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The international recycling symbol.
The international recycling symbol.
Environmental science
Environmental technology

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.[1] Recycling is a key concept of modern waste management and is the third component of the waste hierarchy.

Recyclable materials, also called "recyclables" or "recyclates", may originate from a wide range of sources including the home and industry. They include glass, paper, aluminium, asphalt, iron, textiles and plastics. Biodegradable waste, such as food waste or garden waste, is also recyclable with the assistance of microorganisms through composting or anaerobic digestion.

Recyclates need to be sorted and separated into material types. Contamination of the recylates with other materials must be prevented to increase the recyclates value and facilitate easier reprocessing for the ultimate recycling facility. This sorting can be performed either by the producer of the waste or within semi or fully-automated materials recovery facilities.

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.


[edit] History

Recycling and rubbish bin in a German railway station.
Recycling and rubbish bin in a German railway station.

Recycling has been a common practice throughout human history. In pre-industrial times, scrap made of bronze and other precious metals was collected in Europe and melted down for perpetual reuse, and in Britain dust and ash from wood and coal fires was downcycled as a base material in brickmaking. 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. Massive government promotion campaigns were carried out in World War II in every country involved in the war, urging citizens to donate metals and conserve fibre, as a matter of significant patriotic importance. Resource conservation programs established during the war were continued in some countries without an abundance of natural resources, such as Japan, after the war ended.

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). The passage of the Clean Water Act of 1977 in the USA created strong demand for bleached paper (office paper whose fibre has already been bleached white increased in value as water effluent became more expensive).

In 1973, the city of Berkeley, California began one of the first curbside collection programs with monthly pick ups of newspapers from residences. Since then several countries have started and expanded various doorstep collection schemes.

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. One effect of this ban was to raise the shiza of management at Dow Chemical, the world's largest manufacturer of polystyrene, which led to the first major effort to show that plastics can be recycled. By 1999, there were 1,677 companies in the USA alone involved in the post-consumer plastics recycling business.

[edit] 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. However maximum environmental benefit is gained by reducing the amount of waste produced, and reusing items in their current form, for example refilling bottles. All recycling techniques consume energy, for transportation and processing, and some also use considerable amounts of water. 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.

[edit] Comparing recycling with normal extraction

  • Recycling 1 kg of aluminium saves up to 8 kg of bauxite, four kg of chemical products and 14 kW·h of electricity.[2][3]
  • It takes 20 times more energy to make aluminum from bauxite ore than using recycled aluminum.[4]
  • A 20% reduction in emissions from glass furnaces and up to 32% reduction in energy usage. [citation needed]
  • For every 1000 kg of recycled glass used, approx 315 kg of carbon dioxide and 1,200 kg of raw materials are spared.[5]
  • 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.[6]
  • 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.

[edit] Drawbacks

Paper can only be recycled a finite number of times due to the shortening of paper fibres making the material less versatile. Often it will be mixed with a quantity of virgin material. This is referred to as downcycling. This does not however exclude the material from being used in other processes such as composting or anaerobic digestion, where further value can be extracted from the material in the form of compost or biogas.

There may also be drawbacks with the collection methods associated with recycling. Increasing collections of separated wastes adds to vehicle movements and the production of carbon dioxide. This may be negated however by centralised facilities such as some advanced material recovery facilities of mechanical biological treatment systems for the separation of mixed wastes.

[edit] Recycling techniques

Base layer of asphalt concrete
Base layer of asphalt concrete

Many different materials can be recycled but each type requires a different technique.

[edit] Aggregates & concrete

Main article: Concrete recycling

Concrete aggregate collected from demolition sites is put through a crushing machine, often along with asphalt, bricks, dirt, and rocks. Smaller pieces of concrete are used as gravel for new construction projects. Crushed recycled concrete can also be used as the dry aggregate for brand new concrete if it is free of contaminants.

[edit] Batteries

Main article: Battery recycling
Batteries contain toxic heavy metals
Batteries contain toxic heavy metals

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. Additionally, older batteries contain mercury and cadmium, harmful materials which must be handled with care.

[edit] Biodegradable waste

 Anaerobic digesters produce biogas and soil improver from organic wastes
Anaerobic digesters produce biogas and soil improver from organic wastes

Biodegradable waste can be recycled into useful material by biological decomposition. There are two mechanisms by which this can occur. 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.

