A new remediation method to cap contaminated sediment
In Sweden, as well as in the rest of the world, there are many locations where sediment has been contaminated by heavy metals or organic pollutants. These pollutants are being passed through the ecosystem and causing environmental problems.
These pollutants are transported from the sediment to biota in two major ways. The first is via resuspension of particulate matter and the second through bioturbation. Traditionally, dredging the polluted sediment and disposing of it in landfill sites has provided a solution to these problems.
The Cover-method was
invented and developed by Vattenresurs. This method is based
on the production of a layer of artificial sediment that caps
the contaminated surface, preventing the effects of
resuspension and bioturbation.
The artificial sediment is created from chemical precipitation
and is produced, together with structuring and ballasting
materials, in the mixing process in the nozzles of the spray
unit approximately 2m above the polluted sediment.
A
new bottom, several centimetres thick, is built layer-by-layer
creating a physical barrier between contaminated sediment and
the water above. The fauna which live on the bottom will find
a new life in this artificial sediment. As time goes by new
sediment will cover the bottom and secure future water
quality.
The Cover-method is much cheaper than alternatives like dredging.
The method was developed and laboratory tests were begun in 1993. Further testing of erosion durability was performed in large scale laboratory tests. Later, a field test was carried out in Lake Turingen, ordered by the Lake Turingen Remediation Project. In 1998, the field test showed that the method could be used in full scale. Year 2000-2003 the remediation of Lake Turingen (100 ha) is successfully completed at a cost of 26 mill.SEK.
About chemistry and impact - please read Phosphorus Precipitation of Lakes
The vessel is navigated with a high level of precision home
