Thermophilic Anaerobic Digestion: Enhanced and Sustainable Methane Production from Co-Digestion of Food and Lignocellulosic Wastes

Abstract

This article aims to study the codigestion of food waste (FW) and three different lignocellulosic wastes (LW) (Corn stover (CS), Prairie cordgrass (PCG), and Unbleached paper (UBP)) for thermophilic anaerobic digestion to overcome the limitations of digesting food waste alone (volatile fatty acids accumulation and low C:N ratio). Using an enriched thermophilic methanogenic consortium, all the food and lignocellulosic waste mixtures showed positive synergistic effects of codigestion. After 30 days of incubation at 60 °C (100 rpm), the highest methane yield of 305.45 L·kg−1 volatile solids (VS) was achieved with a combination of FW-PCG-CS followed by 279.31 L·kg−1 VS with a mixture of FW-PCG. The corresponding volatile solids reduction for these two co-digestion mixtures was 68% and 58%, respectively. This study demonstrated a reduced hydraulic retention time for methane production using FW and LW.

Keywords

• thermophilic anaerobic digestion
• corn stover
• prairie cord grass
• unbleached paper
• digester performance
• process stability
• synergistic effects
• microbial community
• Methanothermobacter