The effectivenes of soil washing is based on the fact that most organic and inorganic contaminants tend to bind preferentially to clay, silt, and organic soil particles. In the washing process, the fine clay and silt particles are separated from the coarser sand and gravel soil particles. The separated fines and contaminants are dewatered into a dry filter cake suitable for off-site disposal. Additional treatment of the sand and gravel fractions maybe incorporated into the process as needed. The cleaned sand and gravel fraction can be returned to the site.
The soil washing treatment systems used by ART are based on standard physical and or chemical separation processes that were originally developed in the mineral processing and mining industries. Such techniques have been used successfully for a wide range of polluted soil treatment projects involving removal of heavy metal(-s), organic and radionuclide contaminants from the soils.
Soil washing may include any combination of technologies including (but not limited to): soil separation, density separation (metals removal), attrition scrubbing, flotation (effective for PAH, Pesticides, Dioxin) and surfactant washing. In some cases, (mild) chemical extraction using acids, alkalis, and complexing agents may be used. Because each project varies in the soil type, contamination type, and treatment needs to be cost effective, the soil treatment solution from site-to-site is unique.
ART has a proven track record of adjusting to different site conditions and meeting site specific remediation goals for each project.
The soil washing process best applied to soil and sediment(-s) containing
less than 25 % fines (fraction less than 400 mesh or 38 micron).
Soil washing can be used for cleaning of a wide range of organic, heavy metal and radionuclide contaminants including:
Group | Contaminants |
Semi-Volatile Constituents (SVOC) | Polychlorinated Biphenyls (PCB’s), Polynuclear Aromatic Hydrocarbons (PAH), Hydrocarbon, Crude Oil, Phthalate (-s), Dioxin(-s), Pesticide(-s), Herbicide(-s), Trinitrotoluene (TNT), Dinitrotoluene (DNT) and other SVOC |
Heavy Metals | Lead, Mercury, Arsenic, Chromium, Copper, Nickel, Cadmium and other heavy metals |
Radionuclides | Uranium, Cesium, Thorium, Radium and other Radionuclides |
It is important to determine the feasibility of a soil or sediment treatment process through means of a Soil Treatment Treatability Study.