Effect of low severity hydrothermal pretreatment on anaerobic digestion performance of corn stover.

The anaerobic digestion (AD) performance of corn stover was investigated under low hydrothermal pretreatment (HP) severity. Pretreated corn stover, with and without ammonia was examined at the three temperatures (50, 70, and 90 °C) coupled with different pretreatment time (24-72 h). The results showed that the pH value decreased with increasing pretreatment time for the same temperature. The highest volatile fatty acids (VFAs) concentration (4616.23 mg/L) was achieved at a HP severity of 4.56. The highest removal rate of cellulose, hemicellulose, and lignin were 19.62%, 25.53%, and 32.91% for HP with ammonia (HPA) severities of 3.34, 3.34, and HP severity of 4.35, respectively. The maximum methane yield of corn stover was 148.19 mL/g∙VS under 50 °C held for 24 h (HPA severity of 2.59), which was 31.35% higher than that of the untreated corn stover. The research results suggest that properly pretreatment severity can play an important role in promoting methane production.