Sustainable biohydrogen production by dark fermentation using carbon monoxide as the sole carbon and energy source

摘要

This study evaluated the kinetics of biomass growth, biohydrogen production and substrate utilization using carbon monoxide as the sole carbon and energy source. Experiments were conducted at different initial CO concentration in the range 1.8-5.12 mmol/L over a period of 144 h in order to assess the effect of CO concentration on biomass growth, substrate utilization and H-2 production. Complete utilization (100%) of CO was achieved up to an initial concentration of 3.8 mmol/L and it gradually decreased to 84.5% for 4.4 mmol/L and 83.7% for 5.12 mmol/L. The experimental results of CO utilization were fitted to substrate utilization kinetic models reported in the literature, and it followed a modified Gompertz model. A maximum yield of H-2 on CO was found to be 70.8% and a maximum H-2 production of 29.9 mmol/L was obtained for an initial CO concentration of 5.12 mmol/L. The experimental results on biohydrogen production matched well with the values predicted using the modified Gompertz model. Furthermore, the experimental data on specific growth rate of the ananerobic biomass at different H-2 concentration was fitted to different product inhibition models and the best fit was obtained with Aiba model. This study showed product inhibition on both specific growth rate of biomass and H-2 production due to H-2 accumulation in the gas phase. A very good correlation between the experimental specific growth rate and the Han-Levenspiel model predicted values were obtained with a high determination coefficient (R-2) value of more than 0.96. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.