Biomass Conversion and Biorefinery, cilt.14, sa.19, ss.24021-24039, 2024 (SCI-Expanded)
Pretreatment is compulsory to obtain the greatest possible biofuel production from lignocellulosic biomass. Among the many different pretreatment methods, enzymatic and ultrasonic pretreatments are attracting attention as environmentally friendly methods. In this framework, this study aims to optimize enzymatic and ultrasonic pretreatment to achieve high methane production by anaerobic digestion of lignocellulosic biomass consisting of agricultural residues. The optimization studies selected independent variables such as cellulase and β-glycosidase doses for enzymatic pretreatment and ultrasound power, reaction time, and solid content for ultrasonic pretreatment. The optimum conditions for enzymatic pretreatment were determined as 32.68FPU/gTS cellulase and 14.56 IU/gTS β-glucosidase concentrations to achieve a 60.15% increase in methane production. On the other hand, an 80.04% increase in methane production was obtained in the ultrasonic pretreatment under optimum conditions determined as 20 W ultrasound power, 60-min reaction time, and 5.46% solids content. The decrease in methane production by increasing the cellulose concentration in enzymatic pretreatment and by increasing the ultrasound power in ultrasonic pretreatment shows the importance of process optimization to achieve methane production. The theoretical energy productions were calculated and then compared with other pretreatment methods and the theoretical direct combustion energy. Since 90% energy recovery with ultrasonic pretreatment compared to direct combustion of lignocellulosic biomass was achieved, it is recommended to determine the effects of ultrasound in the pretreatment of other lignocellulosic biomass types. Thus, it will be possible to obtain energy from lignocellulosic waste in a much more environmentally friendly way compared to direct combustion. Graphical Abstract: [Figure not available: see fulltext.]