Options for Enhanced Anaerobic Digestion of Waste and Biomass—a Review

Introduction: Anaerobic digestion (AD) is a promising technology because it is economically feasible, environmentally friendly, and socially acceptable. Moreover, biogas generation from organic waste is considered to be the future of bio-energy. Purpose: In this paper, we review the substrates available for biogas production, different methods for improvement of AD processes (two-stage anaerobic digestion and digestate recirculation) and various pre-treatment techniques used to enhance biogas generation. Method: Two-stage digestion and co-digestion of two or more substrates appear to be promising techniques for enhanced anaerobic digestion. These techniques could help to maintain the nutrient balance in a system without the further addition of nutrients, in addition to enhancing biogas generation. Results: Pre-treatment of various substrates is mainly used to increase the hydrolysis rate and thus enhance the efficiency of AD processes. © 2020, The Korean Society for Agricultural Machinery.