Annex 39 Complementary information to source category 4e Asphalt Mixing
Overview of recent revisions
No revisions of emission factors have been made. Additional guidance has been introduced on classifying sources within this category, estimating activity rates, and on data quality aspects.
Derivation of emission factors
Release to Air
Tests have been carried out on asphalt mixing installations in Germany (SCEP 1994) and the Netherlands (Bremmer et al. 1994). The plants tested had fabric filters and some used cyclones as a pre-separator for dust. An average emission factor of 0.007 μg TEQ/t of product is to be applied to plants with this type of gas cleaning.
For plants without fabric filters an emission factor of 0.07 μg TEQ/t of product is applied (assuming fabric filters would capture approximately 90% of PCDD/PCDF).
Emissions may be highly increased where contaminated materials are used as part of the asphalt – for example fly ash from an old incinerator could lead to increased releases. Any incidence where such materials are used should be noted.
Release to Water
No release to water is expected. If effluents are released, their source in the process should be noted.
Release to Land
It is assumed that the asphalt is used on land but no data are available on the levels of PCDD/PCDF in it.
Release in Products
There may be PCDD/PCDF in the asphalt although levels are unknown. It is expected this will be used on land for road construction.
Release in Residues
Flue gas cleaning residues are likely to have PCDD/PCDF in them. Amounts are unknown. An initial estimate can be made by assuming that 90% capture of the PCDD/PCDF in the flue gas is achieved and assuming that the raw gas contains the same amount as for processes, which are uncontrolled giving an emission factor of 0.06 μg TEQ/t.