Co-hydrothermal carbonization of food waste-woody sawdust blend: Interaction effects on the hydrochar properties and nutrients characteristics

The influence of co-hydrothermal carbonization (co-HTC) on the hydrochar properties and nutrients distribution derived from food waste (FW) and woody sawdust (WS) blend was assessed. The carbon retention, surface functional groups and morphology features involved in hydrochar were evaluated to study the interaction effects. Results suggested that hydrochar yield consistently decreased with increase of both FW ratio and HTC temperature. C retention from 260 °C hydrochar was low (approximately 65%), but more microsphere structures was formed due to the enhanced carbonization degree of hydrochar. Hydrochar obtained at high FW blend ratio and temperature resulted in weaken oxygen-containing groups like OH and CO with enhanced CC and C(O, N). 10.43-60.45% of N and 82-94% of P were retained in hydrochar. NH4+-N (6.63%-15.63%) and organic nitrogen (70.4%-87.7%) were identified as main N-containing species in liquid phase, while total P content (14-166 mg/L) depended more on FW ratio.