Chemical treatment is a process for cleaning contaminated soil in which pollutants are broken down or stabilised by chemical reactions. Various methods can be distinguished here, such as in-situ treatment or ex-situ treatment.

In-situ treatment:

1. Preliminary investigation
   Prior to chemical treatment, a preliminary investigation is carried out to determine the type and concentration of pollutants in the soil. The pH value of the soil is also analysed, as this plays an important role in the success of the chemical treatment.
2. Soil preparation
   The soil is prepared for the chemical treatment by loosening and watering it to allow better mixing with the chemicals applied.
3. Application of the chemicals
   In this step, the required chemicals are introduced into the soil. These may be oxidising agents, reducing agents or chelating agents, for example. The chemicals introduced react with the pollutants in the soil and convert them into non-toxic substances or remove them from the soil.
4. Reaction time
   After the chemicals have been introduced, a certain reaction time is waited so that the chemicals have sufficient time to react with the pollutants.
5. Control
   After the reaction time, the soil is analysed for the residual concentration of pollutants. This involves checking whether the pollutants have been completely broken down by the chemical treatment or whether there is still residual contamination.

Ex-situ treatment:

1. Soil excavation
   In ex-situ treatment, the contaminated soil is first excavated and taken to a special facility for treatment.
2. Soil preparation
   The soil is prepared for chemical treatment by loosening and watering it to allow better mixing with the chemicals introduced.
3. Introduction of the chemicals
   In this step, the required chemicals are introduced into the soil. These can be oxidising agents, reducing agents or chelating agents, for example. The chemicals introduced react with the pollutants in the soil and convert them into non-toxic substances or remove them from the soil.
4. Reaction time
   After the chemicals have been introduced, a certain reaction time is waited so that the chemicals have sufficient time to react with the pollutants.
5. Cleaning and disposal
   After the reaction time, the soil is cleaned and the chemicals are removed. Various methods can be used to clean the soil, such as washing with water or removing solid residues. The cleaned soil is then disposed of in accordance with legal regulations.

It is important to note that chemical treatment is a complex process and should be carried out by a qualified professional. It must also be taken into account that the chemicals used not only affect the pollutants in the soil, but can also change the soil life and structure.

Nevertheless, chemical treatment is an effective method of remediating contaminated soil, especially in heavily polluted or difficult to access areas. The technique is frequently used in industry, but also in the remediation of contaminated sites and landfills.