Ecological factors affecting H2 production capacity of ethanol-type fermentation

The ethanol-type fermentation for bio-production of H-2 using both pure and mixed batch culture was studied, in which some ecological factors, including interspecies cooperation, glucose concentration, temperature and pH, affecting the 142 production capacity and specific rate were investigated in order to maximize the H2 output. The four strains, Bacteroides, Fusobacterium, Aerobacter, and Zymomonas, of higher hydrogen production capacity bacteria were isolated from the anaerobic activated sludge producing hydrogen, and were demonstrated to be ethanol-type fermentation bacteria. It was demonstrated that the complex micro-ecosystems such as anaerobic activated sludge were good for increasing the hydrogen production capacity. It was found that while Bacteroides of ethanol-type fermentation bacteria achieved the H2 production capacity of 43.1 mmol H-2/g SS and the maximum specific H2 production rate of 2.87 mmol H-2/g SS hr, the anaerobic activated sludge could achieve those of up to 51.2 mmol H-2/g SS and 3.58 mmol H-2/g SS. hr, respectively, in its optimum conditions of glucose concentration = 170.8 mM, temperature = 36degreesC and pH 5.0. The optimum parameters were glucose concentration of around 200 mM, temperature of 36degreesC and pH of 5.0.