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

ELECTROKINETIC REMEDIATION PRINCIPLE

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

TRANSPORTATION OF IONS

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

FIELD SETUP

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

TREATMENT IN PADUCAH PLANT, KY

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

ELECTRODE INSTALLATION IN QUICREZ INDUSTRIAL SITE, WISCONSIN

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