How are glass bottles recycled?

Overview

Domestic waste glass (known as cullet) is easy to recycle. The UK currently recycles around 50% of container glass (like bottles and jars) and while this figure has doubled over the last five years it still lags behind other countries. For example, both Switzerland and Finland recycle more than 90% of their glass.

Glass can be collected in bottle banks or as part of your kerbside collection. However, there is still more we can all do, such as remembering to recycle our clear jars (pasta sauce jars and jam jars) which are often forgotten.

The UK business sector still has a lot of work to do to recycle glass – bars, restaurants and pubs currently throw away over 200,000 tonnes of glass every year into landfill.

How is it recycled?

Once glass is collected and taken to be reprocessed, it is:

crushed and contaminants removed (mechanised colour sorting is usually undertaken at this stage if required)
mixed with the raw materials to colour and/or enhance properties as necessary
melted in a furnace
moulded or blown into new bottles or jars.

Environmental impact

The production and use of glass has a number of environmental impacts.

New glass is made from four main ingredients: sand, soda ash, limestone and other additives for colour or special treatments. Although there is no shortage of these raw materials as yet, they all have to be quarried, which can damage the landscape, affect the environment and use more energy.

Glass is 100% recyclable and can be endlessly reprocessed with no loss of quality. Therefore by simply recycling our glass we can:

conserve non-renewable fossil fuels
reduce the emission of harmful gasses into the atmosphere.

Did you know?

The addition of domestic waste glass (known as cullet) to a furnace in the glass manufacturing process, substantially reduces the energy requirement and decreases CO₂ emissions. Each tonne of cullet added to the furnace saves 1.2 tonnes of raw materials – decreasing emissions still further.
New glass takes a lot of energy to make, first in transporting the materials to the furnace and then to heat them to a high temperature. An efficient furnace burns 4 gigajoules (GJ) (unit of energy measuring heat) to melt every tonne of glass – that's the energy equivalent of burning 250kg of wood.

Problems and issues

The main problem with glass recycling is the quality of the glass collected. It can be contaminated, and therefore difficult to use in glass containers again. Due to the relatively low value of the material and the required processing costs, much glass ends up in aggregate where there is no environmental benefit.

To try to counter, this a split target has been put in place to limit the amount of glass that doesn't go through a remelt process.

Made from recycled

Recycled glass can be used to make a wide range of everyday products and some that are completely unexpected, including:

new bottles and jars
glass wool insulation for homes, which also helps with energy efficiency.

The different types of glass

We use many different types of glass in the UK, but at home we mostly use 'soda-lime-silica' glass for containers like bottles and jars. It is important not to mix up the different types of glass as they are re-processed differently.

Different types of glass include:

borosilicate glass – used for heat-resistant cooking equipment like Pyrex
lead glass – for sparkling decorative glassware
glass fibre – for insulation and fibre optic cable.

These different types of glass are not widely recycled so do not add these into your kerbside collection container or bottle banks at the recycling centre.

Colour and quality

During the glass manufacturing process, extra raw materials can be added to give the glass a particular colour or special qualities.

The extra raw materials that can be added are:

iron for a brown or green colour
cobalt for blue
alumina for durability
boron to improve resistance to heat or cold.

Where to recycle glass bottles

Most local authorities collect glass bottles and jars in their household collections. Alternatively, enter your postcode below to find your nearest glass bottle and jar recycling locations.