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

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Abstract
It has been demonstrated that Thiobacillus denitrificans may be readily cultivated anaerobically in batch reactors on H2S (g) under sulfide-limiting conditions. Under these conditions sulfide concentrations in the culture medium were less than 1 μM, resulting in very low concentrations of H2S 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 H2S oxidized/h g biomass. Maximum loading was estimated at 5.4–7.6 mmol H2S/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 CH3SH but relatively tolerant of CS2, COS, and CH3SCH3.