Approximately, 1.3 billion tons of food produced for human consumption is wasted globally per year. 1A common practice is disposing of food waste in landfill, which consequently leads to decomposition of organic matter, emission of greenhouse gases and ground water contamination. Food waste has high moisture content with low energy density. Hydrothermal treatment, as a way to valorize food waste, uses water as a reaction medium to convert wet biomass into energy-dense biocrude by taking advantage of its properties at sub and super critical conditions. Previous studies on HTL of food waste typically used temperatures between 200 °C and 350 °C and pressures high enough to keep water in liquid phase.2,3 We subjected a simulated food waste mixture to hydrothermal liquefaction (HTL) and reported yields and molecular composition of the products over a broad range of reaction conditions including vapor phase, liquid phase and supercritical fluid phase. When examining different pressures at 350 °C, the highest bio-crude yield (36 wt %) was observed at the saturation pressure of 16.5 MPa. At a fixed pressure of 35 MPa, the biocrude yield increased with temperature from 200 °C and decreased gradually beyond the critical temperature (374 °C). Water-soluble products, gases and solid residues were the additional products. The aqueous phase product yields were as high as 19 wt % at 200 °C and decreased with increasing temperature. In addition, no loading effect has been observed on product yields. However, holding time is an important factor. At 300 °C and the saturation pressure of 8.6 MPa, the highest biocrude yield (35 wt %) was observed at a holding time of 18 minutes. The results of this study clarify the effect of reaction conditions (time, temperature, wt % loading, pressure, phase of water) on HTL of food waste and can facilitate the future studies.

Effect of reaction conditions on hydrothermal treatment of food waste

2019 Fall National Meeting

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