Avaliação da inativação de microrganismos indicadores em água para consumo por LED-UVC como tecnologia de inativação em ponto de consumo domiciliar

Abstract

Microbiological contamination of water from surface and groundwater sources remains a significant global public health concern. Among microbial contaminants, viruses have gained increasing attention due to their high prevalence in human waste and potential to cause respiratory and gastrointestinal illnesses, particularly in vulnerable populations. Global interconnectedness further facilitates the rapid spread of viral pathogens, including emerging strains. While chlorination is the most commonly used disinfection method, it poses drawbacks such as the formation of potentially carcinogenic byproducts (e.g., trihalomethanes), as well as undesirable taste and odor, often leading to consumer rejection and increased risk from alternative water sources. Ultraviolet (UV) radiation has emerged as an effective alternative for microbial inactivation, particularly in communities without access to centralized water treatment systems. Within UV technologies, UVC LEDs stand out for their advantages, including low energy consumption, robustness, emission at specific wavelengths, and compatibility with solar power systems. This study evaluated the use of UVC LEDs (265 nm and 275 nm) for drinking water disinfection, focusing on the development and testing of a prototype for potential use in remote Amazonian communities. In bench-scale experiments, treated and untreated water samples were inoculated with E. coli Famp, E. coli CN-13, and bacteriophages MS2 and φX-174. The UV doses required for 4-log (99.99%) inactivation ranged from 13.48 to 15.1 mJ/cm² for Famp, 16.15 to 17.9 mJ/cm² for CN-13, and 35.42 to 55.28 mJ/cm² for the bacteriophages. In a subsequent phase, disinfection tests using pathogenic viruses indicated required doses of 27– 36 mJ/cm² for SARS-CoV-2, 54–63 mJ/cm² for adenovirus (HAdV), 51–90 mJ/cm² for HSV- 1, and 92–102 mJ/cm² for vaccinia virus (VACV), demonstrating efficacy comparable to mercury-based UV lamps. The prototype device achieved 100% inactivation at flow rates up to 100 mL/min. However, higher flow rates reduced particle residence time and led to inactivation below 4-log, indicating the device’s suitability for low-flow applications. The results highlight the potential of UVC LED technology as a viable, decentralized, and sustainable solution for water disinfection in underserved and remote areas.