Hydrothermal carbonization of simulated food waste for recovery of fatty acids and nutrients

We conducted Hydrothermal carbonization (HTC) of simulated food waste under different reaction conditions (180 to 220 degrees C, 15 and 30 min), with the aim of recovering both fatty acids from the hydrochar and nutrients from the aqueous-phase products. HTC of the simulated food waste produced hydrochar that retained up to 78% of the original fatty acids. These retained fatty acids were extracted from the hydrochar using ethanol, a foodgrade solvent, and gave a net recovery of fatty acid of similar to 50%. The HTC process partitioned more than 50 wt % of the phosphorus and around 38 wt% of the nitrogen into the aqueous-phase products. A reaction path consistent with decarboxylation predominated during HTC under all of the reaction conditions investigated. A path consistent with dehydration was also observed, but only for the more severe reaction conditions. This work illustrates the potential that HTC has for valorization of food waste.

Automated summary

In the hydrothermal carbonization experiment, fatty acids can be extracted with ethanol and phosphorus and nitrogen can be partitioned into the aqueous phase products. A reaction path consistent with decarboxylation predominated under all reaction conditions, while a dehydration path was observed for more severe conditions. This work illustrates the potential of hydrothermal carbonization for valorizing food waste.