ABSTRACT
Anaerobic digestion is an age old process in which organic matter is microbially converted to methane under anoxic conditions. It consists of four main stages: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Usually, it involves syntrophic association of various groups of microorganisms such as fermentative bacteria, acetate oxidizing bacteria, and methanogenic archaea, which together lead to biogas (CO2 + methane) generation. Almost any kind of organic waste (solid or liquid) or residues can be used in the anaerobic digestion process. In addition, simple reactor configurations and process conditions are used, which make the process attractive. A typical biomethanation plant mainly consists of a digester in which anaerobic digestion occurs and a gas holder that is used to collect the biogas. Compared to fossil fuels, biogas releases less CO2 per unit energy. Owing to the several benefits, various forms of anaerobic digesters are being operated successfully throughout the world. However, in spite of these advantages, large scale biomethanation processes are not economically viable due to huge capital investments and the refining processes. This chapter provides a brief overview about the basic concepts of the biomethanation process and presents the readers with the perspective ideas to address the challenges of large-scale biogas production.
