ABSTRACT
This chapter outlines the concepts used in the design of treatment facilities for both unit operations and processes. In water and wastewater treatment, flocculation and coagulation processes are mainly used for the removal of colloidal substances which cause color and turbidity. Screening devices are installed to facilitate removal of coarse suspended and floating matter. Presence of coarse solids may damage or interfere with the operation of the pumps and other mechanical equipment. Sedimentation may be defined as the gravitational settling of suspended particles that are heavier than the surrounding fluid. Laboratory experiments are often conducted to evaluate the settling phenomenon of suspended particles, as well as to provide information needed for the design of sedimentation tanks. The removal ratio for flocculent settling increases with a decrease in overflow rate and with an increase in basin depth.
