Abstract

The production of ethanol from agricultural waste was investigated using simultaneous saccharification and fermentation (SSF). Cassava peel (CP) and rice husk (RH) were selected as substrates and analyzed for their proximate composition before pretreatment by steam explosion. Aspergillus niger, which exhibited the highest cellulose conversion potential among isolates from a waste dump, was employed for saccharification, while Saccharomyces cerevisiae was used to convert sugars into ethanol. S. cerevisiae cells were immobilized in sodium alginate for fermentation. The fermentation process was carried out at ambient temperature for 120 h, using a fungal inoculum size of 2.6 ± 0.04 × 10⁶ cellsmL-1 and 5% yeast concentration. Reducing sugar levels were monitored every 24 hours using the dinitrosalicylic acid (DNS) method, and ethanol yield was determined via specific gravity measurements. Proximate analysis revealed that CP contained higher moisture (6.81%), protein (4.77%), lipid (4.01%), and carbohydrate (70.64%) levels compared to RH. Initially, CP produced higher reducing sugar (0.899 mg/ml) and ethanol yield (4.20%) than RH (0.764 mgmL-1 and 1.75%). Fermentation conditions were optimized, with CP achieving a maximum ethanol yield of 23.02% at 30°C, pH 5.0, 25% substrate concentration, and 20% yeast concentration, while RH reached 15.92% at 32°C, pH 5.0, 30% substrate concentration, and 20% yeast concentration. Free yeast cells resulted in lower ethanol yields for both CP (19.92%) and RH (12.96%). Overall, CP proved to be a more effective substrate, and both substrates showed potential for bioethanol production.