Abstract: An improved comminutor for channels or inline conduits that carry the flow of liquid sewage which includes a semi-cylindrical concave cage formed of a plurality of axially spaced apart sections of arcuate rings or bars connected together arcuately and axially. A plurality of comb-like members are mounted at spaced intervals along the inner surface contour of the semi-cylindrical concave cage member with the teeth of its comb-like members in axial alignment with corresponding sections of the rings or bars which form the cage member. A plurality of rotatable cutting and shredding arms are mounted axially along a helical spiral like path in spaced relationship with the cage member with a plurality of comb-like members for interengaging comminuting action with radially extending portions of their respective teeth.