Incinerator Bottom Ash
The ash resulting from the controlled combustion of waste, in the UK primarily MSW is known as Incinerator Bottom Ash (IBA). Not to be confused with Flue Gas APC Residues cleaning residues or boiler (tube) ash. IBA generally represents around 20% of the input material by weight[1].
Following the combustion process non-combustible ash of varying particle size is produced, often containing mineral material and metals. The ash which falls to the bottom of the process is typically dry and dusty and operators will need to ensure that it is appropriately stored in covered containers to prevent emissions to air[1].
Currently, over half a million tonnes of IBA goes to landfill each year in England and Wales. However, as recovery processes have improved this material can now be processed and recycled back as Secondary Aggregate into applications such as aggregate replacement for sub-base road construction, bulk fill, concrete block manufacture or concrete grouting[1]. When recycled back to an aggregate it is known as Incinerator Bottom Ash Aggregate (IBAA).The use of IBAA in construction has specific controls that need to be applied[2].
The graph below displays the incinerator bottom ash produced as a percentage of the total residual waste feedstock being processed by UK Energy from Waste facilities, and how this has changed over recent years.
References
- ↑ 1.0 1.1 1.2 WRAP, 2019. EfW Outputs and Residues Guidance on the management of energy outputs and residues including air pollution control residues and incinerator bottom ash. EfW Development Guidance. [online] [Accessed 30 Oct. 2019].
- ↑ https://www.gov.uk/government/publications/using-unbound-incinerator-bottom-ash-aggregate-ibaa-in-construction-activities-rps-247
- ↑ Tolvik Consulting, 2019. UK Energy from Waste Statistics – 2018. Gloucestershire.[online]