# A Perspective on Emerging Inter-Disciplinary Solutions for the Sustainable Management of Food Waste
## 4 Food Waste Management, Regulations, and Biological Treatment Technologies
[102] emphasized the need to adopt long-term technical innovations, such as using new technologies to quantify waste, its characteristics, and its uses to address the sustainability challenges. In light of the world's growing energy and waste management demands, it is indisputable that anaerobic digestion has emerged as one of the most environmentally friendly and viable approaches for managing food and generating energy [103]. Compared to many other processes, anaerobic treatment of food waste is a better option. While [PERSON] et al. [104] provide a more in-depth discussion of the anaerobic digestion process, we have included a summary of the critical biochemical and microbial activities herein. Figure 3 depicts the multistage process of anaerobic digestion, which includes the sequential steps of hydrolysis, acidogenesis, acetogenesis, and methanogenesis in the breakdown of biodegradable material to produce biogas [105]. Indeed, the anaerobic digestion technology has enormous potential for treating solid organic waste, slurries, sludge, industrial wastewater, and sewage [106]. Hydrolysis is generally the rate-determining step in anaerobic digestion processes [107], since it is required to break down complex solid chemical bonds that are often responsible for resistance to degradation, notably of lignin. Amylases, cellulases, xylanases, lipases, and proteases are all examples of hydrolytic enzymes that may be found in microbes, protozoa, and fungi proliferating in anaerobic digestion systems [108,109]. Cellulolytic and xylanolytic microorganisms generate xylanases that degrade complex cellulose and xylan into glucose and xylose. In contrast, proteolytic bacteria produce extracellular proteases that break down peptide bonds of proteins or polypeptide chains. Additionally, lipolytic bacteria secrete lipases, which break down lipids (fats and oils) into valuable products like long-chain fatty acids and glycerol [110]. In the acidogenesis phase of anaerobic digestion, hydrogen, alcohol, carbon dioxide, and acids, including isobutyric, propionic, and lactic acid, are produced by oxidizing carbohydrates and organic  
Figure 3: An overview of the major biochemical and microbiological reactions that occur throughout the anaerobic digestion process. molecules produced during hydrolysis [111]. On the other hand, acetogenesis is the process by which acetogenic bacteria and obligatory hydrogen-producing bacteria convert acidogenesis products into acetate and hydrogen gas [110; 112; 113]. Thereafter, acetogenic bacteria convert volatile fatty acids and alcohol into hydrogen, carbon dioxide, and acetate, while homoacetogenic bacteria convert carbon dioxide and hydrogen into acetate [114]. Moreover, propionate decomposers, butyrate decomposers, and acid formers also play a significant role in anaerobic digestion processes [110]. Methanogenesis is the final step in the anaerobic digestion process. This stage occurs when acetic acid is converted to methane gas [115]. Methanogenesis can take place via two primary pathways: the hydrogenotrophic pathway, in which hydrogen and carbon dioxide gasses are converted into methane; and the acetotrophic pathway, in which acetate is eventually converted to biogas (methane) [116; 117; 118]. The methane generated by either method can be used in combined heat and power generators [119]. In light of diminishing fossil fuel reserves and ever-increasing oil prices, food waste provides a remarkable opportunity to tap into a vast renewable energy resource and reservoir of valuable compounds. Positive indicators for the future of sustainable development include the possibility of increased use of biofuels to decrease greenhouse gas emissions, ameliorate climate change, enhance waste management, and boost the utilization of renewable resources using environmentally acceptable techniques [120; 121]. There are several techniques for optimizing biogas output through anaerobic digestion, but each approach has a distinct mode of application and generates various amounts of biogas in the form of methane [122].