What is the typical removal efficiency of settable solids in a primary clarifier?

The typical removal efficiency of settable solids in a primary clarifier is generally in the range of 95-99%. This high level of efficiency is achieved because primary clarifiers are designed to allow heavier particles to settle out of the wastewater as it flows through the tank. The physical process of sedimentation takes advantage of gravity, where the denser solids settle down to the bottom of the clarifier, forming a sludge blanket. This process effectively reduces the concentration of suspended solids in the effluent, thereby improving water quality before it moves on to further treatment stages.

The 95-99% efficiency reflects the clarifier's role in maximizing the removal of suspended solids during the initial processing of wastewater. Factors such as detention time, flow rate, and design of the clarifier influence this efficiency, but in well-designed systems, it is expected that the majority of settable solids will be removed within this range.