Whoa! Water Can Be Purified With Solar Energy! Find Out How.

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It is well documented that solar energy can be an effective means of cleaning contaminated water. This is because ultraviolet (UV) light destroys the formation of DNA linkages in microorganisms, thereby preventing them from reproducing and thus rendering them harmless. The World Health Organization lists solar disinfection in clear bottles by the combined action of UV radiation, as well as thermal disinfection (pasteurization) in opaque vessels with sunlight from solar cookers or reflectors and combination systems employing chemical coagulation-flocculation as some of the most promising and accessible technologies for household water treatment.

There are various products available on the market for water purification using solar energy. One method for solar water disinfection (also called Solis) uses solar energy to make water contaminated with bacteria, viruses, protozoa, and worms safe to drink. Water contaminated with non-biological agents such as toxic chemicals or heavy metals require additional steps to make the water safe to drink. It is a simple water treatment method using solar radiation (UV-A light and temperature) to destroy pathogenic bacteria and viruses present in the water. It?s efficiency to kill Protozoa is dependent on the water temperature reached during solar exposure and on the climatic and weather conditions. Microbiologically contaminated water is filled into transparent containers and exposed to full sunlight for 6 hours.

? improves the microbiological quality of drinking water

? does not change the taste of water,

? is applicable at the household level,

? is simple in application, relies on local resources and renewable energy,

? is replicable with low investment costs

Effects of UV-radiation

Solar radiation can be divided into three ranges of wavelength: UV radiation, visible light, and infrared radiation. UV radiation cannot be perceived by the human eye. It is very aggressive radiation that can cause severe damage to the skin and eyes and destroys living cells. Luckily most of the UV-C and UV-B light in the range of 200 to 320 nm is absorbed by the ozone (O3 ) layer in the atmosphere which protects the earth from radiation coming from space. Only a higher fraction of UV-A radiation in the wavelength range of 320nm ? 400nm, near the visible violet light, reaches the surface of the earth. UV-A light has a lethal effect on human pathogens present in water. These pathogens are not well adapted to aggressive environmental conditions as they find their specific living conditions in the human gastrointestinal tract. Therefore, they are more sensitive to sunlight than organisms commonly abundant in the environment. UV-A radiation directly interacts with the DNA, nucleic acids and enzymes of the living cells, changes the molecular structure and leads to cell death. UV radiation also reacts with oxygen dissolved in the water and produces highly reactive forms of oxygen (oxygen free radicals and hydrogen peroxides). These reactive molecules also interfere with cell structures and kill the pathogens.

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