1995 Volume 25 Issue 4 Pages 215-222
Methane production from H2 and CO2 was carried out with acclimated-methanogens in 2 (L) jar fermentor in continuous feed substrate gas (H2/CO2, 80:20v/v) at pH7 and 37°C. A high cell density of methanogens and high methane productivity were obtained by optimizing the nutritional conditions of acclimated-methanogens. With the case of reactor having sufficient mass transfer capacity of substrate gas (H2/CO2) from gas phase to the liquid and fully nitrogen and sulfur source for the growth of methanogens, cell density and methane production rate were only dependent on the trace metals solution concentration added to the medium. By using the optimized HC-medium, the cell density, 26g/L and methane production rate, 21.5L/Lh were obtained respectively. These results are high by contrast with that of a pure culture or a mixed culture using CSTR or cell fixed reactor have been reported. Effects of NH4+ and vitamin on the growth of methanogens were investigated using stopped culture tube and Fe2+ and Mg2+ were found as limiting factor for growth of methanogens. Also, the effects of amount of NH4+ and trace metals solution added to the medium on the growth of methanogens was strongly depended on the cell density of methanogens.
