Bioethanol Fermentation From Acid/Base-Treated Water Hyacinth Biomass Using Fermentation Yeasts Saccharomyces Cerevisiae YRK 017 and Candida Shehatae ATCC 22984

Abstract

Water hyacinth is considered as one of most abundant lignocellulosic feedstock in Thailand. It has been selected as a substrate for producing ethanol at an economically feasible manner.  This study focuses on the bioethanol production from enzyme-treated hydrolysate of acid/base pretreatment water hyacinth.  Two different pretreatment methods of water hyacinth were used including either 2% v/v sulfuric acid or 2% w/v sodium hydroxide at 121°C for 15 min.  After acid/base pretreatments, the biomass residues in order to release glucose molecules were treated with a commercial cellulase enzyme complex (ACCELLERASE^® 1500) at a concentration of 0.30 mL enzyme/g biomass residue. Two yeast species consisting of Saccharomyces cerevisiae YRK 017 and Candida shehatae ATCC 22984 were separately used as inocula in fermentation process of the hydrolysate from enzymatic treatments. The results showed that ethanol yield obtained from acid pretreatment was slightly higher than the yield from base pretreatment. In acid pretreatment, S. cerevisiae YRK 017 could produce bioethanol in a yield of 3.82 + 0.10 g/L, whereas C. shehatae ATCC 22984 could produce yielding 2.85 + 0.04 g/L.