![Municipal waste recycling rate (%), OWID](https://upload.wikimedia.org/wikipedia/commons/e/ee/Municipal_waste_recycling_rate_%28%25%29%2C_OWID.svg)
Recycling is the process of converting
waste
Waste (or wastes) are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor economic value. A waste prod ...
materials into new materials and objects. The
recovery of energy from waste materials is often included in this concept. 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
Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and lar ...
. It can also prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials, reducing energy use, air pollution (from
incineration
Incineration is a waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-energy facilities. Incineration and other high ...
) and water pollution (from
landfill
A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste materials. Landfill is the oldest and most common form of waste disposal, although the systematic burial of the waste ...
ing).
Recycling is a key component of modern waste reduction and is the third component of the "
Reduce
Reduction, reduced, or reduce may refer to:
Science and technology Chemistry
* Reduction (chemistry), part of a reduction-oxidation (redox) reaction in which atoms have their oxidation state changed.
** Organic redox reaction, a redox react ...
,
Reuse
Reuse is the action or practice of using an item, whether for its original purpose (conventional reuse) or to fulfill a different function ( creative reuse or repurposing). It should be distinguished from recycling, which is the breaking down of u ...
, and Recycle"
waste hierarchy
Waste hierarchy is a tool used in the evaluation of processes that protect the environment alongside resource and energy consumption from most favourable to least favourable actions. The hierarchy establishes preferred program priorities based ...
.
It promotes environmental sustainability by removing raw material input and redirecting waste output in the economic system. There are some
ISO standards
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Art ...
related to recycling, such as ISO 15270:2008 for plastics waste and
ISO 14001:2015 for environmental management control of recycling practice.
''Recyclable materials'' include many kinds of glass, paper, cardboard, metal, plastic,
tire
A tire (American English) or tyre (British English) is a ring-shaped component that surrounds a Rim (wheel), wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide Traction (engineering), t ...
s, textiles, batteries, and
electronics
The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...
. The
composting
Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical and biological properties. It is commonly prepared by decomposing plant, food waste, recycling organic materials and manure. The resulting m ...
and other reuse of
biodegradable waste
Biodegradable waste includes any organic matter in waste which can be broken down into carbon dioxide, water, methane or simple organic molecules by micro-organisms and other living things by composting, aerobic digestion, anaerobic digestion ...
—such as
food
Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...
and
garden waste
Green waste, also known as "biological waste", is any organic waste that can be composted. It is most usually composed of refuse from gardens such as grass clippings or leaves, and domestic or industrial kitchen wastes. Green waste does not inc ...
—is also a form of recycling.
Materials for recycling are either delivered to a household recycling center or picked up from curbside bins, then sorted, cleaned, and reprocessed into new materials for manufacturing new products.
In ideal implementations, recycling a material produces a fresh supply of the same material—for example, used office paper would be converted into new office paper, and used
polystyrene
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a ...
foam into new polystyrene. Some types of materials, such as metal cans, can be remanufactured repeatedly without losing their purity.
["7 Things You Didn’t Know About Plastic (and Recycling)"](_blank)
''National Geographic''. Retrieved 26 July 2019. With other materials, this is often difficult or too expensive (compared with producing the same product from raw materials or other sources), so "recycling" of many products and materials involves their ''
reuse
Reuse is the action or practice of using an item, whether for its original purpose (conventional reuse) or to fulfill a different function ( creative reuse or repurposing). It should be distinguished from recycling, which is the breaking down of u ...
'' in producing different materials (for example,
paperboard
Paperboard is a thick paper-based material. While there is no rigid differentiation between paper and paperboard, paperboard is generally thicker (usually over 0.30 mm, 0.012 in, or 12 Inch#equivalences, points) than paper and has certain ...
). Another form of recycling is the
salvage of constituent materials from complex products, due to either their intrinsic value (such as lead from
car batteries
An automotive battery or car battery is a rechargeable battery that is used to start a motor vehicle. Its main purpose is to provide an electric current to the electric-powered starting motor, which in turn starts the chemically-powered intern ...
and gold from
printed circuit board
A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in Electrical engineering, electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a L ...
s), or their hazardous nature (e.g. removal and reuse of
mercury
Mercury commonly refers to:
* Mercury (planet), the nearest planet to the Sun
* Mercury (element), a metallic chemical element with the symbol Hg
* Mercury (mythology), a Roman god
Mercury or The Mercury may also refer to:
Companies
* Merc ...
from
thermometer
A thermometer is a device that temperature measurement, measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a merc ...
s and
thermostat
A thermostat is a regulating device component which senses the temperature of a physical system and performs actions so that the system's temperature is maintained near a desired setpoint.
Thermostats are used in any device or system tha ...
s).
History
Origins
Recycling has been a common practice for most of human history with recorded advocates as far back as
Plato
Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...
in the fourth century BC. During periods when resources were scarce, archaeological studies of ancient waste dumps show less household waste (such as ash, broken tools, and pottery), implying that more waste was recycled in place of new material.
However,
archaeological artefact
An artifact, or artefact (see American and British English spelling differences), is a general term for an item made or given shape by humans, such as a tool or a work of art, especially an object of archaeological interest. In archaeology, the ...
s made from recyclable material, such as glass or metal, may neither be the original object nor resemble it, with the consequence that a successful ancient recycling economy can become invisible when recycling is synonymous with re-melting rather than reuse.
In
pre-industrial
Pre-industrial society refers to social attributes and forums of political and cultural organization that were prevalent before the advent of the Industrial Revolution, which occurred from 1750 to 1850. ''Pre-industrial'' refers to a time before ...
times, there is evidence of
scrap
Scrap consists of Recycling, recyclable materials, usually metals, left over from product manufacturing and consumption, such as parts of vehicles, building supplies, and surplus materials. Unlike waste, scrap Waste valorization, has monetary ...
bronze and other metals being collected in Europe and melted down for continuous reuse.
Paper recycling was first recorded in 1031 when Japanese shops sold repulped paper. In Britain dust and ash from wood and coal fires was collected by "
dustmen
A waste collector, also known as a garbageman, garbage collector, trashman (in the US), binman or (rarely) dustman (in the UK), is a person employed by a public or private enterprise to collect and dispose of municipal solid waste (refuse) and r ...
" and
downcycled as a base material for brick making. These forms of recycling were driven by the economic advantage of obtaining recycled materials instead of virgin material, and the need for waste removal in ever-more-densely populated areas.
In 1813,
Benjamin Law developed the process of turning rags into "
shoddy
Recycled wool, rag wool or shoddy is any woollen textile or yarn made by shredding existing fabric and re-spinning the resulting fibres. Textile recycling is an important mechanism for reducing the need for raw wool in manufacturing.
Shoddy was ...
" and "
mungo" wool in Batley, Yorkshire, which combined recycled fibers with virgin
wool
Wool is the textile fibre obtained from sheep and other mammals, especially goats, rabbits, and camelids. The term may also refer to inorganic materials, such as mineral wool and glass wool, that have properties similar to animal wool.
As ...
. The
West Yorkshire
West Yorkshire is a metropolitan and ceremonial county in the Yorkshire and Humber Region of England. It is an inland and upland county having eastward-draining valleys while taking in the moors of the Pennines. West Yorkshire came into exi ...
shoddy industry in towns such as Batley and Dewsbury lasted from the early 19th century to at least 1914.
Industrialization spurred demand for affordable materials. In addition to rags, ferrous
scrap
Scrap consists of Recycling, recyclable materials, usually metals, left over from product manufacturing and consumption, such as parts of vehicles, building supplies, and surplus materials. Unlike waste, scrap Waste valorization, has monetary ...
metals were coveted as they were cheaper to acquire than virgin ore. Railroads purchased and sold scrap metal in the 19th century, and the growing steel and automobile industries purchased scrap in the early 20th century. Many secondary goods were collected, processed and sold by peddlers who scoured dumps and city streets for discarded machinery, pots, pans, and other sources of metal. By
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
, thousands of such peddlers roamed the streets of American cities, taking advantage of market forces to recycle post-consumer materials into industrial production.
Manufacturers of beverage bottles, including
Schweppes
Schweppes (, ) is a beverage brand that originated in the Republic of Geneva; it is made, bottled and distributed worldwide by multiple international conglomerates, depending on licensing and region, that manufacture and sell soft drinks. Schwep ...
