How do settling tanks operate effectively?

Settling tanks, also known as sedimentation tanks, operate effectively by slowing the speed of the sewage as it flows through them. This reduction in flow velocity allows for the gravitational settlement of suspended solids present in the sewage. As the sewage enters the tank, the slower flow lets heavier particles settle to the bottom, forming sludge, while the lighter materials may remain suspended or float on the surface.

This process is critical in the wastewater treatment cycle, as it helps separate solid waste from the liquid, facilitating further treatment processes. By allowing time for the solids to settle, settling tanks improve the clarity of the effluent that exits the tank, making subsequent treatment steps more efficient.

Increasing the speed of sewage flow, changing its direction, or adding air would interfere with the settling process, potentially stirring up settled materials and reducing the effectiveness of solid separation.