What is the correct order for removing suspended solids in water treatment?

The sequence of processes for removing suspended solids in water treatment is crucial in ensuring effective treatment and purification of water. The correct order is coagulation, flocculation, sedimentation, and then filtration.

Coagulation is the initial step where chemicals, known as coagulants, are added to the water. These coagulants destabilize the suspended particles in the water, causing them to clump together into larger aggregates. This process is essential because individual particles, when present in low concentrations, do not easily settle or can be overlooked by subsequent processes.

Following coagulation, the flocculation process takes place. In this stage, gentle mixing causes the small aggregates formed during coagulation to join together into larger clusters, known as flocs. This step is vital as larger flocs can be more easily removed from water during sedimentation.

After flocculation, the mixed water is allowed to sit in a sedimentation basin. During sedimentation, the larger flocs settle to the bottom due to gravity, forming a sludge layer. This separation of sludge from the clearer water is critical as it significantly reduces the amount of suspended solids remaining in the water.

Finally, filtration is employed to remove any remaining smaller particles or flocs that might have escaped settling