Biological Waste-Derived Dual-Site Catalyst Empowers Electro-Fenton Systems to Sustainably Decontaminate Livestock Wastewater

Livestock and poultry industries are pivotal for meat production, but produced wastewater with heavy pollution challenges environmental sustainability and public health. The electro-Fenton (EF) process, capable of in situ production and activation of hydrogen peroxide, is promising for decontaminating recalcitrant pollutants, yet fabricating a highly active bifunctional cathode catalyst across a broad pH range remains a bottleneck. Guided by green chemistry principles, we synthesized a dual-site catalyst from biological waste to facilitate hydroxyl radical production. Combined experimental and theoretical investigations unveiled that the Fe2O3 sites facilitated H2O2 generation via catalyzing the oxygen reduction reaction, whereas Fe3N sites promoted in situ H2O2 activation into hydroxyl radicals. This electrocatalyst, integrated into a gas diffusion electrode, achieved stable, aeration-free mineralization of antibiotic contaminants at neutral pH with a low energy consumption of just 0.94 kWh/g of removed total organic carbon. The further development of a tandem system that coupled the anammox bioprocess with the EF process exhibited exceptional efficiency in both nitrogen removal and tertiary purification of actual livestock wastewater, obviating the need for pH adjustments or Fenton reagent additives. These findings underscore the potential scalability and application of our proposed approach in promoting sustainable wastewater management practices.