Biohydrogen and Methane Production from Sugarcane Leaves Pretreated by Deep Eutectic Solvents and Enzymatic Hydrolysis by Cellulolytic Consortia

Abstract

This study determined the optimal conditions for the deep eutectic solvent (DES) pretreatment of sugarcane leaves and the best fermentation mode for hydrogen and methane production from DES-pretreated sugarcane leaves. Choline chloride (ChCl):monoethanolamine (MEA) is the most effective solvent for removing lignin from sugarcane leaves. The optimum conditions were a ChCl: MEA molar ratio of 1:6, 120 °C, 3 h, and substrate-to-DES solution ratio of 1:12. Under these conditions, 86.37 ± 0.36% lignin removal and 73.98 ± 0.42% hemicellulose removal were achieved, whereas 84.13 ± 0.77% cellulose was recovered. At a substrate loading of 4 g volatile solids (VS), the simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) processes yielded maximum hydrogen productions of 3187 ± 202 and 2135 ± 315 mL H2/L, respectively. In the second stage, methane was produced using the hydrogenic effluent. SSF produced 5923 ± 251 mL CH4/L, whereas SHF produced 3583 ± 128 mL CH4/L. In a one-stage methane production process, a maximum methane production of 4067 ± 320 mL CH4/L with a substrate loading of 4 g VS was achieved from the SSF process. SSF proved to be more efficient than SHF for producing hydrogen from DES-pretreated sugarcane leaves in a two-stage hydrogen and methane production process as well as a one-stage methane production process.

Comparative Study of Methane Production in a One-Stage vs. Two-Stage Anaerobic Digestion Process from Raw Tomato Plant Waste

“…The hydrogen yields obtained in our study are similar to those reported by other authors from lignocellulosic substrates [25,29]. Miftah et al [29] reported hydrogen yields of 0.8 to 39.8 mL H 2 /g from pretreated and non-pretreated sugarcane leaves.…”

“…The hydrogen yields obtained in our study are similar to those reported by other authors from lignocellulosic substrates [25,29]. Miftah et al [29] reported hydrogen yields of 0.8 to 39.8 mL H 2 /g from pretreated and non-pretreated sugarcane leaves. Perez-Rangel et al [25] obtained 13, 17, and 38 mL H 2 /g VS from agave bagasse, corn stalk, and wheat straw, respectively.…”

“…The average content of methane in the biogas was 66.1%. The methane yield obtained in our study was similar or better than reported for other lignocellulosic substrates [20,29] without the need to pretreat the feedstock. Nkemka et al [20] reported 358 mL CH 4 /g VS from corn silage and Miftah et al [29] reported methane yields of 46.1 to 148.3 mL/g VS from pretreated and non-pretreated sugarcane leaves, respectively.…”

“…Miftah et al [29] added Clostridium butyricum TISTR 1032 preparations as inoculum for their hydrogen assays while Perez-Rangel et al [25] used native microflora of the plants. In previous studies, the presence of facultative bacteria belonging to the genus Enterococcus Acknowledgments: The authors are grateful for the support from the CONACYT scholarship to Sarai Camarena-Martínez, No.…”

Unlocking the potential of sugarcane leaf waste for sustainable methane production: Insights from microbial pre-hydrolysis and reactor optimization

“…Aseptically, a 10 % (v/v) solution of KKU-MC1 was injected into each bottle. The bottles were then incubated at 37 °C and 150 rpm for 5 days [ 11 , 23 ]. The control test followed the same procedure, but without the addition of KKU-MC1.…”