Enhanced Biogas Production During Anaerobic Digestion of Steam-Pretreated Lignocellulosic Biomass from Williams Cavendish Banana Plants

In the context of green energy valorisation, this study reports the chemical analysis and improvement of biogas production via anaerobic digestion of treated and untreated agricultural waste lignocellulosic biomass from Williams Cavendish banana plants (WCLB). With a worldwide annual production of 26 million tons of dry matter (DM), large amounts of this waste are abandoned in plantations after fruit harvesting. Steam explosion (SE) and steam cracking (SC) pretreatments were investigated at severity factors of 3.16 and 4.29, respectively, to improve the biogas potential over 135 days under mesophilic conditions. The study revealed a carbon (C)/nitrogen (N) ratio of 27.3, indicating that WCLB has sufficient N content for successful fermentation. The proportions of liquid and solid fractions recovered after SC were 20 and 80%, respectively, whereas SE yielded 17 and 83% liquid and solids, respectively. The neutral sugar content of the studied fractions indicated that glucose and xylose constituted the highest hexose and pentose fractions, respectively, in WCLB. The highest and lowest total biogas potentials were obtained from LFSC (280 mL g−1 of DM) and untreated WCLB (240 mL g−1 of DM), respectively. The methane yield from untreated WCLB and combined solid and liquid fractions from SE and SC were 40, 42, and 51%, respectively, of the theoretical methane potential. The maximum biogas production rate (7.8 mL g−1 day−1) was obtained with SFSC. This study reveals that SC deconstructs WCLB efficiently and thereby greatly enhances methane production.