Electro-remediation, also known as electrokinetic remediation, utilises physical and chemical processes induced by an electric field to remove or stabilise contaminants in the saturated zone of soil and groundwater. Under direct current (DC) conditions, ions are moved through electromigration and electrophoresis, while electro-osmosis drags groundwater toward the cathode. These processes can mobilise contaminants or transport remediation agents. Electrochemical reactions at electrodes change local pH and redox conditions, enabling both degradation and immobilisation of pollutants. Notably, the technology can also enhance in situ biological processes by directing contaminants or substrates toward microbial zones.
Several variants of electro-remediation exist, including extraction-based methods, redox-driven approaches, and integrated systems with bioremediation. The movement of charged species under an electric field can aid in creating containment barriers or facilitate contaminant mobilisation for recovery or destruction. Electro-remediation was originally developed for metal contamination, with strategies involving either immobilisation on electrodes or above-ground treatment systems, often including water conditioning and reintroduction to maintain geochemical balance.
Electro-remediation also has applications for organic contaminants, where high-energy free radicals generated at electrodes degrade persistent pollutants such as PCBs. It can also change the redox state of metals, aiding in stabilisation. Additionally, the technique supports microbial remediation by modifying subsurface conditions, delivering substrates, or moving organisms to contaminated zones. Emerging uses include microbial fuel cells and enhanced phytoextraction of toxic elements from diffuse soil contamination.
The approach offers benefits such as applicability in low-permeability soils, compatibility with other remediation technologies, and potential for renewable energy use. However, it presents challenges, including interference from buried metals, risks to infrastructure and personnel, and potential environmental side effects. While promising for a range of contaminants—from VOCs and PFAS to complex cyanides—electro-remediation remains a developing technology, with limited field experience and regulatory concerns over subsurface impacts and public safety.