CO2-assisted Hydrothermal Pretreatment of Corn Stover for Enhanced Biomethane Production

Abstract

The hydrothermal pretreatment of lignocellulose biomass for anaerobic digestion applies high temperature and pressure conditions, which are high energy consumption. This study examined the pretreatment of corn stover using low-temperature hydrothermal pretreatment with CO2, to achieve better anaerobic digestion efficiency. The solid, liquid fraction after pretreatment was exposed to anaerobic digestion to produce biogas. Over the range of pretreatment conditions (50, 70, 90°C and 3, 5 MPa of CO2), the results showed that corn stover pretreated under 5 MPa CO2 at 90°C caused the highest removal rate of 56.3 and 31.7% in hemicelluloses and cellulose respectively, which results in 5.8 g L-1 reducing sugar were released in the liquid fraction. The highest methane yield of 185.9 (solid fraction) and 242.7 mL (g-VS-1) (liquid fraction) was obtained, which are 23.3 % and 61.1 % higher than that in untreated corn stover. The results showed that pre-treatments with CO2 have the potential to reduce structural obstacles of lignocellulosic materials and enhance their anaerobic biodegradability.