Waste management is the handling of discarded materials. Recycling and composting, which transform waste into useful products, are forms of waste management. The management of waste also includes disposal, such as landfilling.
Waste can be almost anything, including food, leaves, newspapers, bottles, construction debris, chemicals from a factory, candy wrappers, disposable diapers, old cars, or radioactive materials. People have always produced waste, but as industry and technology have evolved and the human population has grown, waste management has become increasingly complex.
A primary objective of waste management today is to protect the public and the environment from potentially harmful effects of waste. Every individual, business, or organization must make decisions and take some responsibility regarding the management of their waste. On a larger scale, government agencies at the local, state, and federal levels enact and enforce regulations governing waste management. These agencies also educate the public about proper waste management. In addition, local government agencies may provide disposal or recycling services, or they may hire or authorize private companies to perform those functions.
Historically, waste has been handled by depositing it in a designated location such as a dump, burning, and reuse/recycling. How those methods are used depends on the wastes. Municipal solid waste is different than industrial, agricultural, or mining waste. Hazardous waste is a category that should be handled separately, although it sometimes is generated with the other types.
Municipal solid waste is another term for garbage, refuse, or trash. It is generated by households, businesses, and institutions, such as schools and hospitals. Toilet wastes or other liquid wastes from these sources are not considered as solid waste; if treated, they are commonly handled through public sewage treatment systems. Also called biosolids, sewage sludge is not generally considered solid waste, but it is sometimes composted with organic municipal solid waste.
The first humans did not worry much about waste management. They simply left their garbage where it dropped. However, as permanent communities developed, people began to dispose their waste in designated dumping areas. The use of open dumps for garbage is still common in many parts of the world. Open dumps have major disadvantages, especially in heavily populated areas. Toxic chemicals can filter down through a dump and contaminate groundwater. The liquid that filters through a dump or landfill is called leachate. Dumps may also generate methane, a flammable and explosive gas produced when organic wastes decompose under anaerobic (oxygen-poor) conditions.
Waste can be buried. This strategy utilizes a landfill. At a landfill, the garbage is compacted and covered at the end of every day with several inches of soil. Landfilling became common in the United States in the 1940s. By the late 1950s, it was the dominant method for disposing municipal solid waste in the nation.
Early landfills had significant problems with leachate and methane, but those have largely been resolved at facilities built since about the early 1970s. Well-engineered landfills are lined with several feet of clay and with thick plastic sheets. Leachate is collected at the bottom, drained through pipes, and processed. Methane gas is also safely piped out of many landfills. As of 2006, the United States Environmental Protection Agency has strict guidelines and regulations regarding the construction, location, and use of landfills.
The dumping of waste does not just take place on land. Ocean dumping, in which barges carry garbage out to sea, was once used as a disposal method by some United States coastal cities and is still practiced by some nations. Sewage sludge, or waste material from sewage treatment, was dumped at sea in huge quantities by New York City as recently as 1992, but this is now prohibited in the United States.
Burning has a long history in municipal solid waste management. Some American cities began to burn their garbage in the late nineteenth century in devices called cremators. These were not very efficient, however, and cities went back to dumping and other methods. In the 1930s and 1940s, many cities built new types of more-efficient garbage burners known as incinerators. The early incinerators were rather dirty in terms of their emissions of air pollutants, and could release toxic components into the air.
Newer incinerators are more protective of the environment and produce heat or electricity that can be used in nearby buildings or residences, or sold to a utility.
Municipal solid waste will likely always be landfilled or burned to some extent. In the past 25 years, however, non-disposal methods such as waste prevention and recycling have become more common. Municipal solid waste is a relatively small part of the overall waste generated in the United States. More than 95% of the approximately five billion tons of solid waste generated in the United States each year is agricultural, mining, or industrial waste.
Three main, inter-related factors influence the way wastes are handled today: government regulation, cost, and public attitudes. Industry and local governments must comply with increasingly strict federal and state regulations for landfills and incinerators. Partly because those regulations have driven up the costs of disposal, it has become critical for local governments, industry and businesses of all sizes to find the lowest-cost waste management options.
