Advancing Waterborne Fungal Spore Control: UV-LED Disinfection Efficiency and Post-Treatment Reactivation Analysis

The presence of fungal spores in water poses a significant risk to public health, requiring effective inactivation strategies. Ultraviolet (UV) radiation is a widely used approach, traditionally employing mercury vapor lamps. However, these lamps have efficiency limitations and contain hazardous materials. As an alternative, ultraviolet light-emitting diodes (UV-LEDs) have emerged as a safer and more sustainable option. Despite their advantages, research on their efficacy against fungal spores remains limited. This study investigates the inactivation and post-exposure response of Aspergillus niger and Penicillium sp. spores using a collimated UV-LED system. The impact of two different wavelengths (265 nm and 280 nm) and post-treatment conditions (light and darkness for 24 h) on fungal viability was analyzed. Kinetic modeling was applied to assess the resistance of the spores and their capacity for photoreactivation. The results demonstrate that both the UV wavelength and the environmental conditions after exposure significantly influence disinfection outcomes. Penicillium sp. exhibited greater susceptibility to UV radiation but also higher photoreactivation potential, while A. niger showed stronger resistance and lower recovery capacity. The UV dose required for 99% inactivation, considering photoreactivation effects, was 323.7 ± 90.0 mJ cm−2 and 321.9 ± 43.8 mJ cm−2 for A. niger, whereas for Penicillium sp., it was 167.7 ± 13.0 mJ cm−2 and 146.5 ± 29.2 mJ cm−2 at 265 nm and 280 nm, respectively. These findings emphasize the necessity of tailoring UV-LED disinfection strategies based on the specific characteristics of the target organisms and post-treatment environmental factors.