, began offering refundable recycling deposits in Great Britain and Ireland around 1800. An official recycling system with
refundable deposits for bottles was established in Sweden in 1884, and for aluminum beverage cans in 1982; it led to recycling rates of 84–99%, depending on type. (Glass bottles can be refilled around 20 times.)
Wartime
![YorkWhipMaFence2](https://upload.wikimedia.org/wikipedia/commons/0/01/YorkWhipMaFence2.jpg)
New chemical industries created in the late 19th century both invented new materials (e.g.
Bakelite
Polyoxybenzylmethylenglycolanhydride, better known as Bakelite ( ), is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. The first plastic made from synthetic components, it was developed ...
in 1907) and promised to transform valueless into valuable materials. Proverbially, you could not
make a silk purse of a sow's ear—until the US firm Arthur D. Little published in 1921 "On the Making of Silk Purses from Sows' Ears", its research proving that when "chemistry puts on overalls and gets down to business
..new values appear. New and better paths are opened to reach the goals desired."
Recycling—or "salvage", as it was then usually known—was a major issue for governments during
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, where financial constraints and significant material shortages made it necessary to reuse goods and recycle materials.
These resource shortages caused by the
world war
A world war is an international conflict which involves all or most of the world's major powers. Conventionally, the term is reserved for two major international conflicts that occurred during the first half of the 20th century, World WarI (1914 ...
s, and other such world-changing events, greatly encouraged recycling.
It became necessary for most homes to recycle their waste, allowing people to make the most of what was available. Recycling household materials also meant more resources were left available for war efforts.
Massive government campaigns, such as the
National Salvage Campaign in Britain and the
Salvage for Victory campaign in the United States, occurred in every fighting nation, urging citizens to donate metal, paper, rags, and rubber as a patriotic duty.
Post-World War II
A considerable investment in recycling occurred in the 1970s due to rising energy costs. Recycling aluminium uses only 5% of the energy of virgin production. Glass, paper and other metals have less dramatic but significant energy savings when recycled.
Although consumer electronics have been popular since the 1920s, recycling them was almost unheard of until early 1991. The first electronic waste recycling scheme was implemented in Switzerland, beginning with collection of old refrigerators, then expanding to cover all devices. When these programs were created, many countries couldn't deal with the sheer quantity of
e-waste, or its hazardous nature, and began to export the problem to developing countries without enforced environmental legislation. (For example, recycling computer monitors in the United States costs 10 times more than in China.) Demand for electronic waste in Asia began to grow when scrapyards found they could extract valuable substances such as copper, silver, iron, silicon, nickel, and gold during the recycling process. The 2000s saw a boom in both the sales of electronic devices and their growth as a waste stream: In 2002, e-waste grew faster than any other type of waste in the EU.
This spurred investment in modern automated facilities to cope with the influx, especially after strict laws were implemented in 2003.
As of 2014, the
European Union
The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...
had about 50% of world share of waste and recycling industries, with over companies employing people and a turnover of €24 billion. EU countries are mandated to reach recycling rates of at least 50%; leading countries are already at around 65%. The overall EU average was 39% in 2013
and is rising steadily, to 45% in 2015.
In 2015, the United Nations General Assembly set 17 Sustainable Development Goals. Goal 12,
Responsible Consumption and Production, specifies 11 targets "to ensure sustainable consumption and production patterns". The fifth target,
Target 12.5, is defined as substantially reducing waste generation by 2030, indicated by the National Recycling Rate.
In 2018, changes in the recycling industry have sparked a global "crisis". On 31 December 2017, China announced its "
National Sword" policy, setting new standards for imports of recyclable material and banning materials deemed too "dirty" or "hazardous". The new policy caused drastic disruptions in the global recycling market, and reduced the prices of scrap plastic and low-grade paper. Exports of recyclable materials from G7 countries to China dropped dramatically, with many shifting to countries in southeast Asia. This generated significant concern about the recycling industry's practices and environmental sustainability. The abrupt shift caused countries to accept more materials than they could process, and raised fundamental questions about shipping waste from developed countries to countries with few environmental regulations—a practice that predated the crisis.
Legislation
Supply
For a recycling program to work, a large, stable
supply
Supply may refer to:
*The amount of a resource that is available
**Supply (economics), the amount of a product which is available to customers
**Materiel, the goods and equipment for a military unit to fulfill its mission
*Supply, as in confidenc ...
of recyclable material is crucial. Three legislative options have been used to create such supplies: mandatory recycling collection,
container deposit legislation
Container-deposit legislation (also known as a container-deposit scheme, deposit-refund system or scheme, deposit-return system, or bottle bill) is any law that requires the collection of a monetary deposit on beverage containers (refillable or ...
, and refuse bans. Mandatory collection laws set recycling targets for cities, usually in the form that a certain percentage of a material must be diverted from the city's waste stream by a target date. The city is responsible for working to meet this target.
Container deposit legislation mandates refunds for the return of certain containers—typically glass, plastic and metal. When a product in such a container is purchased, a small surcharge is added that the consumer can reclaim when the container is returned to a collection point. These programs have succeeded in creating an average 80% recycling rate. Despite such good results, the shift in collection costs from local government to industry and consumers has created strong opposition in some areas
—for example, where manufacturers bear the responsibility for recycling their products. In the European Union, the
WEEE Directive
The Waste Electrical and Electronic Equipment Directive (WEEE Directive) is the European Community Directive 2012/19/EU on waste electrical and electronic equipment (WEEE) which, together with the RoHS Directive 2011/65/EU, became European La ...
requires producers of consumer electronics to reimburse the recyclers' costs.
An alternative way to increase the supply of
recyclates
Recycling is the process of converting waste materials into new materials and objects. The Energy recycling, recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability t ...
is to
ban the disposal of certain materials as waste, often including used oil, old batteries, tires, and garden waste. This can create a viable economy for the proper disposal of the products. Care must be taken that enough recycling
services
Service may refer to:
Activities
* Administrative service, a required part of the workload of university faculty
* Civil service, the body of employees of a government
* Community service, volunteer service for the benefit of a community or a p ...
exist to meet the supply, or such bans can create increased
illegal dumping
Illegal dumping, also called fly dumping or fly tipping ( UK), is the dumping of waste illegally instead of using an authorized method such as curbside collection or using an authorized rubbish dump. It is the illegal deposit of any waste onto l ...
.
Government-mandated demand
Four forms of legislation have also been used to increase and maintain the demand for recycled materials: minimum recycled content mandates, utilization rates,
procurement
Procurement is the method of discovering and agreeing to terms and purchasing goods, Service (economics), services, or other works from an external source, often with the use of a tendering or competitive bidding process. When a government agenc ...
policies, and recycled
product labeling.
Both minimum recycled content mandates and utilization rates increase demand by forcing manufacturers to include recycling in their operations. Content mandates specify that a certain percentage of a new product must consist of recycled material. Utilization rates are a more flexible option: Industries can meet their recycling targets at any point of their operations, or even contract out recycling in exchange for tradable credits. Opponents to these methods cite their large increase in reporting requirements, and claim that they rob the industry of flexibility.
Governments
A government is the system or group of people governing an organized community, generally a state.
In the case of its broad associative definition, government normally consists of legislature, executive, and judiciary. Government is a ...
have used their own
purchasing power
Purchasing power is the amount of goods and services that can be purchased with a unit of currency. For example, if one had taken one unit of currency to a store in the 1950s, it would have been possible to buy a greater number of items than would ...
to increase recycling demand through "procurement policies". These policies are either "set-asides", which reserve a certain amount of spending for recycled products; or "price preference" programs that provide larger
budgets
A budget is a calculation play, usually but not always financial, for a defined period, often one year or a month. A budget may include anticipated sales volumes and revenues, resource quantities including time, costs and expenses, environmenta ...
when recycled items are purchased. Additional regulations can target specific cases: in the United States, for example, the
Environmental Protection Agency
A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...
mandates the purchase of oil, paper, tires and
building insulation
Building insulation is any object in a building used as insulation for thermal management. While the majority of insulation in buildings is for thermal purposes, the term also applies to acoustic insulation, fire insulation, and impact insul ...
from recycled or re-refined sources whenever possible.
