PROJECT DESCRIPTION
BACKGROUND
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.
OBJECTIVES
The LIFE CLEANSED project would demonstrate, evaluate and disseminate an innovative, integrated, multi-sector approach for the smart and sustainable management of polluted dredged river sediments. Polluted sediments would be dredged, transformed from a contaminated waste into valuable material via a specific decontamination treatment, and subsequently used.
Specific project objectives included:
- 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.
RESULTS
The LIFE CLEANSED project team demonstrated an innovative approach for turning dredged river sediments into valuable materials for plant nurseries and for road construction. The approach was tested within an integrated river basin system in the Tuscany region, Italy. It provides an effective and sustainable management solution for dredged sediments, turning waste into a resource.
The project team first treated the dredged sediments by "Landfarming", a bioremediation technology developed during the previous (non-LIFE) AGRIPORT project, after which the sediment can be used in applications, such as embankment material for road construction or an earth substrate in ornamental plant nurseries. The LIFE CLEANSED project’s results showed that the new sediment material was acceptable both in terms of structural resistance and physical strength in the road embankment, and very good in terms of biological and chemical/nutritional properties for plant cultivation (e.g. good growth, no ecotoxicity).
LIFE CLEANSED contributed to the objectives of the Circular Economy Action Plan, by identifying and testing a technology that adds value to a natural resource (the sediment) for as long as possible and eliminates waste disposal and its associated problems. Beneficial use of sediments is also relevant to EU waste legislation, particularly the Landfill Directive. Treatment and re-use of dredged sediments is politically encouraged, but is currently only applied at a small scale because of the higher costs compared to disposal and the lack of product markets. The project team also identified the other technical and economic barriers that need to be overcome before widespread replication of the approach.
National/regional legislation is therefore crucial for any further development of this technology. The project beneficiaries organised two events specifically aimed at this target. At the local provincial and municipal scale, the project pioneered an authorisation path to the reuse of decontaminated dredged sediments in the construction of road substrates. The lobbying action of the project team was also directed towards research institutions, who have a role in the development of relevant national legislation (e.g. ISPRA and CNR).
Nevertheless, the method, with some improvements in the technology, is being replicated in the same river basin system in Tuscany in Pisa, as well as in the Murcia region in the Segura river basin. In particular, the project consortium wants to improve the technology to make the sediment decontamination process quicker, more efficient, cheaper and more appropriate for different environmental purposes. This work is ongoing.
The project team have raised the awareness of local and regional policymakers to the opportunities offered by the reuse of dredged sediments. They have also disseminated their approach to a wider audience through various media.
Additional potential benefits of the approach are the sustainable conservation of soil in agricultural areas, by reducing the need for structural soil amenders in plant nurseries; reductions in the over-exploitation of soil for road building purposes; and significant financial savings due to the reuse of waste sediment material.
Further information on the project can be found in the project's layman report (see "Read more" section).
