What is the method of sedimentation primarily used for in drinking water treatment?

The method of sedimentation in drinking water treatment is primarily focused on the process of settling out suspended particles by gravity. In this context, sedimentation serves as an essential preliminary step in the water treatment process. When water containing suspended solids is allowed to remain undisturbed in a tank or basin, heavier particles gradually settle to the bottom due to the force of gravity. This accumulation of solids, known as sludge, can be removed, resulting in clearer water.

This method is effective for removing larger particles, such as sand, silt, and organic matter, which can interfere with the effectiveness of subsequent treatment processes. By reducing the concentration of these suspended solids, sedimentation helps to improve the efficiency of filtration and disinfection stages that follow, ensuring that the treated water is safe for consumption.

The other methods outlined in the options, such as adding chemicals for purification or applying a filtration process, serve different roles in the treatment process and do not specifically target the gravitational settling of particles as sedimentation does.