CONTAMINATED SOIL WASHING PLANT
Soil washing or soil scrubbing is a water based process for remediation of excavated soils. Soil washing removes contaminants from soils two ways:s
1. By dissolving and/or separating, suspending contaminants on soil particles into the wash water, wash water can be dosed with chemicals to improve the washing characteristic (such as pH adjustment, surfactants, etc),
2. By concentrating contaminants into a smaller volume of soil through particle size separation and attrition scrubbing. The majority of inorganic and organic contaminants generally bind, either physically or chemically to fine particles (clays, silts, organic matter). These silts and clays in turn are attached to sand and gravel particles in the soils. Soil washing separates the contaminated silts and clays from the "clean" sands and gravels, thereby reducing the volume of contaminated material requiring further treatment or disposal. The most important factor affecting the soil washing process is the percentage of fines (particles with a diameter less than 0.063mm) in the soil, if the percentage of fines is high then there will only be a small volume reduction in the amount of contaminated material and the efficiency of the soil washing process will be low. Generally it is considered that if the fine content of the soil is above 25% then soil washing will not be effective. More granular soils are better suited to soil washing than cohesive or semi cohesive soils.