Decontamination of dredged sediments containing ETM and PAHs by electroremediation
Abstract
The maintenance of harbor waterways generates large amounts of dredged sediments which are often rich in organic and inorganic contaminants. These sediments can be inappropriate for disposal at sea and reuse solutions can be proposed if they are treated before. Electrokinetic (EK) remediation is often developed for heavy metals decontamination but is extremely limited for polycyclic aromatic hydrocarbons (PAHs) which are nonionic and have a low aqueous solubility. Deionized or salt water was circulated through an EK system and various processing fluids were tested to improve the decontamination of a model sediment artificially contaminated with cadmium, lead, chromium, copper, zinc and five PAHs. Nitric acid and citric acid were tested to avoid the formation of an alkaline front into the sediment and were circulated under a constant voltage gradient of 1 V/cm for 14 days. The strong inorganic acid was more effective than the weak acid to remove heavy metals but the complexing citric acid was promising for longer treatments. Concerning PAHs, an anionic surfactant (sodium dodecyl sulfate SDS) was tested to mobilize, solubilize and favor their migration. At last, SDS and citric acid were tested simultaneously on a naturally contaminated dredged sediment from a French Norman harbor.