Public attitudes also play a pivotal role in decisions about waste management. Virtually every proposed new landfill or waste-to-energy plant is opposed by people who live near the site. Public officials and planners refer to this reaction as NIMBY, which stands for “Not In My Back Yard.” If an opposition group becomes vocal or powerful enough, a city or county council is not likely to approve a proposed waste-disposal project. The public also wields considerable clout with businesses. Recycling and waste prevention initiatives enjoy strong public support.
Preventing or reducing waste is typically the least expensive method for managing waste. Waste prevention may also reduce the amount of resources needed to manufacture or package a product. Waste prevention includes many different practices that result in using fewer materials or products, or using materials that are less toxic. For example, a chain of clothing stores can ship its products to its stores in reusable garment bags, instead of disposable plastic bags. Manufacturers of household batteries can reduce the amount of mercury in their batteries. In an office, employees can copy documents on both sides of a sheet of paper, instead of just one side. A family can use cloth instead of paper napkins.
Composting grass clippings and tree leaves at home, rather than having them picked up for disposal or municipal composting, is another form of waste prevention. A resident can leave grass clippings on the lawn after mowing (this is known as grass-cycling), or can compost leaves and grass in a backyard composting bin, or use them as a mulch in the garden.
Waste prevention is preferable over recycling or municipal composting programs, because it does not require transportation, processing, and administration. However, waste prevention does have limitations. It will never eliminate waste; it just reduces the amount that has to be recycled or disposed. Waste prevention also is extremely difficult for a government to measure, since waste that is prevented never really existed in the first place. The lack of good data can make it hard for governments to justify spending money on education programs in support of waste prevention. Even though waste prevention is less expensive than other forms of waste management in the long run, local governments and businesses may need to spend substantial amounts over the short term, to provide education about waste prevention or to make changes in operating procedures so that less waste is produced. Waste prevention can also be a valuable tool for managing industrial and hazardous wastes, since disposal of those materials is particularly expensive and heavily regulated.
Recycling is a simple concept: using disused (or waste) material to make a new product. In practice, however, recycling is far from simple. Recycling consists of three essential elements: collection of the waste materials, also known as secondary materials or recyclables; processing those materials and manufacturing them into new products; and the marketing and sale of those new products. Dozens of different materials can be recycled, including glass bottles, aluminum cans, steel cans, plastic bottles, many types of paper, used motor oil, car batteries, and scrap metal. For each material, the collection, processing, and marketing needs can be quite different.
Composting is considered either a form of recycling, or a close relative. Composting occurs when organic waste, such as yard waste, food waste, and paper, is broken down by microbial processes. The resulting material, known as compost, can be used by landscapers and gardeners to improve the fertility of their soil.
Yard waste, primarily grass clippings and tree leaves, makes up about one-fifth of the weight of municipal solid waste. Some states do not allow this waste to be disposed. These yard-waste bans have resulted in rapid growth for municipal composting programs. In these programs, yard waste is collected by trucks (separately from garbage and recyclables) and taken to a composting plant, where it is chopped up, heaped, and regularly turned until it becomes compost.
Waste from food-processing plants and produce trimmings from grocery stores are composted in some parts of the country. Residential food waste is the next frontier for composting. As a example of a city leading
Composting —The process by which organic waste, such as yard waste, food waste, and paper, is broken down by microorganisms and turned into a useful product for improving soil.
Hazardous wastes —Wastes that are poisonous, flammable, or corrosive, or that react with other substances in a dangerous way.
Incineration —The burning of solid waste as a disposal method.
Landfilling —A land disposal method for solid waste, in which the garbage is covered every day with several inches of soil.
Recycling —The use of disused (or waste) materials, also known as secondary materials or recyclables, to produce new products.
Source reduction —Reduction in the quantity or toxicity of material used for a product or packaging; this is a form of waste prevention.
Waste prevention —A waste management method that involves preventing waste from being created, or reducing waste.
this trend, Halifax, Canada, collects food waste from households and composts it in large, central facilities.
Pichtel, John. Waste Management Practices. Boca Raton: CRC, 2005.
Rodgers, Heather. Gone Tomorrow: The Hidden Life of Garbage. New York: New Press, 2005.
Royte, Elizabeth. Garbage Land: On the Secret Trail of Trash. New York: Little, Brown and Company, 2005.