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Chlorination of Potable Water

Chlorination Process

The primary objective of water supply chlorination is disinfection.  Because of chlorine’s oxidizing powders, it has been found to serve other useful purposes in water treatment, such as

  1. Taste and odor control,
  2. Prevention of algae growths,
  3. Maintaining clean filter media,
  4. Removal of iron and manganese,
  5. Destruction of hydrogen sulfide,
  6. Color removal by bleaching of certain organic colors,
  7. Maintenance of distribution system water quality by controlling slime growths,
  8. Restoration and preservation of pipeline capacity,
  9. Restoration of well capacity, main sterilization,and
  10. Improved coagulation by activated silica.

Chlorine was first introduced to water treatment as disinfectant the turn of the century. Since that time it has become by far the predominant method used for this purpose.

This popularity is deserved because of its potency and range of effectiveness as germicide.

  • It is easy to apply, measure and control,
  • It is free from toxic or physiological effects,
  • It persists reasonably well and is relatively inexpensive.

Other agents may equal or even excel aqueous chlorine in any one of these characteristics, but there are none that combine them in such an advantageous way ozone, bromine, iodine, chlorine dioxide, silver ions, ultraviolet and ultrasonics uses in special situation, but none of them so far has been a serious competitor of chlorine.

As a result, of all the municipal water supplies that are being chemically disinfected, at least 99 percent use chlorine. very few processes enjoy this kind of monopoly. Even in countries where ozone is preferred, theoretically for physiologic reason. Chlorination is almost universally employed in practice as an adjunct to ozone.

Probably the first known use of chlorine as a germicide was Semmelweis when in 1846 he introduced the scrubbing and cleaning of hands in chlorine water between contacts with each mother after he found that child bed fever was being transmitted from mother to mother in maternity wards of Vienna General Hospital. Then in 1881 the German bacteriological Koch demonstrated under controlled laboratory condition that pure cultures of bacteria could be destroyed by hypochlorites.

The earliest record of a suggestion to chlorinate water even before water was known to be a carrier of disease germs, is a statement by Dr. Robley Dunlingsen in Human Health, published in Philadelphia in 1935.

” To make the water of the marshes potable, It has been proposed to add a small quantity of chlorine or one of the chlorides in small but sufficient amounts to destroy the foulness of fluid “

Who originally made this proposal is not known. That water is a mode of transition of disease has been known for only a little more than a hundred years.

Dr. John Snow first theorized in 1849 that water was the mode of communication of Cholera. He proved practically later.


One Response to “Chlorination of Potable Water”

  1. Tripho says:

    Very informative.Thanks.

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