Pretreatment of sugarcane bagasse using hydrodynamic cavitation technology: Semi-continuous and continuous process

Development of new technologies for pretreatment of lignocellulosic biomass is a current research challenge. In this way, hydrodynamic cavitation (HC) was used to assist alkaline hydrogen peroxide pretreatment of sugarcane bagasse (SCB) in sequential batches (SB-HC), semi-continuous (SC-HC) and continuous (C-HC) processes. Pretreatment resulted in compositional modifications in the material, mainly regarding the cellulose and lignin contents. The released sugars after enzymatic hydrolysis resulted, on average, in 42 g and 32-35 g of glucose per 100 g of SCB for samples treated in B-HC (10 min of process) and SC-HC process (7.5 min residence time), respectively. In C-HC process, with an average residence time of 7.5 min and 3.75 min, 38-46 g and 32-38 g of glucose per 100 g of SCB were obtained respectively in enzymatic hydrolysis step. HC technology was shown as a promising alternative for pretreatment of lignocellulosic biomass in all evaluated configurations aiming to produce high value bioproducts.

Continuous alkaline pretreatment of Miscanthus sacchariflorus using a bench-scale single screw reactor

Miscanthus sacchariflorus 'Goedae-Uksae 1' (GU) was developed as an energy crop of high productivity in Korea. For the practical use of GU for bioethanol production, a bench-scale continuous pretreatment system was developed. The reactor performed screw extrusion, soaking and thermochemical pretreatment at the following operating conditions: 3 mm particle size, 22% moisture content, 140 °C reaction temperature, 8 min residence time, 15 g/min biomass feeding and 120 mL/min NaOH input. As a result of minimizing NaOH concentration and enzyme dosage, 90.8±0.49% glucose yield was obtained from 0.5 M NaOH-pretreated GU containing 3% glucan with 10 FPU cellulase/g cellulose at 50 °C for 72 h. The separate hydrolysis and fermentation of 0.5 M NaOH-pretreated GU containing 10% glucan with 10-30 FPU for 102 h produced 43.0-49.6 g/L bioethanol (theoretical yield, 75.8-87.6%). Thus, this study demonstrated that continuous pretreatment using a single screw reactor is effective for bioethanol production from Miscanthus biomass.