Design and Construction of a Model Sedimentaion Tank Using Existing Slow Sand Filter For NDA Treatment Plant

The treatment of water for human consumption involves various processes in which raw water passes through. This processes includes; screening, flocculation/coagulation, sedimentation, filtration and chlorination. Sedimentation is a process between flocculation/coagulation tank and filtration tank. The design of sedimentation tank is necessary to receive effluent of the flocculation/coagulation tank and achieve efficient settling of particles under gravity and then discharge to the slow sand filter as effluent for further treatment. To achieve this grate settling efficiency, a rectangular sedimentation tank withthe following dimensions; depth 3.58m, width 5.76m and 23.0m long, is designed and constructed with a baffle across the inlet perforated with holes, this provides calm area at the settling zone for efficient settling of particles. The base of the tank is sloped towards the inlet zone for collection and disposal of sludge gate valve. While at the outlet zone, a baffle is provided to prevent any particle which did not settle from going out.