18. Microwave

Microwaves heat soil water. This heating can improve the desorption and volatilization of pollutants, making them more accessible to various treatments (venting, etc.) (figure 18 ). This technique is still at the pilot stage, although some companies are already marketing it. It is likely to find applications at sites requiring rapid in situ treatment.

• Principle

  Microwaves have frequencies between 1 and 100 GHz, i.e. wavelengths between 3 mm and 30 cm. These energy ranges correspond to rotational excitation of polar molecules, directly linked to their moment of inertia.

  The absorption of microwaves by liquids takes the form of very broad bands and corresponds to global oscillations of the dipoles, which tend to...