Reaction mechanism and stoichiometry of biological sulfide oxidation

1. Biological oxidation of sulfide is also a multi step process involving a series of biochemical reactions catalyzed by micro-organisms present in sewer biofilm.
2. The reaction product of aerobic biological sulfide oxidation is normally the elemental sulfur and other intermediates such as thiosulfate under oxygen-limited conditions. The intermediate products are subsequently oxidized to sulfate, but the rate of this step is much lower than that of the first step.
3. Actual oxygen consumption rate of oxygen for biological sulfide oxidation is reported to be higher than 0.5 g O₂ per g of S indicating a range of oxidation products.
4. Kinetics of biological sulfide oxidation at a low DO is described by different rate equations as follows: