Electrodialytic remediation of a soil from a wood preservation industry polluted by CCA
A B Ribeiro, A Villumsen, G Bech-Nielsen, A Réfega, J Vieira e Silva
Soil contamination is often found at wood preservation sites due to spills, dripping of excess preservatives and deposition of sludge associated with dissolved salts of copper, chromium and arsenic (CCA). The electrodialytic process is a promising heavy metal soil remediation technique. It is based on a combination of the electrokinetic movement of ions in soil with the principle of electrodialysis. The technique was tested in five experiments using a laboratory cell on a CCA contaminated Portuguese soil. The duration of the experiments varied (from 18 to 125 days) but the dc current density was kept constant (0.2 mA/cm2). The development of the contaminant concentration profiles in the soil after the experiments was investigated. pH and the speciation of contaminants were identified as key parameters of importance to the remediation process. It was found that it was possible to decontaminate the soil to an extent lower than the recommended critical values for copper concentration in soils.