The final government regulation toward increased demand is recycled product labeling. When producers are required to label their packaging with the amount of recycled material it contains (including the packaging), consumers can make more educated choices. Consumers with sufficient
buying power
Bargaining power is the relative ability of parties in an argumentative situation (such as bargaining, contract writing, or making an agreement) to exert influence over each other. If both parties are on an equal footing in a debate, then they wi ...
can choose more environmentally conscious options, prompting producers to increase the recycled material in their products and increase demand. Standardized recycling labeling can also have a positive effect on the supply of recyclates when it specifies how and where the product can be recycled.
Recyclates
![CLOSEUP OF BEER BOTTLES CRUSHED INTO FINE GLASS](https://upload.wikimedia.org/wikipedia/commons/d/d0/CLOSEUP_OF_BEER_BOTTLES_CRUSHED_INTO_FINE_GLASS._THIS_MIXTURE_IS_FED_INTO_THE_GLASS_FURNACE_AND_NEW_BOTTLES_ARE_MADE..._-_NARA_-_543695.jpg)
"Recyclate" is a raw material sent to and processed in a waste recycling plant or materials-recovery facility so it can be used in the production of new materials and products. For example,
plastic bottle
A plastic bottle is a bottle constructed from high-density or low density plastic. Plastic bottles are typically used to store liquids such as water, soft drinks, motor oil, cooking oil, medicine, shampoo, milk, and ink. The size ranges from v ...
s can be made into plastic pellets and synthetic fabrics.
Quality of recyclate
The quality of recyclates is one of the principal challenges for the success of a long-term vision of a
green economy
A green economy is an economy that aims at reducing environmental risks and ecological scarcities, and that aims for sustainable development without degrading the environment. It is closely related with ecological economics, but has a more politi ...
and achieving zero waste. It generally refers to how much of it is composed of target material, versus non-target material and other non-recyclable material.
Steel and other metals have intrinsically higher recyclate quality; it is estimated that two-thirds of all new steel comes from recycled steel. Only target material is likely to be recycled, so higher amounts of non-target and non-recyclable materials can reduce the quantity of recycled products.
A high proportion of non-target and non-recyclable material can make it more difficult to achieve "high-quality" recycling; and if recyclate is of poor quality, it is more likely to end up being
down-cycled or, in more extreme cases, sent to other recovery options or
landfill
A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste materials. Landfill is the oldest and most common form of waste disposal, although the systematic burial of the waste ...
ed.
For example, to facilitate the remanufacturing of clear glass products, there are tight restrictions for colored glass entering the re-melt process. Another example is the downcycling of plastic, where products such as plastic food packaging are often downcycled into lower quality products, and do not get recycled into the same plastic food packaging.
The quality of recyclate not only supports high-quality recycling, but it can also deliver significant environmental benefits by reducing, reusing, and keeping products out of landfills.
High-quality recycling can support economic growth by maximizing the value of waste material.
Higher income levels from the sale of quality recyclates can return value significant to local governments, households and businesses.
Pursuing high-quality recycling can also promote consumer and business confidence in the waste and resource management sector, and may encourage investment in it.
There are many actions along the recycling supply chain, each of which can affect recyclate quality.
Waste producers who place non-target and non-recyclable wastes in recycling collections can affect the quality of final recyclate streams, and require extra efforts to discard those materials at later stages in the recycling process.
Different collection systems can induce different levels of contamination. When multiple materials are collected together, extra effort is required to sort them into separate streams and can significantly reduce the quality of the final products.
Transportation and the compaction of materials can also make this more difficult. Despite improvements in technology and quality of recyclate, sorting facilities are still not 100% effective in separating materials.
When materials are stored outside, where they can become wet, can also cause problems for re-processors. Further sorting steps may be required to satisfactorily reduce the amount of non-target and non-recyclable material.
Recyclate Quality Action Plan (Scotland)
Scotland's Recyclate Quality Action Plan proposes a number of actions the
Scottish Government wants to take to increase the quality of materials collected for recycling and sorted at recovery facilities before it is exported or sold on the reprocessing market.
Its objectives are to:
* Increase recyclate quality, and create greater transparency about it.
* Help those contracting with recycling facilities identify what is required of them.
* Ensure compliance with the Waste (Scotland) Regulations 2012.
* Stimulate a household market for quality recyclate.
* Address and reduce issues around waste shipment regulations.
The plan focuses on three key areas, with 14 actions to increase the quality of materials collected, sorted and presented to the processing market in Scotland.
These areas are:
* Collection systems and input contamination
* Sorting facilities—material sampling and transparency
* Material quality benchmarking and standards
Recycling consumer waste
Collection
![DeutscheBahnRecycling20050814 CopyrightKaihsuTai Rotated](https://upload.wikimedia.org/wikipedia/commons/0/04/DeutscheBahnRecycling20050814_CopyrightKaihsuTai_Rotated.jpg)
A number of systems have been implemented to collect recyclates from the general waste stream, occupying different places on the spectrum of trade-off between public convenience and government ease and expense. The three main categories of collection are drop-off centers, buy-back centers and curbside collection.
About two-thirds of the cost of recycling is incurred in the collection phase.
Curbside collection
![ACT recycling truck](https://upload.wikimedia.org/wikipedia/commons/1/11/ACT_recycling_truck.jpg)
Curbside collection encompasses many subtly different systems, which differ mostly on where in the process the recyclates are sorted and cleaned. The main categories are mixed waste collection, commingled recyclables, and source separation.
A
waste collection vehicle
A garbage truck is a truck specially designed to collect municipal solid waste and transport it to a solid waste treatment facility, such as a landfill, recycling center or transfer station. In Australia they are commonly called rubbish truc ...
generally picks up the waste.
In mixed waste collection, recyclates are collected mixed with the rest of the waste, and the desired materials are sorted out and cleaned at a central sorting facility. This results in a large amount of recyclable waste (especially paper) being too soiled to reprocess, but has advantages as well: The city need not pay for the separate collection of recyclates, no public education is needed, and any changes to the recyclability of certain materials are implemented where sorting occurs.
In a commingled or
single-stream system,
recyclables
Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...
are mixed but kept separate from non-recyclable waste. This greatly reduces the need for post-collection cleaning, but requires
public education
State schools (in England, Wales, Australia and New Zealand) or public schools (Scottish English and North American English) are generally primary or secondary schools that educate all students without charge. They are funded in whole or in pa ...
on what materials are recyclable.
=Source separation
=
Source separation is the other extreme, where each material is cleaned and sorted prior to collection. It requires the least post-collection sorting and produces the purest recyclates. However, it incurs additional
operating cost
Operating costs or operational costs, are the expenses which are related to the operation of a business, or to the operation of a device, component, piece of equipment or facility. They are the cost of resources used by an organization just to main ...
s for collecting each material, and requires extensive public education to avoid recyclate
contamination
Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc.
Types of contamination
W ...
.
In
Oregon
Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
, USA,
Oregon DEQ surveyed multi-family property managers; about half of them reported problems, including contamination of recyclables due to trespassers such as
transients
Transience or transient may refer to:
Music
* ''Transient'' (album), a 2004 album by Gaelle
* ''Transience'' (Steven Wilson album), 2015
* Transience (Wreckless Eric album)
Science and engineering
* Transient state, when a process variable or ...
gaining access to collection areas.
Source separation used to be the preferred method due to the high cost of sorting commingled (mixed waste) collection. However, advances in sorting technology have substantially lowered this overhead, and many areas that had developed source separation programs have switched to what is called ''co-mingled collection''.
Buy-back centers
At Buy-back centers, separated, cleaned recyclates are purchased, providing a clear incentive for use and creating a stable supply. The post-processed material can then be sold. If profitable, this conserves the emission of greenhouse gases; if unprofitable, it increases their emission. Buy-back centres generally need government subsidies to be viable. According to a 1993 report by the U.S.
National Waste & Recycling Association, it costs an average $50 to process a ton of material that can be resold for $30.
In the US, the value per ton of mixed recyclables was $180 in 2011, $80 in 2015, and $100 in 2017.
In 2017, glass was essentially valueless because of the low cost of sand, its major component. Similarly, low oil costs thwarted plastic recycling.
