A Review of the Impact of Co-Digestion Substrates on the Methane Yield

This review highlights the impact of anaerobic co-digestion (ACD) on improving energy recovery from biogas production systems. Various factors from selected papers were reviewed to figure out their influence on ACD performance. Such factors include Carbon/Nitrogen (C/N) ratio, biodegradability of feedstock, microbial diversity, activity, buffering capacity, and trace element concentrations. Findings show ACD significantly enhances process stability and increases methane yield by 20% to 65% compared to mono-digestion. The process shares more insights on mechanisms for addressing environmental pollution challenges as it offers alternative approaches for reducing greenhouse gas emissions. Despite promising achievements in ACD systems, several limitations of the process still exist, requiring the attention of future studies to explore the full potential of technology. Specific areas include optimizing the mixing ratio of substrates to prevent acidification and ammonia toxicity risks that may occur during the process, hence affecting the system efficiency. Research should focus on process design and proper feedstock selection, considering innovative approaches such as bioaugmentation, supplementation with carbon compounds and nanoparticles, to improve microbial activity, process efficiency, and stability. Also, there is a need to develop predictive models that will accurately incorporate C/N ratio effects on digestion kinetics and nutrient transformation. Current models are complex, which hinders their scalability; thus, the use of machine learning could enhance model accuracy.