Recycling glass is a simple but hugely beneficial process. Below are twelve steps to recycling this complex material. The images also demonstrate the complete recycling loop as glass can be recycled over and over again.
As much recycled glass is used as possible as this enables the other materials to melt at a lower temperature. The colour of the glass is controlled by the iron content and the addition of minor colouring agents.
Even though basic ingredients are used in vast quantities, accurate weighing and mixing to achieve precise proportions is absolutely critical. This procedure is carried out electronically in the batch house which supplies the mix to the furnace.
A typical furnace within the glass container industry will operate 24 hours a day, 365 days of the year producing around 300 tonnes of glass a day! This production of glass is continuous for the furnaces' lifetime of approximately 10 years.
Up to 90% recycled glass is mixed with raw materials and fed into the furnace where the recycled glass remelts and becomes pure and pristine again.
The glass is cut into "gobs". These are individual pieces which are literally fired down into the forming machine. Within seconds the glass is pressed and blown into shape within a mould and emerges as a glass bottle or jar!
Each and every container is subjected to a rigorous series of quality checks. base scanning
At intervals a sample of the containers being produced is taken aside for dimensional checks, capacity checks and pressure testing. If any problems are found in production since the last check, it is set aside for further inspection. This procedure is followed until the production again passes the tests.
The data from online and offline quality checks is fed continuously back to the 'hot-end' forming machine operators who can then make adjustments to remove the problem at source.
Each container has a series of dots moulded into the insweep which create a coded number when read by the online inspection machines. This quickly highlights any bottle faults being seen and faults in the mould which is creating it.
The UK glass container manufacturers produced around 1,800,000 tonnes of glass packaging in 2003. 620,000 tonnes of this, or 33% of it, was made from recycled glass.
transportation to retailers
The bottles and jars are filled with food and drinks and taken to retailers such as supermarkets where they are sold to consumers.
UK retailers and brand owners import a further 500,000 tonnes of empty and filled glass packaging each year, meaning that the total UK waste stream for glass packaging in 2003 was approximately 2,300,000 tonnes.
Many bottles of beer, spirits and soft drinks are taken direct to retailers such as pubs, reastaurants and night clubs where they are sold to consumers.
Figures are unclear but it is estimated that around 500,000 to 600,000 tonnes of glass arises in pubs and clubs. Approximately 80% of this is not collected and therefore goes directly to landfill.
use at home
The rest of the glass is taken home by consumers who eat or drink the products inside the bottles or jars.
They then make a crucial decision, do they throw it in the bin or take it to the recycling bank?
If they throw it away it will go to landfill where it will stay forever, never breaking down. If they take it to be recycled, the whole cycle begins again and glass can go on being recycled again and again - forever.
Over ¾ or 1,800,000 tonnes of the UK's glass ends up in our homes.
Any glass which is put into the rubbish bin will go into landfill with all the other waste.
Currently we landfill around 1,400,000 tonnes of glass each year. This is a real lost opportunity!
Glass can be recycled at glass banks all over the country.
Since 1977, the glass industry has been supporting the country's glass recycling infrastructure. The amount collected continues to increase and the industry continues to pay a higher price for recycled glass than for equivalent virgin raw materials.
Glass banks have always been colour separated. A small number are now being switched to mixed glass. It may not be possible for the industry to colour separate glass collected mixed from recycling banks, to get the maximum value and environmental benefit glass banks must remain colour separated.
Kerbside collection schemes make it easier and more convenient for the public to recycle their glass. In areas which introduce kerbside, the glass recycling rate usually doubles. Unfortunately while around 70% of LAs have kerbside collections of at least one material, only 34% or 7.3 million households in the UK have kerbside collections of glass. This needs to increase rapidly if we are to meet European glass recycling targets for 2008.
Glass collected at the kerbside is usually colour separated on the vehicle or is sold as mixed glass for colour separation or for use in alternative markets. Glass which is collected co-mingled is usually separated at an MRF (Materials Recycling Facility) but is generally suitable only for low value markets.
