Mechanical Treatment: Material Recovery Facilities

A wide variety of mechanical treatment unit processes, including manual sorting, is described in Chapter 7.1. These unit processes may be used as a single separate operation (e.g. baling of recyclable cardboard) or as a single operation before or after biological and thermal treatment processes (e.g. shredding prior to incineration or screening after composting). The mechanical treatment unit process is in the latter case an integrated part of the overall treatment usually with the purpose of improving the quality of the input material, or the efficiency or stability of the biological or thermal process, or improving the quality of the output material. Examples hereof appear in the chapters on biological and thermal treatment. Mechanical treatment unit processes may also appear at industries using recycled material as part of their feedstock, for example, for removing impurities and homogenizing the material. Examples hereof appear in the chapters describing the recycling of materials. Mechanical treatment unit processes most often perform only one function, but placing different mechanical unit processes in a series or ‘treatment train’ creating a material recovery facility, often called an MRF, output materials of much higher quality and value can be obtained. This chapter describes the key issues of material recovery facilities (MRFs). Box 7.2.1 describes the historical aspects of MRFs.