Long-term performance of stabilised/solidified polluted sediment in terms of metal leachability and matrix characterization

Abstract

Sustainable and economically feasible polluted sediment treatment is gaining more and more importance. Stabilization/solidification (S/S) technologies are widely used for treatment of sediment and possibilities of using low-cost and readily available materials and binders are increasingly being examined. This work is concerned with aquairing more data about long-term performance of this kind of treatment in therms of metal leaching and microstructural cnaracterization when treating sediment with fly ash and lime. Extraction potential of metals and the effectiveness of the S/S treatment applied, together with compliance with national legislative, were performed by using Toxicity Characteristic Leaching Procedure - TCLP and The German standard leaching test - DIN 3841-4 S4. Leaching test results showed that the applied S/S treatment was effective in immobilizing metals even after seven years of aging. Scanning electron microscope (SEM) and X-ray diffraction analysis confirmed that pozzolanic reactions took place during 28 days and continued along S/S mixture maturation. Compressive strength measurement further proved the treatment efficacy in terms of obtained matrix stability, which enables their subsequent use. It can be concluded that the S/S technique, with the usage abundant materials has a significant potential for treatment of metal polluted sediment.