Desinfecção de água superficial com o uso de reator ultravioleta de bancada

Abstract

Many waterborne diseases result from the improper treatment of water. One alternative for disinfecting surface water is the use of a physical agent: ultraviolet radiation. Disinfection through ultraviolet radiation is a process that eliminates the need for introducing chemical substances into the water. The goal of disinfection is not to destroy all forms of life but rather to deactivate pathogenic microorganisms. Therefore, the objective of this study is to investigate the disinfection of surface water using a benchtop ultraviolet reactor to improve water quality for communities lacking proper water supply systems. This alternative is increasingly proving to be efficient in the inactivation of pathogenic microorganisms over the years. The study was conducted at the Federal University of Santa Maria, Frederico Westphalen campus, using surface water extracted from a lake near the university. The chemical and physical variables related to water quality for human consumption included pH, temperature, turbidity, electrical conductivity, ABS 254 nm, apparent and true color, and Total Organic Carbon (TOC). Microbiological variables included total coliforms, Escherichia coli, and Aerobic Bacterial Spores (ABS). Three batch-scale benchtop experiments were conducted with doses of 1.68 (D1), 3.35 (D2), 5.04 (D3), and 6.72 (D4) Wh/m³. Regarding physicochemical variables, no changes were observed during the process with the application of different radiation doses. Microorganism inactivations yielded reasonable values, given that the water did not contain many suspended solids. However, inactivation values for EBA were not high (0.52 log inactivation), attributed to the short contact time. Similarly, E. coli and total coliforms did not show significant inactivation values, with 0.88 log inactivation for E. coli (87%) at dose D2 and 0.84 log inactivation for total coliforms (85%) also at dose D2. It is concluded that longer contact times are necessary for better inactivation values and that the combined use of disinfection methods would be a solution for more successful microorganism inactivation.