Water Purifiers – How Safe is the Water You Drink?
The Latin expression ‘Aqua pura is Aqua vitae’ perhaps best expresses the value of pure water. Translated into English, it literally means ‘pure water is the water of life’.
Water is life’s mater and matrix, mother and medium. There is no life without water, but water in its raw state is not suitable for drinking. It contains numerous contaminants, which can be dangerous to human health.
But, thanks goes to Science that has invented devices to shield civilization against such aqua ailments. A water purifier is one of such devices that purify our drinking water. A water purifier is a wonderful device that converts raw water so that it tastes like nectar; therefore by this process it makes ordinary tap water perfectly suitable for drinking.
Health Benefits of a Water Purifier:
A water purifier is very beneficial for healthy living. Ordinary untreated water can contain numerous contaminants including bacteria, algae, viruses, fungi, minerals, and man-made chemical pollutants that cannot be seen with the naked eye. These contaminants are very pernicious for one’s health.
A water purifier kills these organisms and filtrates the contaminants to make the water perfectly fit for drinking. Thus water purifiers save us from numerous dangerous bacterial and viral diseases that easily spread when water becomes contaminated.
Water Purification Techniques:
Different water purifiers use different techniques of purification. The common techniques used to purify water include boiling, carbon filtering, distilling, reverse osmosis, ion exchange, electrode ionization, water conditioning and plumbo-solvency reduction.
Carbon filtering: This technique is commonly used in home water filters. Charcoal, a form of carbon with a high surface area due to its mode of preparation, adsorbs many compounds, including some toxic compounds. The water is passed through activated charcoal to remove such contaminants. Granular charcoal filtering and sub-micron solid block carbon filtering are the two types of carbon filtering systems.
Granular charcoal is not very effective for removing contaminants such as mercury, volatile organic chemicals, asbestos, pesticides, disinfections byproduct (trihalomethanes), mtbe, pcbs etc. The sub-micron solid block carbon filter is the better system that removes all of the contaminants.
Home water filters drinking water sometimes also contains silver. These small amounts of silver ions can have a bactericidal effect.
Reverse osmosis: The reverse osmosis water system is the technique in which mechanical pressure is applied to an impure solution to force pure water through a semi-permeable membrane. The process is called reverse osmosis, and is theoretically the most thorough method of large-scale water purification.
Ion exchange: Most common ion exchange systems use a zeolite resin bed and simply replace unwanted Ca2+ and Mg2+ ions with benign (soap friendly) Na+ or K+ ions. This is the common water softener. A more rigorous type of ion exchange swaps H+ ions for unwanted cations and hydroxide (OH-) ions for unwanted anions. The result is H+ + OH- → H2O. This system is recharged with hydrochloric acid and sodium hydroxide, respectively. The result is essentially deionized water.
Electrodeionization: It includes passing the water through a positive electrode and a negative electrode. Ion selective membranes allow the positive ions to separate from the water toward the negative electrode and the negative ions toward the positive electrode. It results in high purity de-ionized water. The water is usually passed through a reverse osmosis unit first to remove nonionic organic contaminants.
Water conditioning: This is a method of reducing the effects of hard water. Hardness salts are deposited in water systems subject to heating because the decomposition of bicarbonate ions creates carbonate ions that crystallize out of the saturated solution of calcium or magnesium carbonate. Water with high concentrations of hardness salts can be treated with soda ash (Sodium carbonate) that precipitates out the excess salts, through the common ion effect, as calcium carbonate of very high purity. The precipitated calcium carbonate is traditionally sold to the manufacturers of toothpaste.
Plumbo-solvency reduction: In areas with naturally acidic waters of low conductivity (i.e. surface rainfall in upland mountains of igneous rocks), the water is capable of dissolving lead from any lead pipes that it is carried in. The addition of small quantities of phosphate ion and increasing the pH slightly both assist in greatly reducing plumbo-solvency by creating insoluble lead salts on the inner surfaces of the pipes.