The process of converting lignocellulosic biomass to ethanol involves pretreatment to disrupt the complex of lignin, cellulose and hemicellulose, freeing cellulose and hemicellulose for enzymatic saccharification and fermentation. Determining optimal pretreatment techniques for fermentation is essential for the success of lignocellulosic energy production process. The study involved the acid pretreatment and use of cellulase enzyme to degrade the complex lignocellulosic biomass to simple sugars. Sugars so formed in turn are converted to ethanol by employing suitable yeast strains and bacterium Zymomonas mobilis. Different fermentation process like separate hydrolysis and fermentation process (SHF) and simultaneous saccharification and fermentation process (SSF) have been evaluated for the biethanol production. In separate hydrolysis and fermentation process, it showed the higher ethanol production in Zymomonas mobilis (47.34±1.2 g/l) and Candida shehatae (47.34±1.5 g/l), average ethanol production in Pichia stipitis (42.60±2.1 g/l) and very low ethanol production in Schizosaccharomyces pombe (31.56±1.6 g/l). In simultaneous saccharification and fermentation process, it showed the higher ethanol production in Zymomonas mobilis (48.12±1.1 g/l) and Saccharomyces uvarum (48.12±1.0 g/l), average ethanol production in Candida shehatae (44.97±1.8 g/l) and very low ethanol production in Saccharomyces cerevisiae (29.98±1.7 g/l) was monitored after the fermentation process. Structural changes of areca nut husk before and after acid pretreatment were further investigated through scanning electron microscopy (SEM) and fourier transformed infrared spectroscopy (FTIR). Hence, acid and enzymatic pre-treatment is more effective for ethanol production. The superiority of ethanol yield and productivity was very high in both SSF and SHF methods. Areca nut husk was revealed as a suitable substrate for ethanol production.
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