What is Incinerator Bottom Ash?
Incinerator Bottom Ash (IBA) is material discharged from an Energy Recovery Facility (ERF) incinerating municipal solid waste. The weight generally represents around 23% of the input waste.
It can contain varying quantities of glass, ceramics, brick, concrete and metals in addition to clinker and ash, depending on the waste being burnt.
Once large objects and metals have been screened out, the remaining ash can be processed into a secondary aggregate that has good pozzolanic (cement-like) properties, so can act as an excellent substitute for natural aggregates.
This can be used in road sub-base, bulk fill, asphalts, foamed concrete and cement bound materials. The Highways Agency accepts the use of processed IBA as an aggregate for bound and unbound layers in road construction.
By using IBA in this way, landfill avoidance of up to 99% can be achieved and valuable ferrous and non-ferrous metals and glass are recovered. Veolia Environmental Services now recycles the majority of the IBA from all of its ERFs and will seek to develop this capacity at new facilities.
The Issues
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IBA is a sustainable source of competitively-priced aggregate that replaces primary aggregate extracted from quarries. It has a lower density than primary aggregate, so is more effective as bulk filler.
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Recycling IBA avoids landfill disposal and although it is essentially inert, containing no more than 3% carbon, using it as a secondary aggregate makes space available for other wastes, as well as avoiding the landfill tax liability.
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Secondary aggregate can use less transport than primary aggregate by utilising IBA processing plants close to the building developments.
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Substantial amounts of both ferrous and non-ferrous metals can be recovered from IBA and the cement-like properties of processed IBA can give enhanced performance over virgin aggregate for certain applications.
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IBA can contain metals such as lead and zinc, arising from the wastes treated at the ERF. However, it is rigorously tested in line with European and UK guidance to ensure that their concentrations do not constitute a hazard.
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IBA is derived from waste so under European and UK regulations, despite being treated, it remains a (non-hazardous) waste until it is put into the final application. Prior to being used, a permit application has to be submitted to the Environment Agency (EA), who will ensure it is not being located on watercourses and the application meets other EA requirements. In May 2002, the Environment Agency published a report on the safety of IBA, indicating that its use posed no exceptional risk to human health.
Our Position
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Veolia Environmental Services supports the use of IBA as a secondary aggregate and continues to develop the processing of incinerator ash for this use. Using IBA as a secondary aggregate makes a positive contribution to lowering the carbon footprint of waste management, thus helping to mitigate climate change
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Our processed IBA meets the requirements laid down by the Environment Agency and is not hazardous
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Veolia Environmental Services is following the establishment of an “end of waste” criteria. This will remove waste regulation obligations for prepared IBA materials. However, we are content to continue with the current regime if required, especially if that provides greater confidence in safe treatment and use
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We believe that metals, glass and aggregate recovered from IBA are recycled in the same way as materials collected through municipal collections. This means they should be counted within local authority recycling performance, as they are in other EU countries
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Veolia Environmental Services will continue to provide traceability of the ash it sends for conversion
to secondary aggregate