Which process forms larger clumps (flocs) that settle more easily?

• A. Coagulation
• B. Sedimentation
• C. Flocculation
• D. Disinfectant added

Answer: (C)

Flocculation is the step that forms larger clumps from small, destabilized particles. After coagulation neutralizes charges and destabilizes colloids, gentle mixing encourages those particles to collide and bond, often with the help of bridging agents like polymers or coagulant flocculants. This growth into larger aggregates—flocs—means they have a higher settling velocity, so they settle out of water more readily in a sedimentation stage. If mixing is too aggressive, flocs can break apart, which is why the intensity is kept low. Disinfection is about killing microbes and does not create or help settle flocs, and sedimentation is the actual settling of the formed flocs, not the formation itself.