TWO-STAGE PRETREATMENT OF SUGARCANE BAGASSE FOR ETHANOL PRODUCTION FROM XYLOSE AND GLUCOSE

Abstract

Introduction:
Sugarcane bagasse is used for bioethanol production due to its high cellulose and hemicellulose content. Pretreatment is necessary to make carbohydrates accessible to enzymes. One way to increase ethanol yield is to utilize all the sugars contained within it.
Objective:
To evaluate ethanol production from xylose and glucose obtained through a two-stage pretreatment.
Materials and Methods:
In the first pretreatment step, 1.25 % H₂SO₄ was used at 120 °C for 40 minutes, producing a hydrolysate rich in xylose that was fermented with Pichia stipitis. The second stage was performed using a 30 % (v/v) ethanol mixture and sodium hydroxide at different concentrations. The enzymatic digestibility of the solids was evaluated with cellulase, and simultaneous hydrolysis and fermentation was carried out with Saccharomyces cerevisiae.
Results and Discussion:
The fermentation yield of the hydrolysate rich in xylose was 19 % with respect to the initial sugars. The alkaline pretreatment reduced lignin by 53 %, improving enzymatic digestibility. The best experimental conditions yielded 39.17 g of sugars per 100 g of bagasse and an ethanol yield of 8.14 g/100 g of bagasse.
Conclusions:
Two-stage pretreatment increases sugar recovery by 25.12 %. Ethanol production rises by 15.13 % using all sugars obtained from pretreatment and enzymatic hydrolysis of bagasse.