Solmaz Saadat - Assistant Professor, Department of Civil and Environmental Engineering, Shiraz University, Iran.
Fatemeh Rezaeitavabe - Master of Science Student, Department of Civil and Environmental Engineering, shirza University, iran
Nasser Talebbeydokhti - Professor, Department of Civil and Environmental Engineering, Shiraz University, Iran.

Bio-hydrogen production by single-step dark and combined dark and photo fermentation of food waste was investigated in batch fermentation. The combined process contained a mixture of Clostridium acetobuytricum and Rhodobacter sphaeroides with a certain light/dark (1/2) bacteria ratio. In darkfermentation, the cumulative hydrogen production was approximately 14.2 L. In subsequent combined system, the average cumulative hydrogen production was approximately 22.7 L. which was about 1.65 times compared to the amount that produced in dark fermentation only. Meanwhile, the COD decreasedwith a removal efficiency of 22.5% in hybrid system and 14% in dark fermentation. These results demonstrate that food waste could be ideal substrate for bio-hydrogen production and a hybrid process combining dark-photo seems ideal to achieve dual benefits to hydrogen and waste stabilization.

Bio-hydrogen, Co-culture, Dark fermentation, Photo fermentation, Volatile Fatty Acids.