Courtesy : https://en.wikipedia.org/

Waste recycling

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 properties it had in its original state. It is an alternative to “conventional” waste disposal that can save material and help lower greenhouse gas emissions. It can also prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials, reducing energy use, air pollution (from incineration) and water pollution (from landfilling).

Recycling is a key component of modern waste reduction and is the third component of the “Reduce, Reuse, and Recycle” waste hierarchy. It promotes environmental sustainability by removing raw material input and redirecting waste output in the economic system. There are some ISO standards 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, tires, textiles, batteries, and electronics. The composting and other reuse of biodegradable waste—such as food and garden waste—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 foam into new polystyrene. Some types of materials, such as metal cans, can be remanufactured repeatedly without losing their purity.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 in producing different materials (for example, paperboard). 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 and gold from printed circuit boards), or their hazardous nature (e.g. removal and reuse of mercury from thermometers and thermostats).

History

Origins

Recycling has been a common practice for most of human history with recorded advocates as far back as Plato 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 artefacts 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 times, there is evidence of scrap 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” 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” and “mungo” wool in Batley, Yorkshire, which combined recycled fibers with virgin wool. The West Yorkshire 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 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, 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,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.)

Wartim

American poster from World War II

British poster from World War I

Poster from wartime Canada, encouraging housewives to “salvage”

Remnants of iron fence bars in York Whip-Ma-Whop-Ma-Gate. Such public property fences were sawed for the iron and recycled during World War I

New chemical industries created in the late 19th century both invented new materials (e.g. Bakelite 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, where financial constraints and significant material shortages made it necessary to reuse goods and recycle materials. These resource shortages caused by the world wars, 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 had about 50% of world share of waste and recycling industries, with over 60,000 companies employing 500,000 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 of recyclable material is crucial. Three legislative options have been used to create such supplies: mandatory recycling collection, container deposit legislation, 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 requires producers of consumer electronics to reimburse the recyclers’ costs.

An alternative way to increase the supply of recyclates 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 exist to meet the supply, or such bans can create increased illegal dumping.

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 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 have used their own purchasing power 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 when recycled items are purchased. Additional regulations can target specific cases: in the United States, for example, the Environmental Protection Agency mandates the purchase of oil, paper, tires and building insulation 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 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

Glass recovered by crushing only one kind of beer bottle

“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 bottles 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 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 landfilled. 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

A three-sided bin at a railway station in Germany, intended to separate paper (left) and plastic wrappings (right) from other waste (back)

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

Main article: Curbside collection

A recycling truck collecting the contents of a recycling bin in Canberra, Australia

Emptying of segregated rubbish containers in Tomaszów Mazowiecki, Poland

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 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 are mixed but kept separate from non-recyclable waste. This greatly reduces the need for post-collection cleaning, but requires public education 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 costs for collecting each material, and requires extensive public education to avoid recyclate contamination. In Oregon, USA, Oregon DEQ surveyed multi-family property managers; about half of them reported problems, including contamination of recyclables due to trespassers such as transients 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

Reverse vending machine in Tomaszów Mazowiecki, Poland

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 was reimbursed about 20% of its recycling costs.

Drop-off center

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 recyclebots enable a form of distributed recycling. Preliminary life-cycle analysis (LCA) indicates that such distributed recycling of HDPE to make filament for 3D printers in rural regions consumes less energy than using virgin resin, or using conventional recycling processes with their associated transportation.

Sorting

Video of recycling sorting facility and processes

Once commingled recyclates are collected and delivered to a materials recovery facility, 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. 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 and plastic bags are removed by hand at this stage, as they can cause later machinery to jam.

Early sorting of recyclable materials: glass and plastic bottles in Poland.

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 (#1) and HDPE (#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 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; their polymer molecules repel each other, similar to oil and water.

Strong magnets are used to separate out ferrous metals such as iron, steel and tin cans. Non-ferrous metals are ejected by magnetic eddy currents: A rotating magnetic field induces 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.

A recycling point in New Byth, Scotland, with separate containers for paper, plastics, and differently colored glass.

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 10 millimetres (0.39 in) cannot be sorted automatically, and are mixed together as “glass fines”.

In 2003, San Francisco’s Department of the Environment set a citywide goal of zero waste by 2020. San Francisco’s refuse hauler, Recology, 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, have achieved similar rates.