Thermal methods, ultraviolet radiation, and ultrasonic waves for the treatment of waterborne pathogens

The chapter describes the physical processes used for water disinfection: thermal methods, ultraviolet (UV) radiation, and ultrasonic waves. The main common feature of these processes is that no additional chemical compounds are added into the water. However, none of those methods protects the treated water from its secondary bacterial contamination, which is their major disadvantage. Thermal disinfection involves the use of the boiling and pasteurization process of water. The principle of destroying pathogens in these methods is similar. The use of sufficiently high temperature for an appropriately long time allows the destruction of bacterial organisms present in water. However, these processes are very energy-consuming and rarely used. UV radiation has a bactericidal and mutagenic effect causing changes in the structure of nucleic acid. Strong bactericidal activity is also caused by ultrasound waves of frequencies above 20kHz. The mechanism of their effect is related to the phenomenon of cavitation. The chapter describes the mechanisms of destroying pathogenic organisms using specific methods. In addition, the main process parameters and facilities used in disinfection with the methods presented are discussed.