Optimization of alkali-extrusion pretreatment with twin-screw for bioethanol production from Miscanthus

This study investigated the production of bioethanol from Miscanthus using a specially designed twin-screw extruder (designated CHEMET) with sodium hydroxide. Pretreatment parameters were optimized using a response surface methodology and we evaluated the efficiency of pretreatment through the biomass to ethanol ratio (BTER). Optimum pretreatment conditions were 95 °C, 0.4 M sodium hydroxide concentration, 80 rpm twin-screw speed, and flow rate of 120 mL/min. Under these optimum conditions, actual BTER was 66 ± 2%, compared with a theoretical maximum of 67 ± 3%. Simultaneous saccharification and fermentation (SSF) was used to optimize enzyme and biomass dosage, giving a maximized ethanol concentration of 67.0 g/L and an ethanol conversion rate of 88.1% for 25% loading of pretreated Miscanthus with 30 FPU/g glucose of enzyme. The findings contribute to the development of continuous-production methods of obtaining bioethanol from lignocellulosic biomass.