Simultaneous removal of polycyclic aromatic hydrocarbons and heavy metals from natural soil by combined non-ionic surfactants and EDTA as extracting reagents: Laboratory column tests

摘要

Simultaneous removal of three polycyclic aromatic hydrocarbons (acenaphthene, fluorene and fluoranthene) coexisting with three heavy metals (Ni, Pb and Zn) in artificially contaminated soil from the vicinity of an oil refinery was examined by column flushing of solutions containing Triton X-100 + Ethylenediaminetetraacetic acid (EDTA) and Tween 80 + EDTA at three levels of surfactant concentrations. While the effectiveness of both combined solutions in removal of heavy metals did not differ significantly, Triton X-100 + EDTA was more efficient in removing PAHs. Results showed that after 21 pore volume flushing of enhancing solution (Triton X-100 7.5% + EDTA 0.01 M) at flow rate of 0.534 mL min(-1) through the column with hydraulic conductivity of 8.5 x 10(-5) cm s(-1), 54, 47 and 40% of acenaphthene, fluorene, and fluoranthene were removed simultaneously. At the same conditions, 75, 85 and 90% of Pb, Ni and Zn, were also simultaneously removed. Increasing the flow rate of flushing solution decreased the removal efficiency of the contaminants.