Kinetic and stoichiometric modelling of acidogenic fermentation of glucose and fructose

In this work, a model based on Monod equation for the description of the acidogenic fermentation of glucose and fructose as the main substrates contained in the winery wastewater was developed. The data used for calibration and validation of the model parameters were obtained from an acidogenic mixed culture fermenting glucose and fructose in a batch reactor at 35 °C and pH 5. The calibrated model accurately describes the experimental results from biomass growth, substrate consumption and fermentation products generation. The results showed that the microorganisms growth rate and biomass yield were higher when glucose was used as substrate: μmax−Glucose = 0.163 h−1, μmax−Fructose = 0.108 h−1, Yx−Glucose = 0.027 g VSS per mmol Glucose and Yx−Fructose 0.017 g VSS per mmol Fructose.Regarding to the fermentation products, the acetic acid was the main fermentation product obtained in both fermentations, followed by lactic and butyric acid. Comparing glucose and fructose fermentations, the main difference was the yield of butyric acid in both fermentations, 0.249 mol per mol Glucose and 0.131 mol per mol Fructose since the other acids concentration were quite similar. In the case of the H2 production, it was 0.76 mol H2 per mol Glucose while 0.85 was the yield in fructose fermentation.

► Acidogenic fermentation of glucose and fructose was studied.
► A model describing the kinetics and stoichiometry of the fermentation was developed.
► The model developed predicted accurately the substrate, products and biomass profiles along the fermentation process.
► The microorganisms growth rate was higher in the glucose fermentation.
► The fructose fermentation presented higher hydrogen yields.