Phosphorus immobilization in sulfide-ferrous oxidation process driven by nitrate reduction during black-odorous sediment remediation.

During remediation of black-odorous sediment, the pathways of phosphorus immobilization require clarification alongside the oxidation of sulfide and ferrous. This study separated the oxidation stages of sulfide and ferrous through controlled sodium nitrate dosing ratios and methods, and analyzed the changes in phosphorus species and immobilization effects throughout these processes. Results showed that iron-bound phosphorus was the primary contributor to the phosphorus immobilization in the oxidation process, with increased 19% in ferrous oxidation stage and affected the transformation between phosphorus sources or sinks in the adsorption experiment. Additionally, the increase in abundance of phosphorus uptake and transport genes, and denitrifying phosphorus accumulation genes in sediment after ferrous oxidation (1 %-18 % and 87 %-164 %, respectively) indicated the potential for biological phosphorus immobilization. These results demonstrated that higher degrees of sediment oxidation correlate with stronger phosphorus immobilization capacities, providing theoretical bases for phosphorus immobilization during the restoration of black-odorous water bodies.