In-situ treatment methods

Soil vapour extraction

Soil vapour extraction is suitable for volatile compounds, such as petrol or solvents. In order to conduct soil vapour extraction vertical or horizontal pipes are installed to remove the air that contains volatile hydrocarbons from soil. Hydrocarbons are destroyed by a catalytic burner or activated carbon filtering, depending on the amount of hydrocarbons. Soil vapour extraction can be enhanced by supplying warm air.

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Biostimulation

Biological treatment (biostimulation) is suitable for sites contaminated with diesel oil. Biostimulation is based on the principle that the natural biodegradation is enhanced by adding oxygen, nutrients, moisture, bacteria and heat to the soil. The additives are fed into the soil in aqueous solution through specially designed piping or by high pressure pumping. The additives are released slowly to the soil for the use of the natural bacteria. The amounts of the feed solution, nutrients and nutrient combinations are determined based on available information of the soil properties and contaminants.

Chemical oxidation

Chemical oxidation can be applied on sites contaminated with oil products. In Chemical oxidation the hydrocarbons are destroyed using a chemical oxidant, usually hydrogen peroxide. Hydrogen peroxide solution is fed into the soil, either through a mounted piping and / or by injection with high pressure pump.

Electro-osmosis

Electro-osmosis is not really a treatment method, but a method by which water and chemicals are moved to the soil horizontally and, therefore, improve their contact with the contaminants. Electro-osmosis is suitable to enhance for example biostimulation, especially if the soil has low water permeability.

Groundwater ventilation

Groundwater ventilation is suitable on sites where volatile hydrocarbons are present in groundwater. Warm air is supplied below the groundwater level and the hydrocarbons migrate to the soil above it. Hydrocarbons are removed from the soil using soil vapour extraction.

Soil encapsulating

Contaminants are isolated so that they cannot disperse to the environment in runoff waters or groundwater. The isolation is done using water impervious materials such as clay, dense asphalt or synthetic materials.