Synergistic antifouling and organic removal using Fe/N co-doped biochar-modified ceramic membranes via in situ peroxymonosulfate activation

In this study, catalytic ceramic membranes (CMs) were modified with N-doped biochar (N-C-CM) and Fe/N co-doped biochar (Fe/N-C-CM) to mitigate membrane fouling and improve pollutant removal during advanced wastewater treatment. The developed catalytic CM filtration system combined peroxymonosulfate activation with filtration, enabling in situ oxidation for enhanced organic removal and membrane self-cleaning. Compared with pristine CMs and N-C-CM, Fe/N-C-CM demonstrated superior pollutant removal efficiency and anti-fouling performance. Under optimal conditions, Fe/N-C-CM achieved significantly higher removal efficiencies for the model foulants, namely sodium alginate (SA) and bovine serum albumin (BSA). Specifically, Fe/N-C-CM removed 55.85% of SA and 83.13% of BSA. In contrast, N-C-CM removed 23.71% of SA and 54.04% of BSA. Additionally, Fe/N-C-CM suppressed pore blockage and cake layer formation, thereby effectively mitigating both reversible and irreversible fouling. In the N-C-CM system, the primary reactive oxygen species were SO₄⁻•/•OH. In Fe/N-C-CM, the dominant reactive species shifted to singlet oxygen (¹O₂). The highly selective ¹O₂-mediated reaction facilitated efficient pollutant mineralization. To assess its practical feasibility, Fe/N-C-CM was used to treat secondary effluent from a wastewater treatment plant. Under optimal conditions, Fe/N-C-CM achieved 68.45% total organic carbon removal and reduced the turbidity of the treated effluent to undetectable levels. Notably, Fe/N-C-CM maintained high flux and fouling resistance over multiple cycles, indicating robust stability and effective self-cleaning. This study provides a sustainable approach combining advanced oxidation with membrane technology for efficient wastewater reclamation.