Which device collects the settled water as it leaves the sedimentation basin?

The device that collects the settled water as it leaves the sedimentation basin is an effluent launder. This component is designed specifically to collect the clear water that has risen above the settled solids in the basin. The launder typically runs along the top edge of the sedimentation basin, allowing for a smooth transfer of clarified water while minimizing the disturbance of the settled solids below.

The design of the effluent launder ensures that the collected water is substantially free of suspended particles, making it suitable for further treatment processes. It is a crucial element in maintaining water quality as it prevents the resuspension of settled solids, which can occur if other designs are used.

Other options may serve functions related to flow management and water distribution, but they do not specifically focus on the collection of settled water in the same manner that an effluent launder does. The effluent launder's design effectively supports the sedimentation process by ensuring the efficient removal of clarified water from the treatment system.