Interfacial catalytic ultrafiltration for surface water purification: Mechanisms from fouling mitigation to metabolic pathway response.

Interface confined catalysis driven by iron minerals (α-FeOOH) offers a promising strategy to mitigate membrane fouling in ultrafiltration (UF) treating surface water, yet its performance and underlying interfacial mechanisms remain insufficiently quantified. In this study, the in-situ Fenton-like oxidation initially induced a sharp flux decline due to Fe(III)-associated interfacial aggregation/deposition of NOMs, followed by a partial flux recovery, suggesting a dynamic equilibrium between the deposition of foulants and their oxidative degradation at membrane interface. DOC removal reached 43.76%, with a priority transformation of humic- and polysaccharide-like components on membrane surface. XDLVO analysis revealed that the in-situ Fenton-like oxidation created an attraction-enhanced interaction regime, followed by electrostatic repulsive barrier (∼15.19 kT) that constrained further foulants approach and attachment. High-throughput sequencing results indicated that the interfacial iron-rich and redox-active environment reshaped microbial community structure and upregulated genes involving in Fe(II)/Fe(III) cycling and NOMs decomposition. KEGG database annotation further clarified the possible metabolic pathways linking microbial activity to Fe/C/N cycling under oxidation stress. Overall, this study provided mechanistic insight for engineering catalytic UF membranes to reduce total fouling resistance, regulate interfacial fouling development, and control biofouling during surface water treatment.