Effect of acidification and modified Fenton treatment on a contaminated harbour sediment

Abstract

This study presents the results of laboratory experimental oxidation treatments conducted on marine sediments highly polluted with hydrocarbons. The purpose of the study was to compare the effect of a modified Fenton treatment conducted with acidified stabilised H₂O₂ with one of simple acidification with H₂SO₄ used as control to evaluate the potential of heavy metal mobilisation. The H₂O₂ initial concentration was 0.62 M and KH₂PO₄=1.15 g·L⁻¹. To evaluate changes in the solid and liquid phase, chemical oxygen demand (COD), thermogravimetric analysis (TGA) and differential thermal analysis (DTA) under O₂ atmosphere analyses were performed on the solid, while total organic carbon (TOC), COD, pH and Eh were measured on the liquid. Evaluation of the heavy metal mobilisation was performed using sequential extraction procedures. Results indicate that the treatment was able to change the organic matter to a less hydrophobic state, to destroy part of the carbon and to lower the COD of the sediment. In addition, the treated sediment showed easier-to handle characteristics, reduced caking and lower aggregation capacity. However some mobilisation of Cu occurred while the concentration of Fe lowered.

Keywords:

• marine sediments
• chemical oxidation
• heavy metals
• metals mobilisation
• sequential extraction