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[Display omitted] • The sediments after oxidation with nitrate show well phosphorus adsorption effect. • Fe-P is the main speciation of phosphorus immobilization in the oxidizing sediment. • Higher sediment oxidation correlates with improved phosphorus immobilization. • Biological phosphorus immobilization is potential pathway in oxidation sediment. 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. [ABSTRACT FROM AUTHOR]

This study investigated the performance of co-digesting cucumber residues, corn stover, and pig manure at different ratios. Microbial community structure was analyzed to elucidate functional microorganism contributing to methane production during co-digestion. Results show that mixing cucumber residues with pig manure and corn stover could significantly improved methane yields 1.27–3.46 times higher than mono-feedstock. The methane yields decreased with the cucumber residues increasing when the pig manure ratio was fixed at 4 and 3, and was opposite at ratio 5. The optimal mixture ratio was T2 with the highest methane yield (305.4 mL/g VS) and co-digestion performance index (1.97). The main microbiological community in T2 was bacteria of Firmicutes (44.6%), Bacteroidetes (32.5%), Synergistetes (3.8%) and archaea of Methanosaeta (37.1%), Methanospirillum (18.2%). The mixture ratios changed the microbial community structures. The adding proportion of cucumber residues changed the community composition of the archaea, especially the proportion of Methanosaeta . [ABSTRACT FROM AUTHOR]