| Front page | | Contents | | Previous | | Next |
Håndtering af imprægneret træaffald
From April 1st 2001 all local councils must assign disposal possibilities
for impregnated wood, as well as systems for separate collection. Incineration of
impregnated wood is causing environmental problems. The heavy metals, which are contained
in impregnated wood, cause problems in incineration, as the substances are not decomposed
but remain in slag and flue gas waste. This in turn makes recycling of waste from these
products difficult.
When landfilling impregnated wood there is a risk that the heavy metals will
contaminate the surrounding area. Furthermore, landfilling of impregnated wood prevents
the utilisation of the considerable resources contained in impregnated wood. As a result
of this, a number of projects on alternative treatment methods have been initiated.
There is a general expectation that within a few years impregnated wood will be treated
in another way than by landfilling and in a way, which allows the utilisation of the
metals contained.
Source separation of impregnated wood requires that it can be distinguished from
non-impregnated wood. A large amount of impregnated wood contains copper, which gives the
wood a greenish colour. This type of wood is easily recognisable. When the wood has been
exposed to wind and weather, however, the green colour may disappear, and the wood will
appear silvery grey or black, and can be difficult to distinguish from non-impregnated
wood. Wood, which has been impregnated with other materials than copper, is colourless and
can be equally difficult to distinguish form non-impregnated wood.
The purpose of this project is to prepare a handbook to help in waste sorting of
impregnated wood. The handbook in words and pictures describes visual characteristics,
typical areas of use and treatment of impregnated wood.
The present report is prepared as background knowledge for the handbook, and
furthermore, it offers recommendations from the working group for handling of impregnated
wood in future.
When preparing this report it became evident that recycling stations handle impregnated
wood very differently. Some recycling stations treat all wood for outdoor use as
impregnated wood. Whereas other recycling stations treat impregnated wood together with
non-combustible/recyclable waste. A result of this is that a varying amount of
non-impregnated wood is needlessly landfilled, and as the impregnated wood is not
deposited separately, it is very difficult to treat it later on.
In this report it is recommended that in the future waste wood should be sorted in two
fractions at the recycling stations: 1) impregnated wood, including pressure-treated wood,
vacuum or surface treated wood, not mixed with other kinds of waste, and 2) wood
suitable for incineration, including non-treated wood, wood treated only with standard
coatings of paint or wood preservatives (oil or polish) or creosoted wood. It is
recommended that impregnated wood be deposited separately for later treatment. Wood
suitable for incineration, including creosoted wood, should be burned at the incineration
plant.
Wood from demolition or building sites should be sorted in three fractions: 1)
impregnated wood (as defined above), 2) wood suitable for incineration (as defined above
but excluding creosoted wood and 3) creosoted wood.
Recommended treatment of Fractions 1 and 2 as described above. Creosoted wood should be
pre-treated (crushed) and then burned at approved incineration plants.
One has to be aware that wood pressure impregnated with arsene and creosote is
classified as hazardous waste which means that excisting legislation for instance
regarding mixtures and management of hazardous waste has to be considered.
By year 2000 the estimated amount of landfilled impregnated wood in Denmark was approx.
4 million tons. From this amount should be deducted biodegraded or incinerated wood, the
amount of which is impossible to estimate.
The energy resources of 4 million tons of waste impregnated wood are approx. 4.4 x 107
GJ, which is equivalent to the heat consumption of approx. 571,500 private households. The
Danish EPA estimates that by year 2010 the annual production of waste impregnated wood is
100,000 tons, which is equivalent to 1.1 x 106 GJ and the annual heat
consumption of approx. 14,300 private households.
| Front page | | Contents | | Previous | | Next | | Top
|