Effect of the Secondary Electrode Configuration in Removing Metal Contaminants from Soils by the CEHIXM Process

The effect of the secondary electrode configuration in removal of metal contaminants from soils under coupled electric hydraulic gradient assisted by ion exchange medium (CEHIXM) process was investigated. Soil samples using a blend of spent foundry sand and millpond sludge were used to investigate the contribution and cost-effectiveness of the secondary electrode configuration in removal of primarily four heavy metals (Pb, Cd, Zn, and Mn). A number of tests were conducted at an optimum constant DC electric voltage of 50 V and an optimum constant flow velocity of 0.00713 cm/sec for a period of 200 hours. The experimental results demonstrated the removal efficiencies of approximately 89.84% of Pb, 96.63% of Cd, 92.89% of Zn, and 91.14% of Mn with the primary electrode (PE) configuration. In case of the secondary electrode (SE) configuration, the removal efficiencies were about 87.34% of Pb, 91.68% of Cd, 95.30% of Zn, and 90.44% of Mn. In the case of the combined PE and SE configuration, the removal efficiencies were about 90.16% of Pb, 93.27% of Cd, 96.34% of Zn, and 90.44% of Mn. The energy expenditures were about 480 kWh/m3 and 522 kWh/m3 of soil in the case of the PE and the SE configurations, respectively. It appeared that the use of the SE configuration and/or combination of the PE and SE configuration was not cost-effective and advantageous over the use of the PE configuration in removing heavy metals from the contaminated soils by the CEHIXM process. © 2011 Copyright Taylor and Francis Group, LLC.