Glass recycling

  Glass recycling is the process of turning waste glass into usable products. Depending on the end use, this commonly includes separating it into different colors. Glass normally comes in a number of colours. The major types are:

• Flint glass (clear glass)
• Green glass
• Brown/amber glass

Glass makes up a large component of household and industrial waste due to its weight and density. The glass component in municipal waste is usually made up of bottles, broken glassware, light bulbs and other items. Glass recycling uses less energy than manufacturing glass from sand, lime and soda. Every tonne of glass used for producing new glass items saves 315kg of carbon dioxide.^[1] Glass that is crushed and ready to be remelted is called Cullet. The term "cullet" derives from the practice of remelting flawed containers which have been "culled" from production lines.  

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Glass reuse

Reuse of glass containers is preferable to recycling according to the waste hierarchy. Refillable bottles are used extensively in many European countries and, until relatively recently, in the United States. In Denmark 98% of bottles are refillable and 98% of those are returned by consumers. ^[2] These systems are typically supported by container deposit laws and other regulations. In some developing nations like India and Brazil, the cost of new bottles often forces manufacturers to collect and refill old glass bottles for selling carbonated and other drinks.

Glass collection

  Glass collection points, known as Bottle Banks are very common near shopping centers, at civic amenity sites and in local neighborhoods. The first Bottle Bank was introduced by Stanley Race CBE, then president of the Glass Manufacturers’ Federation and Ron England in Barnsley on 6 June, 1977;^[3] the second was installed in Oxford.^[4]

Bottle Banks commonly stand beside collection points for other recyclable waste like paper, metals and plastics. Local, municipal waste collectors usually have one central point for all types of waste in which large glass containers are located. There are now over 50,000 bottle banks in the United Kingdom.^[5]

Most collection points have separate bins for clear, green and amber/brown glass. Glass reprocessors require separation by colour as the different colours of glass are usually chemically incompatible. Heat-resistant glass like Pyrex or borosilicate glass should not be disposed of in the glass container as even a single piece of such material will alter the viscosity of the fluid in the furnace at remelt.

Glass recycling

752,000 tons of glass is now recycled annually in the United Kingdom.^[6] Glass is an ideal material for recycling and where it is used for new glass container manufacture it is virtually infinitely recyclable. The use of recycled glass in new containers helps save energy. It helps in brick and ceramic manufacture, and it conserves raw materials, reduces energy consumption, and reduces the volume of waste sent to landfill.^[7]

Secondary uses for recycled glass

In the United Kingdom, the waste recycling industry cannot consume all of the recycled container glass that will become available over the coming years, mainly due to the colour imbalance between that which is manufactured and that which is consumed. The UK imports much more green glass in the form of wine bottles than it uses, leading to a surplus amount for recycling.

The resulting surplus of green glass from imported bottles may be exported to producing countries, or used locally in the growing diversity of secondary end uses for recycled glass.^[8] Cory Environmental are presently shipping glass cullet from the UK to Portugal.^[9]

Secondary markets for glass recycling may include:

• Glass in ceramic sanitary ware production
• Glass as a flux agent in brick manufacture
• Glass in sports turf and related applications (e.g. top dressing, root zone) material or golf bunker sand
• Glass as water filtration media
• Glass as an abrasive

Mixed glass waste streams can also be recycled and converted into an aggregate. Mixed waste streams may be collected from materials recovery facilities or mechanical biological treatment systems. Some facilities can sort out mixed waste streams into different colours using electro-optical sorting units.

See also

• Glass
• Recycling
• Waste management

References