High flow high capture side rails for comminutor

An apparatus for comminuting solid waste material is provided. The apparatus includes a casing and a comminutor assembly including a plurality of cutting elements mounted on said first shaft in interspaced relationship with a plurality of second cutting elements mounted on said second shaft. The casing includes laterally opposed side rails each having a wall extending parallel to the flow direction of the liquid through the comminution chamber, a plurality of planar fins projecting outwardly of said rear wall in the direction of said stack, aligned with the flow direction of the liquid and being spaced from each other in a vertical direction to form slots therebetween, and the planar fins having a leading edge extending from the wall upstream a rearward edge, the rearward edge extending from an outermost portion of the leading edge toward the wall, and the fins have a path ratio greater than 1.55 to 1.