Reviewing the anaerobic digestion and co-digestion process of food waste from the perspectives on biogas production performance and environmental impacts

Abstract

In this paper, factors that affect biogas production in the anaerobic digestion (AD) and anaerobic co-digestion (coAD) processes of food waste are reviewed with the aim to improve biogas production performance. These factors include the composition of substrates in food waste coAD as well as pre-treatment methods and anaerobic reactor system designs in both food waste AD and coAD. Due to the characteristics of the substrates used, the biogas production performance varies as different effects are exhibited on nutrient balance, inhibitory substance dilution, and trace metal element supplement. Various types of pre-treatment methods such as mechanical, chemical, thermal, and biological methods are discussed to improve the rate-limiting hydrolytic step in the digestion processes. The operation parameters of a reactor system are also reviewed with consideration of the characteristics of the substrates. Since the environmental awareness and concerns for waste management systems have been increasing, this paper also addresses possible environmental impacts of AD and coAD in food waste treatment and recommends feasible methods to reduce the impacts. In addition, uncertainties in the life cycle assessment (LCA) studies are also discussed.

Keywords: Anaerobic reactor; Biogas utilization; Co-substrate; Environmental impact; Life cycle assessment; Methane; Pre-treatment; Uncertainty analysis.