Performance of combined hydrochemo-mechanical pretreatment of rice straw for bioethanol production

Abstract

Pretreatment was an inevitable process in the biorefinery process of lignocellulosic biomass utilization. Generally, biomass was considered an essential carbon source that could be converted into several bio-based products such as biofuels and biochemicals. This study aimed to evaluate the performance of combined hydrochemo-mechanical pretreatment of rice straw for bioethanol production. Rice straw was pretreated with autoclave followed by ball-milling pretreatment. The hydrochemical pretreatment was performed in an autoclave with different concentrations of NaOH (1 and 10%) at 121 °C for two different durations (30, 60 min). The pretreated biomasses were then subjected to ball-milling pretreatment for size reduction and subsequently hydrolyzed via enzymatic and bioethanol fermentation. The obtained results indicated that the highest reducing sugars were 0.4513 kg reducing sugar/kg biomass obtained by 1% of NaOH at 121 °C, 30 min, which provided the highest energy efficiency and the lowest waste generation was 0.1423 kg reducing sugar/kWh and 0.2570 kg of waste/kg reducing sugar respectively. Moreover, the highest bioethanol yield was 0.0491 kg/kg biomass obtained from a similar condition. Additionally, the combined pretreatment suggested that it could be an alternative pretreatment for a lignocellulosic biorefinery in industrial applications.

Keywords

• Hydrochemo-mechanical pretreatment
• Bioethanol
• Rice straw
• Energy efficiency
• Waste generation