Retrieved 29 February 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.
Recycling or "salvage", as it was then usually known was a major issue for governments throughout World War II. Financial constraints and significant material shortages due to war efforts made it necessary for countries to reuse goods and recycle materials.
Recycling household materials meant more resources for war efforts and a better chance of victory. A considerable investment in recycling occurred in the s, due to rising energy costs. Although consumer electronics such as the television have been popular since the s, recycling of them was almost unheard of until early They began to export the problem to developing countries without enforced environmental legislation.
This is cheaper, as recycling computer monitors in the United States costs 10 times more than in China. Demand in Asia for electronic waste began to grow when scrap yards found that they could extract valuable substances such as copper, silver, iron, silicon, nickel, and gold, during the recycling process. For a recycling program to work, having a large, stable supply of recyclable material is crucial. Three legislative options have been used to create such a supply: Mandatory collection laws set recycling targets for cities to aim for, 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 then responsible for working to meet this target. Container deposit legislation involves offering a refund 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 to the price. This surcharge can be reclaimed by the consumer if the container is returned to a collection point. These programs have been very successful, often resulting in an 80 percent recycling rate. An alternative way to increase supply of recyclates is to ban the disposal of certain materials as waste, often including used oil, old batteries, tires, and garden waste. One aim of this method is to create a viable economy for proper disposal of banned products.
Care must be taken that enough of these recycling services exist, or such bans simply lead to increased illegal dumping. Legislation has also been used to increase and maintain a demand for recycled materials. Four methods of such legislation exist: Both minimum recycled content mandates and utilization rates increase demand directly 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: Opponents to both of these methods point to the large increase in reporting requirements they impose, and claim that they rob industry of necessary flexibility. Governments have used their own purchasing power to increase recycling demand through what are called "procurement policies".
These policies are either "set-asides", which reserve a certain amount of spending solely towards recycled products, or "price preference" programs which provide a larger budget when recycled items are purchased. Additional regulations can target specific cases: The final government regulation towards increased demand is recycled product labeling. When producers are required to label their packaging with amount of recycled material in the product including the packaging , consumers are better able to make educated choices.
Consumers with sufficient buying power can then choose more environmentally conscious options, prompt producers to increase the amount of recycled material in their products, and indirectly increase demand. Standardized recycling labeling can also have a positive effect on supply of recyclates if the labeling includes information on how and where the product can be recycled.
Recyclate is a raw material that is sent to, and processed in a waste recycling plant or materials recovery facility which will be used to form new products. For example, plastic bottles that are collected can be re-used and made into plastic pellets, a new product. The quality of recyclates is recognized as one of the principal challenges that needs to be addressed for the success of a long-term vision of a green economy and achieving zero waste.
Recyclate quality is generally referring to how much of the raw material is made up of target material compared to the amount of non-target material and other non-recyclable material.
If the 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.
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. There are many actions along the recycling supply chain that can influence and affect the material quality of recyclate. This can affect the quality of final recyclate streams or require further efforts to discard those materials at later stages in the recycling process.
Depending on which materials are collected together, extra effort is required to sort this material back into separate streams and can significantly reduce the quality of the final product. Sorting facilities are not one hundred per cent effective in separating materials, despite improvements in technology and quality recyclate which can see a loss in recyclate quality. Reprocessing facilities may require further sorting steps to further reduce the amount of non-target and non-recyclable material.
The Recyclate Quality Action Plan of Scotland sets out a number of proposed actions that the Scottish Government would like to take forward in order to drive up the quality of the materials being collected for recycling and sorted at materials recovery facilities before being exported or sold on to the reprocessing market.
The plan's objectives are to: The plan focuses on three key areas, with fourteen actions which were identified to increase the quality of materials collected, sorted and presented to the processing market in Scotland. The three areas of focus are: A number of different systems have been implemented to collect recyclates from the general waste stream.
These systems lie along 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". 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.
At one end of the spectrum is mixed waste collection, in which all recyclates are collected mixed in with the rest of the waste, and the desired material is then sorted out and cleaned at a central sorting facility. This results in a large amount of recyclable waste, paper especially, being too soiled to reprocess, but has advantages as well: Any changes to which materials are recyclable is easy to accommodate as all sorting happens in a central location.
In a commingled or single-stream system , all recyclables for collection are mixed but kept separate from other waste. This greatly reduces the need for post-collection cleaning but does require public education on what materials are recyclable. Source separation is the other extreme, where each material is cleaned and sorted prior to collection. This method requires the least post-collection sorting and produces the purest recyclates, but incurs additional operating costs for collection of each separate material.
An extensive public education program is also required, which must be successful if recyclate contamination is to be avoided. Source separation used to be the preferred method due to the high sorting costs incurred by commingled mixed waste collection. However, advances in sorting technology have lowered this overhead substantially. Many areas which had developed source separation programs have since switched to what's called co-mingled collection. Buy-back centers differ in that the cleaned recyclates are purchased, thus providing a clear incentive for use and creating a stable supply.
The post-processed material can then be sold. If this is profitable, this conserves the emission of greenhouse gases; if unprofitable, it increases the emission of greenhouse gasses. Government subsidies are necessary to make buy-back centres a viable enterprise. In , according to the U.
In , glass is essentially valueless, because of the low cost of sand, its major component; low oil costs thwarts plastic recycling.
Drop-off centers require the waste producer to carry the 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. 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 of 3D printers in rural regions is energetically favorable to either using virgin resin or conventional recycling processes because of reductions in transportation energy.
Once commingled recyclates are collected and delivered to a central collection facility , the different types of materials must be sorted. This is done in a series of stages, many of which involve automated processes such that a truckload of material can be fully sorted in less than an hour. In plants, a variety of materials is sorted such as paper, different types of plastics , glass, metals, food scraps, and most types of batteries.
