Prediction of long-term heavy metal leaching from dredged marine sediment applied inland as a construction material

Abstract

Column leaching studies have been suggested as a reference for site-specific prediction of the long-term leaching characteristics of trace constituents in granular materials used as construction materials. In this study, the concept of the long-term leaching prediction using column studies is applied for dredged marine sediment impacted by heavy metals. The column studies show tailing of the liquid to solid ratio-dependent heavy metal leaching for sediment after heavy metal treatment by acid washing. A dual-mode first-order decay model, applied for the first time in this study for column leaching studies, is able to reproduce the leaching characteristics observed. A procedure for long-term leaching prediction using the dual-mode model is developed and applied to a virtual field scenario for which the sediment is beneficially used as a construction material. The prediction results show that by more accurately reproducing the column study results, the dual-mode model generally predicts greater long-term heavy metal loading to the underlying soil layer and longer duration of leaching than the single-mode model. The heavy metal leaching observed in the columns does not show any correlation with the sequential extraction procedure and toxicity characteristic leaching procedure (TCLP) results, suggesting that the column leaching test should be considered to be independent of such batch test procedures.