Recycling by material

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Recycling can be carried out on various raw materials. Recycling is an important part of creating more sustainable economies, reducing the cost and environmental impact of raw materials. Not all materials are easily recycled, and processing recyclable into the correct waste stream requires considerable energy. Some particular manufactured goods are not easily separated, unless specially process therefore have unique product-based recycling processes.

Contents

Asphalt

Asphalt concrete removed during road maintenance, resurfacing, and repair activities can be reclaimed and reused in new pavement mixtures, as an unbound aggregate base, or other civil engineering applications. Very little asphalt concrete — less than 1 percent, according to a survey by the Federal Highway Administration and the National Asphalt Pavement Association conducted annually since 2009 — is actually disposed of in landfills. [1] When asphalt pavement material is reclaimed for reuse, it is able to replace both virgin aggregates and virgin asphalt binder. Similarly, asphalt roof shingles can be recycled for use in new asphalt pavements. [2]

Concrete

Concrete from a building being sent to a portable crusher. This is the first step in recycling concrete. Fotothek df ps 0000433 Ablagerung fur eine spater einsetzende Grossblockproduktio.jpg
Concrete from a building being sent to a portable crusher. This is the first step in recycling concrete.
Crushing concrete from an airfield Recycling an airfield N03 - geograph.org.uk - 379756.jpg
Crushing concrete from an airfield
Concrete recycling is the use of rubble from demolished concrete structures. Recycling is cheaper and more ecological than trucking rubble to a landfill. [3] Crushed rubble can be used for road gravel, revetments, retaining walls, landscaping gravel, or raw material for new concrete. Large pieces can be used as bricks or slabs, or incorporated with new concrete into structures, a material called urbanite. [4] [5]

Glass

A Dutch public glass waste collection point for separating clear, green and amber glass Glass-recycling.jpg
A Dutch public glass waste collection point for separating clear, green and amber glass
Bottles in different colors Beer bottles 2018 G1.jpg
Bottles in different colors
Mixed color glass cullet Glas aus Aufbereitungsanlage bunt - glass cullet various (Alter Fritz).JPG
Mixed color glass cullet
Public glass waste collection point for different colors of containers Glass salvage containers in front of Park Tenreuken during the day (Auderghem, Belgium, DSCF2709).jpg
Public glass waste collection point for different colors of containers

Glass recycling is the processing of waste glass into usable products. [6] Glass that is crushed or imploded and ready to be remelted is called cullet. [7] There are two types of cullet: internal and external. Internal cullet is composed of defective products detected and rejected by a quality control process during the industrial process of glass manufacturing, transition phases of product changes (such as thickness and color changes) and production offcuts. External cullet is waste glass that has been collected or reprocessed with the purpose of recycling. External cullet (which can be pre- or post-consumer) is classified as waste. The word "cullet", when used in the context of end-of-waste, will always refer to external cullet.

To be recycled, glass waste needs to be purified and cleaned of contamination. Then, depending on the end use and local processing capabilities, it might also have to be separated into different sizes and colours. Many recyclers collect different colors of glass separately since glass tends to retain its color after recycling. The most common colours used for consumer containers are clear (flint) glass, green glass, and brown (amber) glass. Glass is ideal for recycling since none of the material is degraded by normal use.

Many collection points have separate bins for clear (flint), green and brown (amber). Glass re-processors intending to make new glass containers require separation by color. If the recycled glass is not going to be made into more glass, or if the glass re-processor uses newer optical sorting equipment, separation by color at the collection point may not be required. Heat-resistant glass, such as Pyrex or borosilicate glass, must not be part of the glass recycling stream, because even a small piece of such material will alter the viscosity of the fluid in the furnace at remelt.

[8]

Metals

Aluminium

Aluminium is one of the most efficient and widely recycled materials. [9] [10] Aluminium is shredded and ground into small pieces or crushed into bales. These pieces or bales 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. This process does not produce any change in the metal, so aluminium can be recycled indefinitely.

