Definition:The process of mixing chemicals to water to neutralize the electrical charges and to form an insoluble, gelatinous flocculent precipitate for absorbing and entraining suspended and colloidal particles of impurities is called coagulation.

Factors Affecting Coagulation

Type of coagulant.

• Dose of coagulant.
• Time and method of mixing the coagulant.
• Character of water.
• pH of water.
• Temperature of water
• Nature and quantity of suspended matter.

Common Coagulants

• Alum or aluminium sulphate.
• Chlorinated copperas.
• Magnesium carbonate and lime.
• Ferrous sulphate and lime.
• Sodium aluminate.
• Polyelectrolytes.