Wikipedia

Glass recycling

Glass recyclingis the processing of wasteglassinto usable products.[1]Glass that is crushed or imploded and ready to be remelted is calledcullet.[2]There are two types of cullet: internal and external.Internal culletis composed of defective products detected and rejected by a quality control process during the industrial process ofglass manufacturing,transition phases of product changes (such as thickness and color changes) and production offcuts.External culletis waste glass that has been collected or reprocessed with the purpose of recycling. External cullet (which can be pre- or post-consumer) is classified as waste. The word "cullet", when used in the context of end-of-waste, will always refer to external cullet.

Bottles in different colors
Mixed color glass cullet
Public glass waste collection point for different colors of containers

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

Many collection points have separate bins for clear (flint), green and brown (amber). Glass re-processors intending to make new glass containers require separation by color. If the recycled glass is not going to be made into more glass, or if the glass re-processor uses neweroptical sortingequipment, separation by color at the collection point may not be required. Heat-resistant glass, such asPyrexorborosilicate glass,must not be part of the glass recycling stream, because even a small piece of such material will alter the viscosity of the fluid in thefurnaceat remelt. [3]

Processing of external cullet

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To use external cullet in production, as much contamination should be removed as possible. Typical contaminations are:

  • Organics: Paper labels, and corks
  • Inorganics: Plastic caps and rings, metal caps, stones, ceramics, porcelains, PVB (Polyvinyl butyral) and EVA (Ethylene-Vinyl Acetate) foils in flat/laminated glass
  • Metals: Ferrous and non-ferrous metals
  • Heat resistant (ex: Pyrex dishes) and lead glass (ex: crystal with lead content)

Manpower or machinery can be used in different stages of purification. Since they melt at higher temperatures than glass, separation of inorganics, the removal of heat resistant glass and lead glass is critical. In the modern recycling facilities, dryer systems andoptical sorting machinesare used. The input material should be sized and cleaned for the highest efficiency in automatic sorting. More than one free fall or conveyor belt sorter can be used, depending on the requirements of the process. Different colors can be sorted by optical sorting machines.

Recycling into glass containers

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A variant of the "Tidyman" symbol, intended to encourage people to recycle glass

Glass bottles and jars are infinitely recyclable.[4]The use of recycled glass in manufacturing conserves raw materials and reduces energy consumption.[5]Because the chemical energy required to melt the raw materials has already been expended, the use of cullet can significantly reduce energy consumption compared with manufacturing new glass from silica (SiO2), soda ash (Na2CO3), and calcium carbonate (CaCO3). Soda lime glass from virgin raw materials theoretically requires approximately 2.671 GJ/tonne compared to 1.886 GJ/tonne to melt 100% glass cullet.[6]As a general rule, every 10% increase in cullet usage results in an energy savings of 2–3% in the melting process, with a theoretical maximum potential of 30% energy saving.[6]Everymetric ton(1,000 kg) of waste glass recycled into new items saves 315 kilograms (694 lb) ofcarbon dioxidefrom being released into the atmosphere during the manufacture of new glass.[7]But recycling glass does not avoid the remelting process, which accounts for 75% of the energy consumption during production.[8]

Recycling into other products

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The use of the recycled glass as aggregate inconcretehas become popular, with large-scale research on that application being carried out at Columbia University in New York.[citation needed]Recycled glass greatly enhances the aesthetic appeal of the concrete. Recent research has shown that concrete made with recycled glass aggregates have better long-term strength and better thermal insulation, due to the thermal properties of the glass aggregates.[9]Glass which is not recycled, but crushed, reduces the volume of waste sent tolandfill.[10][3]Waste glass may also be kept out of landfill by using it for roadbed aggregate.[5]

Glassaggregate,a mix of colors crushed to a small size, is substituted for pea gravel or crushed rock in many construction and utility projects, reducing costs to a degree that varies depending on the size of the project. Glass aggregate is not sharp to handle. In many cases, the state Department of Transportation has specifications for use, size and percentage of quantity for use.[citation needed]Common applications are as pipe bedding—placed around sewer, storm water or drinking water pipes, to transfer weight from the surface and protect the pipe. Another common use is as fill to bring the level of a concrete floor even with a foundation.Foam glass gravelprovides a lighter aggregate with other useful properties.

