Research on Methane-Rich Biogas Production Technology by Anaerobic Digestion Under Carbon Neutrality: A Review
Shiqing Qian, Luming Chen, Sunqiang Xu, Cai Zeng, Xueqi Lian, Zitong Xia, Jintuo Zou
Abstract
Amid the pressing challenge of global climate change, biogas (marsh gas) has garnered recognition as a clean and renewable energy source with significant potential to reduce greenhouse gas emissions and support sustainable energy production. Composed primarily of methane (CH4) and carbon dioxide (CO2), enhancing the CH4 content in biogas is essential for improving its quality and expanding its high-value applications. This review examines the mechanisms underlying CH4 and CO2 production in anaerobic digestion (AD) processes; investigates the effects of raw material types, process routes, and fermentation conditions on biogas production and CH4 content; and proposes feasible technical pathways for producing CH4-rich biogas. Research indicates that CH4-rich biogas can be produced through various strategies. Raw material pretreatment technologies and co-digestion strategies can enhance substrate performance, stabilize the AD process, and boost CH4 production. Process optimizations, such as multiphase AD and CH4 co-production techniques, significantly improve carbon utilization efficiency. Introducing exogenous reinforcement materials, including biochar and zero-valent iron nanoparticles, fosters microbial interactions and facilitates direct interspecies electron transfer (DIET). Furthermore, microbial regulation through genetic engineering and microbial community design presents promising prospects. By reviewing the mechanisms of gas production, influencing factors, and feasible pathways, this work aims to provide valuable insights for the technical research of AD to produce CH4-rich biogas.