Improving methane production from anaerobic digestion of Pennisetum Hybrid by alkaline pretreatment

• Published in: Bioresource technology 2018-05, Vol.255, p.205-212
• Main Authors: Kang, Xihui, Sun, Yongming, Li, Lianhua, Kong, Xiaoying, Yuan, Zhenhong
• Format: Article
• Language: English
• Subjects: Alkaline pretreatment; Anaerobic digestion; Anaerobiosis; Biofuels; Cellulose; Lignin; Methane; Pennisetum; Pennisetum hybrid; Specific methane yield; Structure changes
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2017.12.001

•Pennisetum hybrid was a promising feedstock for methane yield.•The most efficient alkaline pretreatment enhanced the methane yield by 21%.•Removal of hemicellulose and lignin promoted the anaerobic fermentation.•Alkali pretreatment significantly reduced the retention time of Pennisetum hybrid.•High Na+ concentration inhibited the anaerobic digestion performance. Alkaline pretreatment with NaOH was used to improve methane yield from Pennisetum Hybrid. The pretreatments were carried out with different NaOH solutions (2–8% w/w) at three temperatures (35, 55 and 121 °C) for different periods of time (24, 24 and 1 h). All treated and untreated Pennisetum Hybrid were digested under mesophilic conditions (37 °C) to biogas, significant effects of the pretreatments on the yield of methane were observed. Results showed the modified Gompertz equation was reliable (determination coefficients (R2) greater than 0.96) to describe the kinetic behavior of anaerobic digestion of Pennisetum Hybrid. The best result, obtained by the treatment at 35 °C 2% NaOH for 24 h, resulted in the methane yield of 301.7 mL/g VS, corresponding to 21.0% improvement in the methane yield. Compositional, SEM, XRD and FTIR analysis confirmed that lignin removal, structural modification and cellulose crystalline variation were responsible for the improvement.