Enhancing electrokinetic lead removal from sediment: Utilizing the moving anode technique and increasing the cathode compartment length

Abstract

This study investigates the possibility of simultaneous application of the moving anode technique and increased cathode compartment length as an enhanced electrokinetic treatment of lead-contaminated sediment from the River Tamis. The moving anode technique was employed to improve Pb desorption from sediment particles whilst the increased cathode compartment length was meant to prevent hydroxyl ions from penetrating into the sediment, to avoid metal precipitation and accumulation. Overall lead removal efficacies from the sediment were 38% and 62% after the conventional and enhanced treatments, respectively. Water electrolysis at the implemented anodes resulted in: (a) H+ formation (lowering pH) causing more Pb ions to desorb from the sediment particles and (b) oxygen formation causing the redox potential to become more positive, resulting in lead reorganisation from the oxidizable fraction into more soluble fractions (can be removed by electromigration). The increased cathode compartment length prevented hydroxyl ions penetration into the sediment. Finally, the sediment after the enhanced treatment was Class1/2 according to the Dutch standard. We thus demonstrate that the simultaneous use of the moving anode technique and increased cathode compartment length is an effective technique for electrokinetic removal of lead from sediment which does not involve adding chemicals into the system.