ABSTRACT
The purpose of primary sedimentation is to remove the settleable organic solids. This chapter presents the theory of flocculant settling, types of sedimentation basins, basic design factors, and theory and design of enhanced sedimentation. It also presents the step-by-step design procedure, equipment selection, design details, facility operation, and equipment specifications for a plain primary sedimentation facility in the design example. The design of most of the sedimentation basins or clarifiers falls into several categories: horizontal flow, solids contact, inclined surface, stacked or two-tray, and proprietary systems. Solids loading are not an important deciding factor for the primary sedimentation facility. In the design of influent structure, provision is also made to control flows, remove scum, and facilitate maintenance. The effluent structures are designed to provide a uniform distribution of flow over a large area, minimize the lifting of the particles and their escape into the effluent, and reduce the escape of floating matter to the effluent.
