technical guidance documents - Institute for Health and Consumer ...

ENVIRONMENTAL EXPOSURE ASSESSMENT
de novo synthesis may occur. Both types of releases are a result of the technical conditions
(temperature, turbulence and time) of the waste incineration rather than caused by specific types
of chemical substances and they are as such not covered by the risk assessment. An exception
from this general rule may be waste streams, containing organobromine substances or other
halogenated hydrocarbons.
It is assumed that waste incineration processes operated in compliance with EU Directive
89/429/EC and 94/67/EC (or with Directive 2000/76/EC) would lead to sufficient destruction of
organic substances in the waste stream. In special cases it may be known that incineration
conditions differ from ‘best available technology’ conditions and in that case information on
melting and boiling point as well as on thermal stability may be used to assess whether complete
destruction of the substance of concern can be expected. Even though waste incinerators may be
regarded as a major source of PCDD/PCDFs in Europe, the potential risk is related to the
installation rather than the substance under assessment.
While organic substances are destroyed in the municipal incinerator, inorganic substances
such as metals will be distributed among various incineration residues or emitted to the
atmosphere. Typical range of concentration in incineration residues from incineration of
municipal waste can be determined, based on modelling or measurements (e.g. Danish EPA,
2001). The distribution pattern is different for each inorganic substance, depending on its
physico-chemical properties, the gas cleaning technology and the operation conditions. For
metals emissions to the atmosphere with the flue gas may vary from less than 0.1 % to 15%
of the input depending on the substance properties and the employed flue gas treatment
technology (Danish EPA, 2001).
The main emissions source related to waste incinerator residues is leaching from landfilled or
from recovered residues. The high content of salts and metals in bottom ashes and in flue gas
cleaning products suggest that these residues could potentially sustain leaching of salts and
metals for a prolonged period of time (compared to the general time frame within risk
assessment) at elevated concentrations compared to background concentrations in surface and
groundwater. However, the magnitude of the long-term releases depends on processes both
governing and limiting the leaching potential and is therefore uncertain. As a first cautious
approach leaching tests may be used (c.f. Danish EPA, 2001) whereas monitoring data regarded
as representative may be used to modify such an estimation. Concerns related to leaching from
incineration residues are dependent on the present and future intended use of the residues i.e.
concerns are related to a general waste management issue rather than to a substance specific risk
assessment.
Releases from municipal landfills
Modern landfills aim to prevent uncontrolled emissions and reduce emissions of waste
compounds and degradation products into the environment for a number of decades. The
principal means for emission control are:
• a top layer to prevent inflow of rain water;
• a bottom liner to prevent leaching to groundwater;
• leachate treatment;
• active collection of landfill gas (in case of organic landfills).
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