Synergistically enhancing the remediation of low C/N slightly black-odorous water body using pretreated stalk in-situ loaded with sulfidated nano zero-valent iron

Sulfidated nano zero-valent iron (S-NZVI) as reductants coupled with organic carbon are promising in enhancing denitrification which is crucial for remediation of low C/N water body. Nevertheless, the dearth of research on the effectiveness of these materials in actual water remediation limits their application. Additionally, most of the studies utilizes industrial chemical-derived organic carbon, which exacerbates environmental and economic burdens. This study proposes employing pretreated stalks in-situ loaded S/Fe (SS-S/Fe) to remediate the low C/N slightly black-odorous water body. The pretreated stalk acts as carbon source replacing the industrial chemicals. The pretreatment process was carried out by using H₂O₂ and acetic acid to decrease the lignin content. The 2, 4-dichlorophenol was utilized as a target pollutant for optimization of materials. The sediment from the water body was remediated, the impact of SS-S/Fe on water body and microbial community structure were clarified. The lignin residues in the stalk were found to enhance the dispersity, O₂ resistance, and reduction performance toward 2, 4-dichlorophenol of S/Fe. S/Fe facilitates 2, 4-dichlorophenol degradation via reduction and TP removal via forming Fe-P precipitation. SS plays a significant role in TN removal, assisting in enhancing the 2, 4-dichlorophenol and TP removal performance of S/Fe. Crucially, SS and S/Fe synergistically boost sediment microbial activity, conferring resistance to the subsequent pollution shock. The decisive role of SS in enhancing denitrification by cultivating Anaeromyxobacter, unclassified_f_Comamonadaceae, norank_f_norank_o_norank_c_Anaerolineae and Thiobacillus has been demonstrated. This study improves S-NZVI applicability in actual low C/N water bodies and provides new methods for utilizing stalk resources.