To identify optimal hydrogen production conditions using growing cultures of Rhodobacter sphaeroides DSM 158 the effects of varying the reactor's volumetric power input (0.01-1.4kWm-3) and irradiation intensity (5-2500Wm-2) were investigated in batch and continuous production modes. Irradiation intensity had a greater effect on hydrogen production than volumetric power input. Hydrogen production and photofermentative biomass formation were maximized by irradiation at 2250Wm-2 with a volumetric power input of 0.55kWm-3. The bacterial dry weight (2.64gL-1) and rate of hydrogen production (195mLL-1h-1) achieved under these conditions were greater than any that have previously been reported for batch-mode hydrogen production by R. sphaeroides. Continuous mode experiments (D=0.1h-1) yielded a bacterial dry weight, hydrogen production rate, productivity and hydrogen yield of 2.35±0.18gL-1, 165±6.2mLL-1h-1, 3.96LL-1d-1 and 36.6%, respectively.
- Intense irradiation