Oxidation of hydrogen sulfide by Thiobacillus denitrificans : Desulfurization of natural gas

It has been demonstrated that Thiobacillus denitrificans may be readily cultivated anaerobically in batch reactors on H 2 S (g) under sulfide‐limiting conditions. Under these conditions sulfide concentrations in the culture medium were less than 1 μ M , resulting in very low concentrations of H 2 S in the reactor outlet gas. The stoichiometry of the reaction was determined, and stable reactor operation was demonstrated at reactor loadings as high as 4–5 mmol H 2 S oxidized/h g biomass. Maximum loading was estimated at 5.4–7.6 mmol H 2 S/h g biomass under the conditions employed in this study. Indicators of reactor upset were determined and recovery from upset conditions demonstrated. Barotolerance of T. denitrificans to 12.5 MPa as well as a relative insensitivity to pressurization–depressurization cycles were also demonstrated. T. denitrificans was observed to be very sensitive to CH 3 SH but relatively tolerant of CS 2 , COS, and CH 3 SCH 3 .