Electromagnetic Fenton Combined with Electro-Biological Coupling Technology for Treating High-Nitrogen Organic Chemical Wastewater.

High-nitrogen organic chemical wastewater is characterized by high chemical oxygen demand (CODCr), poor biodegradability, and toxic nitrogenous organics, posing significant challenges for conventional biological treatment. In this study, a dual-electrical treatment strategy integrating an electromagnetic Fenton (EM-Fenton) pretreatment unit with a three-dimensional biofilm electrode reactor (3D-BER) is proposed. The EM-Fenton system used iron-carbon fillers under electric and magnetic fields to generate hydroxyl radicals (·OH), enabling efficient oxidation of nitro-aromatic compounds and the conversion of organic nitrogen into NO3--N, while reducing Fe2+ input and iron sludge generation. Subsequently, the 3D-BER, filled with Fe3O4/Mn3O4-modified polyurethane spheres, facilitated autotrophic denitrification and phosphorus removal through enhanced extracellular electron transfer and trace hydrogen (H2) release. Experimental results demonstrated that the EM-Fenton system achieved CODCr and NH4+ removal rates of over 40% and 14%, respectively, under optimal HRT. The 3D-BER further improved removal efficiencies, with TN and TP reductions exceeding 80% and 81%, respectively, significantly outperforming the control groups. Microbial analysis revealed the enrichment of functional genera, such as Pararhodobacter and Thauera, and the upregulation of key denitrification pathways. This coupled system demonstrated high treatment efficiency, process synergy, and microbial selectivity, offering a promising approach for the advanced treatment of high-nitrogen industrial wastewater.