Which option correctly identifies the main purpose of coagulation/flocculation?

• A. Filtration
• B. Coagulation/Flocculation
• C. Sedimentation
• D. Disinfection

Answer: (B)

Coagulation and flocculation are about making the tiny, stable colloidal particles in water become larger, filterable chunks. The process uses coagulants to neutralize the particles’ surface charges, reducing repulsion, and then gentle mixing helps those neutralized particles collide and stick together to form flocs. These larger flocs can then be removed more easily in downstream steps like sedimentation or filtration. So the main purpose is to prepare contaminants for removal by forming flocs that downstream treatment can efficiently remove. The downstream steps themselves (filtration, sedimentation, disinfection) aren’t the purpose of coagulation/flocculation, but the methods that follow.