2. Disinfectants Post-treatment, it is crucial to disinfect the treated effluent to eliminate harmful pathogens. Chlorine, ozone, and ultraviolet (UV) light are commonly used disinfectants in STPs. Chlorination, while effective, requires careful management due to the formation of potentially harmful by-products. Conversely, UV disinfection offers a chemical-free alternative, reducing the risk of toxic residue but necessitating thorough filtration of water before application.