(25f) Catalytic Hydrothermal Liquefaction of Food Waste: Improving Product Properties and Increasing Process Economic Viability

Hydrothermal liquefaction (HTL) is a promising thermochemical conversion technology for biomass valorization and bio-crude oil production. Moving this technology towards commercialization still faces several challenges. Enhancing the economic feasibility and sustainability of the HTL process requires improvement of the bio-crude oil properties and effective valorization of the HTL co-products (aqueous phase and char) for fuels, nutrients and materials.

This study investigated the HTL of food waste using red mud as a catalyst with the goals of increasing the bio-crude oil yield and improving the physicochemical properties of the bio-crude oil and the HTL-char. HTL of food waste (15 wt.% solids loading) and red mud (5 wt.%) was conducted using a 100 ml batch reactor at 240-290 °C with 0-60 min reaction times.

Preliminary results showed that bio-crude yield from HTL at 240 °C and 30 min increased from 27.8 wt.% to 35 wt.% when red mud was added; the bio-crude oil higher heating value showed a slight increase from 36.1 to 37.5 MJ/kg. Bio-crude oil characterization revealed similar families of molecules with and without the presence of the catalyst.

Food waste HTL-char and catalytic HTL-char were tested adsorbents for the removal of lead, copper, and nitrate from wastewater. Batch experiments were used to study the effects of char modification, initial wastewater pH, adsorption contact time, and initial metal concentration on adsorption performance. Surface characterization of HTL-chars using X-ray diffraction (XRD), Fourier transform infrared (FTIR), and N₂ gas adsorption analysis indicated the red mud particles were successfully introduced into the HTL-char during HTL.