Optimization of the Ethanol Fermentation of Cassava Wastewater using Response Surface Method

Abstract

This research work focused on the optimisation of the cassava wastewater medium for ethanol fermentation. The main thrust was the investigation of the influence of the glucose concentration, nutrient (NH₄Cl) level, and cell concentration on the yield of ethanol from cassava wastewater. Twenty experiments based on rotatable central composite design (CCD) were conducted. The factors affecting the ethanol yield were optimised within the following range of values (15 to 25) g/l of glucose concentration, (2 to 4) g NH₄Cl level and (300 to 400) CFU cell concentration in 100 ml of the substrate using response surface methodology (RSM). The optimum values of these factors- glucose concentration, nutrient level, and cell concentration were found to be 24.991 g/l, 3.991 g and 399.94 CFU respectively. These gave a yield of 8.69 % v/v of ethanol in the broth within the range of the values of the factors that were investigated. Optimising cassava wastewater as the medium for ethanol production would improve the ethanol yield, and thereby reduce the cost of production.

Keywords: Ethanol, cassava wastewater, optimization, culture medium, response surface methodology