Solid Waste Recycling and Recovery
Solid waste recycling and recovery
Recycling is the recovery and reuse of materials from wastes. Solid waste recycling refers to the reuse of manufactured goods from which resources such as steel, copper , or plastics can be recovered and reused. Recycling and recovery is only one phase of an integrated approach to solid waste management that also includes reducing the amount of waste produced, composting , incinerating, and landfilling.
Municipal solid waste (MSW) comes from household, commercial, institutional, and light industrial sources, and from some hospital and laboratory sources. In 2000 the United States produces nearly 232 million tons (210.5 million metric tons) of MSW per year, almost 4.5 lb (2 kg) per resident per day. The percentages of MSW generated in this country include paper and paperboard, 38.1%; yard wastes, 12.1%; metals, 7.8%; glass, 5.5%; rubber , textiles, leather and wood, 11.9%; food wastes, 10.9%; plastics, 10.5%; and other, 3.2%.
Recycling is a significant way to keep large amounts of solid waste out of landfills, conserve resources, and save energy. As of 2000, Americans recovered, recycled, or composted 30.1% of MSW, incinerated 14.5%, and landfilled 55.3%.
The technology of recycling involves collection, separation, preparing the material to buyer's specifications, sale to markets, processing, and the eventual reuse of materials. Separation and collection is only the first step; if the material is not also processed and returned to commerce, then it is not being recycled. In many parts of the country, markets are not yet sufficiently developed to handle the growing supply of collected material.
Intermediate markets for recyclable materials include scrap dealers or brokers, who wait for favorable market conditions in which to sell their inventory. Final markets are facilities where recycled materials are converted to new products, the last phase in the recycling circle.
The materials recycled today include aluminum , paper, glass, plastics, iron and steel, scrap tires, and used oil. Aluminum, particularly cans, is a valuable commodity. By the late 1980s, over 50% of all aluminum cans were recycled. Recycling aluminum saves a tremendous amount of energy: it takes 95% less energy to produce an aluminum can from an existing one rather than from ore. Other aluminum products that are recycled include siding, gutters, door and window frames, and lawn furniture.
Over 40% of the paper and paperboard used in the U.S. is collected and utilized as either raw material to make recycled paper, or as an export to overseas markets. Recycled paper shows up in newsprint, roofing shingles, tar paper, and insulation. Other recyclable paper products include old corrugated containers, mixed office waste, and high-grade waste paper. Contaminants must be removed from paper products before the remanufacture process can begin, however, such as food wastes, metal, glass, rubber, and other extraneous materials.
The market for crushed glass, or cullet, has increased. Recycled glass is used to make fiberglass and new glass containers. About 1.25 million tons (1.14 million metric tons) of glass is recycled annually in the United States.
Three types of plastic are successfully being recycled, the most common being PET (polyethylene terephthalate), or soft drink containers. Recycled PET is used for fiberfill in sleeping bags and ski jackets, carpet backing, automobile bumpers, bathtubs, floor tiles, and paintbrushes. HDPE plastic (high density polyethylene) is used for milk jugs and the bottoms of soft drink bottles. It can be recycled into trash cans and flower pots, among other items. Polystyrene foam is crushed into pellets and turned into plastic lumber for benches and walkways. Commingled plastics are recycled into fence posts and park benches.
Iron and steel are the most recycled materials used today. In 1987, 51 million tons (46 million metric tons) were recycled, more than twice the amount of all other materials combined. The material is remelted and shaped into new products.
More than one billion discarded tires are stockpiled in the United States, but scrap tires can be shredded and used for asphalt-rubber or retreading; are incinerated for fuel; or used to construct artificial marine reefs.
Used oil is a valuable resource, and of the 1.2 billion gal (4.5 billion L) generated annually, two-thirds is recycled. The rest, about 400 million gal (1.5 billion L), is disposed of or dumped. About 57% of used oil is reprocessed for fuel, 26% is refined and turned into base stock for use as lubricating oil, and about 17% is recycled for other uses.
Composting is the aerobic biological decomposition of organic waste materials, usually lawn clippings. Composting is not an option for a major portion of the solid waste stream , but is an important component of the resource recovery program.
Recycling collection methods vary, but curbside collection is the most popular and has the highest participation rates. It is also the most expensive way for municipalities to collect recyclables in their communities. Collection centers do not yield as many recyclables because residents must do the sorting themselves, but centers offer the most affordable method of collection.
Precycling is an option that is gaining widespread recognition in this country. Basically, precycling refers to the consumer making environmentally sound choices at the point of purchase. It includes avoiding products with extra packaging, or products made to satisfy only short-term needs, such as disposable razors.
Resource recovery or materials recovery is the recycling of waste in an industrial setting. It does not involve recycling consumer waste or municipal solid waste, but includes reprocessed industrial material that, for whatever reason, is not able to be used as it was initially intended. Some consumer groups are pressing for government guidelines on labeling packaging or products "reprocessed" as opposed to "recycled."
While the Environmental Protection Agency (EPA) insists that no single alternative to the municipal solid waste problem should be relied upon, its generally accepted hierarchy of waste management alternatives is 1) source reduction and 2) reusing products. Waste that is not generated never enters the waste stream.
If recycling is to be used as a genuine MSW management alternative rather than a "feel good" way to conserve resources, then materials must be recovered and made into new products in large quantities. For some materials, however, an insufficient market exists, so communities must pay to have some recyclable materials taken away until a market is developed. Recycling programs depend on the will of the community to follow through, and in many areas, response is weak and enforcement lacking. However, dwindling landfill space in the 1990s may force communities to mandate recycling programs.
Recent EPA regulations seriously affected the number of operable landfills. The requirements include installing liners, collecting and treating liquids that leach, monitoring groundwater and surface water for harmful chemicals , and monitoring the escape of methane gas. These regulations will increase the number of corporate-run landfills, but the cost of building and maintaining a landfill that adheres to the regulations will top $125 million. The end cost to consumers to have trash hauled away may also force many garbage makers to become reducers, reusers, and recyclers.
[Linda Rehkopf ]
Kharbanda, O. P., and E. A. Stallworthy. Waste Management: Towards a Sustainable Society. Westport, CT: Auburn House/Greenwood, 1990.
Robinson, W. D., ed. The Solid Waste Handbook. New York: Wiley, 1986.
Franklin, W. E., and M. A. Franklin. "Recycling." The EPA Journal (July-August 1992): 7.
Solid Waste Recycling: The Complete Resource Guide. Washington, DC: Bureau of National Affairs, 1990.