Kinetic modeling, sensitivity analysis, and techno-economic feasibility of ethanol fermentation from non-sterile carob extract-based media in Saccharomyces cerevisiae biofilm reactor under a repeated-batch fermentation process

This study aimed to model kinetically ethanol fermentation by Saccharomyces cerevisiae in the biofilm reactor, analyze the sensitivity of the developed model, and determine the techno-economic feasibility of ethanol fermentation. Two different media including the non-sterile enriched (NSE) and non-sterile unenriched media (NSUE) were evaluated for ethanol production. Based on the results, the experimental biomass production, ethanol production, and substrate consumption data from both the NSE and NSUE media were fitted very well by the logistic, Luedeking-Piret, and modified Luedeking-Piret models developed for each fermentation with higher R² values than 0.96. Besides, it was determined that the ethanol production processes were growth-associated as α values (g ethanol/g substrate) were higher than β values (g ethanol/g substrate/h). Sensitivity analysis gave extremely satisfactory results with high R² values ranging from 0.960 to 0.995. According to the techno-economic analysis, ethanol production from the NSUE medium was more economical than that of the NSE medium since its economic yield and economic productivity values were 21.0–21.1 and 13.4–16.8 times higher, respectively. Consequently, the developed models estimated successfully the experimental data yielded from non-sterile (un)enriched media in the biofilm reactor and can be used to describe ethanol fermentation under non-sterile conditions.