Pretreatment of Corn Stover with Diluted Nitric Acid for the Enhancement of Acidogenic Fermentation

In this study, dilute nitric acid was selected as the catalyst to pretreat corn stover. The effects of nitric acid pretreatments on the efficiency of acidogenic fermentation and the acidogenic characteristic of prehydrolysates were evaluated. The results showed that about 97% hemicelluloses were recovered at the optimal condition (150 °C, 0.6% HNO3, 2 min). Acidogenic fermentation of prehydrolysate B (the highest yield of total sugar) obtained at the optimal condition proved to be more efficient compared with prehydrolysate A (no inhibitor) and prehydrolysate C (the highest yield of inhibitors), the VFAs concentration can reach the highest level, and the distribution of VFAs exhibited butyric acid type fermentation; this was more suitable for subsequent methanogenic fermentation. This research provided an effective and suitable method for accelerating biogas production from corn stover.