Carbon dioxide and weak magnetic field enhance iron-carbon micro-electrolysis combined autotrophic denitrification

Combining iron-carbon micro-electrolysis and autotrophic denitrification is promising for nitrate removal wastewater. In this study, four continuous reactors were constructed using CO2 2 and weak magnetic field (WMF) to address challenges like iron passivation and pH stability. In the reactors with CO2 2 + WMF (10 and 35 mT), increase in total nitrogen removal efficiency was significantly higher (96.2 +/- 1.6 % and 94.1 +/- 2.7 %, respectively) than that of the control (51.6 +/- 2.7 %), and Fe3O4 3 O 4 converted to low-density FeO(OH) and FeCO3, 3 , venting passivation film formation. The WMF application decreased the N2O 2 O emissions flux by 8.7 % and 20.5 respectively. With CO2 2 + WMF, the relative enzyme activity and abundance of denitrifying bacteria, especially unclassified_Rhodocyclaceae and Denitratisoma, , increased. Thus, this study demonstrates that CO2 2 and optimize the nitrate removal process, significantly enhancing removal efficiency, reducing greenhouse emissions, and improving process stability.