Iron-Ozone Catalytic Oxidation Reactive Filtration of Municipal Wastewater at Field Pilot and Full-Scale with High-Efficiency Pollutant Removal and Potential Negative CO 2 e with Biochar.

Iron-ozone catalytic oxidation (CatOx) shows promise in addressing challenging wastewater pollutants. This study investigates a CatOx reactive filtration (Fe-CatOx-RF) approach with two 0.4 L/s field pilot studies and an 18-month, 18 L/s full-scale municipal wastewater deployment. We apply ozone to leverage common sand filtration and iron metal salts used in water treatment into a next-generation technology. The process combines micropollutant and pathogen destructive removal with high-efficiency phosphorus removal and recycling as a soil amendment, clean water recovery, and the potential for carbon-negative operation with integrated biochar water treatment. A key process innovation is converting a continuously renewed iron oxide coated, moving bed sand filter into a "sacrificial iron" d-orbital catalyst bed after adding O 3 to the process stream. Results for the Fe-CatOx-RF pilot studies show >95% removal efficiencies for almost all >5×LoQ detected micropollutants, with removal rates slightly increasing with biochar addition. Phosphorus removal for the pilot site with the most P-impacted discharge was >98% with serial reactive filters. The long-term, full-scale Fe-CatOx-RF optimization trials showed single filter 90% TP removal and high-efficiency micropollutant removals for most of the compounds detected, but slightly less than the pilot site studies. TP removal decreased to a mean of 86% during the 18 L/s, 12-month continuous operation stability trial, and micropollutant removals remained similar to the optimization trial for many detected compounds but less efficient overall. A >4.4 log reduction of fecal coliforms and E. coli in a field pilot sub-study suggests the ability of this CatOx approach to address infectious disease concerns. LCA modeling suggests that integrating biochar water treatment into the Fe-CatOx-RF process for P recovery as a soil amendment makes the overall process carbon-negative at -1.21 kg CO 2 e/m 3 . Results indicate positive Fe-CatOx-RF process performance and technology readiness in full-scale extended testing. Further work exploring operational variables is essential to establish site-specific water quality limitations and responsive engineering approaches for process optimization.