Improved energy recovery from food waste through hydrothermal carbonization and anaerobic digestion

• DOI: 10.1016/j.wasman.2022.02.003
• Publication Date: 2022-02-11T12:15:17Z
• Authors: Gemma Mannarino; Andres Sarrion; Elena Diaz; Riccardo Gori; M. Angeles De la ...; Angel F. Mohedano
• Keywords: Hydrothermal Carbonization; Food Waste; Heat of combustion; Biogas; Energy Recovery; Digestion

Here we studied energy valorization of food waste by hydrothermal carbonization coupled with anaerobic digestion. Hydrothermal treatment was carried out at 200 °C and 230 °C for 1 h, obtaining hydrochar with properties suitable for solid biofuel according to ISO/TS 17225-8. The increase in temperature improved the fuel properties of hydrochar (higher heating value 20.3 and 23.7 MJ kg-1, fuel ratio 0.33 and 0.37, energy density 1.07 and 1.25). The anaerobic digestion of process water achieved methane yields around 150 mL CH4 STP g-1 CODadded and made it possible to remove some specific recalcitrant compounds, such as 2-methylpyridine and 2-ethyl-3-methylpyrazine. Energy recovery from hydrochar and process water seems to be an interesting alternative way to sustain the process energetically and economically, despite the significant energy inputs required for hydrothermal carbonization.