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Web-based Class Project on Geoenvironmental Remediation
Report prepared as part of course CEE 549: Geoenvironmental Engineering
Winter 2013 Semester Instructor: Professor Dimitrios Zekkos
Department of Civil and Environmental Engineering University of Michigan
ELECTROKINETIC REMEDIATION Prepared by:
With the Support of: Vidhya Ramalingam
OUTLINE
• INTRODUCTION TO ELECTROKINETIC REMEDIATION
• TYPES OF CONTAMINANT TRANSPORT MECHANISMS
• PHYSICAL AND CHEMICAL PROCESS INVOLVED
• APPLICABILITY
• ADVANTAGES AND DISADVANTAGES
• FIELD SETUP
• SIMILAR TECHNOLOGIES
• CASE STUDIES
• SUMMARY
INTRODUCTION
• In-Situ remediation technique
• Electrodes are inserted in contaminated soil
• A low density DC (mA/cm) is passed through the soil
• Contaminants get transported towards electrodes and are pumped out
• Ground water or external processing fluids are used as conductive medium
TYPES OF TRANSPORT CONTAMINANT MECHANISMS
Electroosmosis
• Columbic forces are induced by the applied electric field
• The water molecules move in the soil and carry the contaminants
• Flow depends on temperature, ion concentration, viscosity of pore water, dielectric constant and ion mobility
TYPES OF TRANSPORT CONTAMINANT MECHANISMS(cont.)
Electromigration
• Ionic transportation towards electrodes
• Faster than electroosmosis
• Movement depends on ionic mobility, valence numbers and electrolyte concentration
Electrophoresis
• Movement of colloids towards electrodes and is similar to electromigration
• Insignificant if the soil is tightly packed
PHYSICAL AND CHEMICAL PROCESS
Electrolysis • Reaction occurs at the anode and cathode when
an electric field is applied
Diffusion • Contaminants move due to difference in
concentration gradient • Depends on porosity of the medium and the
concentration of the species
PHYSICAL AND CHEMICAL PROCESS (cont.)
Adsorption-Desorption
• Movement of contaminants from pore water to the soil particles
• Desorption is the reverse of adsorption and involves the transport of contaminants from soil to pore water
• Depends on soil type, soil charge, contaminant, organic matter and pore water characteristics
PHYSICAL AND CHEMICAL PROCESS (cont.)
Precipitation-dissolution • Contaminants could be precipitated or dissolved
during remediation • Dissolved contaminants would be easier to
remove than the precipitated contaminants Oxidation-Reduction • Redox reactions take place during the
remediation process • Valence of the metal ions decide on their
solubility and impacts removal
APPLICABILITY OF ELECTROKINETIC REMEDIATION
• Removal of organic and inorganic pollutants
• Heavy metals, radionuclides and hydrocarbons from soils with low permeability
• Very effective in removal of strontium and cesium from high water content soil
• Used for remediating soils, sludges, sediments and groundwater
ADVANTAGES AND DISADVANTAGES
Advantages • Less expensive • Can target a specific area • Applicable for a wide range of contaminants • Flexible to be used as both in-situ and ex-situ method Disadvantages • Buried metal objects may prove to be a big challenge • Large presence of non-targeted contaminants would be
a challenge • Acidic conditions near anode will cause decay and
degradation of the electrolyte
FIELD SETUP AND IMPLEMENTATION
• Carbon, graphite, or platinum electrodes are used in the soil
• Power supply is expected to deliver 1 A/sq. ft power between the electrodes
• Ceramic wells are set up to avoid corrosion
• Pumps are used to remove contaminated water from wells
SIMILAR TECHNOLOGIES FOR SOIL REMEDIATION
• Electrical Resistive Heating Remediation (ERH) is a
technology where the Direct current is replaced by Alternating current
• Depends on heating of the soil and more effective in unsaturated soils for the removal of volatile organic compounds
• Electrokinetically enhanced bioremediation- involves supplying the much needed nutrients, heat and water for the microorganisms so that they can carry out the contaminant degradation faster
CASE STUDY 1: U.S DEPARTMENT OF ENERGY PADUCAH
GASEOUS DIFFUSION PLANT, PADUCAH, KENTUCKY
• First nuclear weapons program in the United States
• TCE (Trichloroethylene) contamination
• Field contamination - 620 sq. ft. and a depth of 45 feet.
