Ethanol production from horticultural waste treated by a modified organosolv method

In this study, we investigated the use of horticultural waste (HW) collected in Singapore as a renewable raw material for bioethanol production. A modified organosolv method using ethanol cooking under mild conditions followed by H2O2 post-treatment was investigated for HW pretreatment. It was found that the addition of acid catalysts in the pretreatment process was not critical and post-treatment using H2O2 was essential for the enhancement of HW digestibility. Enzymatic hydrolysis of the organosolv pretreated HW with 17.5% solid content, enzyme loading of 20 FPU/g HW of filter paper cellulase, and 80 CBU/g HW of beta-glucosidase resulted in a HW hydrolysate containing 26.9 g/L reducing sugar after 72 h. Fermentation of the above hydrolysate medium produced 11.69 g/L ethanol at 8 h using Saccharomyces cerevisiae. It proved that horticultural waste was a potential feedstock for fuel ethanol production and organosolv pretreatment method developed in this study was effective. (C) 2011 Elsevier Ltd. All rights reserved.