Apparatus and method are provided for separating grit from liquid sewage while retaining organic solids in suspension. A sustained rotational liquid sewage first fluid flow, an induced upward liquid sewage second fluid flow, and a sustained rotational liquid sewage third fluid flow are employed in an apparatus having a cylindrical grit settling main chamber, a grit storage secondary chamber including a central grit settling access top mouth opening, a vertical shaft, a means for causing rotation of the vertical shaft, and a partition extending transversely through the main chamber and forming upper and lower subchambers. A fluid flow speed gradient is established between the liquid sewage third fluid flow and the liquid sewage first fluid flow. In this manner, grit is separated from liquid sewage.