Initially, the 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.
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. This separation is usually done by hand but has become automated in some sorting centers: 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 in which a rotating magnetic field induces an electric current around the aluminum cans, which in turn creates a magnetic eddy current inside the cans.
This magnetic eddy current is repulsed by a large magnetic field, and the cans are ejected from the rest of the recyclate stream. Finally, glass is sorted according to its color: It may either be sorted by hand,  or via an automated machine that uses colored filters to detect different colors.
Glass fragments smaller than 10 millimetres 0. This process of recycling as well as reusing the recycled material has proven advantageous because it reduces amount of waste sent to landfills, conserves natural resources, saves energy, reduces greenhouse gas emissions, and helps create new jobs.
Recycled materials can also be converted into new products that can be consumed again, such as paper, plastic, and glass. The City and County of San Francisco's Department of the Environment is attempting to achieve a citywide goal of generating zero waste by Food packaging should no longer contain any organic matter organic matter, if any, needs to be placed in a biodegradable waste bin or be buried in a garden . Since no trace of biodegradable material is best kept in the packaging before placing it in a trash bag , some packaging also needs to be rinsed.
The ubiquitous nature of cardboard packaging makes cardboard a commonly recycled waste product by companies that deal heavily in packaged goods, like retail stores , warehouses , and distributors of goods.
Other industries deal in niche or specialized products, depending on the nature of the waste materials that are present. The glass, lumber, wood pulp and paper manufacturers all deal directly in commonly recycled materials; however, old rubber tires may be collected and recycled by independent tire dealers for a profit. Levels of metals recycling are generally low. The report authors observed that, as metals are inherently recyclable, the metal stocks in society can serve as huge mines above ground the term " urban mining " has been coined with this idea in mind .
However, they found that the recycling rates of many metals are very low. The report 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 stepped up these critical metals will become unavailable for use in modern technology.
The military recycles some metals. Navy 's Ship Disposal Program uses ship breaking to reclaim the steel of old vessels. Ships may also be sunk to create an artificial reef. Uranium is a very dense metal that has qualities superior to lead and titanium for many military and industrial uses.
The uranium left over from processing it into nuclear weapons and fuel for nuclear reactors is called depleted uranium , and it is used by all branches of the U. The construction industry may recycle concrete and old road surface pavement, selling their waste materials for profit. Some industries, like the renewable energy industry and solar photovoltaic technology, in particular, are being proactive in setting up recycling policies even before there is considerable volume to their waste streams, anticipating future demand during their rapid growth.
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 of the material, which means only products of lower quality standard can be made with the recycled material. A new approach which allows an equal level of quality is the Vinyloop process. E-waste is a growing problem, accounting for 20—50 million metric tons of global waste per year according to the EPA. It is also the fastest growing waste stream in the EU.
After the cargo barge Khian Sea dumped 14, metric tons of toxic ash in Haiti , the Basel Convention 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. This works alongside other prominent legislation, such as the Waste Electrical and Electronic Equipment Directive of the EU the United States 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 10 centimetres 3.
The remaining pieces are further shredded to 10 millimetres 0. An eddy current 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 or the mercury backlight from LCDs. 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. 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.
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. Another process involves conversion of assorted polymers into petroleum by a much less precise thermal depolymerization process. Such a process would be able to accept almost any polymer or mix of polymers, including thermoset materials such as vulcanized rubber tires and the biopolymers in feathers and other agricultural waste.
Like natural petroleum, the chemicals produced can be used as fuels or as feedstock. 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 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: This happens in one of two ways: 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.
In order to meet recyclers' needs while providing manufacturers a consistent, uniform system, a coding system was developed. The recycling code for plastics was introduced in by the plastics industry through the Society of the Plastics Industry.
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 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 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, and sunglasses.
Types 1 and 2 are the most commonly recycled. 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.
There is some debate over whether recycling is economically efficient. According to a Natural Resources Defense Council study, waste collection and landfill disposal creates less than one job per 1, tons of waste material managed; in contrast, the collection, processing, and manufacturing of recycled materials creates 6—13 or more jobs per 1, tons. According to the U. Recycling Economic Informational Study, there are over 50, recycling establishments that have created over a million jobs in the US.
Fiscal efficiency is separate from economic efficiency. Economic analysis of recycling does not include what economists call externalities , which are unpriced costs and benefits that accrue to individuals outside of private transactions.
About 4, minerals are known, of which only a few hundred are relatively common. 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: These principles appear to divide economic thinkers today. 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 fly-tipping. Kinnaman concludes that a landfill tax would force consumers, companies and councils to recycle more. Most free-market thinkers detest subsidy and intervention because they waste resources. 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.
Benjamin argues that it wastes people's resources and lowers the wealth of a population. Certain countries trade in unprocessed 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. Although the Chinese government has banned these practices, it has not been able to eradicate them.
Certain regions have difficulty using or exporting as much of a material as they recycle. This problem is most prevalent with 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. It uses a single stream process in which all material is automatically sorted. 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: 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 will either return to the natural ecosystem through biodegradation or be recycled indefinitely.
Complete recycling is impossible from a practical standpoint. In summary, substitution and recycling strategies only delay the depletion of non-renewable stocks and therefore may buy time in the transition to true or strong sustainability , which ultimately is only guaranteed in an economy based on renewable resources.
While recycling diverts waste from entering directly into landfill sites, current recycling misses the dissipative components. 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 packaging for food products is more easily recycled than most plastic, but is heavier to ship and may result in more waste from spoilage. Can't get enough TreeHugger? Sign up now and have it sent straight to your inbox. Daily and Weekly newsletters available. Email Address Email is required. Related Content on Treehugger.
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