Rare materials, such as gold and silver, are recycled because acquiring new supplies is expensive. Other materials may not be as expensive to replace, but they are recycled to conserve energy, reduce pollution, conserve land, and to save money.
In general, using recycled materials to make new products costs less and requires less energy than using new materials. Recycling can also reduce pollution, either by reducing the demand for high-pollution alternatives or by minimizing the amount of pollution produced during the manufacturing process. Recycling decreases the amount of land needed for trash dumps by reducing the volume of discarded waste.
Recycling can be done internally (within a company) or externally (after a product is sold and used). In the paper industry, for example, internal recycling occurs when leftover stock and trimmings are salvaged to help make more new product. Since the recovered material never left the manufacturing plant, the final product is said to contain pre-consumer waste. External recycling occurs when materials used by the customer are returned for processing into new products. Materials ready to be recycled in this manner, such as empty beverage containers, are called post-consumer waste.
1. Resource Conservation
Recycling conserves natural resources by reducing the need for new material. Some natural resources are renewable, meaning they can be replaced, and some are not. Paper, corrugated board, and other paper products come from renewable timber sources. Trees harvested to make those products can be replaced by growing more trees. Iron and aluminum come from nonrenewable ore deposits. Once a deposit is mined, it cannot be replaced.
2. Energy Conservation
Recycling saves energy by reducing the need to process new material, which usually requires more energy than the recycling process. To make an aluminum can from recycled metal takes only 5 percent of the total energy needed to produce the same aluminum can from un-recycled materials, a 95 percent energy savings. Recycled paper and paperboard require 75 percent less energy to produce than new products. Significant energy savings result in the recycling of steel and glass, as well.
3. Pollution Reduction
Recycling reduces pollution because recycling a product creates less pollution than producing a new one. For every ton of newspaper recycled, 7 fewer kg (16 lb) of air pollutants are pumped into the atmosphere. Recycling can also reduce pollution by recycling safer products to replace those that pollute. Some countries still use chlorofluorocarbons (CFCs) to manufacture foam products such as cups and plates. Many scientists suspect that CFCs harm the atmosphere’s protective layer of ozone. Using recycled plastic instead for those products eliminates the creation of harmful CFCs.
4. Land Conservation
Recycling saves valuable landfill space, land that must be set aside for dumping trash, construction debris, and yard waste . In the United States, each person on average discards almost a ton of municipal solid waste (MSW) per year. MSW is raw, untreated garbage of the kind discarded by homes and small businesses. Waste from industry and agriculture normally is not part of MSW, but construction and demolition wastes are. The United States has the highest MSW discard level of any country in the world. Landfills fill up quickly and acceptable sites for new ones are difficult to find because of objections by neighbors to noise and smells, and the hazard of leaks into underground water supplies. The two major ways to reduce the need for new landfills are to generate less initial waste and to recycle products that would normally be considered waste. In 2000 about 15 million metric tons (16.5 million U.S. tons) of food and yard debris were composted in the United States, accounting for almost a quarter of all recycling by weight. The combined effort of reducing waste and recycling resulted in 37.6 million fewer metric tons (41.4 million U.S. tons) of material going to landfills. Solid waste can also be burned instead of buried in the ground. Typically, waste-to-energy (WTE) facilities burn trash to heat water for steam-turbine electrical generators. This WTE recycling keeps another 14.5 percent of municipal solid waste out of the landfills.
5. Economic Savings
Recycling in the short term is not always economically profitable or a break-even financial operation. Most experts contend, however, that the economic consequences of recycling are positive in the long term. Recycling will save money if potential landfill sites are used for more productive purposes and by reducing the number of pollution-related illnesses.
Reference : Encarta encyclopedia, Wikipedia