Phytoremediation
The use of plants to extract, sequester, or degrade heavy metals from contaminated soil.
- Phytoextraction uses hyperaccumulator plants to absorb metals into harvestable shoots.
- Phytostabilization employs plants to immobilize metals, reducing their bioavailability and movement.
Soil Washing
A physical/chemical process that separates contaminated fine soil particles from less contaminated coarse particles using a washing solution.
- Involves excavating soil and washing it with water, sometimes with chemical additives like acids or chelating agents.
- The cleaned coarse fraction can often be returned to the site, while the contaminated fines require further treatment or disposal.
Solidification And Stabilization
A process that binds contaminated soil to reduce the mobility of heavy metals and their leaching potential.
- Solidification involves adding binding agents like cement to encapsulate contaminants in a solid mass.
- Stabilization uses chemical agents to convert contaminants into less soluble, mobile, or toxic forms.
Electrokinetic Remediation
An in-situ technique that uses a low-intensity electric current to move metal ions through the soil towards collection electrodes.
- The electric field induces the migration of charged metal species (cations and anions).
- Metals are then removed from the soil by concentrating them at the electrodes for extraction or precipitation.
Bioremediation
The use of microorganisms to transform or immobilize heavy metals in soil.
- Microbes can change the oxidation state of metals, affecting their solubility and toxicity (e.g., reducing Cr(VI) to less toxic Cr(III)).
- Some bacteria and fungi can biosorb metals onto their cell surfaces or produce compounds that precipitate metals.