| A non-heterocystous marine blue-green alga Oscillatoria sp. Miami BG 7 showed high biomass yields and hydrogen production rates in a natural seawater based system. Variations in water quality such as salinity, pH, trace metal concentration and combined nitrogen level did not affect either the biomass or the hydrogen production. Recycling of the two steps involved in hydrogen production (i.e., aerobic growth phase and anaerobic hydrogen production phase) significantly increased (>400%) the hydrogen yield. Immobilization of cells improved hydrogen production activity and its tolerance to adverse environmental conditions. Both the biomass and hydrogen production were not affected under uncontrolled outdoor environments. High biomass yield (250 mg dry wt/l/day or 40 g/m('2)/day), solar energy conversion efficiency (3.2%) and hydrogen production rate (1 ml H(,2)/ml gel/day) were obtained in small scale outdoor systems. |
