Investigation of sediment washing kinetic and heavy metal remediation of contaminated sediment

Heavy metal contamination of marine sediments give rise to serious environmental problem and some times remediation actions are necessary for decontamination. Sediment washing with chelating solutions have been widely investigated as efficient extracting agents. In this work ethylenediaminetetraacetic acid (EDTA), S,S - isomer of the ethylenediaminedisuccinic acid ([S,S]-EDDS ) and citric acid were used to study remediation of sediments collected in the Mar Piccolo of Taranto characterized by high concentrations of metals. Different chelating agents were used at different extraction time (from 0.5 to 48 h): in sediment washing process, in fact, kinetic study provided useful information about metal extraction time. The optimum removal time was found to be 48 h. Metals were removed adequately by EDTA and EDDS, while citric acid was not very efficient for contamination process. The results suggest that bioavailability metals in sediments and extraction time were the main factors affecting sediment washing. Metal speciation, using sequential extraction technique, were determined before and after washing: this approach was useful to evaluate heavy metals mobility in treated and untreated sediments.