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5.1. Water disinfection
The larger part of pathogenic microorganisms in drinking water is removed by means of water treatment techniques, such as coagulation, flocculation, settling, and filtration. To increase drinking water safety, disinfection is applied as a final treatment step.
Disinfection is of unquestionable importance in the supply of safe water for drinking purposes. Water disinfection means the removal, deactivation or killing of pathogenic microorganisms. During this process microorganisms are destroyed or deactivated, causing termination of growth and reproduction. When microorganisms are not removed from drinking water, its usage will cause illness in humans. Disinfection is a process related to sterilization and during this process all present microorganisms are killed, both harmful and harmless. It can be performed by means of physical or chemical disinfectants. These disinfectants also remove organic contaminants from water, serving as nutrients or shelters for microorganisms. They should not only kill microorganisms, but must also have a residual effect, which means that they remain active in the water after disinfection. A disinfectant should prevent pathogenic microorganisms from growing in the plumbing after disinfection, causing the water to be decontaminated.
For chemical disinfection of water the following disinfectants can be used:
- Chlorine (Cl2)
- Chlorine dioxide (ClO2)
- Hypochlorite (OCl-)
- Ozone (O3)
- Halogens: Bromine (Br2), iodine (I)
- Bromine chloride (BrCl)
- Metals: copper (Cu2+), silver (Ag+)
- Kaliumpermanganate (KMnO4)
- Fenols
- Alcohols
- Soaps and detergents
- Kwartair ammonium salts
- Hydrogen peroxide
- Several acids and bases
For physical disinfection of water the following disinfectants can be used:
- Ultraviolet light (UV)
- Electronic radiation
- Gamma rays
- Sounds
- Heat
