Abstract
Autotrophic denitrification was studied using hydrogen gas as the hydrogen donor. It was confirmed that microorganisms which have the ability of autotrophic denitrification using hydrogen gas are distributed widely. It was concluded that Alcaligenes eutrophus (ATCC 17697), Paracoccus denitrificans (IFO 13301) and Pseudomonas pseudoflava (ATCC 33668) can reduce nitrate to nitrogen gas in the presence of hydrogen gas. The effect of pH value for autotrophic denitrification of these bacteria was not significant within the range of 7 to 8. The effect of temperature on the specific denitrification rate was also examined and the calculated Arrhenius constant was within the range of 44.1 to 63.2 kJ·mole-1. The specific denitrification rate of A. eutrophus and P. pseudoflava was above 1 mgN·mgSS-1·d-1 at 15 degree centigrade. The specific denitrification activity was constant above 10 kPa of partial pressure of hydrogen gas and the Michaelis-Menten half-velocity constant for hydrogen gas was found to be less than 3% of saturation.
