The so-called “soil washing” consists in excavating the contaminated soil and treating it in a plant to reclaim it, possibly without moving it.
The technique is based on the principle that the contaminants are conveyed through the finest particles present in the soil fractions and espacially to these is carried out a real washing with water, aqueous solutions of surfactants, biosurfactants, or with organic solvents.
In the worst case scenarios, the soil can be treated within gasifiers or plasma torches.
In other cases, but it is a practice that exposes to risks of different nature, it is possible to use genetically modified micro organisms capable of attacking and therefore eliminating a specific kind of problem.
With regard to the washing of polluted soil, a careful study of the problem of the soil to be worked in order to determine the most correct reaction to be applied will be conducted in the laboratory.
The soil will be introduced into our apparatus where it will be treated, transformed into aqueous slurry, with specially developed Chemicals (alkaline phosphate solutions) with a ratio of 4 gr of soil and 40 ml of extracted solution.
The reactants will subsequently be separated from the solution by centrifugation and filtration.
With this initial process it is possible to recover any arsenic present.
By lowering the pH of the Chemicals used and increasing the concentration of the extraction solution, other metals such as Copper, Zinc, Lead, Nickel, Aluminum, Manganese, and Iron can be extracted.
Once the preponderant part of the polluting agents has been eliminated, the soil is reactivated by specially selected microorganisms, which complete the purification revitalizing it, and making it usable again.
If traces of cobalt artificially radioactive are found in the ground, the ground will be treated with a plasma torch, specially shielded for radioactivity. Here cobalt will lose its radioactive charge and can be recovered and then reused in the foundry.
The same plasma torch can be used, in any case, for the recovery of gold from sands, instead of using ovens, with clearly improved results.