Improvement of Biohydrogen Production from Dark Fermentation by Cocultures and Activated Carbon Immobilization

To improve biohydrogen production, the performance of dark fermentation by cocultures and the immobilization system with activated carbon (AC) were investigated. Results of batch tests illustrated that lower yield was obtained by monoculture Enterobacter cancerogeous HG6 2A (A) and Enterobacter homaechei 83 (B). The defects of monocultures could be overcome by cocultures in dark fermentation. The optimum A:B number ratio of 0.9:1 was recommended. The optimum loading rate of AC was 200 g/L in the immobilization system, corresponding to the biohydrogen yield of 1.203 mol/mol-glucose. The biohydrogen production of the immobilization system increased 259% in comparison to that of the suspension cell system, indicating that immobilization was an effective method of improving biohydrogen production. The surface attachment and the synergistic effect explained the higher performance of the cell immobilization system.