Recycling aluminium saves 96%  of the energy cost of processing new aluminium, it also helps divert significant amounts of waste from landfills. [11] This is because the temperature necessary for melting recycled, nearly pure, aluminium is 600 °C, while to extract mined aluminium from its ore requires 900 °C. To reach this higher temperature, much more energy is needed, leading to the high environmental benefits of aluminium recycling. Americans throw away enough aluminium every year to rebuild their entire commercial air fleet. Also, the energy saved by recycling one aluminium can is enough to run a television for three hours. [12]

Copper

Like aluminium, copper is recyclable without any loss of quality, both from raw state and from manufactured products. [13] In volume, copper is the third most recycled metal after iron and aluminium. [14] An estimated 80% of all copper ever mined is still in use today. [15] According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of copper in use in society is 35–55 kg. Much of this is in more-developed countries (140–300 kg per capita) rather than less-developed countries (30–40 kg per capita).

The process of recycling copper is roughly the same as is used to extract copper but requires fewer steps. High-purity scrap copper is melted in a furnace and then reduced and cast into billets and ingots; lower-purity scrap is refined by electroplating in a bath of sulfuric acid. [16]

Iron and steel

Steel crushed and baled for recycling. Steel recycling bales.jpg
Steel crushed and baled for recycling.

Iron and steel are the world's most recycled materials, and among the easiest materials to reprocess, as they can be separated magnetically from the waste stream. 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). [17] 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. [18]

Other metals

For information about recycling other, less common metals, refer to:

Plastic

Plastic recycling
Municipal recycling facilities, Montgomery County, MD. 2007, Credit USEPA (14410405277).jpg
Bales of PET bottles stacked.jpg
Watering can made from 12 recycled bottles, Intratuin Winschoten (2020) 01.jpg
Aglomerat PVD.JPG
Clockwise from top left:
  • Sorting plastic waste at a single-stream recycling centre
  • Baled colour-sorted used bottles
  • Recovered HDPE ready for recycling
  • A watering can made from recycled bottles

Plastic recycling is the processing of plastic waste into other products. [19] [20] [21] Recycling can reduce dependence on landfill, conserve resources and protect the environment from plastic pollution and greenhouse gas emissions. [22] [23] Recycling rates lag those of other recoverable materials, such as aluminium, glass and paper. From the start of production through to 2015, the world produced some 6.3 billion tonnes of plastic waste, only 9% of which has been recycled, and only ~1% has been recycled more than once. [24] Of the remaining waste, 12% was incinerated and 79% either sent to landfill or lost into the environment as pollution. [24]

Almost all plastic is non-biodegradable and without recycling, spreads across the environment [25] [26] where it can cause harm. For example, as of 2015 approximately 8 million tons of waste plastic enter the oceans annually, damaging the ecosystem and forming ocean garbage patches. [27] Even the highest quality recycling processes lead to substantial plastic waste during the sorting and cleaning process, releasing large amounts of microplastics in waste water, and dust from the process. [28] [29]

Almost all recycling is mechanical: melting and reforming plastic into other items. This can cause polymer degradation at a molecular level, and requires that waste be sorted by colour and polymer type before processing, which is complicated and expensive. Errors can lead to material with inconsistent properties, rendering it unappealing to industry. [30] In feedstock recycling, waste plastic is converted into its starting chemicals, which can then become fresh plastic. This involves higher energy and capital costs. Alternatively, plastic can be burned in place of fossil fuels, in energy recovery facilities or biochemically converted into other useful chemicals for industry. In some countries, burning is the dominant form of plastic waste disposal, particularly where landfill diversion policies are in place.

Plastic recycling is low in the waste hierarchy. It has been advocated since the early 1970s, [31] but due to economic and technical challenges, did not impact plastic waste to any significant extent until the late 1980s. The plastics industry has been criticised for lobbying for expansion of recycling programs, even while research showed that most plastic could not be economically recycled. [32] [33] [34]

Timber

A tidy stack of pallets awaits reuse or recycling. Tidy Stacks of Pallets.jpg
A tidy stack of pallets awaits reuse or recycling.

Recycling timber has become popular due to its image as an environmentally friendly product, with consumers commonly believing that by purchasing recycled wood the demand for green timber will fall and ultimately benefit the environment. Greenpeace also view recycled timber as an environmentally friendly product, citing it as the most preferable timber source on their website. The arrival of recycled timber as a construction product has been important in both raising industry and consumer awareness towards deforestation and promoting timber mills to adopt more environmentally friendly practices.

