Pre-treatment and anaerobic digestion of food waste for high rate methane production – A review

Food waste with high decomposition potential can be successfully digested anaerobically for the production of biogas. As the fossil-fuel reserves decline anaerobic digestion can be a better alternative as a renewable energy source. The byproducts such as biogas with 50–60% methane content can be efficiently used for electricity production and the final digested sludge as a fertilizer. Even though anaerobic digestion is a proven technology, still there exist some technical difficulties (organic loading rate, solid retention time, biogas composition, specific gas production) and scientific understandings (carbon to nitrogen ratio, volatile fatty acids production, pH variation, nutrient concentration) in operating reactors for solid organic wastes. First the paper gives an overview of certain fundamental aspects of anaerobic digestion considered important for the digestion of food waste and its biochemical reactions. Then it describes food waste as the substrate for anaerobic digestion and its optimal conditions for the increased activity of biogas production. Finally it has been reviewed about the performance of the different pre-treatment methods and anaerobic reactor configurations in the digestion of food waste for increasing methane content in the biogas.