Abstract

Cocoa pod husks (CPH) and unripe plantain peels (UPP) are some of the agricultural residues that are improperly disposed in Nigeria with serious environmental consequences. In this study, CPH and UPP that were hydrothermally pretreated in a previous study were used for the production of bioethanol. An optimization of the simultaneous saccharification and fermentation of the substrates was carried out using the Box-Behnken design of the Response Surface Methodology of the Design Expert software. The process parameters that were varied include temperature, pH and solid loading. The study showed that these parameters were optimal at 40 °C, 6 and 17.5 %w/v respectively. These optimal parameters were used to scale-up bioethanol production that resulted in a maximum ethanol concentration of 19.89 and 36.08 g/L from the CPH and UPP respectively. The logistic kinetic model was used to fit the growth rate of biomass while the dual pool model and the modified Gompertz model were used to fit the experimental bioethanol production. It was observed that the dual pool kinetic model described the bioethanol production from the substrates better than the modified Gompertz model.