Other uses for recycled glass include:

Mixed waste streams may be collected frommaterials recovery facilitiesormechanical biological treatmentsystems. Some facilities can sort mixed waste streams into different colours usingelectro-optical sortingunits.

Recycled glass in construction

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The alternative markets for recycled glass waste include theconstruction sector(usingglass wastefor roadpavementconstruction, as an aggregate inasphalt,pipe bedding material,drainageor filler aggregate), the production ofcementandconcrete(using glass waste asaggregate),[12][13][14]as partial replacement to cement,[15][16][17]partial replacement for cement and aggregate in the same mixture[17]or raw material for cement production,[17]as well as decorative aggregate,[18]abrasives,[19]or filtration media.[20]

Recycled glass in road pavement

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Three different samples of recycled glass with different gradation curves produced from residential and industrial waste glass streams in Victoria were studied in this research to investigate their usage as a construction material in geotechnical applications. The Fine Recycled Glass (FRG) and Medium Recycled Glass (MRG) were classified as well-graded (SW-SM), while Coarse Recycled Glass (CRG) was poorly graded (GP) according to theUnified Soil Classification System(USCS). The specific gravity of recycled glass was approximately 10% lower than that of natural aggregate. MRG exhibited higher maximum dry unit weight and lower optimum water content compared to FRG. LA abrasion tests showed FRG and MRG to have abrasion resistance similar to construction and demolition material, while CRG had higher abrasion values. Post-compaction analysis indicated stability for FRG and MRG, but CRG displayed poor compaction behavior due to particle shape and moisture absorption issues. CBR and direct shear tests revealed MRG's superior shear resistance and slightly higher internal friction angle compared to FRG. Consolidated drained triaxial shear tests confirmed these findings, suggesting FRG and MRG behave similarly to natural sand and gravel mixtures in geotechnical applications. Hydraulic conductivity tests demonstrated medium permeability and good drainage characteristics for FRG and MRG. Compliance with EPA Victoria requirements for fill material was also confirmed. Overall, the study supports using recycled glass in various geotechnical engineering applications.[21]

Recycled glass in bricks

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Polymer concrete,a material commonly used in industrial flooring, usespolymers,typicallyresins,to replacelime-type cementsas abinder.Researchers have found thatgrounded recycled glasscan be used as a substitute for sand when making polymer concrete.[22] According to research, using recycled glass instead of sand produces a high strength, water-resistant material suitable for industrial flooring and infrastructure drainage, particularly in areas subject to heavytrafficsuch as service stations,forkliftoperating areas and airports.[22][peacock prose]

Challenges

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Despite all the improvement in the waste and recovery processes, challenges include:

  • Lack of incentive to recycle when inconvenient; opt-in and subscription models lead to low participation
  • Rising material recovery facility fees and pressure from the waste management industry have caused some municipalities to remove glass from curbside recycling
  • Lack of recycling mandates and high levels of contamination cause a significant portion of materials to be disposed of in landfills.
  • Low landfill tip fees for many MRFs (material recovery facilities) incentivize sending glass to the landfill.
  • Lack of capacity in certain areas hinders the ability to meet the market demand and reduces the incentive to invest in materials recovery facilities.
  • In some regions, strong demand for cullet from other end markets reduces potential supply for glass containers.
  • Distance between the sources of and markets for cullet requires long-haul shipping.
  • Virgin materials are often cheaper than cullet, sometimes by as much as 20%.[23]

By country

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Europe

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Container glass collection
Country 2021[24]
Austria 87%
Belgium 114%
Bulgaria 78%
Croatia 59%
Cyprus 52%
Czech Republic 81%
Denmark 88%
Estonia 78%
Finland 91%
France 82%
Germany 84%
Greece 36%
Hungary 38%
India 85%
Ireland 84%
Italy 85%
Latvia 70%
Lithuania 63%
Luxembourg 99%
Malta 63%
Netherlands 87%
Norway 90%
Poland 73%
Portugal 54%
Romania 64%
Slovakia 74%
Slovenia 98%
Spain 73%
Sweden 88%
Switzerland 95%
United Kingdom 74%
Europe 80%

Germany

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In 2004, Germany recycled 2.116 million tons of glass. Reusable glass or plastic (PET) bottles are available for many drinks, especially beer and carbonated water as well as soft drinks (Mehrwegflaschen). Thedeposit per bottle(Pfand) is €0.08-€0.15, compared to €0.25 for recyclable but not reusable plastic bottles. There is no deposit for glass bottles which do not get refilled.

