Disposal Of Various Waste Materials example essay topic

Waste disposal is the process of getting rid of the waste materials that people generate. People produce gaseous waste, such as carbon monoxide from cars; liquid waste, such as sewage; and solid waste. The many kinds of solid waste include paper and plastic products, bottles and cans, food scraps, and junked automobiles. Solid waste is also called refuse or garbage.

If not disposed of properly, it looks ugly, smells foul, and creates health problems by attracting insects, rats, and other animals that spread disease. Solid waste from homes, offices, and stores is called municipal solid waste. This article discusses how to dispose of such waste. Solid waste also comes from industries and farms. For information on these sources of waste, see the World Book article on ENVIRONMENTAL POLLUTION.

See also the SEWAGE article for information on the disposal of waste matter from sinks and toilets. Most cities and towns have waste-collecting departments or private firms that gather refuse from homes and other buildings. Workers haul the refuse away in trucks. Disposing of refuse has become a serious problem because we produce more waste each year.

At the same time, places to put the waste are filling up, and not enough new locations are available. We also produce more and more wastes that are difficult to get rid of. For example, paper packaging that can easily be recycled or burned is being replaced by plastic packaging that is harder to recycle or that gives off gases when burned. Communities use three chief methods to dispose of municipal solid waste.

They are (1) land disposal, (2) incineration, and (3) recycling and waste reduction. Land disposal involves hauling garbage to an area owned by a community or a private firm. Such areas range from unsanitary open dumps to properly operated sanitary landfills. Open dumps are a poor method of waste disposal because they cause environmental problems. For example, they can ruin an area's appearance and provide a home for animals that spread disease. In addition, rain water drains through refuse and can carry harmful substances to nearby streams and to water used for drinking.

Unregulated dumps where waste is burned in the open can cause smoke and foul-smelling air. Burning in open dumps has been prohibited in the United States. Properly operated sanitary landfills cause little damage to the environment. The waste is packed firmly by tractors and covered with earth each day. The cover of earth prevents insects and other animals from getting into the refuse.

In time, sanitary landfill sites become filled up. Many communities then cover the site with earth a final time and use the area for recreational purposes. Concern for the environment has led to the establishment of many strict laws and ordinances to control land disposal sites. Operators of landfills expected the refuse in them to decay. However, environmental experts have found that many materials decompose (break down) slowly because of the lack of oxygen in tightly packed landfills. Some materials are called biodegradable because they decompose from the action of bacteria or sunlight.

However, even biodegradable materials take a very long time to decompose when packed tightly in a landfill. Many new landfills have liners of plastic or clay to seal in the refuse. Rain water that drains into the landfill can then be collected and pumped out so that it does not pollute nearby ground water. Incineration is the process of burning waste products. Many large cities use incinerators because they do not have suitable areas nearby for land disposal sites.

Older municipal incinerators often lack adequate air pollution control devices. Burning in many of these incineration plants releases gases and solid particles that may harm human health, damage property, and kill plants. In the United States and Canada, incinerators are required to limit the amount of pollution they release. Ash produced by incineration should be monitored to ensure that it will not harm the environment.

Most new incineration plants use the heat from burning waste to produce steam, which can then drive electric power generators. One type of incineration plant turns some of the waste into fuel, which is burned to produce energy. Recycling and waste reduction help lessen the amount of refuse that is buried in landfills or burned in incinerators. Recycling is the process of reusing materials instead of throwing them away.

Commonly recycled materials include metals, glass, and paper. Waste reduction is the process of producing less waste. For example, people can reduce waste by using handkerchiefs instead of disposable tissues. See RECYCLING. Few people want to live or work near a garbage disposal site.

As it grows increasingly difficult to find locations for new landfills and incinerators, recycling and waste reduction will gain importance as methods of waste management. In the mid-1990's, Americans buried about 63 percent of their municipal solid waste in landfills, recycled about 21 percent of it, and burned 16 percent in incinerators. Recycling is a process designed to recover and reuse materials instead of throwing them away. Commonly recycled wastes include aluminum and steel cans, glass containers, and paper. Other recycling programs collect plastic, used motor oil, and automobile tires. Recycling helps conserve raw materials that manufacturers would otherwise need to use.

It also keeps materials out of landfills, helping reduce the pollution that may result from the disposal of various waste materials. Recycling has been an important source of materials for the iron and steel industry and for paper manufacturers since the early 1900's. A growing concern over the dwindling supply of natural resources and the increase in environmental pollution has led to renewed emphasis on recycling since the late 1960's. Recycled wastes provide materials for a variety of products. Manufacturers use aluminum from recycled cans to make new cans and various other metal products. Recycled paper is used not only in making paper and cardboard, but also in manufacturing such building materials as insulation and plasterboard.

Manufacturers grind up waste glass and use it to make new glass containers and some materials used in road construction. Some plastic containers can be remelted and molded into new plastic products. Recycled motor oil can be used as industrial fuel oil. Recyclable materials have the most value if they are not mixed in with garbage but sorted before the garbage is sent for disposal.

Separating recyclable materials is much more complicated when done at a waste-processing plant. Such special equipment as conveyor belts, screens, and magnets is needed to separate waste mechanically. There are three basic ways to collect recyclable materials. The materials are collected through buy-back centers, drop-off centers, and curbside collection programs. Buy-back centers pay people for materials they bring in. People are asked to separate recyclables by type and to separate glass by color.

Drop-off centers are usually open longer hours than buy-back centers but do not offer money for materials. In curbside collection programs, residents of a community separate their materials and put them on curbs by their homes. Trucks pick up the materials and bring them to a central place. From there, they are sent to manufacturers who convert them back into usable products. An increasing number of communities require residents to participate in curbside collection programs. Many businesses and industries also contribute to recycling efforts.

Offices can recycle such wastes as paper and cardboard. In addition, composting is a process of collecting yard waste and food waste and letting it rot into a substance that can be used for fertilizer.