Biocidal and photocatalytic nanofibre systems for tertiary wastewater treatment from lab to pilot scale

Conventional tertiary wastewater treatment processes often fail to ensure the complete removal of pathogenic microorganisms and contaminants of emerging concern, highlighting the need for advanced yet scalable post-treatment solutions. In this work, a modular nanofibre-based system was developed and validated from laboratory to pilot scale, combining two function-specific electrospun materials rather than a single multifunctional medium. A biocidal polyacrylonitrile nanofibre module containing silver was designed for microbial inactivation. In contrast, a photocatalytic poly(vinylidene fluoride-co-hexafluoropropylene) nanofibre module loaded with TiO2 was tailored for organic contaminant degradation. At laboratory scale, the PAN/silver nanofibres achieved complete Escherichia coli inactivation, while the PVDF-HFP/TiO2 nanofibres showed photocatalytic degradation efficiencies of 25.6 % for methylene blue and 24.4 % for rhodamine B. The two modules were validated at pilot scale using secondary settler effluent from a municipal wastewater treatment plant, achieving removal efficiencies of 99 % for Escherichia coli, 57.1 % for methylene blue, and 30.8 % for rhodamine B under realistic operating conditions. By separating structural-functional modules while integrating them at the system level, this study demonstrates the practical feasibility of electrospun nanofibre technologies for tertiary wastewater treatment beyond laboratory conditions, demonstrating a flexible solution for addressing both microbiological and chemical water quality challenges.