield could be higher than the lipid content in the algae. The GC-MS analysis of biocrude oils showed the contribution of both lipids and proteins to the yield of biocrude. The highest bio-crude oil yield of 30 wt % (of dry algae) was obtained with a Dunaliella Tertiolecta sample cultivated in a regular tap water medium. A similar amount of biocrude was achieved with a geothermal water medium. Using a calorie meter, the high heating values of bio-crude oils were measured and these values ranged from 36 to 38 MJ/kg, which are close to that of crude petroleum oils. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 910–915, 2013

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