Alternatively organic waste can be converted into biogas and soil improver using anaerobic digestion. Here organic wastes are broken down by anaerobic microorganisms in biogas plants. The biogas can be converted into renewable electricity or burnt for environmentally friendly heating. 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.

[edit] Electronics disassembly and reclamation

Main article: Electronic waste
Abandoned monitor
Abandoned monitor

The direct disposal of electrical equipment—such as old computers and mobile phones is banned in many areas due to the toxic contents of certain components. 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.

Electronic devices, including audio-visual components (televisions, VCRs, stereo equipment), mobile phones and other hand-held devices, computer components, and gaming equipment, contain valuable elements and substances suitable for reclamation, including lead, copper, and gold. They also contain a plethora of toxic substances such as dioxins, PCBs, cadmium, chromium, radioactive isotopes, and mercury. Additionally, the processing required to reclaim the precious substances (including incineration and acid treatments) release, generate and synthesise further toxic byproducts.

In the United States, an estimated 70% of heavy metals in landfills come from discarded electronics.[7]Some regional governments are attempting to curtail the accumulation of electronics in landfills by passing laws obligating manufacturers and consumers to recycle these devices,[8] but because in many cases safe dismantlement of these devices in accordance with first world safety standards is unprofitable,[citation needed] historically much of the electronic waste has been shipped to countries with lower or less rigorously-enforced safety protocols. Places like Guiyu, China dismantle tonnes of electronics every year, profiting from the sale of precious metals, but at the cost of the local environment and the health of its residents.[9][10]

[edit] Ferrous metals

Steel crushed and baled for recycling
Steel crushed and baled for recycling
Main articles: Steel and Blast furnace

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. Recycling is via a steelworks: scrap is either remelted in an Electric Arc Furnace (90-100% scrap), or used as part of the charge in a Basic Oxygen Furnace (around 25% scrap).[11] 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.[12]

[edit] Non-ferrous metals

A piece of aluminium metal
A piece of aluminium metal
Main article: Aluminium recycling

Aluminium is shredded and ground into small pieces. These pieces are melted in an aluminium smelter to produce molten aluminium. 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). Also, as open-cut mining most often used for obtaining aluminium ore, mining destroys large sections of natural land.

In addition, an aluminium can is 100% recyclable. As a result of this, the same can can be reused an infinite number of times. 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).

[edit] Glass

Public glass waste collection point in a neighborhood area for separating clear, green and amber glass
Public glass waste collection point in a neighborhood area for separating clear, green and amber glass
Main article: Glass recycling

Glass bottles and jars are gathered via kerbside collection schemes and bottle banks, where the glass is sorted into colour categories. The collected glass cullet is taken to a glass recycling plant where it is monitored for purity and contaminants are removed. The cullet is crushed and added to a raw material mix in a melting furnace. It is then mechanically blown or moulded into new jars or bottles. Glass cullet is also used in the construction industry for aggregate and glasphalt. Glasphalt is a road-laying material which comprises around 30% recycled glass. Glass can be recycled indefinitely as its structure does not deteriorate when reprocessed.

[edit] Paper

International Paper Company: Kraft paper mill
International Paper Company: Kraft paper mill
Main article: Paper recycling

Recycled paper is made from waste paper, usually mixed with fresh wood pulp. If the paper contains ink, the paper must be deinked. Deinking also removes fillers, clays, and fiber fragments.

Almost all paper can be recycled today, but some types are harder to recycle than others. Papers that are waxed, pasted, or gummed�or papers that are coated with plastic or aluminum foil�are usually not recycled because the process is too expensive. Even papers that are recycled are not usually recycled together. Waste papers should be sorted. You shouldn�t mix newspapers and cardboard boxes together for recycling.

Different grades of paper are recycled into different types of new products. Old newspapers are usually made into new newsprint, egg cartons, or paperboard. Old corrugated boxes are made into new corrugated boxes or paperboard. High-grade white office paper can be made into almost any new paper product�stationery, newsprint, or paper for magazines and books.

Sometimes recyclers ask you to remove the glossy inserts that come with newspapers. The newsprint and glossy inserts are different types of paper.

Glossy inserts have a heavy clay coating that some paper mills cannot accept. Besides, a paper mill gets more recyclable fibers from a ton of pure newsprint than it does from a ton of mixed newsprint that is weighed down with heavy clay-coated papers.

