A solids separator for use in a composting system for separating solid waste from liquid waste in a stream of waste includes a housing defining a waste inlet for receiving the stream of waste, a liquids outlet for passing the liquid waste, and a solids outlet for passing the solid waste. A separator belt is positioned within the housing and extending between the liquids outlet and the solids outlet, the separator belt defining a plurality of apertures through which the liquid waste passes through the separator belt and into the liquids outlet. A drive cylinder is rotatably mounted within the housing for selectively rotating the separator belt such that a top surface of the belt is moved toward the solids outlet along with the solid waste that is extracted from the stream of waste.