Abstract: A motor driven grinding apparatus, and a system incorporating the inventive grinder, for reducing the size of waste material. The apparatus includes a housing having an interior, an exterior, an inlet for introducing material into the interior, and an exit for expelling material from the interior. The housing also includes a front wall, a back wall, a pair of spaced apart side walls, and a bottom grate. The apparatus also includes a substantially cylindrical, balanced, drum having a shaft, and a plurality of cutting blocks rotatably mounted thereto. The drum is rotated by a drive motor engageable with the shaft. An airfoil is attached to the front wall for establishing a static air curtain within the interior of the housing enabling air to be drawn into the housing through the inlet and expelled from the exit when the drum rotates. The drum and cutting block configuration are particularly useful for grinding, and sheafing, cellulose, plastics, glass, and other solid waste materials.