A system for comminuting solid waste material comprising: a casing (150, 160, 180, 190) defining a comminution chamber having two side walls and being open on opposite sides thereof for permitting the flow of liquid therethrough bearing solid waste material and being adapted for connection in a solid waste disposal channel; a first shredding device and a second shredding device disposed along a line extending perpendicular to a flow direction in the channel; a rotating screening drum disposed within the casing upstream of the first and second shredding devices, the rotating screening drum configured to permit fluid to pass therethrough while capturing solids on an outer surface for delivery to shredding device (140, 145), an upstream portion of the rotating screening drum disposed upstream of an upstream portion of the shredding device, characterized in that each of the first and second shredding devices comprises parallel first and second shredding stacks that include first and second rotating parallel shafts, each of the first and second parallel shafts includes 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, each of said cutting elements has at least one cutting tooth thereon, said cutting elements being positioned between and separated in an axial direction by spacers which are coplanar with the cutting elements of the adjacent stack such that a cutting element from one stack and a spacer from the other stack form a pair of interactive shredding members; and the rotating screening drum is positioned between the first and second shredding devices and configured to rotate clockwise and counter clockwise to alternately distribute solids captured thereon to one of the first and second shredding devices. a casing (150, 160, 180, 190) defining a comminution chamber having two side walls and being open on opposite sides thereof for permitting the flow of liquid therethrough bearing solid waste material and being adapted for connection in a solid waste disposal channel; a first shredding device and a second shredding device disposed along a line extending perpendicular to a flow direction in the channel; a rotating screening drum disposed within the casing upstream of the first and second shredding devices, the rotating screening drum configured to permit fluid to pass therethrough while capturing solids on an outer surface for delivery to shredding device (140, 145), an upstream portion of the rotating screening drum disposed upstream of an upstream portion of the shredding device, characterized in that each of the first and second shredding devices comprises parallel first and second shredding stacks that include first and second rotating parallel shafts, each of the first and second parallel shafts includes 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, each of said cutting elements has at least one cutting tooth thereon, said cutting elements being positioned between and separated in an axial direction by spacers which are coplanar with the cutting elements of the adjacent stack such that a cutting element from one stack and a spacer from the other stack form a pair of interactive shredding members; and the rotating screening drum is positioned between the first and second shredding devices and configured to rotate clockwise and counter clockwise to alternately distribute solids captured thereon to one of the first and second shredding devices.