This work aims to study the production of the biomass of S. cerevisiae on an optimized medium using date extract as the only carbon source in order to obtain a good yield of the biomass. The biomass production was carried out according to the central composite experimental design (CCD) as a response surface methodology using Minitab 16 software. Indeed, under optimal biomass production conditions, temperature (32.9 °C), pH (5.35) and the total reducing sugar extracted from dates (70.93 g/L), S. cerevisiae produced 40 g/L of their biomass in an Erlenmeyer after only 16 h of fermentation. The kinetic performance of the S. cerevisiae strain was investigated with three unstructured models i.e., Monod, Verhulst, and Tessier. The conformity of the experimental data fitted showed a good consistency with Monod and Tessier models with R2 = 0.945 and 0.979, respectively. An excellent adequacy was noted in the case of the Verhulst model (R2 = 0.981). The values of kinetic parameters (Ks, Xm, μm, p and q) calculated by the Excel software, confirmed that Monod and Verhulst were suitable models, in contrast, the Tessier model was inappropriately fitted with the experimental data due to the illogical value of Ks (−9.434). The profiles prediction of the biomass production with the Verhulst model, and that of the substrate consumption using Leudeking Piret model over time, demonstrated a good agreement between the simulation models and the experimental data.
A large number of theories are reported in the literature for the calculation of individual mass transfer coefficients and each has a well defined application range, which depends on the nature of the continuous and the dispersed phases. Each theory is also based on a different transfer mode, e.g., the dispersed phase depends essentially on the drop behavior, which is directly related to the drop size. However, an accurate determination of the overall mass transfer coefficient depends upon the choice of the combination of theories to be used for the calculation of the individual mass transfer coefficients, i.e., for the continuous and dispersed phases. In the present work, different combinations for the calculation of the overall mass transfer coefficient have been tested for the commonly recommended Acetone/Toluene/Water system, which is characterized by relatively large drop sizes.
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