Bioethanol Production From Aquatic Weed Water Hyacinth (Eichhornia crassipes) by Yeast Fermentation

Bioethanol production from biomass has high potential to substitute fossil fuels. Pretreatment of lignocellulosic materials is one of the vital keys for an economical process for bioethanol production. The main aim of the study was identifying the potent ethanol producing yeast strains (Pachysolen tannophilus, Candida intermedia, Pichia stipitis and Saccharomyces cerevisiae) using enzymatic hydrolysis. Trichoderma reesei NRRL-3652 was used to produce cellulase and xylanase under solid state condition, using acid pretreated water hyacinth biomass as a substrate. The enzyme complex (cellulase 18.33 IU/mL and xylanase 31.43 IU/mL) thus produced was utilized for hydrolyses resulting in soluble sugars. The alterations in physical, chemical structures and delignification was determined by scanning electron microscopy, Fourier transformed infrared spectroscopy and X-ray diffraction. The best results of ethanol production were obtained with P. tannophilus reaching a maximum ethanol concentration of 0.043 g/g, followed by 0.021-0.037 g/g for C. intermedia and P. stipitis. On the contrary, ethanol yield of S. cerevisiae was decreased (0.015 g/g) due to non-assimilation of pentose sugar. This study represents the suitability of biologically delignified water hyacinth as a feedstock for fuel ethanol production.