In 2017,
Napa, California
Napa is the largest city and county seat of Napa County and a principal city of Wine Country in Northern California. Located in the North Bay region of the Bay Area, the city had a population of 77,480 as of the end of 2021. Napa is a major t ...
was reimbursed about 20% of its recycling costs.
Drop-off centers
Drop-off centers require the waste producer to carry recyclates to a central location—either an installed or mobile collection station or the reprocessing plant itself. They are the easiest type of collection to establish but suffer from low and unpredictable throughput.
Distributed recycling
For some waste materials such as plastic, recent technical devices called
recyclebot
A recyclebot (or RecycleBot) is an open-source hardware device for converting waste plastic into filament for open-source 3D printers like the RepRap. Making DIY 3D printer filament at home is both less costly and better for the environment tha ...
s
enable a form of distributed recycling. Preliminary
life-cycle analysis
Life cycle assessment or LCA (also known as life cycle analysis) is a methodology for assessing environmental impacts associated with all the stages of the life cycle of a commercial product, process, or service. For instance, in the case o ...
(LCA) indicates that such distributed recycling of
HDPE
High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density ratio, ...
to make filament for
3D printers
3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer co ...
in rural regions consumes less energy than using virgin resin, or using conventional recycling processes with their associated transportation.
[M. Kreiger, G. C. Anzalone, M. L. Mulder, A. Glover and J. M Pearce (2013). Distributed Recycling of Post-Consumer Plastic Waste in Rural Areas. MRS Online Proceedings Library, 1492]
mrsf12-1492-g04-06
doi:10.1557/opl.2013.258
open access
/ref>
Sorting
Once commingled recyclates are collected and delivered to a materials recovery facility
A materials recovery facility, materials reclamation facility, materials recycling facility or Multi re-use facility (MRF, pronounced "murf") is a specialized plant that receives, separates and prepares recyclable materials for marketing to end-u ...
, the materials must be sorted. This is done in a series of stages, many of which involve automated processes, enabling a truckload of material to be fully sorted in less than an hour. Some plants can now sort materials automatically; this is known as single-stream recycling
Single-stream (also known as “fully commingled” or "single-sort") recycling refers to a system in which all paper fibers, plastics, metals, and other containers are mixed in a collection truck, instead of being sorted by the depositor into sepa ...
. Automatic sorting may be aided by robotics and machine learning. In plants, a variety of materials is sorted including paper, different types of plastics, glass, metals, food scraps, and most types of batteries. A 30% increase in recycling rates has been seen in areas with these plants. In the US, there are over 300 materials recovery facilities.
Initially, commingled recyclates are removed from the collection vehicle and placed on a conveyor belt spread out in a single layer. Large pieces of corrugated fiberboard
Corrugated fiberboard or corrugated cardboard is a type of packaging material consisting of a fluted corrugated sheet and one or two flat linerboards. It is made on "flute lamination machines" or "corrugators" and is used for making corrugated ...
and plastic bag
A plastic bag, poly bag, or pouch is a type of container made of thin, flexible, plastic film, nonwoven fabric, or plastic textile. Plastic bags are used for containing and transporting goods such as foods, produce, powders, ice, magazines, c ...
s are removed by hand at this stage, as they can cause later machinery to jam.
Next, automated machinery such as disk screens and air classifiers separate the recyclates by weight, splitting lighter paper and plastic from heavier glass and metal. Cardboard is removed from mixed paper, and the most common types of plastic—PET
A pet, or companion animal, is an animal kept primarily for a person's company or entertainment rather than as a working animal, livestock, or a laboratory animal. Popular pets are often considered to have attractive appearances, intelligence, ...
(#1) and HDPE
High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density ratio, ...
(#2)—are collected, so these materials can be diverted into the proper collection channels. This is usually done by hand; but in some sorting centers, spectroscopic
Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter wav ...
scanners are used to differentiate between types of paper and plastic based on their absorbed wavelengths. Plastics tend to be incompatible with each other due to differences in chemical composition
A chemical composition specifies the identity, arrangement, and ratio of the elements making up a compound.
Chemical formulas can be used to describe the relative amounts of elements present in a compound. For example, the chemical formula for ...
; their polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
molecules repel each other, similar to oil and water.
Strong magnets are used to separate out ferrous metal
In chemistry, the adjective Ferrous indicates a compound that contains iron(II), meaning iron in its +2 oxidation state, possibly as the divalent cation Fe2+. It is opposed to "ferric" or iron(III), meaning iron in its +3 oxidation state, such ...
s such as iron, steel and tin can
A steel can, tin can, tin (especially in British English, Australian English, Canadian English and South African English),
steel packaging, or can is a container for the distribution or storage of goods, made of thin metal. Many cans re ...
s. Non-ferrous metal
In metallurgy, non-ferrous metals are metals or alloys that do not contain iron (allotropes of iron, ferrite, and so on) in appreciable amounts.
Generally more costly than ferrous metals, non-ferrous metals are used because of desirable proper ...
s are ejected by magnetic eddy current
Eddy currents (also called Foucault's currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of a conductor in a mag ...
s: A rotating magnetic field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
induces
Electromagnetic or magnetic induction is the production of an electromotive force (emf) across an electrical conductor in a changing magnetic field.
Michael Faraday is generally credited with the discovery of induction in 1831, and James Cler ...
an electric current around aluminum cans, creating an eddy current inside the cans that is repulsed by a large magnetic field, ejecting the cans from the stream.
Finally, glass is sorted according to its color: brown, amber, green, or clear. It may be sorted either by hand, or by a machine that uses colored filters to detect colors. Glass fragments smaller than cannot be sorted automatically, and are mixed together as "glass fines".
In 2003, San Francisco
San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...
's Department of the Environment set a citywide goal of zero waste by 2020. San Francisco's refuse hauler, Recology
Recology, formerly known as Norcal Waste Systems, is a waste management company headquartered in San Francisco, California. The company collects and processes municipal solid waste, reclaiming reusable materials. The company also operates transfer ...
, operates an effective recyclables sorting facility that has helped the city reach a record-breaking landfill diversion rate of 80% as of 2021. Other American cities, including Los Angeles, hav
achieved similar rates
Recycling industrial waste
Although many government programs concentrate on recycling at home, 64% of waste in the United Kingdom is generated by industry. The focus of many recycling programs in industry is their cost-effectiveness. The ubiquitous nature of cardboard
Cardboard is a generic term for heavy paper-based products. The construction can range from a thick paper known as paperboard to corrugated fiberboard which is made of multiple plies of material. Natural cardboards can range from grey to light b ...
packaging makes cardboard a commonly waste product recycled by companies that deal heavily in packaged goods, such as retail store
Retail is the sale of goods and services to consumers, in contrast to wholesaling, which is sale to business or institutional customers. A retailer purchases goods in large quantities from manufacturers, directly or through a wholesaler, and t ...
s, warehouse
A warehouse is a building for storing goods. Warehouses are used by manufacturers, importers, exporters, wholesalers, transport businesses, customs, etc. They are usually large plain buildings in industrial parks on the outskirts of cities ...
s, and goods distributors. Other industries deal in niche and specialized products, depending on the waste materials they handle.
Glass, lumber, wood pulp
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw mate ...
and paper manufacturers all deal directly in commonly recycled materials; however, independent tire dealers may collect and recycle rubber tires
A tire (American English) or tyre (British English) is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which t ...
for a profit.
The waste produced from burning coal
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Coal is formed when dea ...
in a Coal-fired power station
A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Worldwide, there are about 8,500 coal-fired power stations totaling over 2,000 gigawatts Nameplate capacity, capacity. They ...
is often called fuel ash
Fly ash, flue ash, coal ash, or pulverised fuel ash (in the UK) plurale tantum: coal combustion residuals (CCRs)is a coal combustion product that is composed of the particulates (fine particles of burned fuel) that are driven out of coal-fired ...
or fly ash
Fly ash, flue ash, coal ash, or pulverised fuel ash (in the UK) plurale tantum: coal combustion residuals (CCRs)is a coal combustion product that is composed of the particulates (fine particles of burned fuel) that are driven out of coal-fired ...
in the United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
. It is a very useful material and used in concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...
construction. It exhibits Pozzolanic activity
The pozzolanic activity is a measure for the degree of reaction over time or the reaction rate between a pozzolan and Ca2+ or calcium hydroxide (Ca(OH)2) in the presence of water. The rate of the pozzolanic reaction is dependent on the intrinsic ...
