Biohythane, Biogas, and Biohydrogen Production from Food Waste: Recent Advancements, Technical Bottlenecks, and Prospects

Abstract

Food waste (FW) is a significant global issue with a carbon footprint of 3.3 billion tonnes (Bt), primarily generated due to improper food supply chain management, storage issues, and transportation problems. Acidogenic processes like dark fermentation, anaerobic digestion, and a combination of DF-AD can produce renewable biofuels (Bio-CH4, Bio-H2) by valorising FW, aligning with the UN SDGs. FW is an ideal substrate for acidogenic processes due to its high moisture content, organic matter, and biodegradability. However, the choice of FW valorisation pathways depends on energy yield, conversion efficiency, and cost effectiveness. Acidogenic processes are not economically viable for industrial scale FW treatment due to reduced energy recovery from stand-alone processes. So, this study reviews comparative studies on biogas, biohydrogen, and biohythane production from FW via acidogenic processes, focusing on energy yield, energy recovery, and environmental and economic impact to provide a clear understanding of energy recovery and yield from all acidogenic processes. Additionally, this review also explores the recent advancements in digestate slurry management and the synergistic effects of AD and HTC processes. Lastly, a futuristic integrated bio-thermo-chemical process is proposed for maximum energy recovery, valuing food waste to energy vectors (Bio-H2, Bio-CH4, and hydro-char) along with digestate management and biofertilizer production.

Keywords

• food waste
• anaerobic digestion
• dark fermentation
• energy yield
• environmental impact assessment
• circular biorefinery