Sediments – originating in freshwater basins mainly through erosion processes – are drifted to the coast with the river flow. Along the way, they are contaminated by heavy metals, nutrients from pesticides and other organic micro-pollutants. Every year in Europe 130 million m3 of polluted river sediments are dredged and need to be disposed of in specific and expensive ways (costing up to €7 000/tonne). Moreover, every year 5.2 million m3 of soil are extracted from the ground to support plant nursing activities. To prevent the risk of an 8-10 mm/yr lowering of the ground level, plant nurseries are forced to buy soil from third-party catchments, which are often of poor quality and contribute to soil exploitation elsewhere.

Similar problems are faced by the EU road building industry, whose yearly demand for sand, gravel and aggregates for stability and draining purposes is around 30 million m3, for an average value of €450 million.

The LIFE CLEANSED project will demonstrate, evaluate and disseminate an innovative, integrated, multi-sector approach for the smart and sustainable management of polluted dredged river sediments. Polluted sediments will be dredged, transformed from a contaminated waste into valuable material via a specific decontamination treatment, and subsequently used.

Specific project objectives include:

• Turning the polluted sediments from a valueless and expensive waste into a valuable raw material for plant nursing and road building, guaranteeing the full environmental and financial sustainability of the approach;
• Using the decontaminated sediments as a substrate/amender to prevent the loss of soil and biomass because of plant nursing activities; and
• Using the decontaminated sediments as a filler material for the construction of roads.

Expected results: The project expects to achieve the following results:

• The decontamination of 836 m3 of dredged river sediments, which will be turned from valueless waste into a usable and marketable raw material;
• The smart management of contaminated sediments: instead of treatment costing an average price of €75/m3, it will cost €35/m3 and the sediments will be turned into clean raw material with a market value between €10 and €20/m3. This will mean a 66-80% net saving for sediment decontamination and the valorisation of a waste stream;
• Demonstration of the efficacy of using decontaminated river sediments as a substrate for the cultivation of 72 ornamental plants of three different species characterised by different levels of saline stress tolerance;
• The demonstration of decontaminated river sediments as a suitable structural material for the construction of a 100m-long road;
• The use of 836 m3 of decontaminated sediments instead of aggregates from third-party catchments, with subsequent conservation of quarry and river environments; and
• The sustainable restoration of agricultural soil used for plant nursing.