Conversion of waste products derived from rice processing industry into bioethanol

Abstract

The effects of acid and alkali hydrolysis, as well as rice husk varieties (pure and mixed), on bioethanol production using saccharification and fermentation, were investigated in this study. Microbes such as Saccharomyces cerevisiae are currently used for fermenting agricultural wastes to bioethanol, an environmentally friendly alternative to petroleum energy sources. Rice husks were ground to a fine powder, then hydrolyzed with acid and alkali, and incubated for five days. A refractometer was used to perform a sugar reduction test, which determined the presence of fermentable sugar in the media. The parameters revealed that the variety of rice husk used did not affect the ethanol percent yield, which was 14.8 ± 0.5% and 15.0 ± 0.5% for the pure and mixed varieties, respectively; however, there was a substantial difference in the percentage yield in the method of pre-treatment. The percentage yield of ethanol in the acid pre-treated sample was higher (14.8 ± 0.5% and 15.0 ± 0.5%) than that of the alkali (6.1 ± 0.5% and 4.8 ± 0.5%). The presence of alcohol in the sample was confirmed by FTIR analysis, while GC-MS identified the specific compounds and their percentage composition – ethanol (9.67%). This suggests that using H2SO4 in the hydrolysis of rice husk is a promising and effective method for producing bioethanol.