The Removal of Pb and Cd from Heavily Contaminated Soil in Kayseri,Turkey by a Combined Process of Soil Washing and Electrodeposition

In this study, a combined system of soil washing and electrodeposition was designed to remove Pb (16381±643 mg/kg) and Cd (34347±1310 mg/kg) from contaminated soil. 0.05 M Na₂EDTA was used as a chelating agent for the remediation of soil, taken from the nearby city Kayseri, Turkey. As a result of the batch extraction tests, maximum removals were determined as; at the 20:1 liquid: soil ratio for Pb is 60.7%, for Cd at the 30:1 liquid: soil ratio is 67.4%. An electrochemical treatment was applied to the waste washing solution which appeared to be the second pollutant after the Na₂EDTA extraction from the soil. With extraction tests of Pb and Cd, being transformed from the solid phase to the liquid phase. The electrochemical treatment (electrodeposition), performed in three different potential (6 V, 8 V and 10 V) and maximum removal efficiencies, were found 99.7% and 80.3% at 10 V for Pb and Cd, respectively.

Speciation tests (BCR) were carried out, both before and after the soil washing process, to evaluate the redistribution of metal fraction in the soil. The fraction, associated with the organic substance, was found as 10.67% for Pb and 1.81% for Cd. The metal bioavailability factor increased after soil washing, which indicates that EDTA could enhance the mobility of Pb and Cd.