Research on anaerobic digestion of corn stover enhanced by dilute acid pretreatment: Mechanism study and potential utilization in practical application

The utilization of lignocelluloses for biogas production is limited for several aspects, and an efficient pre-treatment is essential to increase the enzyme accessibility of cellulose. This research focused on the mechanism of biogas production and biodegradation properties under the treatments with different acid agents, including sulfuric acid (H2SO4), acetic acid (CH3COOH), and phosphoric acid (H3PO4). The H3PO4 pretreated corn stover was then co-digested with cow dung in a pilot test to investigate the performance of acid pretreatment in practice. The results showed that the main compositions of corn stover were cellulose, hemicellulose, and lignin, and their proportions in the corn stovers were increased after the acid pretreatments. This hence increased the final biogas yields (up to 40.75%), methane content, and promoted the biodegradation process. More significantly, the acid pretreatments delayed the appearance of the peak value of the biogas yield for 3 to 8 days depending on the acid concentrations. This study proposed that the dilute weak acid pretreatment, especially H3PO4 pretreatment, efficiently enhanced the biogas production by increasing the degradation of hemicellulose. Further on, the H3PO4 pretreatment also improved the stability of fermentation, which would benefit the biogas generation in practice. This research contributes to a better understanding of the mechanism of acid influence on enhancing the biogas generation and substrate biodegradation, and provides pratically sound guidance for reclamation of lignocellulosic materials. (C) 2016 AIP Publishing LLC.