See also

Related Research Articles

<span class="mw-page-title-main">Recycling</span> Converting waste materials into new products

Recycling is the process of converting waste materials into new materials and objects. This concept often includes the recovery of energy from waste materials. The recyclability of a material depends on its ability to reacquire the properties it had in its original state. It is an alternative to "conventional" waste disposal that can save material and help lower greenhouse gas emissions. It can also prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials, reducing energy use, air pollution and water pollution.

<span class="mw-page-title-main">Asphalt concrete</span> Composite material used for paving

Asphalt concrete is a composite material commonly used to surface roads, parking lots, airports, and the core of embankment dams. Asphalt mixtures have been used in pavement construction since the beginning of the twentieth century. It consists of mineral aggregate bound together with bitumen, laid in layers, and compacted.

<span class="mw-page-title-main">Polymer degradation</span> Alteration in the polymer properties under the influence of environmental factors

Polymer degradation is the reduction in the physical properties of a polymer, such as strength, caused by changes in its chemical composition. Polymers and particularly plastics are subject to degradation at all stages of their product life cycle, including during their initial processing, use, disposal into the environment and recycling. The rate of this degradation varies significantly; biodegradation can take decades, whereas some industrial processes can completely decompose a polymer in hours.

<span class="mw-page-title-main">Materials recovery facility</span> Plant to process recyclates

A materials recovery facility, materials reclamation facility, materials recycling facility or multi re-use facility is a specialized waste sorting and recycling system that receives, separates and prepares recyclable materials for marketing to end-user manufacturers. Generally, the main recyclable materials include ferrous metal, non-ferrous metal, plastics, paper, glass. Organic food waste is used to anaerobic digestion or composting. Inorganic inert waste is used to make building materials. Non-recyclable high calorific value waste is used to making RDF and SRF.

<span class="mw-page-title-main">Plastic recycling</span> Processes which convert waste plastic into new items

Plastic recycling is the processing of plastic waste into other products. Recycling can reduce dependence on landfill, conserve resources and protect the environment from plastic pollution and greenhouse gas emissions. Recycling rates lag those of other recoverable materials, such as aluminium, glass and paper. From the start of production through to 2015, the world produced some 6.3 billion tonnes of plastic waste, only 9% of which has been recycled, and only ~1% has been recycled more than once. Of the remaining waste, 12% was incinerated and 79% either sent to landfill or lost into the environment as pollution.

<span class="mw-page-title-main">Glass recycling</span> Processing of turning glass waste into usable products

Glass recycling is the processing of waste glass into usable products. Glass that is crushed or imploded and ready to be remelted is called cullet. There are two types of cullet: internal and external. Internal cullet is composed of defective products detected and rejected by a quality control process during the industrial process of glass manufacturing, transition phases of product changes and production offcuts. External cullet is waste glass that has been collected or reprocessed with the purpose of recycling. External cullet is classified as waste. The word "cullet", when used in the context of end-of-waste, will always refer to external cullet.

<span class="mw-page-title-main">Concrete recycling</span> Re-use of rubble from demolished concrete structures

Concrete recycling is the use of rubble from demolished concrete structures. Recycling is cheaper and more ecological than trucking rubble to a landfill. Crushed rubble can be used for road gravel, revetments, retaining walls, landscaping gravel, or raw material for new concrete. Large pieces can be used as bricks or slabs, or incorporated with new concrete into structures, a material called urbanite.

<span class="mw-page-title-main">Biodegradable plastic</span> Plastics that can be decomposed by the action of living organisms

Biodegradable plastics are plastics that can be decomposed by the action of living organisms, usually microbes, into water, carbon dioxide, and biomass. Biodegradable plastics are commonly produced with renewable raw materials, micro-organisms, petrochemicals, or combinations of all three.

<span class="mw-page-title-main">Tire recycling</span> Reuse of waste tires

Tire recycling, or rubber recycling, is the process of recycling waste tires that are no longer suitable for use on vehicles due to wear or irreparable damage. These tires are a challenging source of waste, due to the large volume produced, the durability of the tires, and the components in the tire that are ecologically problematic.

