摘要：Water and wastewater require disinfection to meet the regulated limit conditions for the microbial load. The main objective of disinfection is to reduce the concentration of pathogens (bacteria, viruses and protozoa) in the water at levels below the limits of infections. Disinfection can be carried out by thermal (heat pasteurisation, solar pasteurisation), physical (filtration, ultrasounds, high pressure, electron beam, gamma irradiation, ultraviolet irradiation) or chemical means (chlorination, acidification, alkaline addition, ozone, enzymes, carbon-based materials). Ultraviolet (UV) light is a form of electromagnetic radiation having wavelengths between 10 and 400 nm. Experimental UV wavelength ranges from 200 nm to 400 nm and is subdivided in UV-A (315–400 nm), UV-B (280–315 nm) and UVC (200–280 nm). The last one is called the germicidal range because it effectively inactivates bacteria and viruses. UV light is able to inactivate microorganisms, reducing the microbial load in thin film of drinking water and wastewaters. The germicidal effect consists of damaging the nucleic acid, thus preventing the replication of microorganisms. UV light inactivates water-borne pathogens in the following order: protozoa, bacteria, bacterial spores, viruses and bacteriophages. While UV light irradiation has not been largely used in drinking because it leaves no residual to provide protection against further contamination, it is well suited for wastewater treatment, the absence of any residual in treated water being an advantage for the aquatic life.