Non-deposit bottles are collected in three colours: white, green and brown.

India

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In 2021, India recycled 78.6 million tons of glass. Many drinks are packaged in reusable glass and plastic (PET) bottles, especially beer and carbonated water. Recycled waste glass has many uses such as cement and paint additives as well as remanufacturing into glass tiles.

Specially, Indian recycling companies (Faizal Ahamed & Co, AMB Traders, Abubakkar Sons and JBA Groups in Tamil Nadu, India) collect 5 million tons of glass for recycling per month.

Non-deposit bottles are typically collected in three colors: clear, green and brown.

Netherlands

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The first bottle bank for non-deposit bottles (glasbak) was installed inZeistin 1972. Glass is collected in three colours: white, green and brown.[25] There is a deposit for refillable beer bottles when returned tosupermarkets.[26]

United Kingdom

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Vehicle emptying a glass recycling container in Vienna

Glass collection points, known asbottle banksare very common nearshopping centres,atcivic amenity sitesand in local neighborhoods in theUnited Kingdom.The first bottle bank was introduced by Stanley RaceCBE,then president of theGlass Manufacturers' Federationand Ron England inBarnsleyon 6 June 1977.[27]Development work was done by the DoE atWarren Spring Laboratory,Stevenage, (now AERA at Harwell) and Nazeing Glass Works,Broxbourneto prove if a usable glass product could be made from over 90% recycled glass. It was found necessary to use magnets to remove unwanted metal closures in the mixture.

Bottle banks commonly stand beside collection points for other recyclable waste likepaper,metalsandplastics.Local, municipalwaste collectorsusually have one central point for all types of waste in which large glass containers are located.

In 2007 there were over 50,000 bottle banks in the United Kingdom, and 752,000 tons of glass was being recycled annually.[28]

Asia

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India

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Approximately 45% glass waste gets recycled each year.[29]

North America

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United States

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Rates of recycling and methods of waste collection vary substantially across the United States because laws are written on the state or local level and large municipalities often have their own unique systems. Many cities docurbside recycling,meaning they collect household recyclable waste on a weekly or bi-weekly basis that residents set out in special containers in front of their homes and transported to amaterials recovery facility.This is typicallysingle-stream recycling,which creates an impure product and partly explains why, as of 2019, the US has a recycling rate of around 33% versus 90% in some European countries.[30]European countries have requirements for minimum recycled glass content, and more widespread deposit-return systems that provide more uniform material streams.[31]The lower population density and long distances in much of the United States, and the cost of shipping heavy glass also mean that recycling is not inherently economical in places where there are no nearby buyers.[31]

Apartment dwellers usually use shared containers that may be collected by the city or by private recycling companies which can have their own recycling rules. In some cases, glass is specifically separated into its own container because broken glass is a hazard to the people who later manually sort the co-mingled recyclables. Sorted recyclables are later sold to companies to be used in the manufacture of new products.

In 1971, thestate of Oregon passed a lawrequiring buyers of carbonated beverages (such as beer and soda) to pay five cents per container (increased to ten cents in April 2017) as a deposit which would be refunded to anyone who returned the container for recycling. This law has since been copied innine other statesincluding New York and California. The abbreviations of states with deposit laws are printed on all qualifying bottles and cans. In states with these container deposit laws, most supermarkets automate the deposit refund process by providingmachineswhich will count containers as they are inserted and then print credit vouchers that can be redeemed at the store for the number of containers returned. Small glass bottles (mostly beer) are broken, one-by-one, inside these deposit refund machines as the bottles are inserted. A large, wheeled hopper (very roughly 1.5 m by 1.5 m by 0.5 m) inside the machine collects the broken glass until it can be emptied by an employee. Nationwide bottle refunds recover 80% of glass containers that require a deposit.[5]