The recycling rate for glass in the UK in 2003 was 38% but if more were put into kerbside boxes more would be used to make new containers
Glass from pubs and clubs is usually collected colour separated in wheeled bins, but often it is collected in mixed bins due to lack of space.
Where glass is collected mixed it can be colour separated and used within the container industry. This is happening now and will grow in the future as more collections from pubs and clubs are established.
Recycled glass contains contaminants which must be removed before the recycled glass is used to make new containers. Metal, paper, plastic, organics, ceramic and pyro-ceramic must all be removed. This is done using manual inspection and high-tech equipment utilising metal detectors, vacuums, crushers, screens, lasers, digital cameras and even x-rays to detect and remove contamination.
The glass container industry's customers demand a very high quality product. Glass packaging gives shape and identity to some of the world's leading brands. As such the packaging comes to represent the brand and must live up to the high standards consumers come to expect from their trusted brands.
Some recycling plants have colour separation facilities which use manual inspection and digital scanning cameras to separate glass which has been collected in mixed colour form. There is limited capacity for this process, which requires high levels of investment and produces relatively high waste levels. However, this technology will grow and is essential in making the most of glass recycling.
Once the recycled glass has been cleaned and prepared it is mixed with raw materials and the whole process begins again!
This cycle can be repeated an infinite number of times and the quality of the glass will never deteriorate. Each time bottles and jars go round this cycle they generate environmental benefits:
- 345 kwh of energy is saved for every tonne used
- 225 kg of CO2 is saved for every tonne used
- 1.2 tonnes of raw materials quarrying is saved for every tonne used
- 1 tonne of landfill is saved for every tonne used
100% of recycled glass can be used to make new glass bottles and jars, without any loss in quality. Glass containers made with high levels of recycled glass are as pure and clear as those made solely from virgin raw materials. Green bottles are made with up to 90% recycled glass content. If more glass was recycled, recycling rates for all glass colours could be increased.
The container industry is the largest user of recycled glass in the UK, using around 80% or 620,000 tonnes in 2003. If additional supplies of clear and brown glass can be
secured from the waste stream, the industry could increase its use to over one million tonnes each year. The industry is determined that glass should maintain its
position as the most recyclable packaging material.
Can you believe that glass recycling in 2003 saved enough energy to launch 10 space shuttle missions? Glass recycling also reduces quarrying for raw materials, reduces emissions and reduces waste going to landfill.
As the UK consumes high levels of imported wine bottles made of green glass, yet has a relatively small domestic production level for green glass there will, when we reach higher recycling rates, be more recycled green glass than the container industry alone can use.
This has been a limiting factor on the recycling rate for glass in the UK in the past.
Once the container industry has used around 350,000 tonnes each year other alternative markets are available, such as:
- water filtration
- fluxing agents in bricks and clay pipes
- shot blasting
While these uses are much more beneficial than landfill they are less environmentally beneficial than close loop recycling into containers, for example even after all the transport has been taken into account, use in closed loop container making is 50 times more beneficial to the environment than use in aggregates.
However, without alternative markets such as aggregates the extra green glass that is collected will undermine the value of all glass collection. Overall we need all markets to grow.
One of the largest alternative markets for green glass is export to other European glass container manufacturers. In Europe there is a high demand for green glass. This is because the continental glass bottle makers have a high demand for green wine bottles. Use in glass container manufacturing in Europe is still beneficial to the environment. This is because more energy is saved than is used in transport by shipping across to Europe. In 2003 approximately 100,000 tonnes of glass were exported to European container makers.
closing the loop
Taking all markets into consideration, 865,000 tonnes of glass were recycled in 2003 (DEFRA). By 2008 the UK needs to increase this to around 71% to meet the targets set by the Packaging & Packaging Waste Directive. That's over 1.4 million tonnes of glass!
This is an unprecedented rate of growth. While there are sufficient markets for this level of material, the key challenge is to increase the levels of good quality glass collected.
This is a challenge for all of us.