• Efficiency of the technique was 99.7%
• Cost was about $80 per cubic yard for a quarter of an acre at a depth of 45 feet
CASE STUDY 2: QUICREZ INDUSTRIAL SITE IN FOND DU
LAC, WISCONSIN
• Site had extremely high levels of TCE [DNAPL levels of TCE]
• Remediation was started with two anodes and one cathode
• Funding was stopped
• Post treatment sampling showed significantly lesser DNAPL concentrations
• Two thirds of the total TCE was removed and the zones of DNAPL diminished
SUMMARY
• In-Situ technique
• Good for metals, radionuclides, organic contaminants and combinations
• Average cost - $25 - $225 per cubic yard but varies depending on soil factors and contaminant involved
• More scope for research in this field to overcome some of the existing challenges
REFERENCES
• Acar, Y. B., and Alshawabkeh, A. N. (1993). "Principles of electrokinetic remediation." Environ.Sci.Technol., 27(13), 2638.
• Acar, Y. B., Gale, R. J., Alshawabkeh, A. N., Marks, R. E., Puppala, S., Bricka, M., and Parker, R. (1995). "Electrokinetic remediation: Basics and technology status." J.Hazard.Mater., 40(2), 117.
• De Battisti, A., and Ferro, S. (2007). "Electrokinetic remediation." Electrochim.Acta, 52(10), 3345.
• DeGarady, C. J., and Halbrook, R. S. (2003). "Impacts from PCB Accumulation on Amphibians Inhabiting Streams Flowing from the Paducah Gaseous Diffusion Plant." Arch.Environ.Contam.Toxicol., 45(4), 525.
• Jane E. Apatoczky, January 1992. "The Chemical Enhancement of Electrokinetic Soil Decontamination". M.S Thesis, Lehigh University.
• Kim, S., Han, H., Lee, Y., Kim, C. W., and Yang, J. (2010). "Effect of electrokinetic remediation on indigenous microbial activity and community within diesel contaminated soil." Sci.Total Environ., 408(16), 3162.
• Kornilovich, B., Mishchuk, N., Abbruzzese, K., Pshinko, G., and Klishchenko, R. (2005). "Enhanced electrokinetic remediation of metals-contaminated clay." Colloids Surf.Physicochem.Eng.Aspects, 265(1), 114.
• Lageman, R., Clarke, R. L., and Pool, W. (2005). "Electro-reclamation, a versatile soil remediation solution." Eng.Geol., 77(3), 191.
• Li, S., Li, T., Li, G., Li, F., and Guo, S. (2012). "Enhanced electrokinetic remediation of chromium-contaminated soil using approaching anodes." Frontiers of Environmental Science & Engineering in China, 6(6), 869.
• Reddy, K. R., Darko-Kagya, K., and Al-Hamdan, A. Z. (2011). "Electrokinetic Remediation of Pentachlorophenol Contaminated Clay Soil." Water, Air, & Soil Pollution, 221(1), 35.
• Sharma, H. D., and Reddy, K. R. (2004). "Geoenvironmental engineering: site remediation, waste containment, and emerging waste management technologies". Wiley, Hoboken, N.J.
• US Army Environmental Center. July 2000, "In-Situ electrokinetic Remedition of Metal Contaminated Soils Technology Status Report". SFIM-AEC-ET-CR-99022
• US Department of Energy. "Paducah gaseous Dissusion Plant" http://www.pppo.energy.gov/paducah.html
• US EPA Office of Solid Waste and Emergency Response. 1997. "Ground Water issue". EPA/540/S-97/502
• US EPA Office of Solid Waste and Emergency Response. 1995, April. "In-Situ Remediation Technology Status Report". EPA/542/K-94/007
• US EPA Office of Research and Development. 1997, March 5, "Recent Developments for In-Situ Treatment of Metal Contaminated Soils"
• Virkutyte, J. (2002). "Electrokinetic treatment overview 2002, science of the total environment." .
MORE INFORMATION
More detailed technical information on this project can be found at:
http://www.geoengineer.org/education/web-based-class-projects/geoenvironmental-remediation-technologies