Recent Advances in Hydrothermal Carbonization of Food Waste Derived Bioproducts: Valorization Approaches, Applications, and the Prospective Assessment

One of the world's most serious environmental issues is caused by food waste and its losses generated in every stage of the food supply chain. Food waste is an important concern for human well-being and the ecosystem, as well as the hidden opportunity for value-added product conversion. Various parameters of food supply chains and waste management systems contribute to the social, environmental, and economic aspects. Thus, valorization and utilization of food waste is an emerging field focused on converting waste to valuable products such as biofuels, platform chemicals, energy, and carbon materials. As reported in previous studies, food waste is a potential source of valuable bioactive molecules and bioenergy. Earlier studies indicate that the advanced valorization processes of food waste are not applied in developing countries, leading to underutilization of food waste in these regions due to limited research initiatives. This comprehensive review examines several vital and advanced options for the sustainable valorization of food waste, emphasizing its prospects and challenges. Given the inevitable waste generated during handling, transportation, and food processing, the sustainable valorization of food waste is a promising option for the achievement of the United Nations Sustainable Development Goals. This review aims to promote the adoption of sustainable technologies to convert waste into wealth of valuable products through biorefinery approaches and integrated valorization approaches, leading to the efficient recycling of global food waste. Herein, biorefinery approaches especially focusing on advanced hydrothermal carbonization (HTC) and potential applications of bioproducts derived from food waste have been investigated succinctly. Other conventional valorization approaches such as incineration, landfilling, etc. are described briefly. Additionally, the general comparison and in-depth discussion regarding the sustainability and feasibility of food waste valorization techniques and their technological, economic, and environmental assessments from state-of-the-art perspectives have been discussed. Food waste derived from HTC process has great potential to produce biobased carbon materials for environmental and energy applications. This can significantly contribute to reducing environmental pollution and addressing the shortage of energy crisis. Finally, knowledge gaps and potential risks in the synthesis of bioproducts especially focusing on hydrochar derived from food waste are pointed out, with highlights of the challenges and prospects of this study.