UV-C LED Disinfection of Antibiotic-Resistant Escherichia coli in Water: Integration with Ceramic Membrane Filtration

The growing problem of antibiotic resistance poses a serious threat to public health and ecosystems. New disinfection methods could help address this global issue. In this study, ultraviolet-C light-emitting diodes (UV-C LEDs) were used to inactivate Escherichia coli isolates resistant to antibiotics. These isolates were obtained from various real water sources, including seawater, surface water, and treated wastewater. Inactivation assays were performed using two wavelengths (255 nm and 265 nm), applying UV fluences ranging from 1 to 7 mJ/cm2 to a phosphate-buffered saline solution inoculated with a mixture of 10 E. coli strains. Using an UV fluence of 2 mJ/cm2, a log reduction of about 5 was achieved with both UV-C wavelengths tested. SEM imaging revealed no observable alterations in cell morphology after UV-C exposure. Pyrimidine dimer formation was quantified, yielding approximately 40 ng/mL of cyclobutane pyrimidine dimers after 2 mJ/cm2 of exposure to both wavelengths. Additionally, water treatment was tested using ceramic silicon carbide membranes. High average rejection efficiencies (99.9%) were obtained for both total coliforms and E. coli using uncut flat sheet membranes. The combination with UV-C LEDs led to treatment of the concentrated membrane retentate (99.985% or higher), highlighting the potential of this treatment approach for effective water disinfection.