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LIFE SURE - Sediment Uptake and Remediation on Ecological basis (LIFE SURE)
Date du début: 1 août 2016, Date de fin: 31 juil. 2020 PROJET  TERMINÉ 

Background The natural characteristics of the Baltic Sea, namely, a long water residency time (around 30 years), a large catchment area, a population of about 90 million people, and a brackish water environment poor in species, predisposes it to harmful contamination effects. One environmental problem comes from shallowed overgrown bays, which occur when dead biota and particles accumulate at the bottom, adding to the sediments. This process is sped up by climate change and human activities, such as river straightening, leaving exposed soil in fields and paving/sealing land, which all increase the outflow of particles to shallow water bodies and contribute to further sedimentation. Due to human activities, these sediments might contain hazardous substances and high levels of nutrients, leading to eutrophication. The removal of hazardous substances is a priority area of the Baltic Sea Strategy. Disturbance of contaminated sediments, whether physical (e.g. by dredging) or biophysical (e.g. bio-turbation by organisms), can result in the re-suspension of hazardous substances and an increase in their availability to chemical and biological processes. To prevent overgrowth of shallow waters, dredging is often necessary. However, traditional dredging causes great disturbance to the water environment. Sustainable dredging methods are available but are too expensive to employ on a large scale. Like many areas along the Baltic coast, the coastline of Kalmar is heavily affected by this phenomenon. Objectives The LIFE SURE project will demonstrate a cost-effective and ecologically sustainable process for retrieving and recycling sediments in shallow eutrophic waters. Hazardous substances will be removed with a minimum of negative impact, turning such sediments into a resource instead of a waste problem. The project will demonstrate an innovative dredging concept that is mobile, cost-effective, environmentally friendly and easy to use. In particular, the new dredging system uses an unmanned, totally automated unit. It consists of a surface raft pulling the underwater unit, which has 18 specially-designed nozzles that pump sediments up from the seabed. The system moves slowly (1 cm/s) and therefore does not cause any re-suspension of sediments. The system can be continuously operated and supervised locally or remotely using built-in sensors. The system moreover has great potential for replication, given that it can be handled by non-professionals and used anywhere there is a need for taking up sediments. Once sediments have been dredged, they pass through a treatment and dewatering system, which removes water and pollutants via decantation and centrifugation. Sediments are separated into three fractions: water, organic sediments and mineral sediments. The project will recycle dredged materials for use in construction or agriculture. It will propose a solution for increasing the recycling rate of dredged sediments in the EU, which stood at just 12% in 2012 (Eurostat), helping preserve the physical and chemical features of marine ecosystems. Such a move will contribute to the implementation of the Water Framework Directive and the Marine Strategy Framework Directive, which both aim to achieve a good status for all European coastal waters. Expected results: More than 70% of the dredged sediments recycled; 50% lower costs for the dredging, dewatering and purification process than existing techniques; Levels of hazardous substances and nutrients not higher during uptake of sediments than in undisturbed water areas 50 m from the site of uptake; Around 6 tonnes of phosphorus removed along with 400 kg of lead and 10 kg of cadmium; and Continuous sampling of the water and the local ecosystems will be made to ensure that no adverse effects arise.  

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