Optimization of ethanol production from fermentation of cassava mill effluent

The quantity of ethanol produced from fermentable waste is usually small. The aim of this research was to maximize ethanol production from cassava mill effluent (CME) using Bacillus and Saccharomyces. Effluent pH, inocula-effluent ratio, and fermentation duration were selected as the adjustable parameters. Ethanol concentrations obtained from different value combinations of these parameters were fitted using a polynomial model so as to obtain a predicting polynomial equation. The equation was used in generating prediction profile from which the combined values of the parameters that lead to the highest achievable ethanol concentration (AEC) was determined. The predicted combined values were implemented in a new setup, and the ethanol produced determined. The results showed that ethanol produced from different combinations of the parameters ranged from 8.2 – 18.2 % v/v. Prediction profile generated from the resolved polynomial equation showed that the highest ethanol concentration (18.0%) is achievable at pH = 7, Inoculum-Effluent ratio = 0.02, and Fermentation/Incubation duration = 3 days. Ethanol concentration and yield obtained using these values were 17.6±0.2% v/v and 48.6±0.6% respectively. It is concluded that optimization studies is advantageous, and should be applied in assessing fermentation of an agro-substrate for ethanol production before using such substrate.