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

Abstract

Sediment contamination is a growing worldwide issue that poses significant risks to human health. Among other remediation techniques, electrokinetic remediation (EKR) is a novel method for addressing both organic and inorganic pollutants. Dredged sediments can be reused in an environmentally sustainable manner after removing or reducing unwanted chemicals. This study aims to examine treat carbonate-rich estuarine sediments by EKR and to assess the consequent physico-chemical, mineral, organic, and chemical changes. To achieve this, a series of laboratory experiments were carried out on dredged sediments from Tancarville, France, using a 360 ml setup. The electric current, voltage, electroosmotic flow, pH, and electric conductivity were monitored during treatment. The treated sediments were then sectioned and analyzed for physico-chemical properties as well as mineral (mainly carbonate), organic, and metal contents. The results showed that the variations in running parameters affected the pH of the medium, leading to changes in carbonate dissolution. This, in turn, reduced buffering capacity and removed associated metals. Moreover, calcium and other released metals could be transported within the system or competing with other surface-bound metals. Statistical data indicated that the physico-chemical processes that occur in the anode and cathode chambers depended largely on the experimental conditions (mainly current density and voltage gradient). Although Cl and Mn contents were reduced from the sediments without any direct link to pH, Mg was only redistributed in the sediments within the setup. Finally, by monitoring physico-chemical parameters, characterizing sediment composition before and after treatment, and applying statistical approaches, the remediation process was better understood. This methodology can be used to treat sediments and other environmental matrices effectively.