This method uses large tanks or reservoirs with slow-moving or still water. The settling of larger solids (sand, gravel and large debris) precedes other treatment processes. Part of other contaminants also removed with solids. A common method for the purification of surface water.
Both construction costs and O&M costs are low. Natural basins can be used, requiring less finances to use it for a treatment reservoir. In case of specific settling tanks, costs are still limited. Affordable method both for implementation and use.
Typically applied at municipal treatment plants or at small community level. Limited labor is required for the management. Since sedimentation is applied jointly with other processes (e.g. flocculation), caretakers can combine maintenance activities of more installations.
Mainly used for surface water. Reservoirs take significant amount of surface area. New contaminations might blow into the open basins. Sludge needs safe disposal. If put in waste pit, leaching contaminants might affect groundwater sources and pose health risk.
Simple to construct, mostly using masonry or concrete. Design inlet arrangement must ensure the even and turbulence-free supply of water in tank to keep settling efficiency high. Regular removal of sludge required. Installation maintenance is minimal.
Does not require specific actions from users. Since the method is widely known and applied acceptance will be good. Sedimentation does not give the guarantee of safe water, it should always be used in combination with other disinfection processes.
No relevant remarks for Pre-Settling.