Fused Filament Fabrication of Recycled Nylon‐TiO ₂ Honeycomb Filters for Grey Wastewater Filtration

ABSTRACT This research focuses on fabricating a nylon honeycomb‐structured three‐dimensional (3D) filter for grey wastewater treatment using fused filament fabrication (FFF) and evaluating its performance in water treatment. The honeycomb module offered a tortuous pathway for particulate deposition during dead‐end and depth filtration. A titanium dioxide (TiO 2 ) nanoparticle coating was applied via spin coating to enhance clogging effects and contaminant retention. A custom test setup was developed to analyse clogging behavior and estimate the filter lifespan. In dead‐end mode, the coated filter achieved up to 85% removal of biochemical oxygen demand (BOD) and 80% removal of chemical oxygen demand (COD) during the first cycle, while depth filtration achieved 80% BOD and 75% COD removal. By the fifth cycle, removal efficiencies decreased to 58% BOD and 50% COD in depth filtration, indicating sustained performance over repeated use. Scanning electron microscopy (SEM) visualized progressive particulate accumulation; Fourier‐transform infrared spectroscopy (FTIR) confirmed TiO 2 presence; and energy‐dispersive X‐ray spectroscopy (EDX) showed increased surface carbon content after filtration. Ultraviolet‐visible (UV‐Vis) spectroscopy confirmed moderate absorbance reduction at peak wavelengths. However, turbidity and total suspended solids (TSS) remained above acceptable limits (e.g., turbidity > 235 NTU; TSS > 410 mg/L), revealing the need for finer pore sizes or multilayer filtration. Clogging Index (CI) reached 0.45 in dead‐end and 0.40 in depth filtration by the fifth cycle. The results demonstrate that this 3D‐printed nylon‐TiO 2 module provides moderate contaminant removal with rapid clogging kinetics, offering promise for non‐potable reuse and decentralized greywater treatment applications.