Abstract:
This research aims to study the efficiency of wastewater treatment and biohydrogen production from cassava wastewater by the two-stage dark and photo fermentation process. The batch experiments were conducted to investigate the optimum condition of pH and temperature for increasing hydrogen production efficiency from cassava wastewater in which COD concentration was about 5,000 mg/l., using anaerobic mixed cultures in dark fermentation and the photosynthetic bacteria in photo fermentation. The results showed that optimum pH and temperature for the maximum hydrogen production in dark fermentation was achieved at pH 5 and 55oC, providing the hydrogen yield of 52.9 ml H2/gCOD. The maximum H2 production rate per a liter of wastewater of 28.72 ml/L-hr and the efficiency of COD removal of 30.04%, respectively. Photo fermentation provided the hydrogen yield of 5.5 ml H2/gCOD, the maximum H2 production rate per a liter of wastewater of 1.07 ml/L-hr and the efficiency of COD removal of 17.89%, respectively. The overall efficiency of the two-stage dark and photo fermentation achieved the hydrogen yield of 58.4 ml H2/gCOD and the COD removal of 47.94%. Our result suggested that using the two-stage process combining dark and photo fermentation might enhance the biohydrogen production and the COD removal efficiency.