Fig. 2

Variation of the steady-state concentrations of a biomass, b ethanol, c dissolved oxygen and residual glucose with the feed concentration of glucose at fixed D = 0.1 h⁻¹ and two mass-transfer coefficients, namely, k_la ≈ 50 h⁻¹ (blue) and k_la ≈ 100 h⁻¹ (red). The arrows point in the direction of increasing k_la. The lines in the carbon- and oxygen-limited regimes represent best fits to Eqs. (14)–(16) and (23)–(25), respectively. The lines in the dual-limited regime are obtained by linearly interpolating the end points of the carbon- and oxygen-limited regimes. The inset in c shows the dissolved oxygen levels