Catalytic Hydrothermal Liquefaction of Solid Food Waste for Light Bio-oil Production: Process Optimisation

Feedstocks availability has posed a big question on sustainability of biodiesel, bioethanol and biogas production. FWs (food wastes) are emerging sustainable renewable energy feedstocks, especially with the bio-refinery concept and other emerging technologies like pyrolysis and HTL (hydrothermal liquefaction). In this research work, process optimisation for the production of light bio-oil from solid restaurant waste is been reported. Solid restaurant waste was thermally liquefied using hot water under highpressure condition. Effects of heating temperature (150°C, 200°C and 250°C), biomass to solvent ratios (1:5, 1:10 and 1:15) as well as catalyst loading (5 wt%, 7.5 wt% and 10 wt%) are investigated. From the results as expected, increasing reaction temperature improved the production of light bio-oil and its fuel quality as well, with an optimum reaction temperature of 225°C. In contrast, increasing biomass to solvent ratiofrom 1:10 to 1:15 did not increase the oil yield. As such, the optimum biomass to solvent ratio was 1:10. Similarly, catalyst concentration of 5 wt% (weight of slurry) gives the best oil production. It could be concluded that HTL of solid restaurant waste into light bio-oil is a sustainable renewable energy source.