Effect of operating conditions on yield and quality of biocrude during hydrothermal liquefaction of halophytic microalga Tetraselmis sp.

The biomass of halophytic microalga Tetraselmis sp. with 16% w/w solids was converted into biocrude by a hydrothermal liquefaction (HTL) process in a batch reactor at different temperatures (310, 330, 350 and 370 °C) and reaction times (5, 15, 30, 45 and 60 min). The biocrude yield, elemental composition, energy density and severity parameter obtained at various reaction conditions were used to predict the optimum condition for maximum recovery of biocrude with improved quality. This study clearly indicated that the operating condition for obtaining maximum biocrude yield and ideal quality biocrude for refining were different. A maximum biocrude yield of ∼65 wt% ash free dry weight (AFDW) was obtained at 350 °C and 5 min, with a severity parameter and energy density of 5.21 and ∼35 MJ/kg, respectively. The treatment with 45 min reaction time recorded ∼62 wt% (AFDW) yield of biocrude with and energy density of ∼39 MJ/kg and higher severity parameter of 7.53.