Fig. 1
Performance in syngas–glucose co-fermentation bottles: a syngas consumption at steady state, b produced VFA in the effluent at steady state, c degradation of glucose in 24 h and d syngas consumption rate in 24 h. The steady state was defined by a sustained VFAs production and syngas consumption within ± 5% deviation. The CO/H2 conversion efficiencies calculated with the CO/H2 consumptions dividing by the total volume of CO/H2 in bottles. Ethanol production was insignificant (< 10 mg/L), and the concentration of ethanol was not shown in this study