[Cultivation and isolation of bacteria coupling nitrogen removal from wastewater and hydrogen sulfide removal from...

It was studied that during the startup of reactors the crucial bacteria coupling nitrogen removal from swine wastewater and hydrogen sulfide removal from biogas using bubbling absorption reactors without seeding sludge, with seeding anaerobic sludge and aerobic sludge, respectively. During the prophase of the experiment (before the 26th d), the removal rate of nitrogen and hydrogen sulfide were from 50% to 64% in reactors with seeding sludge, that in the reactor without seeding sludge was only 11%-14%. At the end of experiment (the 56th d after startup), the removal rates of nitrogen for three reactors were about 90%. The removal rates of hydrogen sulfide were more than 70%. The result showed that though the finishing time for startup of the reactor without seeding sludge was longer than that with seeding sludge, it could be obtained the same effect of removal of nitrogen and hydrogen sulfide as the latter after two months cultivation. In the different period of startup of the reactors, the variation of the population of bacteria was studied, which had the same trend as the removal effect of nitrogen and hydrogen sulfide. Two strains which could remove the nitrogen and hydrogen sulfide more than 60% simultaneously were isolated from the three reactors, and primarily identified as Thiobacillus denitrificans and Pseudomonas respectively, based on their morphology and physiological characters.