What is the main purpose of a sedimentation basin (clarifier)?

The primary purpose of a sedimentation basin, also known as a clarifier, is to allow suspended solids in water to settle out by gravity. When water containing particulate matter enters the basin, the flow velocity is reduced, allowing heavier particles to settle to the bottom over time, forming a sludge layer. This process effectively removes solids from the water column, thereby clarifying the water. The settled solids can then be removed periodically, helping to maintain the basin's efficiency and keep the water clean for further treatment or discharge.

In contrast, mixing chemicals into water is typically done in a separate facility or process stage, not specifically within a sedimentation basin. Flocculation involves the agglomeration of particles into larger clumps called flocs, and while some contact time may occur in sedimentation basins, it is not the main function of these structures. Cooling down heated water is related to thermal management processes and is not a function of sedimentation basins, which focus primarily on solids removal.