Color and turbidity can be removed from water with this method. The procedure entails the addition of a coagulant (e.g. iron chloride or aluminum-sulphate) to the water. Positive coagulant particles attract to negatively charged turbidity particles resulting in precipitating flocks. Efficiency of particle collision can be increased by mixing.


Coagulant requirement makes it a relatively expensive method…


Can be applied at local level or centralized level. Typical application as part of a treatment-train, followed by sedimentation or filtration. Skilled people are required for proper application of coagulation chemicals and proper mixing.


Highly contaminated flocks removed in next treatment step. In case of sedimentation it will be clogged into sludge, in case of granular filtration the flocks will end up in backwash water. Aluminium-containing sludge presents high risk for surrounding groundwater contamination.


Coagulants are stored and added to water in solution form. Optimal dosing depends on composition/contamination of water, which requires adequate testing equipment/laboratory. Mixing can be conducted mechanically or hydraulically. Maintenance is minimal compared to operational requirements. Effluent monitoring required.


Coagulation/flocculation is typically part of a larger treatment installation. No specific concern for users, therefore no special awareness-raising required. Treatment workers need to be aware of health risks of coagulants and sludge, they need protecting gear when handling these materials.

Relevant remarks:

No relevant remarks for Coagulation/flocculation.