As contaminants in various products and materials chlorinated dioxins are furthermore
imported to Denmark and extracted from the nature around us, as dioxins can be found both
in clay, fish, animals and vegetation due to historical and ongoing contamination.
Moreover the atmospheric deposition on the Danish land area is estimated at 13 - 130 g
I-TEQ/year. This estimate is made on the basis of measurements conducted by The National
Environmental Research Institute in 2002. Finally may be emphasized that a export of
dioxin with residual products for landfilling abroad of 55-413 g ITEQ/ year is taking
place.
Formation of dioxins in Denmark is almost entirely related to combustion
processes. Combustion process is in this context used for any process leading to
combustion of organic matter present, including processes such as wood and straw burning,
waste incineration, fires, cement manufacturing and steel reclamation. Formation of
dioxins is thus widespread in the society.
Formation of dioxins is highly influenced by local process conditions
including raw materials and temperature pattern in flue gas emission systems. The emission
of dioxins furthermore depends on whether a flue gas cleaning system exists - and if so,
the kind of system is used. Estimating formation and emissions is a matter of dealing with
a host of uncertainties. The large ranges of formation and emissions stated above reflect
the uncertainties related to the estimates.
This study has been initiated by the Danish EPA in September 2002 in order
to improve the existing understanding of the circulation of dioxins in the Danish society
on the basis of the newest Danish knowledge.
The objective of the study has been to collect and integrate the latest
Danish knowledge concerning formation of dioxins primarily through new measurements from
2000 - 2002 from The National Environmental Research Institute, municipal waste
incineration plants and industrial sources. This report is therefore an update of the
sustance flow analysis from 2000 /Hansen, 2000/, and the update is made on the basis of
the report from 2000. As a consequence of this the report also has the objective to narrow
the intervals that have so far been reported from Denmark. On a number of sources Danish
data are however still limited. With the described objective the report is a contribution
to meeting the obligations in article 5 of the Stockholm Convention on persistent Organic
Pollutants.
Previous studies on emissions of dioxins in Denmark have been published in
1995, 1997 and 2000.
This study has been carried out in accordance with the paradigm of
substance flow analysis of the Danish Environmental Protection Agency. The knowledge
presented is based on data from Statistics Denmark, the literature, and public
institutions, among these especially the counties and the National Environmental Research
Institute, as well as from private organisations and companies. In the analysis, all the
information has been held together to describe the flow of dioxins through the Danish
society.
During 2000 – 2002 several dioxin analyses have been undertaken at
Danish industries and plants, and many measurements have been made on soil, bio ash,
compost and air. These measurements especially cover emissions to air. The update of the
substance flow analysis from 2000 /Hansen, 2000/ has meant that Danish emission factors
can be used to a greater extent to estimate the dioxin emission. Nevertheless it is still
necessary to use international emission factors either as a supplement to the Danish
measurements or as best estimate, as there are still processes with too few Danish
measurements, nonreliable measurements or no Danish measurements at all. In adopting such
international figures it has been assumed more correct to use minimum and maximum figures
instead of average figures, as average figures generally give a false impression of the
accuracy of the estimates presented. The same approach has in some cases been adopted also
for processes for which Danish measurements actually exist, e.g. for municipal waste
incineration. One of the problems addressed by this approach – at least partly –
is the fact that dioxin formation and emission may differ considerably from
"normal" process conditions to "deviating" process conditions, and
that deviating process conditions could contribute significantly to the total dioxin
formation and emission. Most measurements available should be assumed to reflect normal
process conditions and do not necessarily give a reliable picture of the total emission
from the individual plants.
The total Danish formation of chlorinated dioxins in 2000 - 2002 is
estimated at 72 – 689 g I-TEQ/year. The dominant source is municipal waste
incineration. Other significant sources also include private wood stoves and other smaller
plants for biomass combustion as well as PCP-treated wood and fires, both accidental fires
and others. The interval for formation contains estimates for all identified dioxin
sources in Denmark. Some of the estimates are however subject to substantial uncertainty
due to lack of precise data, which has resulted in high maximum values for the concerned
sources. If the uncertain sources are not included the total emission to air, water, soil
and depots would correspond to 13 - 107 g I-TEQ/year. It is however in this report chosen
to use the values for all known Danish sources and the mentioned results are therefore
based on the total emission to air, water, soil and depots which is 17 - 332 g I-TEQ/year.
