Chlorine is the most common and effective disinfectant at the moment is. Among the chlorine-free water purification methods, ultraviolet radiation, the copper and silver ions, ozonation, the use of preparations of the active oxygen of the organic polymer are widespread. In some cases a combination of above mentioned methods is the most effective. Nowadays, new technologies allow to use following methods for water perification.
UV-radiation of a certain wavelength and intensity, when exposed for some time to microorganisms, damages their DNA, making them incapable of reproduction. This principle is based on UV disinfection, it kills even those bacteria which survive in the chlorination of water: e.g., spore-forming bacteria (Mone, "Ultraviolet (UV) Water Purifiers - What Are They and How Do They Work.").
Ozone (O3) is one of the most powerful oxidizers. It quickly and efficiently removes water from bacteria and other contaminants without changing its natural properties and it is not acting on the person, because a few minutes after the formation and dissolution in water, it turns into oxygen. However, this feature has a disadvantage: ozone can not conserve water and it is used together with chlorination. Ozone is destroying bacteria, viruses, fungi, algae, and nitrogen compounds that are present in human sweat and urine and serve as the basis for the formation of chloramines (Oram, "Ozonation in Water Treatment.").
Ions of silver and copper are also used for water purification. The first metal is a well-known bactericide, and the second is algaecide. The effectiveness of disinfection of water depends on the concentration of silver ions in it. Guaranteed destruction of the bacteria happens when the ion concentration in water excesses of 0.15 mg/l. Water disinfection with active oxygen involves the introduction of a reagent containing oxygen, in particular hydrogen peroxide H2O2, which reacts with the aqua releases active oxygen in the form of the radical (O). It destroys many representatives of pathogenic organisms. ("Copper-silver Ionization as a Disinfectant.").
Works Cited
Mone, John. "Ultraviolet (UV) Water Purifiers - What Are They and How Do They Work." HarvestH2O. Web. 04 May 2016.
Oram, Brian. "Ozonation in Water Treatment." Water Research Center. Web. 04 May 2016.
"Copper-silver Ionization as a Disinfectant." Water Treatment Solutions. Web. 04 May 2016.
