Sanitary sewage disinfection of a municipal treatment plant: use of individual and combined ozonation with UVC-LED radiation

Abstract

The systematic articulation of water resources involves the use of technical and management instruments capable of minimizing environmental impacts with optimization of available capital and constitution of sewage treatment plants (STPs) to seek greater efficiency in the removal of contaminants, including microbiological ones, and enhance the quality of the water to be released into the receiving bodies. In systems where tertiary treatment is present, disinfection methods such as chlorination and UV radiation are commonly used as a final polishing of the effluent, and the monitoring of their effectiveness in disinfection is extremely important to avoid unnecessary expenses. Thus, this research sought to analyze the efficiency of disinfection of effluent samples from an STP of the sanitation system in the municipality of Indaial-SC using ozonation methods and the process combined with UVC-light-emitting diode (LED) radiation, on a bench scale, in batches. The determination of treatment efficiency was carried out by quantifying colony-forming units (CFU), and variables such as pH (5, 7, and 9) and application time (10, 20, and 30 min) formed the configuration of the analysis. The optimal disinfection point was reached within 20 min of the process, regardless of the disinfection method. In 10 min time, whenever the combined application was used, it showed improvement in efficiency at all pHs, most notably in alkaline medium. The application of UV radiation through LED is a recent technology and, therefore, has aroused interest in research worldwide.