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Abstract

. Hydrothermal liquefaction (HTL) is a thermochemical process that uses subcritical water (270-350°C and 8-18 MPa) both as a solvent and a reaction medium to convert organic biomass constituents into energy-rich bio-crude oil. HTL is most suitable for conversion of wet feedstocks including algae. In this study, we compare the oil yields and energy recoveries from the HTL of a filamentous algae polyculture grown on freshwater dairy effluent as part of a pilot-scale Algal Turf Scrubber® system at Eastern New Mexico University. Batch HTL conversion experiments were carried out in a 1.8 L autoclave reactor at reaction temperatures and retention times of 310 and 350°C, and 30 and 60 minutes, respectively. Algae and reaction conditions were compared based on product yields and the higher heating values (HHV) of the bio-crude oils. The light bio-crude oil (LBO) yield ranged from 11-15 wt. %, heavy bio-crude oil (HBO) yield and char yield were ranged from 5-6 wt. % and 13-20 wt. % respectively. Due to the algae‘s high ash content, the biomass was pretreated with several organic and inorganic acids to lower ash content prior to HTL to improve bio-crude oil yields. Future work will focus on bio-crude oil and char characterization and applications, and the evaluation of the dairy effluent wastewater treatment and renewable energy production combined process.