Alkaline hydrogen peroxide pretreatment, enzymatic hydrolysis and fermentation of sugarcane bagasse to ethanol

• Evaluation of sugarcane bagasse pretreated with hydrogen peroxide.
• Evaluation of necessity of particle size reduction.
• Influence of increasing solids loadings in the pretreatment and hydrolysis stages.
• Performance evaluation of batch fermentation of pure hydrolysate.
• Evaluation of continuous fermentation of hydrolysate with sugarcane molasses.

The pretreatment of sugarcane bagasse with alkaline hydrogen peroxide was evaluated for second generation ethanol production via enzymatic hydrolysis and fermentation using Saccharomyces cerevisiae. Factorial designs were used to determine the need for particle size reduction as well as to optimize pretreatment conditions and enzymes loadings in the hydrolysis. The influence of increasing solids loadings in the pretreatment and hydrolysis stages was determined; batch fermentation of pure hydrolysate, as well as continuous fermentation of hydrolysate concentrated with sugarcane molasses were performed. Furthermore, mass balances were used to determine the mass of ethanol obtained by mass of raw bagasse in different operational conditions. The pretreatment increased bagasse enzymatic digestibility without the need for prior size reduction. In the optimal pretreatment (1 h, 25 °C, 1.84 mL hydrogen peroxide/g bagasse) and hydrolysis conditions (3.5 FPU/g bagasse of cellulase and 25 CBU/g bagasse of β-glucosidase), 416.7 kg glucose/ton of raw bagasse were obtained. Fermentation of pure hydrolysate led to an ethanol yield of 187.85 kg/ton of raw bagasse.