Radial-flow settling units, also called circular center-feed sedimentation basins, are the
most common settling tank design used in municipal wastewater treatment plants (Metcalf
and Eddy Inc., 1991). A radial-flow settler is only similar to a swirl separator in that they
are both cylindrical settling tanks with effluent launders located around the top perimeter of
the vessels and sometimes with cone bottoms. However, radial-flow settlers have
completely different flow hydraulics from swirl separators.