A modified indirect mathematical model for evaluation of ethanol production efficiency in industrial-scale continuous fermentation processes

M. ALEJANDRA CANSECO GRELLET; ANA CASTAGNARO; KARINA I. DANTUR; GUILLERMO DE BOECK; PABLO M. AHMED; GERÓNIMO J. CÁRDENAS; BJÖRN G. WELIN; R. MARCELO RUIZ

JOURNAL OF APPLIED MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016

1364-5072

Aims: To calculate fermentation efficiency in a continuous ethanol productionprocess, we aimed to develop a robust mathematical method based on theanalysis of metabolic by-product formation.Methods and Results: This method is in contrast to the traditional way ofcalculating ethanol fermentation efficiency, where the ratio between the ethanolproduced and the sugar consumed is expressed as a percentage of thetheoretical conversion yield. Comparison between the two methods, atindustrial scale and in sensitivity studies, showed that the indirect method wasmore robust and gave slightly higher fermentation efficiency values, althoughfermentation efficiency of the industrial process was found to be low (~75%).Conclusions: The traditional calculation method is simpler than the indirectmethod as it only requires a few chemical determinations in samples collected.However, a minor error in any measured parameter will have an importantimpact on the calculated efficiency. In contrast, the indirect method ofcalculation requires a greater number of determinations but is much morerobust since an error in any parameter will only have a minor effect on thefermentation efficiency value.Significance and Impact of the Study: The application of the indirectcalculation methodology in order to evaluate the real situation of the processand to reach an optimum fermentation yield for an industrial-scale ethanolproduction is recommended. Once a high fermentation yield has been reachedthe traditional method should be used to maintain the control of the process.Upon detection of lower yields in an optimized process the indirect methodshould be employed as it permits a more accurate diagnosis of causes of yieldlosses in order to correct the problem rapidly. The low fermentation efficiencyobtained in this study shows an urgent need for industrial process 17optimization where the indirect calculation methodology will be an importanttool to determine process losses.