DEVELOPMENT OF BIOETHANOL PRODUCTION FROM PLANT BIOMASS

Depletion of the fossil fuel stocks as well as the endeavors to achieve a safer, greener and more sustainable environment highlight the importance of developing alternative fuel sources. Bioethanol from lignocellulosic sources is a good alternative for fossil fuels. It is renewable, can be used for transportation and does not contribute to the greenhouse effect. In the present work, Eichhornia crassipes (water hyacinth) and the cactus Opuntia ficus-indica were used as sources for lignocellulose. These plants have high hemicellulose and cellulose and low lignin content and may therefore serve as a source of sugars for bioconversion into bioethanol. Another significant advantage of these plants is that they do not compete with agricultural crop plants over growth areas and nutrients. Soluble mono-sugars can be produced from plant biomass by means of traditional multistage acid-base or enzymatic hydrolysis or, as proposed in this study, by single-stage mechanochemical hydrolysis. The results show that hydrolysis of the polysaccharides occur due to the mechanochemical activation, without the addition of any catalyst. Furthermore, it was demonstrated that the components obtained by a mechanochemically-treated hyacinth biomass can serve as a full growth medium for fermentation of Pichia stipitis for bioethanol production. The yeasts Pichia stipitis and Saccharomyces cerevisiae were found to be able to grow on model media containing various concentrations of sugars that are known to compose the polysaccharides of the chosen plants.