Using Electrical Currents to Transport Chemicals Through Soils and Clean Contaminants

Achievement date: 
2017
Outcome/accomplishment: 

Applying a low-intensity direct current across electrodes in soil was shown to transport nitrate ions through the silt, according to research conducted at the NSF-funded Engineering Research Center (ERC) for Bio-mediated and Bio-inspired Geotechnics (CBBG), based at Arizona State University.

Impact/benefits: 

Called electro-kinetics, the use of electric currents to move chemicals through soil could be useful to several technologies under development at the CBBG, including bioremediation and soil-stabilization.  Proving the effectiveness of electro-kinetics boosts the potential to distribute microbes to clean solvents from contaminated soils and to induce carbonates to cement silt and clay soils.

Explanation/Background: 

Electrical currents have long been known to spur osmosis and chemical migration in soils. The work at CBBG and other research centers is showing how the technology could overcome the otherwise limited transport of chemical compounds through soil, an obstacle to applying environmental and geotechnical technologies.

Electro-kinetics could transport nutrients needed for bacteria that consume a contaminant in soil or groundwater, chemicals that would remove other contaminants, and ions that cement soil for stabilization. CBBG feels electro-kinetics could prove particularly effective in extending the application of bioremediation and soil stabilization technologies to silt and clay soils, which have required expensive and disruptive remediation at their respective sites, as well as the use of taxing grouts. The technology is showing promise, for one, to clean trichloroethene contamination, often left by the dumping or leakage of solvents into soil.