Synergistic effect of zero-valent iron and static magnetic field on wastewater purification and bioelectricity generation in electroactive constructed wetlands

Abstract

This study investigated the enhancement effect of zero-valent iron and static magnetic field on the pollutant removal and power generation of electroactive constructed wetland. As demonstration, a conventional wetland was systematically modified by introducing zero-valent iron and then a static magnetic field, leading to progressive increases in pollutant (namely NH4+-N and chemical oxygen demand) removal efficiencies. By introducing both zero-valent iron and a static magnetic field, the power density increased four-fold to 9.2 mW/m2 and the internal resistance decreased by 26.7% to 467.4 Ω. Notably, static magnetic field decreased the relative abundance of electrochemically active bacteria (such as Romboutsia), while significantly enhancing species diversity. The permeability of the microbial cell membrane was improved, leading to a reduction in activation loss and internal resistance, thereby enhancing power generation capacity. Results showed that the addition of zero-valent iron and the applied magnetic field were beneficial to the pollutants removal and bioelectricity generation.