.
Levels of metals recycling are generally low. In 2010, the International Resource Panel
The International Resource Panel is a scientific panel of experts that aims to help nations use natural resources sustainably without compromising economic growth and human needs. It provides independent scientific assessments and expert advice on ...
, hosted by the United Nations Environment Programme
The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the United Nations Conference on th ...
(UNEP), published reports on metal stocks and their recycling rates. It reported that the increase in the use of metals during the 20th and into the 21st century has led to a substantial shift in metal stocks from below-ground to use in above-ground applications within society. For example, in the US, in-use copper grew from 73 to 238 kg per capita between 1932–1999.
The report's authors observed that, as metals are inherently recyclable, metal stocks in society can serve as huge above-ground mines (the term "urban mining" has thus been coined). However, they found that the recycling rates of many metals are low. They warned that the recycling rates of some rare metals used in applications such as mobile phones, battery packs for hybrid cars and fuel cells, are so low that unless future end-of-life recycling rates are dramatically increased, these critical metals will become unavailable for use in modern technology.
The military recycles some metals. The U.S. Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage o ...
's Ship Disposal Program uses ship breaking
Ship-breaking (also known as ship recycling, ship demolition, ship dismantling, or ship cracking) is a type of ship disposal involving the breaking up of ships for either a source of parts, which can be sold for re-use, or for the extraction ...
to reclaim the steel of old vessels. Ships may also be sunk to create artificial reef
An artificial reef is a human-created underwater structure, typically built to promote marine life in areas with a generally featureless bottom, to control erosion, block ship passage, block the use of trawling nets, or improve surfing.
Many re ...
s. Uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
is a dense metal that has qualities superior to lead and titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...
for many military and industrial uses. Uranium left over from processing it into nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...
s and fuel for nuclear reactor
A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nu ...
s is called depleted uranium
Depleted uranium (DU; also referred to in the past as Q-metal, depletalloy or D-38) is uranium with a lower content of the fissile isotope than natural uranium.: "Depleted uranium possesses only 60% of the radioactivity of natural uranium, hav ...
, and is used by all branches of the U.S. military for the development of such things as armor-piercing shells and shielding.
The construction industry may recycle concrete and old road surface pavement, selling these materials for profit.
Some rapidly growing industries, particularly the renewable energy
Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
and solar photovoltaic technology industries, are proactively creating recycling policies even before their waste streams have considerable volume, anticipating future demand.
Recycling of plastics is more difficult, as most programs are not able to reach the necessary level of quality. Recycling of PVC often results in downcycling
Downcycling, or cascading, is the recycling of waste where the recycled material is of lower quality and functionality than the original material. Often, this is due to the accumulation of tramp elements in secondary metals, which may exclude the ...
of the material, which means only products of lower quality standard can be made with the recycled material.
E-waste is a growing problem, accounting for 20–50 million metric tons of global waste per year according to the EPA
The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
. It is also the fastest growing waste stream in the EU. Many recyclers do not recycle e-waste responsibly. After the cargo barge Khian Sea dumped 14,000 metric tons of toxic ash in Haiti
Haiti (; ht, Ayiti ; French: ), officially the Republic of Haiti (); ) and formerly known as Hayti, is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean Sea, east of Cuba and Jamaica, and ...
, the Basel Convention
The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal, usually known as the Basel Convention, is an international treaty that was designed to reduce the movements of hazardous waste between nations ...
was formed to stem the flow of hazardous substances into poorer countries. They created the e-Stewards certification to ensure that recyclers are held to the highest standards for environmental responsibility and to help consumers identify responsible recyclers. It operates alongside other prominent legislation, such as the Waste Electrical and Electronic Equipment Directive
The Waste Electrical and Electronic Equipment Directive (WEEE Directive) is the European Community Directive 2012/19/EU on waste electrical and electronic equipment (WEEE) which, together with the RoHS Directive 2011/65/EU, became European Law ...
of the EU and the United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
National Computer Recycling Act, to prevent poisonous chemicals from entering waterways and the atmosphere.
In the recycling process, television sets, monitors, cell phones, and computers are typically tested for reuse and repaired. If broken, they may be disassembled for parts still having high value if labor is cheap enough. Other e-waste is shredded to pieces roughly in size and manually checked to separate toxic batteries and capacitor
A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals.
The effect of ...
s, which contain poisonous metals. The remaining pieces are further shredded to particles and passed under a magnet to remove ferrous metals. An eddy current
Eddy currents (also called Foucault's currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of a conductor in a mag ...
ejects non-ferrous metals, which are sorted by density either by a centrifuge or vibrating plates. Precious metals can be dissolved in acid, sorted, and smelted into ingots. The remaining glass and plastic fractions are separated by density and sold to re-processors. Television sets and monitors must be manually disassembled to remove lead from CRTs and the mercury backlight from LCDs.
Vehicles
A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), wate ...
, solar panels and wind turbines can also be recycled. They often contain rare-earth elements
The rare-earth elements (REE), also called the rare-earth metals or (in context) rare-earth oxides or sometimes the lanthanides (yttrium and scandium are usually included as rare earths), are a set of 17 nearly-indistinguishable lustrous silve ...
(REE) and/or other critical raw materials. For electric car production, large amounts of REE's are typically required.[The dark side of green energies documentary]
Whereas many critical raw elements and REE's can be recovered, environmental enginee
Phillipe Bihouix
reports that recycling of indium, gallium, germanium, selenium, and tantalum is still very difficult and their recycling rates are very low.
Plastic recycling
Plastic recycling is the process of recovering scrap or waste plastic and reprocessing the material into useful products, sometimes completely different in form from their original state. For instance, this could mean melting down soft drink bottles and then casting them as plastic chairs and tables. For some types of plastic, the same piece of plastic can only be recycled about 2–3 times before its quality decreases to the point where it can no longer be used.
Physical recycling
Some plastics are remelted to form new plastic objects; for example, PET water bottles can be converted into polyester destined for clothing. A disadvantage of this type of recycling is that the molecular weight of the polymer can change further and the levels of unwanted substances in the plastic can increase with each remelt.
A commercial-built recycling facility was sent to the International Space Station
The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...
in late 2019. The facility takes in plastic waste and unneeded plastic parts and physically converts them into spools of feedstock for the space station additive manufacturing
3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer co ...
facility used for in-space 3D printing
3D printing or additive manufacturing is the Manufacturing, construction of a three-dimensional object from a computer-aided design, CAD model or a digital 3D modeling, 3D model. It can be done in a variety of processes in which material is ...
.
Chemical recycling
For some polymers, it is possible to convert them back into monomers, for example, PET can be treated with an alcohol and a catalyst to form a dialkyl terephthalate. The terephthalate diester can be used with ethylene glycol to form a new polyester polymer, thus making it possible to use the pure polymer again. In 2019, Eastman Chemical Company
Eastman Chemical Company is an American company primarily involved in the chemical industry. Once a subsidiary of Kodak, today it is an independent global specialty materials company that produces a broad range of advanced materials, chemicals and ...
announced initiatives of methanolysis
In organic chemistry, transesterification is the process of exchanging the organic group R″ of an ester with the organic group R' of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. The reaction can ...
and syngas
Syngas, or synthesis gas, is a mixture of hydrogen and carbon monoxide, in various ratios. The gas often contains some carbon dioxide and methane. It is principly used for producing ammonia or methanol. Syngas is combustible and can be used as ...
designed to handle a greater variety of used material.
Waste plastic pyrolysis to fuel oil
Another process involves the conversion of assorted polymers into petroleum by a much less precise thermal depolymerization Depolymerization (or depolymerisation) is the process of converting a polymer into a monomer or a mixture of monomers. This process is driven by an increase in entropy.
Ceiling temperature
The tendency of polymers to depolymerize is indicated by ...
process. Such a process would be able to accept almost any polymer or mix of polymers, including thermoset
In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening (" curing") a soft solid or viscous liquid prepolymer (resin). Curing is induced by heat or suitable radiation and ...
materials such as vulcanized rubber tires and the biopolymer
Biopolymers are natural polymers produced by the cells of living organisms. Like other polymers, biopolymers consist of monomeric units that are covalently bonded in chains to form larger molecules. There are three main classes of biopolymers, cl ...
s in feathers and other agricultural waste. Like natural petroleum, the chemicals produced can be used as fuels or as feedstock. A RESEM Technology plant of this type in Carthage, Missouri
Carthage is a city in Jasper County, Missouri, United States. The population was 15,522 as of the 2020 census. It is the county seat of Jasper County and is nicknamed "America's Maple Leaf City."
