title: Electrokinetic-enhanced permanganate delivery and remediation of contaminated low permeability porous media.
abstract: Back diffusion of contaminants from low permeability strata has inhibited site remediation and closure due to an inability to deliver remediants into these strata. This study demonstrates the potential of electrokinetics (EK) to significantly reduce back diffusion of chlorinated compounds from low permeability porous media. Experiments were conducted in a two-dimensional sandbox packed with vertical layers of coarse sand and silt contaminated with aqueous trichloroethene (TCE). Three experiments, each approximately 41 days in duration, compared EK-enhanced in situ chemical oxidation (EK-ISCO) to EK or ISCO alone. EK-ISCO successfully delivered the oxidant (permanganate, PM) throughout the silt cross-section while ISCO without EK resulted only in PM delivery to the edges of the silt layer fringes. EK-ISCO resulted in a 4.4-fold reduction in TCE concentrations in the coarse sand compared to a 3.5-fold reduction from ISCO alone. EK-ISCO with a 25 mA current was found to be more effective than with 300 mA current. Overall, this study suggests that electrokinetics coupled with an appropriate in situ remediation technique, such as ISCO, can enhance remediation of lower permeability strata and limit the extent of contaminant back diffusion.
authors.affiliation: Department of Civil and Environmental Engineering, Western University, 1151 Richmond St., London, ON N6A 5B9, Canada.
authors.forename: Ahmed I A
authors.initials: AIA
authors.lastname: Chowdhury
authors.affiliation: Department of Civil and Environmental Engineering, Western University, 1151 Richmond St., London, ON N6A 5B9, Canada.
authors.forename: Jason I
authors.initials: JI
authors.lastname: Gerhard
authors.affiliation: Geosyntec Consultants, 130 Stone Road W., Guelph, ON N1G 3Z2, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Reynolds
authors.affiliation: Department of Civil Engineering, University of Toronto, 35 St. George St., Toronto, ON M5S 1A4, Canada.
authors.forename: Brent E
authors.initials: BE
authors.lastname: Sleep
authors.affiliation: Department of Civil and Environmental Engineering, Western University, 1151 Richmond St., London, ON N6A 5B9, Canada; School of Civil and Environmental Engineering, Connected Water Initiative, University of New South Wales, Manly Vale, NSW 2093, Australia. Electronic address: d.ocarroll@unsw.edu.au.
authors.forename: Denis M
authors.initials: DM
authors.lastname: O'Carroll
mesh_terms: D052918:Environmental Restoration and Remediation; D010084:Oxidation-Reduction; D010539:Permeability; D016062:Porosity; D014241:Trichloroethylene / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D014874:Water Pollutants, Chemical; D014241:Trichloroethylene
keywords: Back diffusion; Electrokinetics; ISCO; Low permeable zone; Permanganate; Remediation