Investigations and reports
Type of material used for packaging soil containing PFAS
At the storage locations, we use three-layer co-extrusion foil. This is resistant to frost, sun and chemicals, among other things. It is often used in construction and to cover contaminated soil. At the storage locations we use the 0.20mm variant.
How the soil treatment facility works
After a lot of research, we decided on the soil remediation process by DEME. The soil treatment facility works using a cleaning process especially for soil containing PFAS. The good solubility of PFAS is made use of in this process. The most important parts in this process are the separation of the fine fraction (sludge) and the coarse fraction (sand) in combination with the cleaning of the soil.
This soil cleaning technique is already being used at several DEME soil recycling centres, under the supervision of the appropriate authorities. After cleaning the Schiphol soil, 80% reusable sand is left. The rest (20%) is contaminated sludge. That residual sludge still contains some PFAS, but a large part of the PFAS ends up in the water used to clean it.
After cleaning the soil, there is PFAS in the water. The cleaning water is not a waste fraction and is not discharged. It is always reused in a closed system and purified in the process itself.
The water passes through activated carbon filters to remove the PFAS.
How are the activated carbon filters in the soil treatment facility cleaned?
The activated carbon filters are cleaned by way of a heating process. DEME does this through a partner who has the relevant expertise.
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Results of DEME cleaning tests with Schiphol soil
To make sure that the cleaning process works for our own soil, we have done extensive testing under the supervision of independent experts. The soil at Schiphol that needs to be cleaned contains an average of 20% clay and loam (fraction <63 μm, also known as 'sludge' or 'lutum'). The proportion of sludge is important for soil remediation. The treatment facility can even work with soils of up to 40% sludge. Laboratory tests were carried out that mimic the cleaning process. The results were positive. After that, a full-scale test cleaning was carried out with soil that we brought to Belgium by ship. This test cleaning also gave good results. At DEME's soil remediation plant in Kallo (Port of Antwerp), 1013 tonnes of our Schiphol soil was cleaned. The cleaning efficiency of PFOS was over 99%.