Once the unit operations to process the materials are selected, the garbage separation equipment needed to carry out the operations must be chosen and installed. The capabilities, reliability, maintenance requirements, flexibility, safety, efficiency, environmental effects, market specifications, and costs of the various alternatives will govern the selection of sorting equipment for the facility.
The green bags (paper) are deposited on an inclined conveyor that is lined with screws. The screws serve the dual purpose of carrying the material up the incline and breaking the bags. At the first waste sorting station, non-recyclable materials are removed from the paper stream. Once the contaminants that can interfere with the subsequent unit operations are removed, the paper stream is directed along the conveyor to a trommel screen. The trommel will allow large materials (overs) such as newspaper and corrugated paper to pass through, while smaller mixed paper (unders) fall through the screen openings. The trommel can be adjusted to remove contaminants that are even smaller than the mixed paper if necessary. The trommel must be monitored so that very large sections of corrugated paper do not jam the cylinder. The two streams of material from the trommel are then conveyed to manual sorting machine.
The “overs” stream from the trommel (large paper items) are directed to a sorting conveyor where old corrugated cardboard (OCC), mixed paper, magazines and kraft are manually removed and placed into appropriate containers. Since newspaper is generally the largest quantity item, it is negatively sorted. The exact method and extent of separation will depend on the requirements of the paper vendors. The “unders” from the trommel (smaller paper items) are conveyed to a different group of manual sorters who will sort mail, ledger, and other grades of paper depending on available markets. Once the storage bunkers for the different paper materials are filled, they are emptied through a door at the bottom of the bins. Conveyors then move each paper material to a baler, which compresses and ties the paper with wire into cubes. Forklifts will be used to load the bales of paper onto tractor-trailers for shipment.
