Anaerobic digestion (AD) is a biological process that happens naturally when bacteria breaks down organic matter in environments with little or no oxygen. It is effectively a controlled and enclosed version of the anaerobic breakdown of organic waste in landfills which release methane. In this book, the authors present current research in the study of the processes, products and application of anaerobic activity. Topics discussed include the anaerobic treatment of wastewater; a scientific review of the agronomic, environmental and social benefits of anaerobic digestion and the microbial aspects of anaerobic digestion for biogas production.