Effect of ozonolysis pretreatment parameters on the sugar release, ozone consumption and ethanol production from sugarcane bagasse

• Ozone concentration is the fundamental parameter on sugar release yield from SCB.
• Moisture is the fundamental parameter on ozone consumption per gram of sugar released.
• Ozone consumption presented good linear fitting with sugars release yields.
• Degradation compounds inhibited P. stipitis but not fermentation by S. cerevisiae.
• Fermentation of glucose and xylose is necessary to achieve viable ethanol production.

A L9(3)4 orthogonal array (OA) experimental design was applied to study the four parameters considered most important in the ozonolysis pretreatment (moisture content, ozone concentration, ozone/oxygen flow and particle size) on ethanol production from sugarcane bagasse (SCB). Statistical analysis highlighted ozone concentration as the highest influence parameter on reaction time and sugars release after enzymatic hydrolysis. The increase on reaction time when decreasing the ozone/oxygen flow resulted in small differences of ozone consumptions. Design optimization for sugars release provided a parameters combination close to the best experimental run, where 77.55% and 56.95% of glucose and xylose yields were obtained, respectively. When optimizing the grams of sugar released by gram of ozone, the highest influence parameter was moisture content, with a maximum yield of 2.98 gSUGARS/g O3. In experiments on hydrolysates fermentation, Saccharomyces cerevisiae provided ethanol yields around 80%, while Pichia stipitis was completely inhibited.