Most chlorinated dioxins formed by processes in Denmark are emitted to the
environment. In absence of domestic treatment opportunities Denmark has started to export
the majority of fly ash and flue gas treatment products from the Danish waste incineration
plants for deposit abroad. The waste is classified as hazardous. The continuous production
of the waste is exported and contracts have moreover been made concerning digging-up and
export of already deposited flue gas treatment products. This explains why Denmark exports
a relatively high share (55-413 g I-TEQ/year of the total annual formation of 72 - 689 g
I-TEQ/year) to other countries.
Denmark also receives chlorinated dioxins by products imported to Denmark
and by raw materials extracted from nature. The import by products is estimated at 3.4
– 106 g I-TEQ/year and is partly related to import of products like wood, leather and
textiles treated by pentachlorophenol (PCP) abroad, as chlorinated dioxins are
contaminants in PCP. Chlorinated dioxins are also imported with products like clay,
paper/cardboard and feedstuff. Raw materials extracted from nature in Denmark accounts for
5 - 1010 g ITEQ/ year dominantly in clay but also in fish, grass and animals used for food
and feedstuff.
The total Danish emission of chlorinated dioxins to air in 2000 - 2002 is
estimated at 11-163 g I-TEQ/year. This emission was in the substance flow analysis from
2000 /Hansen, 2000/ estimated at 19 - 170 g I-TEQ/year.
The dominant sources include municipal waste incineration, biomass
combustion in small units without flue gas cleaning like wood stoves and farm boilers,
evaporation from PCP-treated wood in use in Denmark and fires. Other sources of emission
that could be significant are cable scrap reclamation, lime and cement manufacturing,
traffic and landfills that in this context cover fires in temporary depots for combustible
waste. In 1999 incineration of hazardous waste was a significant source as well, but the
kiln with high dioxin emission is closed down for reconstruction until 2003, and ioxin
abatement will be installed. The other kilns have already dioxin abatement installed and
this has resulted in a lower annual emission in 2000 – 2002 than in 1998 – 1999.
The contribution from this source is likely to be further reduced due to redesign of the
kilns.
The atmospheric deposition on the Danish land area is estimated at 13 -
130 g I-TEQ/year. This estimate is made on the basis of measurements conducted by The
National Environmental Research Institute in 2002.
The total Danish emission to water in 2000 - 2002 is estimated at 0.4
– 1.4 g I-TEQ/year, approximately the same level as in 1998 - 1999, where the
interval was 0.3 - 1.4 g I-TEQ/year. The dominant source seems to be atmospheric
deposition, but congener profiles for sewage sludge partly also correspond to textiles.
The knowledge is limited, and any definite conclusions on this issue should be taken as
premature.
The calculated total contribution of 0.4 - 4.8 g I-TEQ/year should be
taken as comparable to the estimated total content in discharged waste and storm water of
0.4 - 1.4 g I-TEQ/year and the calculated total content in sewage sludge of 1.2 - 2.3 g
I-TEQ/year indicating that the contribution to waste water treatment plants in Denmark is
at least 1.6 - 3.7 g I-TEQ/year. These observations indicate that the deposition level
stated in chapter 6 is realistic estimate.
The total direct emission of chlorinated dioxins to the soil environment
is estimated at 0.7 - 42 g I-TEQ/year, which is lower than the estimate in SFA 2000
/Hansen, 2000/ which was 1.3 - 54 g I-TEQ/year. The dominant sources are residues from
miscellaneous fires (garden fires, bonfires etc.) not removed from the place of the fire
and by time mixed into soil, and manure from domestic animals applied to farmland.
Especially for combustion of biomass on industrial plants there has been a
substantial reduction of the interval for emission of dioxin to soil and depots. This
reduction means that the total emission equals approximately 0.3-20 g ITEQ/ year. The
total emission from industrial plants was in SFA 2000 /Hansen, 2000/ estimated at 0.34 -
55 g I-TEQ/year. The narrowing of the interval is caused by new Danish measurements on
industrial plants (district heating, large stoker boilers and CHP plants), which show
lower emissions than earlier estimated. The Danish Environmental Protection Agency has in
2001 started a campaign about dioxin and private wood stoves, but the effect of the
campaign is difficult to evaluate as it depends on to what extend the citizens in fact
change their habbits regarding firing and only use clean wood for combustion. At the same
time there is still only few measurements regarding this subject.
