A critical review of food waste and poultry manure anaerobic co-digestion: an eco-friendly valorization for sustainable waste management and biogas production

Anaerobic co-digestion (AcoD) has emerged as an effective technology for treating poultry manure (PM) and food waste (FW), converting these organic materials into valuable biogas and bio-fertilizers. The management of PM and FW has become increasingly critical due to environmental challenges associated with their disposal, which often leads to pollution and greenhouse gas (GHG) emissions. By employing AcoD, both PM and FW can be processed simultaneously, optimizing resource utilization and enhancing waste management (WM) strategies. This strategy relies on the use of sustainable waste-to-energy technology (WET) that harnesses agricultural biomass as a clean, renewable, and carbon-neutral energy source. The advantages of AcoD over traditional anaerobic digestion (AD) include improved biogas yields, better nutrient balance, and enhanced microbial stability due to the diverse substrate mix. Co-digesting animal-based wastes, such as PM, with plant-based wastes like FW enables more efficient degradation of organic matter, leading to increased methane production. Various studies have demonstrated the successful co-digestion of PW with various types of FW, resulting in significant increases in methane yields, as a potent renewable energy source. This review critically highlights the characteristics and benefits of AcoD, focusing on the synergistic effects that various FW substrates have when paired with PM. Essential process parameters influencing microbial activity, such as pH, organic loading rate (OLR), temperature, carbon-to-nitrogen (C/N) ratio, and hydraulic retention time, are discussed for optimizing biogas production (BGP). The findings underscore the greenness of AcoD as an eco-friendly approach, reducing dependency on fossil fuels, and mitigating environmental pollution, thereby contributing to sustainable WM practices and BGP.