Electrokinetic remediation of metals and organics from historically contaminated soil

Abstract

The electrokinetic remediation of an historically contaminated soil is described. The soil was contaminated with a range of metals including lead, zinc, manganese, copper and arsenic, polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene and xylene (BTEX). A small-scale experiment (973.2 g dry weight soil), utilising a planar electrode con®guration, investigated the potential for moving metals and organics. After 23 days treatment at a current density of 3.72 A /m À2 , 44% of calcium and 29% of manganese were removed from the soil at the cathode. Of the other contaminating metals, zinc and lead moved towards the cathode, but with no signi®cant removal from the soil. Movement of PAHs was also observed, with a 94% reduction in concentration in the third of the soil closest to the anode after 23 days. A larger scale experiment (46.7 kg dry weight soil) utilised a hexagonal array of tubular anodes surrounding a central tubular cathode. Treatment for 112 days led to acidi®cation of the soil to pH 2.59 closest to the anode in a direct line between the anode and cathode. Soil not directly in line between the electrodes was not acidi®ed signi®cantly. Movement of metal ions was observed, in line with the electrodes, with concentrations of lead and arsenic increasing to 162% and 171% of starting concentrations closest to the anode, respectively, and those of zinc, copper and manganese decreasing to 42%, 68% and 57%, respectively. At positions not directly in line with the electrodes, no signi®cant metal movements were observed. Overall, there was no signi®cant removal of contaminating metals from the soil. PAHs and BTEX compounds were moved by electroosmosis towards the cathode, with soil concentrations of PAHs reduced from 720 mgkg À1 to 4.7 mgkg À1 after 22 days. PAHS (28 mg) and benzene (9660 mg) were recovered in granular activated carbon (GAC) columns.

On-site and in situ remediation technologies applicable to petroleum hydrocarbon contaminated sites in the Antarctic and Arctic

“…This technique can improve the performance of electrokinetic remediation substantially as petroleum hydrocarbons are typically strongly sorbed to soil. However, caution should be exercised when implementing this approach to co-contaminated soils as surfactants can mobilize heavy metals (Maini et al 2000;Singh & Turner 2009;Huang et al 2012;Camenzuli et al 2013).…”

Enhanced ex-situ bioremediation of soil contaminated with petroleum refinery waste effluents by biostimulation through electrokinetics and inorganic fertilizer

“…Several studies have made efforts to enhance the transport of bacteria or nutrients for effective biodegradation through the application of EKB [22 -24].Over the last two decades, there has been increasing interest in employing electrokinetic remediation for the treatment of contaminated soil. Most of the EKR studies have mainly been for the remediation of metals [15,25], radio nuclides [15,26] and polar inorganic pollutants from saturated/unsaturated soil, sediments and groundwater [27] while few researches have been carried out on the electrobioremediation of soil and sediments contaminated with organic chemicals or hydrocarbons such as gasoline hydrocarbons, aromatic compounds or trichloroethylene in weak electric fields [12 -14, 28 -29]. These studies seem to suggest that EKB can be effectively used for the mineralization of many organics, with lower energy expenditure.…”

Electrokinetic extraction of lead from kaolinites: II. Experimental investigation

“…The technique of electrokinetic extraction has been applied successfully in laboratory bench-scale experiments to mobilize and to remove organic contaminants such as phenol (Acar et al 1992;Shapiro and Probstein 1993;Gopinath 1994;Yang and Long 1999) and gasoline hydrocarbons (Bruell et al 1992;Maini et al 2000); and inorganic contaminants such as Cu(II), Pb(II), Hg(II), and Cd(II) (Hamed et al 1991;Pamukcu and Wittle 1992;Eykholt and Daniel 1994;Yeung et al 1996;Sawada et al 2003;Suèr and Allard 2003;Yeung and Hsu 2005) spiked in clayey soil specimens. Banerjee et al (1991), and Lageman and Godschalk (2007) conducted pilot-scale field electrokinetic extraction experiments and obtained very promising results.…”