The total quantity of chlorinated dioxins directed to landfills and other
types of depots in Denmark is estimated at 5 – 126 g I-TEQ/year, which was in 2000
estimated at 38 - 420 g I-TEQ/year. The reduction is caused by the flue gas treatment
residues which are now exported for landfilling. The major sources of the quantity of
dioxins directed to Danish landfills, are primarily residues from coal combustion; but
neither biomass combustion nor fires should be overlooked. The quantity of dioxin being
exported can in the period 2000 - 2002 be estimated at 55 - 413 g I-TEQ/year.
Apart from steel reclamation and waste incineration, no specific trend in
dioxin emissions should be noted. The Danish steel reclamation plant has based on the
company’s dioxin measurements from 2001 apparently succeeded in reducing emissions
considerably (The plant has been closed down for a period in 2002, but was reopened at the
end of 2002. The electrostatic furnaces, where the reported measurements have been
conducted, are however not expected to be opened again). The same development is seen at
the Danish aluminium reclamation plant, where a heavy excess of the limit value was found
in 2000. This plant is now keeping to the limit value after installation of dioxin
cleaning. The Danish waste incineration plants are at the moment focussing on the dioxin
emission, as the plants have to comply the limit value of 0.1 ng I-TEQ/Nm3 before 2005.
This means that some plants have installed dioxin abatement in the period 2000 –
2002, and more plants have plans of installing it in the coming years. For other
industrial plants and activities the focus on dioxin emissions in Denmark is still
limited, however growing.
A significant destruction of chlorinated dioxins corresponding to 13
– 1465 g I-TEQ/year is assumed to take place. The destruction is related to high
temperature manufacturing of products based on clay, besides that thermal waste treatment
like incineration of municipal waste and sewage sludge are believed to destroy – more
or less – the dioxins present in the waste materials treated. It should be stressed
that recycling of materials like coal fly ash and paper sludge for cement manufacturing
also should imply destruction of the dioxins present in the recycled materials due to the
temperatures involved by cement manufacturing. To this an unknown amount of dioxins from
special dioxin abatement burned in the ovens/kilns at the plant, from where they were used
can be added.
It must be recognised that the plants effective in destruction of dioxins
at the same time may belong to the dominant sources of dioxin formation. For municipal
waste incineration the overall picture is that the amount of dioxins emitted by flue gas
and incineration residues is significantly higher than the amount assumed to be destroyed.
Municipal waste incineration should be regarded as the most important source for dioxin
formation and emission in Denmark.
A stock of chlorinated dioxins in the Danish society exists in the form of
dioxins in PCP-treated wood. The stock is mainly due to the widespread use of PCP as wood
preservative that took place in Denmark from 1950 to 1978. By 2002 the size of this stock
was roughly estimated at 100 – 5,000 g I-TEQ, the same as in 1999, as no new
measurements have been found. The stock should be assumed slowly decreasing due to
replacement of the wood in question as well as evaporation of dioxins from the wood, as
the use of PCP in Denmark is now banned. The wood replaced is assumed directed to
incineration.
Another group of dioxins is the brominated dioxins. New Danish
measurements of brominated dioxins in flue gas from the waste incineration plant
Vestforbrænding and from Kommunekemi have been made in 2002. If the results of these
measurements are used to estimate the total annual emission of brominated dioxins from
waste incineration plants and treatment of hazardous waste, the annual emission will be
approximately <0.01 - 0.1 g ITEQ/ year. This range is however very uncertain due to the
few measurements and to the fact that no official method for calculating I-TEQ for
brominated dioxins exists. Furthermore the estimate does not include all measured congener
groups, as it has only been possible to calculate I-TEQ-values for the specific congeners.
The non specific congener groups are therefore no included in the interval of 0.01 - 0.1 g
I-TEQ/year. This emission value represents with certainty an under estimate of the reel
emission, but any estimate of the reel emission value must be regarded as highly
uncertain. Based on an anlysis of the chromatographies for the congeners it is estimated
that the reel estimate can be up to approximately a factor 5 higher, but most likely not a
factor 100 /Vikelsøe, 2003a/. Because of the uncertainty the value for emission of
brominated dioxins is not included in the overall dioxin emission for Denmark.
Denmark is importing an estimated 2 – 60 g I-TEQ/year of brominated
dioxins as contaminants in plastics containing brominated flame retardants. To the extent
such plastics are exposed to accidental fires or further processing, e.g. recycling,
further formation of brominated dioxins may take place. Brominated dioxins in plastics are
likely to be destroyed by waste incineration, but formation of brominated dioxins as well
as mixed brominated/chlorinated dioxins may take place by flue gas cleaning and emission
processes parallel to formation of chlorinated dioxins.
| Front page | | Contents | | Previous
| | Next | | Top
|