(741a) Co-Hydrothermal Liquefaction of Guayule Bagasse and Wastewater Treatment Microalgae

Guayule is a desert shrub native to the southwestern US that is a source of natural rubber. After solvent extraction of hard rubber for tires and resin, approximately 70 wt.% of the guayule biomass, the bagasse, remains as a dry, woody material as a potential biofuels feedstock. Galdieria sulphuraria is an extremophile algae species capable of thriving in warm-hot and acidic conditions. Used as an effective treatment method to remove excess nutrients and BOD from municipal wastewater, G. sulphuraria culture produces a wet, low-lipid, protein-rich material. Here, co-hydrothermal liquefaction (co-HTL) of guayule bagasse and G. sulphuraria biomass was conducted under varying operating conditions (310-350 °C) and biomass ratios (all bagasse, all algae, and 1/3:2/3 combinations). The synergetic effect of carbon-rich lignocellulosic fibers in guayule bagasse and less recalcitrant proteins from G. sulphuraria were studied in terms of yields and chemistry of bio-crude oil, aqueous phase and char. HTL product distribution mass and energy balances were characterized by bomb calorimetry, elemental analysis, thermogravimetric analysis, and analysis of total organic carbon and total nitrogen. The project is intended to evaluate the spatial integration of an HTL conversion facility with guayule cultivation and municipal wastewater treatment to provide rubber, resin, clean water, bio-crude oil and char, and heat for improving the economic feasibility of the biorefinery.