A mini-review on the metabolic pathways of food waste two-phase anaerobic digestion system

Food waste (FW) disposal has become a global social, environmental, and economic problem. The current practice of landfilling is undesirable due to its potential emission of greenhouse gas, nutrient recycling, and pollution of water resources. Anaerobic digestion (AD), particularly two-phase AD is a promising option to manage FW and recover energy in the form of methane and obtain value-added by-products. However, most current review literature focuses on operating conditions while often placing little emphasis on improving conversion efficiency through regulating intermediate products. The AD process involves complex metabolic reactions carried out by several microbial groups. Therefore, understanding of these metabolic pathways existing in AD is the key to design effective strategies for enrichment of specific microbial groups which can produce desired intermediates for methane production, which can possibly be achieved by an understanding of the influence of critical process parameters on these metabolic pathways. Thus, it is the aim of this review to describe the effect of process conditions on underlying metabolic pathways in order to allow an efficient manipulation of these pathways for enhancing methane production.