Energy recovery from food waste and garden and park waste: Anaerobic co-digestion versus hydrothermal treatment and anaerobic co-digestion

The feasibilities of the anaerobic co-digestion of two of the most relevant biowastes, food waste and garden and park waste, were evaluated and compared with the hydrothermal treatment of each waste and the anaerobic co digestion of raw biowastes with the process water generated. The effects on the process stability and energy recovery were also analyzed. Anaerobic digestion was the best option for food waste treatment from an energetic point of view, with 81% recovery of the energy stored in the feedstock, while the highest energy recovery from garden and park waste was obtained for the solid fraction generated from hydrothermal treatment (85.5%). In addition, the anaerobic co-digestion of food waste with 5% of the process water generated from garden and park waste showed a similar energy recovery to that of food waste only (~80%), thus improving the biological stability of the process.

Automated summary

This study evaluated the anaerobic co-digestion of food waste and garden and park waste, as well as the hydrothermal treatment of each waste and the anaerobic co-digestion of raw biowastes with process water. The results showed that anaerobic digestion was the best option for energy recovery from food waste, while the solid fraction generated from hydrothermal treatment had the highest energy recovery for garden and park waste. Additionally, the anaerobic co-digestion of food waste with process water improved process stability and achieved similar energy recovery to food waste alone.