History
Jasper County was formed in 1841. ...
, US, uses turkey waste as input material. Gasification is a similar process but is not technically recycling since polymers are not likely to become the result.
Plastic Pyrolysis can convert petroleum based waste streams such as plastics into quality fuels, carbons. Given below is the list of suitable plastic raw materials for pyrolysis
The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''py ...
:
* Mixed plastic (HDPE
High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density ratio, ...
, LDPE
Low-density polyethylene (LDPE) is a thermoplastic made from the monomer ethylene. It was the first grade of polyethylene, produced in 1933 by Imperial Chemical Industries (ICI) using a high pressure process via free radical polymerization. Its ...
, PE, PP, Nylon
Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic.
Nylon is a silk-like thermoplastic, generally made from petro ...
, Teflon
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemou ...
, PS, ABS plastic, ABS, Fibre-reinforced plastic, FRP, PET
A pet, or companion animal, is an animal kept primarily for a person's company or entertainment rather than as a working animal, livestock, or a laboratory animal. Popular pets are often considered to have attractive appearances, intelligence, ...
etc.)
* Mixed waste plastic from waste paper mill
* Multi-layered plastic
Recycling loops
The (ideal) recycling process can be differentiated into three loops, one for manufacture (production-waste recycling) and two for disposal of the product (product and material recycling).
The product's manufacturing phase, which consists of material processing and fabrication, forms the ''production-waste recycling'' loop. Industrial waste materials are fed back into, and reused in, the same production process.
The product's disposal process requires two recycling loops: ''product recycling'' and ''material recycling''.
The product or product parts are reused in the ''product recycling'' phase. This happens in one of two ways: the product is used retaining the product functionality ("reuse") or the product continues to be used but with altered functionality ("further use"). The product design is unmodified, or only slightly modified, in both scenarios.
Product disassembly requires ''material recycling'' where product materials are recovered and recycled. Ideally, the materials are processed so they can flow back into the production process.
Recycling codes
In order to meet recyclers' needs while providing manufacturers a consistent, uniform system, a Recycling codes, coding system was developed. The recycling code for plastics was introduced in 1988 by the plastics industry through the Society of the Plastics Industry. Because municipal recycling programs traditionally have targeted packaging—primarily bottles and containers—the resin identification code, resin coding system offered a means of identifying the resin content of bottles and containers commonly found in the residential waste stream.
Plastic products are printed with numbers 1–7 depending on the type of resin. Type 1 (polyethylene terephthalate) is commonly found in soft drink and water bottles. Type 2 (high-density polyethylene) is found in most hard plastics such as Plastic milk container, milk jugs, laundry detergent bottles, and some dishware. Type 3 (polyvinyl chloride) includes items such as shampoo bottles, shower curtains, hula hoops, credit cards, wire jacketing, medical equipment, siding, and piping. Type 4 (low-density polyethylene) is found in shopping bags, squeezable bottles, tote bags, clothing, furniture, and carpet. Type 5 is polypropylene and makes up syrup bottles, straws, Tupperware, and some automotive parts. Type 6 is polystyrene
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a ...
and makes up meat trays, egg cartons, clamshell containers, and compact disc cases. Type 7 includes all other plastics such as bulletproof materials, 3- and 5-gallon water bottles, cell phone and tablet frames, safety goggles and sunglasses. Having a recycling code or the chasing arrows logo on a material is not an automatic indicator that a material is recyclable but rather an explanation of what the material is. Types 1 and 2 are the most commonly recycled.
Cost–benefit analysis
In addition to environmental impact, there is debate over whether recycling is Economic efficiency, economically efficient. According to a Natural Resources Defense Council study, waste collection and landfill disposal creates less than one job per 1,000 tons of waste material managed; in contrast, the collection, processing, and manufacturing of recycled materials creates 6–13 or more jobs per 1,000 tons. According to the U.S. Recycling Economic Informational Study, there are over 50,000 recycling establishments that have created over a million jobs in the US. The National Waste & Recycling Association (NWRA) reported in May 2015 that recycling and waste made a $6.7 billion economic impact in Ohio, U.S., and employed 14,000 people. Economists would classify this extra labor used as a cost rather than a benefit since these workers could have been employed elsewhere; the cost effectiveness of creating these additional jobs remains unclear.
Sometimes cities have found recycling saves resources compared to other methods of dispoal of waste. Two years after New York City declared that implementing recycling programs would be "a drain on the city", New York City leaders realized that an efficient recycling system could save the city over $20 million. Municipalities often see finance, fiscal benefits from implementing recycling programs, largely due to the reduced landfill
A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste materials. Landfill is the oldest and most common form of waste disposal, although the systematic burial of the waste ...
costs. A study conducted by the Technical University of Denmark according to the Economist found that in 83 percent of cases, recycling is the most efficient method to dispose of household waste. However, a 2004 assessment by the Danish Environmental Assessment Institute concluded that incineration was the most effective method for disposing of drink containers, even aluminium ones.
Fiscal efficiency is separate from economic efficiency. Economic analysis of recycling does not include what economists call externality, externalities: unpriced costs and benefits that accrue to individuals outside of private transactions. Examples include less air pollution and greenhouse gases from incineration and less waste leaching from landfills. Without mechanisms such as taxes or subsidies, businesses and consumers following their private benefit would ignore externalities despite the costs imposed on society. If landfills and incinerator pollution is inadequately regulated, these methods of waste disposal appear cheaper than they really are, because part of their cost is the pollution imposed on people nearby. Thus, advocates have pushed for legislation to increase demand for recycled materials. The United States Environmental Protection Agency (EPA) has concluded in favor of recycling, saying that recycling efforts reduced the country's carbon emissions by a net 49 million metric tonnes in 2005. In the United Kingdom, the Waste and Resources Action Programme stated that Great Britain's recycling efforts reduce Greenhouse gas, CO2 emissions by 10–15 million tonnes a year. The question for economic efficiency is whether this reduction is worth the extra cost of recycling and thus makes the artificial demand creates by legislation worthwhile.
Certain requirements must be met for recycling to be economically feasible and environmentally effective. These include an adequate source of recyclates, a system to extract those recyclates from the waste stream, a nearby factory capable of reprocessing the recyclates, and a potential demand for the recycled products. These last two requirements are often overlooked—without both an industrial market for production using the collected materials and a consumer market for the manufactured goods, recycling is incomplete and in fact only "collection".
Free-market economist Julian Simon remarked "There are three ways society can organize waste disposal: (a) commanding, (b) guiding by tax and subsidy, and (c) leaving it to the individual and the market". These principles appear to divide economic thinkers today.[Alt URL]
Frank Ackerman favours a high level of government intervention to provide recycling services. He believes that recycling's benefit cannot be effectively quantified by traditional ''laissez-faire'' economics. Allen Hershkowitz supports intervention, saying that it is a public service equal to education and policing. He argues that manufacturers should shoulder more of the burden of waste disposal.
Paul Calcott and Margaret Walls advocate the second option. A deposit refund scheme and a small refuse charge would encourage recycling but not at the expense of illegal dumping. Thomas C. Kinnaman concludes that a landfill tax would force consumers, companies and councils to recycle more.
Most free-market thinkers detest subsidy and intervention, arguing that they waste resources. The general argument is that if cities charge the full cost of garbage collection, private companies can profitably recycle any materials for which the benefit of recycling exceeds the cost (e.g. aluminum) and do not recycle other materials for which the benefit is less than the cost (e.g. glass). Cities, on the other hand, often recycle even when they not only do not receive enough for the paper or plastic to pay for its collection, but must actually pay private recycling companies to take it off of their hands. Terry L. Anderson, Terry Anderson and Donald Leal think that all recycling programmes should be privately operated, and therefore would only operate if the money saved by recycling exceeds its costs. Daniel Benjamin, Daniel K. Benjamin argues that it wastes people's resources and lowers the wealth of a population. He notes that recycling can cost a city more than twice as much as landfills, that in the United States landfills are so heavily regulated that their pollution effects are negligible, and that the recycling process also generates pollution and uses energy, which may or may not be less than from virgin production.
