Highly dispersed nano zero-valent iron supported by pretreated stalks for the remediation of low C/N water bodies polluted by 2,4-dichlorophenol

Nano zero-valent iron (NZVI) is a promising material for reducing chlorophenol pollutants and remediating low C/N water bodies. However, NZVI particles tendency to aggregate and limited ability to supply electrons to microorganisms constrain its practical applications. In this study, in situ loading of NZVI onto pretreated stalks (PSS/NZVI) was proposed. Results show that pretreated stalks (PSS) effectively disperse NZVI. Additionally, PSS serves as a carbon source, promoting denitrification during the remediation of simulated low C/N water bodies when PSS/NZVI is added into sediment. Compared with the control sample, total nitrogen (TN) removal efficiency in the supernatant and interstitial water of the sediment increased from 64.5% and 71.4–96.3% and 94.7%, respectively. Notably, during remediation, NZVI in PSS/NZVI combines with P to remove total phosphorus (TP) as Fe-P precipitates. Furthermore, PSS/NZVI significantly enhances sediment microbial activity, enabling the system to withstand subsequent pollution shocks. This study provides an environmentally benign method to improve NZVI dispersity. Moreover, through simulated water bodies applications, the practical value of PSS/NZVI was demonstrated, improving the degradation efficiency of TN, TP, and 2,4-dichlorophenol (2,4-DCP) in low C/N water bodies, proving that the combination of zero-valent iron and waste stalk carbon sources is feasible for remediating chlorophenol-polluted low C/N water bodies. This research enhances the practical value of NZVI for remediating low C/N water bodies.