EVALUATION AND REMEDIATION OF SEDIMENTS FOR FURTHER USE IN BUILDING SECTOR (READY4USE)

Sedimentation affects the safety of hydropower plant dams, and reduces energy production, storage, discharge capacity and flood attenuation capabilities. It increases loads on the dam and gates, damages mechanical equipment and creates a wide range of environmental impacts. About 0.5% to 1.0% of the total volume of 6,800 km3 of water stored in reservoirs around the world is lost annually as a result of sedimentation. Without active management, the continual accumulation of sediments will gradually displace the storage volume in a reservoir, which will ultimately render the reservoirs useless for capturing and storing water. Additional environmental problem present sediment pollution with heavy metals, and the remediation of heavy metal contaminated sediments is crucial to river ecosystem protection. Slovenian Dravske Elektrarne Maribor d.o.o. (DEM), the company that operates eight hydropower plants on the Drava River, is facing sedimentation problems. Between 30,000 - 40,000 m3 of sediment, contaminated with heavy metals, is annually accumulated in the hydro reservoirs, which need to be appropriate handled. Because of the lack of space in the Drava valley for sludge deposition and new imposed regulations, there is an urgent need for new solutions in sediment management. Current treatment methods aiming to restore the normal function of contaminated sediment are similar to those used for soil and include physical, chemical and biological methods. Although much is known about technologies for the remediation of heavy metal contaminated soil, much less is known about sediment treatment. Another successful remediation method is solidification/stabilization, where heavy metal pollutants are physical encapsulated in a solid matrix. Encapsulation involves the mixing of the contaminated soils or sediments with other materials and producing building products such as geopolymers (alkali activated materials - AAMs), cement clinker, bricks, lightweight aggregates, concrete etc. The contaminated soil/sediment becomes immobile and thus prevents contamination of the surrounding materials. Although a lot of research all over the world was already conducted in applying marine and river sediments in brick and AAMs, the River Drava sediments were not examined as a raw material yet. But given its known composition and continuous availability, this material is perfect candidate as a major component for manufacturing of sustainable final products. The key objective of proposed Ready4use project is to (i) develop a new procedure for removal of heavy metals from River Drava sediment and (ii) develop new building materials (bricks and AAMs) by using River Drava sediment raw material. Partners in the project consortium (i.e. Slovenian National Building and Civil Engineering Institute, Faculty of Chemistry and Chemical technology, and company Dravske Elektrarne Maribor) have devised a systematic work-plan consisting of R&D activities that will fully encompass the entire development procedure of the novel sediment remediation process and construction materials production, from design to the actual production of the prototype. The main scientific contribution of the work will be in defining the most successful remediation processes of sediments by using new ecological friendly biosurfactants, and design of optimal mixtures for brick and AAM, where many parameters will need to be studied in order to define the most influential ones. These innovative processes and products will provide the knowledge, which will be applicable also to other waste holders worldwide. All researched technologies will be beside technical parameters, assessed also from environmental point of view by analysis of life cycle assessment (LCA), which will contribute to the interdisciplinarity of the Ready4use project.