Chlorination
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Brief History of Chlorine

The United States of America has an intimate relationship with chlorine (Cl2) - they were "born" around the same time.  Just two years before the signing of The Declaration of Independence, Swedish pharmacist Carl Wilhelm Scheele released a few drops of hydrochloric acid on a piece of manganese.  A greenish-yellow gas arose from the reaction and chlorine was discovered.  The strange gas wasn't identified as an element or named until later in 1810 when English chemist Sir Humphry Davy gave the appellation of "chloric gas" or "chlorine" to the element (Science Encyclopedia, 2008).  Chlorine is a naturally occurring element usually found bonded to other elements in rocky compounds, and in all of the oceans around the world. Chlorine is a principle component in the salt we eat everyday (NaCl).

Bottle of chlorine

Figure 1:  Chlorine (Cl2) is a greenish-yellow gas at room temperature (Schwartz, 2005).

The disinfecting properties of chlorine were first realized in the mid 1800's where it was used to wipe down contaminated surfaces.  The use of chlorine as a disinfectant in municipal water systems took root in Europe around the turn of the century and became the standard form of water disinfection in the United States by 1920.  Legislation governing water quality standards encouraged an ever increasing demand for chlorine throughout the twentieth century.

    Brief Chlorination Timeline
  • 1847 - Chlorine was first used as a disinfectant in Vienna to prevent the spread of "child bed fever".
  • 1890's - The use of chlorine becomes commonplace in English municipal water systems.
  • 1908 - Initial U.S. applications of chlorination in Chicago and Jersey City water districts prove effective.
  • 1918 - Over one-thousand cities in the United States use chlorination for drinking water supplies.
  • 1970 - Twenty-thousand chlorinated water municipalities exist in the United States.

Wastewater chlorination was next step in the use of chlorine to stop the spread of pathogens.