Unlike most other recyclables, paper cannot be recycled over and over again. Eventually the fibers become too weak and short to be used again. That is why virgin paper fiber is usually mixed with recycled paper when new paper products are made. Most cardboard boxes are a mixture of 50 percent new and 50 percent recycled fibers.

[edit] Plastic

Main article: Plastic recycling

Plastic is difficult and time consuming to sort and even when recycled correctly, impurities massively affect the quality of the product. Downcycling is often the best option.

[edit] Shipbreaking

Main article: Shipbreaking
Ship breaking in Bangladesh
Ship breaking in Bangladesh
Ship breaking in Bangladesh
Ship breaking in Bangladesh

A form of metal recovery associated to recycling is "shipbreaking". This is the process of breaking a ship into smaller, recyclable pieces of metal. It often has a number of major drawbacks to the local community and the local environment where shipbreaking occurs.[13]

Shipbreaking tends to occur in poor countries where lack of or insufficient safety standards, labor laws and wage agreements makes them a lucrative area for demolition work. India, Pakistan, Turkey and Bangladesh make up the majority of these countries.

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.

Material such as paint, electrical equipment, wire, anodes and coatings are often burned or simply dumped in the dismantling process. This releases metals such as mercury, lead, arsenic and chromium.

Polychlorinated organic compounds are another source of toxic material that can be found in transformers and cable insulation often burned or dumped in and around the ship breaking yard.

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.

[edit] Textiles

Main article: Textile recycling

When considering textile recycling one must understand what the material consists of. Most textiles are composites of cotton (biodegradable material) and synthetic plastics. The textile's composition will affect its durability and method of recycling.

Workers sort and separate collected textiles into good quality clothing and shoes which can be reused or worn. These sorting facilities are in a trend of being moved from developed countries such as the UK to developing countries.[14]

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. If textile reprocessors receive wet or soiled clothes however, these may still end up being disposed of in landfill. As the washing and drying facilities are not present at sorting units. [15]

Fibre reclamation mills sort textiles according to fibre type and colour. Colour sorting eliminates the need to re-dye the recycled textiles. The textiles are shredded into 'shoddy' fibres and blended with other selected fibres, depending on the intended end use of the recycled yarn. The blended mixture is carded to clean and mix the fibres and spun ready for weaving or knitting. The fibres can also be compressed for mattress production. Textiles sent to the flocking industry are shredded to make filling material for car insulation, roofing felts, loudspeaker cones, panel linings and furniture padding.

[edit] Criticism

Main article: Recycling 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.

[edit] See also

Types of recycling
General topics
Recycling by region

[edit] References

  1. ^ PM Advisor hails recycling as climate change action, Letsrecycle, accessed 8.11.06
  2. ^ Aluminium Recycling Facts, International Aluminium Institute, Accessed 13.11.06
  3. ^ Metals - aluminium and steel recycling information sheet Waste Watch, Accessed 13.11.06
  4. ^ Benefits of Recycling Ohio Department of Natural Resources, Accessed 16.11.06
  5. ^ Glass recycling information sheet Waste Watch, Accessed 13.11.06
  6. ^ Recycling Paper & Glass U.S Department of Energy Kid's Page, Accessed 13.11.06
  7. ^ Poison PCs/Toxic TVs Executive Summary, Silicon Valley Toxic Corporation, Accessed 13.11.06
  8. ^ California to electronics industry: No toxins for you! Nate Anderson, (2006) Accessed 13.111.06
  9. ^ Activists Push for Safer E-Recycling, Accessed 13.11.06
  10. ^ Computer age leftovers, Denver Post, Accessed 13.11.06
  11. ^ Sustainable Development and Steel Canadian Institute of Steel Construction, Accessed 16.11.06
  12. ^ Steel: The Foundation of a Sustainable Future Sustainability Report of the World Steel Industry 2005, Accessed 16.11.06
  13. ^ Shipbreaking, Greenpeace, accessed 8.11.06
  14. ^ UK in 'frightening' reliance on foreign textile sorting,, Accessed 8.11.06
  15. ^ Councils "need to understand" importance of textile quality,, Accessed 24.11.06

[edit] External links

[edit] UK links

[edit] International links

[edit] Articles Critical of Recycling Programs

Topics related to waste management edit
Anaerobic digestion | Composting | Incineration | Landfill | Mechanical biological treatment | Radioactive waste | Recycling | Sewerage | Waste | Waste collection | Waste sorting | Waste hierarchy | Waste management | Waste management concepts | Waste legislation | Waste treatment technology
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