Hydrothermal carbonization of food waste for sustainable biofuel production: Advancements, challenges, and future prospects

With the improvement of living standards, food waste (FW) has become one of the most important organic solid wastes worldwide. Owing to the high moisture content of FW, hydrothermal carbonization (HTC) technology that can directly utilize the moisture in FW as the reaction medium, is widely used. Under mild reaction conditions and short treatment cycle, this technology can effectively and stably convert high-moisture FW into environmentally friendly hydrochar fuel. In view of the importance of this topic, this study comprehensively reviews the research progress of HTC of FW for biofuel synthesis, and critically summarizes the process parameters, carbonization mechanism, and clean applica-tions. Physicochemical properties and micromorphological evolution of hydrochar, hydrothermal chemical reactions of each model component, and potential risks of hydrochar as a fuel are highlighted. Furthermore, carbonization mechanism of the HTC treatment process of FW and the granulation mechanism of hydrochar are systematically re-viewed. Finally, potential risks and knowledge gaps in the synthesis of hydrochar from FW are presented and new cou-pling technologies are pointed out, highlighting the challenges and prospects of this study.

Automated summary

With the improvement of living standards, food waste has become a significant organic solid waste globally. Hydrothermal carbonization (HTC) technology, which can directly use the moisture in food waste as the reaction medium, is widely used to convert high-moisture food waste into environmentally friendly hydrochar fuel. This study comprehensively reviews the research progress of HTC of food waste for biofuel synthesis and summarizes the process parameters, carbonization mechanism, and clean applications.