Gravity-driven membrane system for secondary wastewater effluent treatment: Filtration performance and fouling characterization

•A gravity-driven membrane (GDM) system was tested for wastewater post-treatment.•Fouling evolution was monitored by optical coherence tomography (OCT) in a real-time.•Flux variation and effluent quality was investigated to associate them with fouling.•Fouling characterization and reversibility confirmed a sustainable operation of GDM.