Biokinetics of microbial consortia using biogenic sulfur as a novel electron donor for sustainable denitrification

In this study, the biokinetics of autotrophic denitrification with biogenic S⁰ (ADBIOS) for the treatment of nitrogen pollution in wastewaters were investigated. The used biogenic S⁰, a by-product of gas desulfurization, was an elemental microcrystalline orthorhombic sulfur with a median size of 4.69 µm and a specific surface area of 3.38 m²/g, which made S⁰ particularly reactive and bioavailable. During denitritation, the biomass enriched on nitrite (NO₂^–) was capable of degrading up to 240 mg/l NO₂^–-N with a denitritation activity of 339.5 mg NO₂^–-N/g VSS·d. The use of biogenic S⁰ induced a low NO₂^–-N accumulation, hindering the NO₂^–-N negative impact on the denitrifying consortia and resulting in a specific denitrification activity of 223.0 mg NO₃^–-N/g VSS·d. Besides Thiobacillus being the most abundant genus, Moheibacter and Thermomonas were predominantly selected for denitrification and denitritation, respectively.