Enhanced enzymolysis and fermentation of reed straw by recyclable ethanol-assisted lactic acid pretreatment

The organic acid pretreatment strategy has attracted research attention in separating the main components of renewable biomass sources. Herein, ethanol was proposed to assist the lactic acid pretreatment of reed straw by facilitating lignin and hemicellulose removal. The lactic acid amount, treatment temperature, and time were optimized in the orthogonal experiment to enhance the lignin removal rate and the glucan recovery, which reached 59.32% and 95.73% at 175 °C, respectively. The obtained product underwent following enzymatic hydrolysis, achieving a glucan digestibility of 98.80% and a total sugar yield of 69.63%. The fermentable sugar was further fermented into lactic acid or bioethanol, showing satisfactory comparable conversion rates (33.60% and 70.15%) with those obtained using commercial glucose as the sugar source. The reported efficient lignin and hemicellulose removal, superior glucan recovery, and especially the recyclability of produced valuable chemicals proved that our facile ethanol-assisted organic acid pretreatment strategy was promising for refining cash crops into fermentable sugars or valuable chemicals.