Combined use of reactive barrier and electrokinetics for remediation of Cr contaminated soil

A reactive barrier (RB) of transformed red mud (TRM), a by-product of the refinement of bauxite in alumina production, was fitted adjacent to the anode of an electrokinetic (EK) system with the aim of enhancing removal and favouring entrapment of chromium added to a low permeability clayey soil. The innovative study focused on evaluation of the synergic interaction between the EK system and the RB, and of efficiency when compared to traditional EK remediation. The results obtained underlined the successful outcome of treatment. In presence of the TRM RB, 19.4% wt. of total Cr content was detected in the anolyte and 20.6% wt. trapped in the anodic RB after 6 days, versus 6.6% wt. in the anolyte and 8.8% wt. in the soil adjacent to the anode following the control run without RB. On increasing duration of treatment up to 12 days, 60.8% wt. of total initial Cr was found in the anolyte and 25.5% wt. trapped in the RB, versus 9.1% wt. and 5.3% wt., respectively, after a control run of the same duration. Finally, on increasing the mass of TRM in the RB, 60.6% wt. of initial Cr content was found to have accumulated in the RB, with Cr being completely absent from the anodic chamber