Heavy metals removal from dredged sediments using electro kinetics

Abstract

Abstract. This study focuses on the use of a remediation process to remove particle-bound recalcitrant pollutants (heavy metals) from dredged harbor sediments which must be previously treated before reuse in civil engineering. Electrokinetic (EK) remediation is generally accepted as one of the most suitable technologies for extracting cationic heavy metals from fine grained sediments. Many batch tests were performed to better understand the capacity of various additives to improve sediment decontamination (when applying a constant voltage gradient of 1 V.cm-1), and the combination of enhancing agents (acids + surfactants) were assessed to obtain an efficient removal of heavy metals. We succeeded in proving that mixing citric acid and a nonionic surfactant (Tween 20), additives which are environmentally friendly, was a good association to enhance heavy metals (Cd, Cr, Cu, Pb and Zn) removal.

Physico-chemical, mineral, and chemical variation of dredged sediments caused by electrokinetic remediation

“…Subsequently, the conductivity started to decrease in all experiments, with a nal conductivity value of ~ 25 mS/cm in Exp. 4 The main variation in pH, as well as the conductivity, occurs in the rst 168 hours of the EKR experiments. These ndings suggest that the oxidizing and reducing conditions of the compartments played a crucial role in determining the pH trend, with the anode compartment being more acidic due to the release of H + ions and the cathode compartment being more basic due to the production of OH − ions.…”