Research Progress in CO

Carbon dioxide (CO2) levels have significantly increased since the onset of industrialization, driving climate change and highlighting the urgent need for emission reduction strategies. Among various CO2 capture and utilization technologies, CO2 bio-methanation emerges as a promising biological approach for converting CO2 into CH4. This technology offers advantages such as mild operating conditions and environmental sustainability. However, its large-scale industrial application is currently impeded by low process efficiency and high costs. While the low gas-liquid mass transfer rate is a recognized abiotic limitation, biotic factors are equally important yet often overlooked. This review summarizes the current state of CO2 bio-methanation technology, detailing its biological processes from both organic and inorganic sources. It provides a focused analysis of key biotic limiting factors, including the species, activity, quantity, and metabolic pathways (such as hydrogenotrophic methanogenesis and the Wood-Ljungdahl pathway) of vital microbial consortia involving methanogenic archaea, homoacetogens, and syntrophic acetate-oxidizing bacteria. Furthermore, the paper discusses existing enhancement strategies, such as zero-valent iron (ZVI), microbial electrolysis cells (MECs), and conductive materials. Finally, it explores the potential application of this technology in achieving agricultural carbon neutrality and suggests that future research should leverage genetic and metabolic engineering to optimize microbial performance, thereby facilitating the efficient and scalable production of biomethane from CO2.