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Particulate Matter Removal by Coagulation

Municipal Water Supply

  1. Rasheed Ahmad

Published Online: 15 JUL 2005

DOI: 10.1002/047147844X.mw401

Water Encyclopedia

Water Encyclopedia

How to Cite

Ahmad, R. 2005. Particulate Matter Removal by Coagulation. Water Encyclopedia. 1:137–139.

Author Information

  1. Khafra Engineering Consultants, Atlanta, Georgia

Publication History

  1. Published Online: 15 JUL 2005


Coagulation is used in water treatment plants as a pretreatment step to remove particulate matter and dissolved materials, especially natural organic material (NOM). Examples of particulate matter in surface water include clay and silt particles, bacteria, viruses, and protozoan cysts such as Giardia and Cryptosporidium. NOM is formed in surface water from biodegradation and/or transformation of plant and animal material in the watershed. Although the removal of particulate matter continues to be an important reason for using coagulation, recent concern about carcinogenic by-products has emphasized that the coagulation process must also optimize the removal of NOM to reduce the formation of disinfection by-products.

The major purposes of coagulation include destabilizing colloidal particles, removing color and precursors of disinfection by-products, enhancing flocculation, improving filtration, and pretreating to prolong the life of granular activated carbon contactors.


  • coagulation;
  • flocculation;
  • double layer;
  • DLVO theory;
  • sweep coagulation;
  • interparticle bridging;
  • heterocoagulation;
  • charge neutralization;
  • coagulants;
  • polymers;
  • alum;
  • ferric chloride