Trade in recyclates
Certain countries trade in unprocessed wikt:recyclate, recyclates. Some have complained that the ultimate fate of recyclates sold to another country is unknown and they may end up in landfills instead of being reprocessed. According to one report, in America, 50–80 percent of computers destined for recycling are actually not recycled. There are reports of illegal-waste imports to China being dismantled and recycled solely for monetary gain, without consideration for workers' health or environmental damage. Although the Chinese government has banned these practices, it has not been able to eradicate them. In 2008, the prices of recyclable waste plummeted before rebounding in 2009. Cardboard averaged about £53/tonne from 2004 to 2008, dropped to £19/tonne, and then went up to £59/tonne in May 2009. PET plastic averaged about £156/tonne, dropped to £75/tonne and then moved up to £195/tonne in May 2009.
Certain regions have difficulty using or exporting as much of a material as they recycle. This problem is most prevalent with glass: both Britain and the U.S. import large quantities of wine bottled in green glass. Though much of this glass is sent to be recycled, outside the American Midwest there is not enough wine production to use all of the reprocessed material. The extra must be downcycled into building materials or re-inserted into the regular waste stream.
Similarly, the northwestern United States has difficulty finding markets for recycled newspaper, given the large number of pulp mills in the region as well as the proximity to Asian markets. In other areas of the U.S., however, demand for used newsprint has seen wide fluctuation.
In some U.S. states, a program called RecycleBank pays people to recycle, receiving money from local municipalities for the reduction in landfill space that must be purchased. It uses a single stream process in which all material is automatically sorted.
Criticisms and responses
Critics dispute the net economic and environmental benefits of recycling over its costs, and suggest that proponents of recycling often make matters worse and suffer from confirmation bias. Specifically, critics argue that the costs and energy used in collection and transportation detract from (and outweigh) the costs and energy saved in the production process; also that the jobs produced by the recycling industry can be a poor trade for the jobs lost in logging, mining, and other industries associated with production; and that materials such as paper pulp can only be recycled a few times before material degradation prevents further recycling.
Much of the difficulty inherent in recycling comes from the fact that most products are not designed with recycling in mind. The concept of sustainable design aims to solve this problem, and was laid out in the book ''Cradle to Cradle: Remaking the Way We Make Things'' by architect William McDonough and chemist Michael Braungart. They suggest that every product (and all packaging it requires) should have a complete "closed-loop" cycle mapped out for each component—a way in which every component either returns to the natural ecosystem through biodegradation or is recycled indefinitely.
While recycling diverts waste from entering directly into landfill sites, current recycling misses the dispersive components. These critics believe that complete recycling is impracticable as highly dispersed wastes become so diluted that the energy needed for their recovery becomes increasingly excessive.
As with environmental economics, care must be taken to ensure a complete view of the costs and benefits involved. For example, paperboard
Paperboard is a thick paper-based material. While there is no rigid differentiation between paper and paperboard, paperboard is generally thicker (usually over 0.30 mm, 0.012 in, or 12 Inch#equivalences, points) than paper and has certain ...
packaging for food products is more easily recycled than most plastic, but is heavier to ship and may result in more waste from spoilage.
Energy and material flows
The amount of energy saved through recycling depends upon the material being recycled and the type of energy accounting that is used. Correct accounting for this saved energy can be accomplished with life-cycle analysis
Life cycle assessment or LCA (also known as life cycle analysis) is a methodology for assessing environmental impacts associated with all the stages of the life cycle of a commercial product, process, or service. For instance, in the case o ...
using real energy values, and in addition, exergy, which is a measure of how much useful energy can be used. In general, it takes far less energy to produce a unit mass of recycled materials than it does to make the same mass of virgin materials.
Some scholars use emergy (spelled with an m) analysis, for example, budgets for the amount of energy of one kind (exergy) that is required to make or transform things into another kind of product or service. Emergy calculations take into account economics that can alter pure physics-based results. Using emergy life-cycle analysis researchers have concluded that materials with large refining costs have the greatest potential for high recycle benefits. Moreover, the highest emergy efficiency accrues from systems geared toward material recycling, where materials are engineered to recycle back into their original form and purpose, followed by adaptive reuse systems where the materials are recycled into a different kind of product, and then by-product reuse systems where parts of the products are used to make an entirely different product.
The Energy Information Administration (EIA) states on its website that "a paper mill uses 40 percent less energy to make paper from recycled paper than it does to make paper from fresh lumber." Some critics argue that it takes more energy to produce recycled products than it does to dispose of them in traditional landfill methods, since the curbside collection of recyclables often requires a second waste truck. However, recycling proponents point out that a second timber or logging truck is eliminated when paper is collected for recycling, so the net energy consumption is the same. An emergy life-cycle analysis on recycling revealed that fly ash, aluminum, recycled concrete aggregate, recycled plastic, and steel yield higher efficiency ratios, whereas the recycling of lumber generates the lowest recycle benefit ratio. Hence, the specific nature of the recycling process, the methods used to analyse the process, and the products involved affect the energy savings budgets.
It is difficult to determine the amount of energy consumed or produced in waste disposal processes in broader ecological terms, where causal relations dissipate into complex networks of material and energy flow. For example, "cities do not follow all the strategies of ecosystem development. Biogeochemical paths become fairly straight relative to wild ecosystems, with reduced recycling, resulting in large flows of waste and low total energy efficiencies. By contrast, in wild ecosystems, one population's wastes are another population's resources, and succession results in efficient exploitation of available resources. However, even modernized cities may still be in the earliest stages of a succession that may take centuries or millennia to complete." How much energy is used in recycling also depends on the type of material being recycled and the process used to do so. Aluminium is generally agreed to use far less energy when recycled rather than being produced from scratch. The EPA states that "recycling aluminum cans, for example, saves 95 percent of the energy required to make the same amount of aluminum from its virgin source, bauxite." In 2009, more than half of all aluminium cans produced came from recycled aluminium. Similarly, it has been estimated that new steel produced with recycled cans reduces greenhouse gas emissions by 75%.
Economist Steven Landsburg has suggested that the sole benefit of reducing landfill space is trumped by the energy needed and resulting pollution from the recycling process.[Landsburg, Steven E. ''The Armchair Economist''. p. 86.] Others, however, have calculated through life-cycle assessment that producing recycled paper uses less energy and water than harvesting, pulping, processing, and transporting virgin trees. When less recycled paper is used, additional energy is needed to create and maintain farmed forests until these forests are as self-sustainable as virgin forests.
Other studies have shown that recycling in itself is inefficient to perform the "decoupling" of economic development from the depletion of non-renewable raw materials that is necessary for sustainable development. The international transportation or recycle material flows through "... different trade networks of the three countries result in different flows, decay rates, and potential recycling returns". As global consumption of a natural resources grows, their depletion is inevitable. The best recycling can do is to delay; complete closure of material loops to achieve 100 percent recycling of nonrenewables is impossible as micro-trace materials dissipate into the environment causing severe damage to the planet's ecosystems. Historically, this was identified as the metabolic rift by Karl Marx, who identified the unequal exchange rate between energy and nutrients flowing from rural areas to feed urban cities that create effluent wastes degrading the planet's ecological capital, such as loss in soil nutrient production. Energy conservation also leads to what is known as Jevon's paradox, where improvements in energy efficiency lowers the cost of production and leads to a rebound effect where rates of consumption and economic growth increases.
Costs
The amount of money actually saved through recycling depends on the efficiency of the recycling program used to do it. The Institute for Local Self-Reliance argues that the cost of recycling depends on various factors, such as gate fee, landfill fees and the amount of disposal that the community recycles. It states that communities begin to save money when they treat recycling as a replacement for their traditional waste system rather than an add-on to it and by "redesigning their collection schedules and/or trucks".
In some cases, the cost of recyclable materials also exceeds the cost of raw materials. Virgin plastic resin costs 40 percent less than recycled resin. Additionally, a United States Environmental Protection Agency (EPA) study that tracked the price of clear glass from 15 July to 2 August 1991, found that the average cost per ton ranged from $40 to $60 while a USGS report shows that the cost per ton of raw silica sand from years 1993 to 1997 fell between $17.33 and $18.10.
