Flocculation typically occurs after which process in water treatment?

Flocculation is a crucial step in the water treatment process that follows coagulation. During coagulation, chemicals called coagulants are added to water to destabilize suspended particles and create small aggregates. These aggregates, or flocs, tend to remain suspended in the water. Flocculation then involves gently mixing the water to encourage these tiny flocs to collide and combine into larger aggregates, which can then settle out more easily during the subsequent sedimentation process.

Understanding the sequence is important: if flocculation followed filtration, for example, the larger particles would already have been removed, rendering the mixing process unnecessary and ineffective. Therefore, the relationship between coagulation and flocculation, as well as their positions in the treatment sequence, underlines why flocculation typically occurs after coagulation.