Integrated electrokinetic-soil flushing to remove mixed organic and metal contaminants |
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Authors: | Krishna R Reddy Claudio Cameselle and Prasanth Ala |
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Affiliation: | (1) Department of Civil and Materials Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, IL 60607, USA;(2) Department of Chemical Engineering, University of Vigo, University Campus, Fundicion Building, 36310 Vigo, Spain |
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Abstract: | The integrated use of hydraulic flushing and electrokinetic treatment was investigated for the remediation of silty sand contaminated
by both PAHs and heavy metals. The soil was collected from a polluted former manufactured gas plant (MGP). Four bench-scale
experiments were conducted to analyze the ability of the combined hydraulic flushing and the electrokinetic treatment for
the simultaneous removal of PAHs and heavy metals. Sequential flushing with ethylenediaminetetraacetic acid (EDTA) or Igepal
CA-720 were tested with or without the simultaneous application of a low intensity direct electric field (1 VDC cm−1). The best results were obtained with 0.2 M EDTA flushing in two stages (without and with voltage gradient, 1 VDC cm−1), followed by 5% Igepal flushing in two stages (without and with 1 VDC cm−1). Heavy metals were removed mainly during the EDTA flushing, with removal efficiencies of about 60% for Zn, 80% for Pb, and
30% for Cu. During Igepal flushing, no heavy metals were removed, but PAHs were removed, including 40% phenanthrene, 30% pyrene,
and 20% benzoa]pyrene. Overall, this study showed that a carefully designed sequential hydraulic flushing scheme with selected
chelant and surfactant is needed for the removal of both heavy metals and PAHs from MGP silty sands. Combining electrokinetics
with hydraulic flushing may not necessarily improve contaminant removal from such soils. |
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