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

Kang, Xihui, Sun, Yongming, Li, Lianhua, Kong, Xiaoying, Yuan, Zhenhong
Bioresource technology 2018 v.255 pp. 205-212
Fourier transform infrared spectroscopy, Pennisetum, X-ray diffraction, alkali treatment, anaerobic digestion, biogas, cellulose, equations, hybrids, lignin, methane, methane production, scanning electron microscopy, sodium hydroxide, temperature
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.