Designing, Prototyping, and Testing of an Automated Solar-Powered UV-LED System for Microbial Deactivation

Ultraviolet (UV) radiation in the 200–300 nm range is highly effective for microbial deactivation and has become a promising disinfection technology. There are several sources of UV radiation, including mercury vapor lamps, xenon arc lamps, deuterium lamps, and light emitting diodes (LEDs). Because of the associated damage to the skin, UV-LEDs are considered the safest and can provide a sustainable, energy-efficient, and environmentally friendly solution. However, there are some limitations in energy management, efficiency, automation, and optimization of UV-LEDs due to their wavelengths. Therefore, to optimize the efficiency in view of the application to microbial disinfection four UV-LED wavelengths (255 nm, 265 nm, 275 nm, 285 nm) were investigated. Thus, the dissertation work focused on the design, prototyping, and testing of an automated solar-powered UV-LED-based disinfection system, which serves as a sustainable and efficient solution for microbial deactivation in water, air, and surface applications.
Using the double-agar layer technique, the testing of these UV-LEDs for their ability to disinfect microbes/bacteriophages (MS2 and Phi6) was performed. Experimental results indicate that shorter wavelengths (255 nm) achieved the highest microbial inactivation with lower energy input, while longer wavelengths (285 nm) required significantly higher doses. The 255 nm UV-LED system, at a UV dose of 94.3 mJ/cm², achieved a 2.03 log reduction (99.08% reduction) for MS2, and at 117.9 mJ/cm², it achieved a 2.14 log reduction (99.28% reduction) for Phi6. In contrast, the 285 nm UV-LED system required 174.6 mJ/cm² for a 1.65 log reduction (97.78% for MS2) and 192.06 mJ/cm² for a 1.75 log reduction (98.25% for Phi6). The regression analysis and two-way ANOVA showed that the UV dose and wavelength are statistically significant in deactivating the microbial organisms. Finally, an automated solar-powered UV-LED-based disinfection system was designed, built, and tested. Similar results were obtained with the same statistical significance.
This research established solar-powered UV-LED disinfection systems as a scalable, sustainable, and highly effective solution for microbial decontamination. These findings will contribute to advancements in UV-LED technology, renewable energy integration, and automated disinfection, with diverse applications in healthcare, surface, water treatment, and public sanitation.