Efficiency
of
Sedimentation
Tank - The sedimentation velocity (Vs) of a particle can be determined by calculating the depth of the tank (H) it traverses during the detention time (T)
Thus the sedimentation efficiency of a tank depends only upon the ratio between the influent flow rate and the surface area of the tank. This ratio is called as surface loading and is independent of the depth of the tank. Generally there is no difference in the settling efficiency between a shallow and a deep tank.
When sedimentation is used without pre-treatment, as in the case of clarification of river water, the process is called plain sedimentation. The surface loading for this process will generally be in the range from 0.1 - 1 m/hr. For water treated by chemical coagulation and flocculation, a higher surface loading is possible between 1 and 3m/hour. In both cases, lower the surface loading better the clarification of water and settled water will have less turbidity.
