7. MATERIALS COLLECTION, SEPARATION, AND RECYCLING
This section describes programs and processes to collect and separate recyclable material from waste and to recycle the separated materials into potentially useful products. The reusable materials that are most commonly recycled are newspaper, glass, aluminum and ferrous metals, plastic, and cardboard. The entire process that is needed for successful recycling consists of five steps:
- Separating reusable materials from other municipal waste, often at curbside, but sometimes at a central materials recovery facility
- Transporting and processing (including remanufacturing) the separated materials for use as replacements for virgin materials
- Managing the wastes from separation and recycling
- Returning the materials to beneficial use or to commerce, often as parts of other products
- Selling the recycled product to consumers (NSWMA, 1991; Kiser, 1992).
Many different options are available for each of these steps. This section focuses mainly on the processes that a municipality can use to separate potentially recyclable materials from its waste stream because only collection and separation programs are operated under the direct control of a municipality. However, unless beneficial uses are found for the separated materials, separation is usually insufficient to reduce the amount of waste.
Four approaches to separation are common:
- Drop-off centers-Community members transport certain separated wastes (e.g., bottles, cans, newsprint) to a convenient site where the recyclables may be cleaned before they are shipped to a processor or user. Grocery chains that accept or give credit for plastic and paper grocery bags and centers that dispense payments for beverages containers with deposit or redemption values are also functioning as drop-off centers.
- Curbside collection-Residents set out recyclable materials separated by type for pick up by the waste hauler in a compartmented truck.
- Mixed recyclable collection-Residents place all recyclables in a single bag and set the bags out with the trash for collection.
- Mixed waste separation-Normal MSW is manually and/or mechanically separated into recyclable materials at a central facility.
Materials recovery facilities (MRFs) are the newest separation tool, and they are being implemented more rapidly than any other method for solid waste management. MRFs can be broadly defined as the plants where recyclables are separated and consolidated for shipment. In this section, the term "MRF' refers to a facility that receives separated materials for further processing. The term "mixed waste MRF" refers to a facility that accepts raw refuse (trash, MSW) and manually or mechanically separates recyclable materials from it. (The residue could be landfilled, mass burned, or processed with RDF.) In addition, plants that prepare RDF can be considered as facilities that separate recyclable material.
One reason for adding material recovery systems is to meet the U.S. Environmental Protection Agency's (EPA's) goal of voluntarily reducing the quantity of MSW by 25% by 1992 through source reduction and recycling. Many states have translated those goals into regulations mandating recycling. Another objective of recycling is to provide an economic benefit by reducing the use of virgin materials and the consumption of process energy. Other expectations for recycling include reducing emissions from disposal and extending landfill life. Either source-separation with processing at an MRF or mixed-waste processing can help to reduce the amount of material that ends up in a landfill.
Technology Description
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