Recycling benefit

Amount recycled
91,057t
Estimated disposal saving
£10,289,411
Reported as exported
16%

Incinerator bottom ash, also known as IBA, is a by-product of residual waste incineration with or without energy recovery that collects at the bottom of municipal incinerators. Approximately 20 per cent of waste material sent for incineration is recovered as IBA, which can be processed to recover valuable metals, with the remainder being used for construction purposes. 

In the recovery process, before IBA is deemed suitable for recycling, it is sampled and measured to ensure that it is non-hazardous and compliant under the European Waste Code 19 01 12. When the material is classified as hazardous, it then requires further treatment and stricter controls for disposal.

Once sent for reprocessing, the IBA is passed along on conveyor belts through large magnets that remove the ferrous IBA elements, particular steel. Following this, non-ferrous ash is also separated for onward reprocessing. This is passed through eddy current separators, inductive sorting and x-ray technology to separate the different types of non-ferrous metal, including zinc, brass, copper and aluminium (which makes up the large fraction, due to the prevalence of aluminium in packaging that does not get initially separate in the recycling process).

These recovered metals, which can be as small as a few millimetres, are then sent onward for further processing, to be melted down for subsequent use in metal products, such as copper pipes, brass taps, aluminium vehicle engines or zinc oxide (in paints). These can be recovered in significant amounts, with an estimated 1,000 tonnes of aluminium recovered from IBA in Wales every year.

The remaining, largest fraction of the IBA is then used for construction as a secondary aggregate, principally as a sub-base for highways, car parks and other constructions for vehicle traffic. When it is bound with cement, the use of IBA can be extended and is particularly suited to road paving. The use of IBA in construction aggregates displaces the use of other materials for use in aggregate, potentially reducing the carbon footprint if used locally. 


Where does incinerator bottom ash recycling go?

Top countries (selected materials) - 2021/22

Top UK recycling destinations

Country Tonnes
England 75,881t
Wales 829t
Company Country Tonnes
Day Aggregates Ltd England 40,467t
Ballast Phoenix Ltd England 17,650t
unspecified England 3,346t
Ballast Phoenix Limited England 3,266t
Johnsons Aggregates Ltd England 2,775t
Carbon8 Aggregates Limited England 2,333t
OCO Technology Ltd England 1,571t
Blue Phoenix Limited England 1,262t
IBA recovery England 659t
Gloucester EFW England 460t
LaFarge Cement UK Plc Wales 393t
Cemex UK Cement Ltd England 301t

Top world recycling destinations

Company Country Tonnes
unspecified unspecified 6,288t
unspecified Sweden 2,579t
Baudelet Environnement France 838t
Svergie AB unspecified 785t
Svergie AB Sweden 753t
EON VARME SVERGIE AB unspecified 704t
Global Alternative Fuels unspecified 573t
Jorgen Rasmussen Gruppen Denmark 514t
Tekniskaverken I Linkoping AB Sweden 495t
Alpet Geri Donusum Sanayi VE Turkey 368t
EOn Energy From Waste Delfzijl B Netherlands 146t
Unspecified Denmark 113t
WRAP Cymru