Interrelationships between bioreactor volume, effluent recycle rate, temperature, pH, %H2, hydrogen productivity and hydrogen yield with undefined bacterial cultures

► Effluent recycle rate per unit volume (V/F) and temperature controlled H2 yield, HY. ► V/F and T also controlled volumetric H2 productivity, HP. ► When T = 70 °C and V/F = 1.8 min, HY = 3.55 mol H2/mol glucose. ► When T = 70 °C and V/F = 1.8 min, HP = 231 mmol H2/L/h. ► Hence, high HPs and HYs were simultaneously achieved.