Putting waste substances back into productive use, a procedure advocated by many conservationists. It is a means of reducing the demand on non-renewable resources, and of preventing problems of pollution and waste disposal. Examples include the pulping of waste paper to make recycled paper, the existence of bottle banks to collect used glass, and the smelting of metals from scrap. Incentives for recycling can be provided by government subsidies or by a deposit tax on containers.
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Recycling is the reprocessing of materials into new products. Recycling prevents useful material resources being wasted, reduces the consumption of raw materials and reduces energy usage, and hence greenhouse gas emissions, compared to virgin production. Recycling is a key concept of modern waste management and is the third component of the waste hierarchy. Biodegradable waste, such as food waste or garden waste, is also recyclable with the assistance of microorganisms through composting or anaerobic digestion. Contamination of the recylates with other materials must be prevented to increase the recyclates value and facilitate easier reprocessing for the ultimate recycling facility.
There are two common household methods of helping increase recycling. Firstly kerbside collection (US: curbside collection) is where consumers leave presorted materials for recycling at the front of their property, typicially in boxes or sacks to be collected by a recycling vehicle. Alternatively, with a "bring system", the householder may take the materials to recycling banks or civic amenity centres where recyclates are placed into recycling bins based on the type of material.
Recycling does not include reuse where items retain their existing form for other purposes without the need for reprocessing.
History
Recycling has been a common practice throughout human history. The main driver for these types of recycling was the economic advantage of obtaining recycled feedstock instead of acquiring virgin material, as well as a lack of public waste removal in ever more-populated sites.
Paper recycling began in Britain in 1921, when the British Waste Paper Association was established to encourage trade in waste paper recycling.
Resource shortages caused by the world wars, and other such world changing occurances greatly encouraged recycling.
In the USA, the next big investment in recycling occurred in the 1970s, due to rising energy costs (recycling aluminium uses only 5% of the energy required by virgin production; glass, paper and metals have less dramatic but very significant energy savings when recycled feedstock is used).
One event that initiated recycling efforts occurred in 1989 when the city of Berkeley, California, banned the use of polystyrene packaging for keeping McDonald's hamburgers warm.
Benefits
One of the main benefits of recycling comes from reducing the amount of new material required. In theory, recycling allows a material to be continually reused for the same purpose, and in many cases this theory holds true, most notably in the recycling of metals and glass.
Since less raw material is required, recycling creates further benefits for materials where cost of the initial extraction or production is high—either economically, socially or environmentally. The recycling of aluminium, for example, saves 95% of the CO2 emissions—an environmentally harmful greenhouse gas—compared to refining new metal.
Concerns about limited resources such as raw materials and land space for disposal of waste have increased the importance of recycling. Both of these resources have an environmental impact which is why campaigners use the slogan "Reduce, Reuse, Recycle" to indicate the preferred order for waste management in the waste hierarchy.
Comparing recycling with normal extraction
| Aluminium | Recycling 1 kg of aluminium saves up to 8 kg of bauxite, four kg of chemical products and 14 kW·h of electricity. | It takes 20 times more energy to make aluminum from bauxite ore than using recycled aluminum. | For every 1000 kg of recycled glass used, approx 315 kg of carbon dioxide and 1,200 kg of raw materials are spared. |
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| Paper | 1000 kg of paper from recycled material conserves about 7,000 US gal (26,000 L) of water, 17-31 trees and 4,000 kW·h of electricity. | Milling paper from recycled paper uses 20% less energy than it does to make paper from fresh paper trees grown on tree farms at the cost of more pollution caused by additional transportation and chemical cleaning treatment. |
Drawbacks
Paper can only be recycled a finite number of times due to the shortening of paper fibres making the material less versatile.
There may also be drawbacks with the collection methods associated with recycling.
Recycling techniques
Many different materials can be recycled but each type requires a different technique.
Batteries
The large variation in size and type of batteries makes their recycling extremely difficult: they must first be sorted into similar kinds and each kind requires an individual recycling process.
Biodegradable waste
Biodegradable waste can be recycled into useful material by biological decomposition. The most common mechanism of recycling of household organic waste is home composting or municipal kerbside collection of green wastes sent to large scale composting plants. Advanced technologies such as mechanical biological treatment are able to sort the recyclable elements of the waste out before biological treatment by either composting, anaerobic digestion or biodrying. The recycling process works by mechanically separating the metals, plastics and circuit boards contained in the appliance. When this is done on a large scale at an electronic waste recycling plant, component recovery can be achieved in a cost-effective manner.
In the United States, an estimated 70% of heavy metals in landfills come from discarded electronics.Some regional governments are attempting to curtail the accumulation of electronics in landfills by passing laws obligating manufacturers and consumers to recycle these devices, but because in many cases safe dismantlement of these devices in accordance with first world safety standards is unprofitable, historically much of the electronic waste has been shipped to countries with lower or less rigorously-enforced safety protocols.
Ferrous metals
Iron and steel are the world's most recycled materials, and among the easiest materials to recycle, as they can be separated magnetically from the wastestream. Any grade of steel can be recycled to top quality new metal, with no 'downgrading' from prime to lower quality materials as steel is recycled repeatedly. 42% of crude steel produced is recycled material. The collected glass cullet is taken to a glass recycling plant where it is monitored for purity and contaminants are removed. Glasphalt is a road-laying material which comprises around 30% recycled glass.
Paper
Paper can be directly recycled or treated with other biodegradable wastes. In direct recycling it is separated into its component fibres in water, which creates a pulp slurry material. This fibre is then ready to be used to make new recycled paper. Paper is the main material that gets recycled in most countries. By this stage the recycled aluminium is indistinguishable from virgin aluminium and further processing is identical for both.
The environmental benefits of recycling aluminium are also enormous. Only around 5% of the CO2 is produced during the recycling process compared to producing raw aluminium (and an even smaller percentage when considering the complete cycle of mining and transporting the aluminium).
In addition, an aluminium can is 100% recyclable. Plus, every time it is recycled, it saves enough energy to watch television for about three hours (compared to mining and producing a new can).
Plastic
Shipbreaking
A form of metal recovery associated to recycling is "shipbreaking". This is the process of breaking a ship into smaller, recyclable pieces of metal.
Toxic material in the form of metals, gas, fumes and exhaust often contaminate a large area surrounding the ship breaking yards, including nearby villages and sleeping quarters for the workers, which are commonly placed nearby the yards.
It is believed that many of the social, economical and environmental drawback in shipbreaking could be alleviated greatly by adhering to safe handling of the recycling process, or the ship owner decontaminating the toxins from the ship before it gets sent to be demolished.
Textiles
When considering textile recycling one must understand what the material consists of.
Damaged textiles are further sorted into grades to make industrial wiping cloths and for use in paper manufacture or material which is suitable for fibre reclamation and filling products. The textiles are shredded into 'shoddy' fibres and blended with other selected fibres, depending on the intended end use of the recycled yarn.
Criticism
Many areas of recycling have come under criticism or scrutiny, most notably the claimed benefits that recycling saves energy, reduces greenhouse gas emissions and creates jobs.
Recycling by region
Recycling in the United Kingdom
Recycling in the United States
Recycling in Canada
UK links
Chartered Institute of Wastes Management UK trade body for waste and recycling Letsrecycle News website with excellent coverage of the UK waste and recycling industry. Recycle-more UK based recycling information siteInternational links
Directory of US recycling programs Guide to recycling Informal Recycling Cartoneros (Argentina)Articles Critical of Recycling Programs
Swedes trash myth of refuse recycling 8 Great Myths of Recycling
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