Abstract: A system and method for treating solid waste includes a trommel screen and a composting unit. The trommel screen includes an inlet hopper and a rotating screening drum, which can be equipped with internal channeling members and bag rippers with blades. A composting and/or dewatering apparatus has a vessel portion, a cover portion and an internal auger. The apparatus includes a plurality of openings along its vessel portion to permit a volume of liquid from within the composting apparatus to be eliminated. The composting/dewatering unit can also include a sleeve member along the outside of the vessel portion. In one embodiment, waste items passing through the screening drum of the trommel screen are conveyed into the composting unit. In another embodiment, the discharged liquid is collected in one or more liquid collection structures and is conveyed to a clarifier tank.