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Chlorine Treatment for Water Purification

Water obtained from various sources such as ground, rain, canal, sea, river etcetera contain some or the other undesired chemical, effluent, waste or simply unwanted constituents. The process of removing these impurities from raw water, in order to improve the quality of water for specific purposes, is known as water purification. Among various chemicals used for this purpose, chlorine is a commonly used one.

  1. History of Chlorine as a Purification Agent

    • Chlorine as a water purification agent came into the lime light after John Snow used it for the first time to treat cholera by adding it to water from broad street pump. Snow's primary purpose to use chlorine was based on its disinfectant properties. Chlorine is a chemical that kills bacteria and other pathogens as well as sterilizes water from further contamination by them. Snow's application of chlorine helped curb cholera as he had predicted but it also helped combat typhoid. A sudden drop in the number of deaths due to typhoid cemented chlorine as a solution to water purification.

    Rising Use of Chlorine

    • The use of chlorine spread throughout the world soon after Snow's triumph; and along with the use of sand filters, water was purified to wipe out the causes of fatal diseases such as dysentery, cholera and typhoid. In fact, it was such a huge success in water purification that it was called the discovery of the millennium with regard to public health. Chlorine remains to be the preferred disinfectant for drinking water.

    Side Effects of Chlorinated Water

    • The biggest side effect is in the connection of chlorinated water with asthma. Chlorine vapors can irritate the nasal linings and cause inflammation of lungs if taken in large quantities. The chlorine in water vaporizes. A regular intake of chlorine vapors leads to asthma just as high concentration vapors do. Furthermore, chlorine is also known to produce trihalomethanes, a known carcinogen. Although the content of this compound in chlorinated water is low, it is still a threat.

    Limitations of Chlorine in Water Purification

    • Chlorine is an excellent disinfectant, but it does not eradicate all kinds of pathogens. In particular, cryptosporidia is unaffected even after the action of chlorine. Commonly called crypto, it is the most common cause of diarrhea. Crypto is immune to the effects of chlorine and therefore cannot be removed by simple chlorination of water. Hence, water purification through chlorine has serious limitations since a microorganism as dangerous as crypto remains unaffected after the use of chlorine.

    Facts

    • Chlorine is used widely because of its 99 percent disinfection rate. Chlorine is also used by general households to disinfect well water and ground water. When using chlorine, the chlorine content of the water body must be replenished regularly because some of it is lost through vaporization and some through chemical reaction with other compounds present in the water body.

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