New technique may clean contaminated soil quickly

SYDNEY - Scientists in Denmark have found a powerful new technique to rid soil of toxic heavy metals faster and more efficiently than current methods.

Our aim was to speed up the established process for removing metals like lead and cadmium from soil using electrokinetic methods to protect community health and safety, says Lisbeth Ottossen of the Technical University of Denmark, who led the study.

Experimenting with soils from a former wood preserving plant, heavily polluted with lead, copper, chromium and arsenic, the team found that 90 percent of the contaminating lead and 99 percent of the copper could be removed in about two weeks.

The fact that the mixture was more acidic than the surrounding soil helped in freeing up the metal ions so they could be removed.

The combined method also removed up to 28 percent of the chromium and 65 percent of the arsenic from the soil. We concluded we need to add an enhancement to the solution to achieve proper remediation of the soil, for these two metals, she adds.

Electrokinesis, developed in the 1980s, works very slowly and it may take months of treatment to achieve effective clean-up.

Her team has combined traditional electrokinetic remediation with conventional electrodialysis to produce a newer, faster and more thorough way of cleansing contaminated soils.

These findings were presented at the CleanUp 09 conference in Adelaide.