Major companies in the space include Strategic Materials, which purchases post-consumer glass for 47 facilities across the country.[32]Strategic Materials has worked to correct misconceptions about glass recycling.[33]Glass manufacturers such asOwens-Illinoisultimately include recycled glass in their product. The Glass Recycling Coalition is a group of companies and stakeholders working to improve glass recycling.[34]

Oceania

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Australia

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In 2019, many Australian cities after decades of poor planning and minimum investment are winding back their glass recycling programmes in favour of plastic usage.[35]

For many years, there was only one state in Australia with a return deposit scheme on glass containers. Other states had unsuccessfully tried to lobby for glass deposit schemes.[36]More recently this situation has changed dramatically, with the original scheme in South Australia now joined bylegislated container deposit schemesin New South Wales,[37]Queensland,[38]Australian Capital Territory,[39]and the Northern Territory, with schemes planned in Western Australia (2020), Tasmania (2022) and Victoria (2023).

Africa

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South Africa

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South Africa has an efficient returnable bottle system which includes beer, spirit and liquor bottles. Bottles and jars manufactured in South Africa contain at least 40% recycled glass.[40]

Life Cycle Analysis

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Life Cycle Analysis (LCA) is an important tool for ecological evaluation of products or processes. LCA is an internationally accepted standard (ISO 14040 & ISO 14044) and scientific tool that is used to quantify the environmental performance attributable to the different life stages of our products, including upstream stages such as raw material production and energy supply. Results are benchmarked based on LCA indicators with the final aim of identifying operational efficiencies and optimising product design while providing a higher level of environmental transparency.[41] The life-cycle of glass starts from extraction of raw materials, to distribution, use by final consumers to disposal/landfilling. In light of saving the economy and the environment, researchers are working to eliminate the linearity of this lifecycle to have a circular/closed loop life cycle where extraction of raw materials and landfilling after final consumption will be eliminated.[41] Glass takes up to millions of years to decompose in the environment and even more in landfill. Fortunately, glass is 100% recyclable, making it a sustainable resource for producing new forms of packaging without relying on raw materials. The problem now is that only 70% of glasses are being collected for recycling in the EU (30% in the US) (which is already good, but can be better).[8]Its recyclability can hence be improved by improving its collection rate all around the world. The only way we can increase collection rate is to enlighten every single consumer of glass to properly dispose and speak up against improper disposal of this glass.

Cradle to cradle Analysis

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The Cradle-to-Cradle analysis is an approach which evaluates a product's overall sustainability across its entire life cycle. It expands the definition of design quality to include positive effects on economic, ecological and social health. The Cradle to cradle analysis of glass showed that the most impactful phase of a glass lifecycle is at its raw materials usage. Hence, why the sustainability of this product is focused on eliminating this stage of production by recycling used glasses to make secondary raw materials.[42]

Regulatory Framework

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  • Waste Framework Directive (2008/98/EC) establishes specific targets for the re-use and recycling of building waste, including glass. Defines high levels of recycling as key for Europe's resource efficiency.
  • A ban on landfill disposal of single clear glass panes and insulating glass units should be introduced in the revised version of Directive 1999/31/EC.

ISO

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International Organization for Standardization (ISO) is a non-governmental institution (established under the aegis of the UN) bridging public and private sectors. ISO is an international standard setter for “business, government and society,” through its pursuit of voluntary standards. These standards range from those dealing with size, clarity, and weights measures to the systems businesses ought to put in place to enhance customer satisfaction. Its work thus has an intimate impact on daily life by shaping and molding the way in which commerce is conducted, the operating procedures of business, and the way in which consumers engage with markets.[43] Some of this standard setting was the result of government and business agreement on product development; others were the consequence of commercial battles fought out over the most appropriate format. The organization boasts having developed more than 17,000 international standards in its 60-year history and claims that it is engaged in producing an additional 1,100 standards each year.[43]ISO are usually put in consideration in lifecycle assessment of products.

TheISO 81.040contains the international standards for glass. It's divided in four chapters.

Other related ISO:

See also

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References

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