Since 1910 chlorine has been used in the disinfection process of wastewater because of its success in eliminating high rates of water-borne illnesses.[1]


Chlorine (Cl2) reacts with water (H2O):[2]

Cl2 + H2O → HOCl + HCl

The resulting hypochlorous acid (HOCl) disassociates into hydrogen (H+) and hypochlorite (OCl-) ions:

HOCl ---> H+ + OCl¯

Hypochlorous acid (HOCl) is a weak acid that penetrates the cell membrane of wastewater pathogens, destroying the enzymes within the cytoplasm. Wastewater pathogens killed through chlorination include bacteria, viruses, protozoa, and amoebic cysts.[3]

NicoleKraftBasin Page 2.jpg

Chlorine’s effectiveness as a disinfectant depends upon:[3]

  • chlorine detention time and concentration
  • wastewater pH and temperature
  • total suspended solids (turbidity)
  • other reactive species in the water (hydrogen sulfide, organics)
  • pathogen (cryptosporidium, for example, is highly resistant to chlorine)
  1. Water Quality and Health Council. Wastewater Chlorination: An Enduring Public Health Practice. Accessed online 5/02/08.
  2. Chlorination. Accessed online March 27th, 2008.
  3. 3.0 3.1 Davis, Mackenzie, and Susan Masten. Principles of Environmental Engineering and Science. McGraw Hill: New York, NY 2004.

See also[edit | edit source]

FA info icon.svg Angle down icon.svg Page data
Authors Nicole Kraft, Chris Watkins
License CC-BY-SA-3.0
Language English (en)
Related 0 subpages, 11 pages link here
Impact 444 page views
Created March 31, 2008 by Nicole Kraft
Modified April 30, 2024 by StandardWikitext bot
Cookies help us deliver our services. By using our services, you agree to our use of cookies.