What structure is specifically designed for settling particles out of water?

The correct answer is a sedimentation basin. This structure is designed to allow water to flow slowly, which facilitates the settling of suspended solids and particles due to gravity. The water enters the basin and is held there for a specified period, allowing heavier particles to sink to the bottom, forming sludge. The design of a sedimentation basin optimizes this process by minimizing turbulence and controlling the flow rate, which is critical for effective particle removal.

While the other structures mentioned play important roles in water treatment, they are not specifically tailored for the process of sedimentation. A filtration system, for instance, is focused on removing smaller particles and impurities by passing water through a filter medium. A clarifier is similar to a sedimentation basin, as it can also serve the purpose of removing solids, but it often has additional features like mechanical means of sludge removal and may involve some form of chemical treatment to aid in coagulation. Finally, a flocculator is designed to assist in coagulating small particles into larger ones that can settle more easily, but it does not settle particles itself; rather, it supports the sedimentation process. Therefore, the sedimentation basin is specifically designed for the settling of particles out of water, making it the most appropriate choice.