Management and valorization of digestate from food waste via hydrothermal

Hydrothermal treatments (HTT) at moderate temperatures (120-200 degrees C) were investigated in this study for the management and valorization of food waste digestate (DFW). The dehydration was the main reaction in HTT at a temperature lower than 180 degrees C. After HTT, the hydrophobicity and dewaterability of DFW were improved significantly, which resulted in a 69% and 37% reduction in the digestate cake volume and solid residue mass, respectively. During HTT, the organic matter and carbon were mostly solubilized from solid to liquid, while the multivalent metals were concentrated in the solid residue. The more stable characteristics of the digestate cake after HIT eliminated its environmental risk. The accumulation of organic carbon and a reasonable ammonia nitrogen concentration in the HTT liquid increased the biochemical methane potential from 147 to 245 mL CH4/g TCOD, which demonstrated the feasibility of recovering energy from the HTT liquid.

Automated summary

The study found that hydrothermal treatments can significantly improve the properties of food waste digestate, effectively reducing the amount of solid residue after treatment. Through hydrothermal treatment, organic matter and carbon dissolve into the liquid, while multivalent metals concentrate in the solid residue, making the digestate more stable.