The soil washing theory relies on the chemical reactions that take place between solid soil particles and the liquid solution they disperse in. The soil-washing process is generally based upon the idea that soil contaminants will adhere to fine-grained soils.
These soils in turn are more likely to adhere with coarser soils through adhesion or compaction. The coarse-grained soils can be separated from the fines by washing with water, and perhaps adding additives. To find out more about Soil Remediation, visit soilfix.co.uk/services/soil-and-groundwater-remediation
The soil washing process is an effective way to remediate excavated soils. Soil washing can remove contaminants in soils by two different methods:
- Wash water can be dosed chemically to improve its washing characteristics (such as pH adjustment or surfactants).
- Concentrating contaminants into a small volume of soil by particle size separation and scrubbing attrition.
Most inorganic and organic contaminants bind to fine particles, whether physically or chemically (clays, sludge, organic matter). The silts, clays, and organic matter are then attached to the sands and gravels in soils. Soil washing removes the silts, clays and contaminated sands or gravels.
The soil’s fine content (particles smaller than 0.063mm in diameter) is a major factor in the soil-washing process. If the fines are high, there will be only a modest reduction in contaminated material.
In general, soil washing is not effective if soil fines are above 25%. Soils that are more granular will be better suited for soil washing.