<span class="mw-page-title-main">Upcycling</span> Recycling waste into products of higher quality

Upcycling, also known as creative reuse, is the process of transforming by-products, waste materials, useless, or unwanted products into new materials or products perceived to be of greater quality, such as artistic value or environmental value.

<span class="mw-page-title-main">Demolition waste</span> Waste debris from destruction of buildings, roads, bridges, or other structures

Demolition waste is waste debris from destruction of buildings, roads, bridges, or other structures. Debris varies in composition, but the major components, by weight, in the US include concrete, wood products, asphalt shingles, brick and clay tile, steel, and drywall. There is the potential to recycle many elements of demolition waste.

<span class="mw-page-title-main">Plastic</span> Material of a wide range of synthetic or semi-synthetic organic solids

Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be molded, extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to their widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum; however, recent industrial methods use variants made from renewable materials, such as corn or cotton derivatives.

Products made from a variety of materials can be recycled using a number of processes.

<span class="mw-page-title-main">Plastic pollution</span> Accumulation of plastic in natural ecosystems

Plastic pollution is the accumulation of plastic objects and particles in the Earth's environment that adversely affects humans, wildlife and their habitat. Plastics that act as pollutants are categorized by size into micro-, meso-, or macro debris. Plastics are inexpensive and durable, making them very adaptable for different uses; as a result, manufacturers choose to use plastic over other materials. However, the chemical structure of most plastics renders them resistant to many natural processes of degradation and as a result they are slow to degrade. Together, these two factors allow large volumes of plastic to enter the environment as mismanaged waste which persists in the ecosystem and travels throughout food webs.

Plastic roads are paved roadways that are made partially or entirely from plastic or plastic composites, which is used to replace standard asphalt materials. Most plastic roads make use of plastic waste a portion the asphalt. It is currently unknown how these aggregates will perform in the mid- to long-term, or what effect their degradation might have on surrounding ecosystems.

<span class="mw-page-title-main">Economics of plastics processing</span> Economic aspects of plastic manufacturing


The economics of plastics processing is determined by the type of process. Plastics can be processed with the following methods: machining, compression molding, transfer molding, injection molding, extrusion, rotational molding, blow molding, thermoforming, casting, forging, and foam molding. Processing methods are selected based on equipment cost, production rate, tooling cost, and build volume. High equipment and tooling cost methods are typically used for large production volumes whereas low - medium equipment cost and tooling cost methods are used for low production volumes. Compression molding, transfer molding, injection molding, forging, and foam molding have high equipment and tooling cost. Lower cost processes are machining, extruding, rotational molding, blow molding, thermoforming, and casting. A summary of each process and its cost is displayed in figure 1.

<span class="mw-page-title-main">Recycling in Australia</span> Method of waste management in Australia

Recycling in Australia is a widespread, and comprehensive part of waste management in Australia, with 60% of all waste collected being recycled. Recycling is collected from households, commercial businesses, industries and construction. Despite its prominence, household recycling makes up only a small part (13%) of Australia's total recycling. It generally occurs through kerbside recycling collections such as the commingled recycling bin and food/garden organics recycling bin, drop-off and take-back programs, and various other schemes. Collection and management of household recycling typically falls to local councils, with private contractors collecting commercial, industrial and construction recycling. In addition to local council regulations, legislation and overarching policies are implemented and managed by the state and federal governments.

<span class="mw-page-title-main">Packaging waste</span> Post-use container and packing refuse

Packaging waste, the part of the waste that consists of packaging and packaging material, is a major part of the total global waste, and the major part of the packaging waste consists of single-use plastic food packaging, a hallmark of throwaway culture. Notable examples for which the need for regulation was recognized early, are "containers of liquids for human consumption", i.e. plastic bottles and the like. In Europe, the Germans top the list of packaging waste producers with more than 220 kilos of packaging per capita.

China's waste import ban, instated at the end of 2017, prevented foreign inflows of waste products. Starting in early 2018, the government of China, under Operation National Sword, banned the import of several types of waste, including plastics with a contamination level of above 0.05 percent. The ban has greatly affected recycling industries worldwide, as China had been the world's largest importer of waste plastics and processed hard-to-recycle plastics for other countries, especially in the West.

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