Usesultraviolet (UV) rays to penetrate the harmful pathogens in your home drinking water. The light does not necessarily destroy the organisms, butdisables their ability to multiply. Ultraviolet light is invisible but we areexposed to it every day from all sources including the earth sun. Ultravioletwater purification is a simple but effective process that destroys around99.99% of the harmful organisms in water. Aside from drinking water at homes,it is also used by untreated private water systems. UV water purification isusually done in conjunction with other forms of filtration such as reverseosmosis or carbon block.
UV Light Types
Thereare 3 recognized types of UV light. Long-wave UV light has the least germicidalvalue and has a wavelength range of 3250 to 3900 Angstrom Unit (A). Middle-waveUV light is the one found in sunlight and ranges from 2950 to 3250. It is knownfor its tanning effect and provides more germicidal action than the long-waveUV light. Short-wave UV light is the type commonly used in water purification.It has the greatest germicidal effect and destroys almost all types ofpathogens; bacteria, fungi, molds, spores and viruses. Its wavelength range is2000 to 2950 A.
However,short-wave UV light does not naturally occur in the earth surfaces because ofthe atmospheric protection from sunlight radiation below 2950 A. To utilizethis type of UV light for water purification, a mercury vapor lamp is needed toconvert electrical energy to short-wave UV light energy.
Themercury vapor lamp, also known as germicidal lamp, is considered the mostcost-effective source of short-wave UV light. These lamps are made out ofspecial quartz glass that usually permits short UV rays to pass through.Because of the low pressure inside the lamp, it can emit radiation that isaround 2537 A. Within this range, maximum germicidal effectiveness is achieved.
Anelectric arc is needed to produce heat enough to vaporize the small amount ofmercury inside the lamp. The vaporized mercury becomes ionized which in turngives off the short-wave UV radiation.
Itis important that water to be purified through UV radiation should be clearenough to allow the penetration of UV light. Turbid water should be filteredfirst to allow UV light penetration at its maximum effect. Most purificationwater systems use a 5-micron filter before using the mercury vapor lamp.
UVwater purification is affordable and effective at the same time. It onlyrequires the same amount of energy as when you turn on a 60 watt light bulb.
Chemicalsare not introduced into the water so this lessens the possibility of chemicalsposing harm to the human body. UV rays do not also damage septic tank andplumbing systems.
Inorder for the purification to really work, you need pre-filtration techniquesto remove sediments that may hinder the UV light from penetrating the water.Electricity is also required to run the mercury vapor lamp. This may not workin third world countries with frequent electricity shortages.
Thelamps need replacement once a year to ensure peak performance andeffectiveness.
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