PILOT SCALE REMOVAL OF HEAVY METALS FROM SODIC-SALINE CLAY SOIL USING HYBRID ELECTROKINETIC-ADSORPTION TECHNIQUE

摘要

Electrokinetic remediation (EKR) technologies for contaminated soils are faced with significant technical challenges, especially for sodic-saline soils which inherently exhibit characteristics that render them difficult in getting remediated from mixed contaminants. The feasibility of the remediation of saline-sodic clay heavily contaminated with mixed contaminants at lab scale has been recently reported. However, these studies limit understanding of the feasibility of the process treatment of the contaminated soil at larger scale. In this study, remediation of saline-sodic clay contaminated with Zn, Pb, Cu, Cd, Cr and Hg, kerosene and phenol (initial concentration ranged 8.82-76.5 mg/kg) at pilot scale using hybrid electrokinetic-adsorption (HEKA) cell. The HEKA cell was ran continuously for 35 days at fixed voltage gradient of 0.2 v/cm and the soil pH, water content, organic carbon, electrical conductivity and electro-osmotic flow were monitored. At estimated energy expenditure at 4.70 kWh/kg or 1187.65 kWh/m3 of the treated soil, the achievable removal efficiencies of the heavy metals were estimated at 31.9, 38.1, 55.7, 36.0, 70.2 and 47.4%, respectively. The pilot scale results obtained were found to be comparable to the bench scale results, though at the expense of drastic increase in cumulative energy consumption