Comparing the market cost of recyclable material with the cost of new raw materials ignores economic externalities—the costs that are currently not counted by the market. Creating a new piece of plastic, for instance, may cause more pollution and be less sustainable than recycling a similar piece of plastic, but these factors are not counted in market cost. A life cycle assessment can be used to determine the levels of externalities and decide whether the recycling may be worthwhile despite unfavorable market costs. Alternatively, legal means (such as a carbon tax) can be used to bring externalities into the market, so that the market cost of the material becomes close to the true cost.
Working conditions
The recycling of waste electrical and electronic equipment can create a significant amount of pollution. This problem is specifically occurrent in India and China. Informal recycling in an underground economy of these countries has generated an environmental and health disaster. High levels of lead (Pb), polybrominated diphenylethers (PBDEs), polychlorinated dioxins and furans, as well as polybrominated dioxins and furans (PCDD/Fs and PBDD/Fs), concentrated in the air, bottom ash, dust, soil, water, and sediments in areas surrounding recycling sites. These materials can make work sites harmful to the workers themselves and the surrounding environment.
Environmental impact
Economist Steven Landsburg, author of a paper entitled "Why I Am Not an Environmentalist", claimed that paper recycling actually reduces tree populations. He argues that because paper companies have incentives to replenish their forests, large demands for paper lead to large forests while reduced demand for paper leads to fewer "farmed" forests.
When foresting companies cut down trees, more are planted in their place; however, such farmed forests are inferior to natural forests in several ways. Farmed forests are not able to fix the soil as quickly as natural forests. This can cause widespread soil erosion and often requiring large amounts of fertilizer to maintain the soil, while containing little tree and wild-life biodiversity compared to virgin forests.[Baird, Colin (2004). ''Environmental Chemistry'' (3rd ed.). W. H. Freeman. .] Also, the new trees planted are not as big as the trees that were cut down, and the argument that there would be "more trees" is not compelling to forestry advocates when they are counting saplings.
In particular, wood from tropical rainforests is rarely harvested for paper because of their heterogeneity. According to the United Nations Framework Convention on Climate Change secretariat, the overwhelming direct cause of deforestation is subsistence farming (48% of deforestation) and commercial agriculture (32%), which is linked to food, not paper production.
Other non-conventional methods of material recycling, like Waste-to-Energy (WTE) systems, have garnered increased attention in the recent past due to the polarizing nature of their emissions. While viewed as a sustainable method of capturing energy from material waste feedstocks by many, others have cited numerous explanations for why the technology has not been scaled globally.
Possible income loss and social costs
In some countries, recycling is performed by the entrepreneurial poor such as the karung guni, zabbaleen, the rag-and-bone man, waste picker, and junk man. With the creation of large recycling organizations that may be profitable, either by law or economies of scale, the poor are more likely to be driven out of the recycling and the remanufacturing job market. To compensate for this loss of income, a society may need to create additional forms of societal programs to help support the poor.[''PBS NewsHour'', 16 February 2010. Report on the Zabaleen] Like the parable of the broken window, there is a net loss to the poor and possibly the whole of a society to make recycling artificially profitable, e.g. through the law. However, in Brazil and Argentina, waste pickers/informal recyclers work alongside the authorities, in fully or semi-funded cooperatives, allowing informal recycling to be legitimized as a paid public sector job.
Because the social support of a country is likely to be less than the loss of income to the poor undertaking recycling, there is a greater chance for the poor to come in conflict with the large recycling organizations. This means fewer people can decide if certain waste is more economically reusable in its current form rather than being reprocessed. Contrasted to the recycling poor, the efficiency of their recycling may actually be higher for some materials because individuals have greater control over what is considered "waste".
One labor-intensive underused waste is electronic and computer waste. Because this waste may still be functional and wanted mostly by those on lower incomes, who may sell or use it at a greater efficiency than large recyclers.
Some recycling advocates believe that laissez-faire individual-based recycling does not cover all of society's recycling needs. Thus, it does not negate the need for an organized recycling program. Local government can consider the activities of the recycling poor as contributing to the ruining of property.
Public participation rates
Changes that have been demonstrated to increase recycling rates include:
* Single-stream recycling
* Pay as you throw fees for trash
In a study done by social psychologist Shawn Burn, it was found that personal contact with individuals within a neighborhood is the most effective way to increase recycling within a community. In her study, she had 10 block leaders talk to their neighbors and persuade them to recycle. A comparison group was sent fliers promoting recycling. It was found that the neighbors that were personally contacted by their block leaders recycled much more than the group without personal contact. As a result of this study, Shawn Burn believes that personal contact within a small group of people is an important factor in encouraging recycling. Another study done by Stuart Oskamp examines the effect of neighbors and friends on recycling. It was found in his studies that people who had friends and neighbors that recycled were much more likely to also recycle than those who didn't have friends and neighbors that recycled.
Many schools have created recycling awareness clubs in order to give young students an insight on recycling. These schools believe that the clubs actually encourage students to not only recycle at school but at home as well.
Recycling of metals varies extremely by type. Titanium and lead have an extremely high recycling rates of over 90%. Copper and cobalt have high rates of recycling around 75%. Only about half of aluminum is recycled. Most of the remaining metals have recycling rates of below 35%, while 34 types of metals have recycling rates of under 1%.
"Between 1960 and 2000, the world production of plastic resins increased 25 times its original amount, while recovery of the material remained below 5 percent." Many studies have addressed recycling behaviour and strategies to encourage community involvement in recycling programs. It has been argued that recycling behavior is not natural because it requires a focus and appreciation for long-term planning, whereas humans have evolved to be sensitive to short-term survival goals; and that to overcome this innate predisposition, the best solution would be to use social pressure to compel participation in recycling programs. However, recent studies have concluded that social pressure does not work in this context. One reason for this is that social pressure functions well in small group sizes of 50 to 150 individuals (common to nomadic hunter–gatherer peoples) but not in communities numbering in the millions, as we see today. Another reason is that individual recycling does not take place in the public view.
Following the increasing popularity of recycling collection being sent to the same landfills as trash, some people kept on putting recyclables on the recyclables bin.
Recycling in art
Art objects are more and more often made from recycled material.
See also
* 2000s commodities boom
* E-Cycling
* Greening
* Index of recycling articles
* List of elements facing shortage
* List of waste management acronyms
* Nutrient cycle
* Optical sorting
* Recycling rates by country
* Recycling symbol
* Resource recovery
* Refurbishment (electronics)
* USPS Post Office Box Lobby Recycling program
References
Further reading
* Ackerman, F. (1997). ''Why Do We Recycle?: Markets, Values, and Public Policy''. Island Press. ,
* Ayres, R.U. (1994). "Industrial Metabolism: Theory and Policy", In: Allenby, B.R., and D.J. Richards, ''The Greening of Industrial Ecosystems''. National Academy Press, Washington, DC, pp. 23–37.
* Braungart, M., McDonough, W. (2002). ''Cradle to Cradle: Remaking the Way We Make Things''. North Point Press, .
* Huesemann, M.H., Huesemann, J.A. (2011
''Technofix: Why Technology Won't Save Us or the Environment''
"Challenge #3: Complete Recycling of Non-Renewable Materials and Wastes", New Society Publishers, Gabriola Island, British Columbia, Canada, , pp. 135–137.
*
*
* Porter, R.C. (2002). ''The Economics of Waste''. Resources for the Future. ,
* Sheffield, H.
Sweden’s recycling is so revolutionary, the country has run out of rubbish
' (December 2016), The Independent (UK)
*
External links
Related journals
* ''Environment and Behavior''
* ''International Journal of Physical Distribution & Logistics Management''
* ''Journal of Applied Social Psychology''
* ''Journal of Environmental Psychology''
* ''Journal of Environmental Systems''
* ''Journal of Industrial Ecology''
* ''Journal of Socio-Economics''
* ''Journal of Urban Economics''
* ''Psychology and Marketing''
* ''Recycling: North America's Recycling and Composting Journal''
* ''Resources, Conservation and Recycling''
* ''Waste Management & Research''
{{authority control
Recycling,
Articles containing video clips
Energy conversion
Waste management concepts
Water conservation