Inhibition of a biological sulfide oxidation under haloalkaline conditions by thiols and diorgano polysulfanes

A novel approach has been developed for the simultaneous description of reaction kinetics to describe the formation of polysulfide and sulfate anions from the biological oxidation of hydrogen sulfide (H₂S) using a quick, sulfide-dependent respiration test. Next to H₂S, thiols are commonly present in sour gas streams. We investigated the inhibition mode and the corresponding inhibition constants of six thiols and the corresponding diorgano polysulfanes on the biological oxidation of H₂S. A linear relationship was found between the calculated IC₅₀ values and the lipophilicity of the inhibitors. Moreover, a mathematical model was proposed to estimate the biomass activity in the absence and presence of sulfurous inhibitors. The biomass used in the respiration tests originated from a full-scale biodesulfurization reactor. A microbial community analysis of this biomass revealed that two groups of microorganism are abundant, viz. Ectothiorhodospiraceae and Piscirickettsiaceae.