Size reduction is the unit operation for mechanically reducing the size of materials in garbage sorting plant. Size reduction is carried out through shredding, grinding and milling. Since the effectiveness of many unit operations within the facility depends on keeping the materials as large as possible, size reduction will only be utilized after all waste separation is accomplished.
The main size reduction equipment that will be used in the proposed MRF will be shredders and glass crushers. The shredders will be used for large items that are initially removed from the waste stream and for organic material that is brought to the facility if the MRF were to accept mixed waste. The size-reduced product is reasonably uniform and has greater surface area to volume ratios, which increases decomposition. The increased surface area also increases air exposure, reducing odors and promoting dryness. The choice of shredder will depend on the material to be shredded, the amount of energy required, the size changes needed and the benefits of those size changes. Glass crushers in the form of hammer mills will be used to reduce storage space and shipping costs for the separated glass.
