BAUER Environment Group

In-situ Application of Radio Frequency (RF) Heating Systems

Fig.: Microbial Treatment plant with RF heating system in the soil treatment centre of BAUER Umwelttechnik GmbH in Hirschfeld

As an in-situ or on-site method, radio frequency heating offers the unique opportunity of steady and controlled warming of soil or other materials at relatively high heating rates.

The RF-method is able to heat insulating materials and bases on the same principle as microwave ovens. With frequencies ranging between 3 and 50 MHz, the low-frequency RF radiation is capable of treating large volumes of possibly contaminated soils.

Schematic Diagram

Potential Applications

1. Defrosting frozen materials as a prerequisite for the application of treatment techniques, especially in cold climatic conditions (e.g. perma frost)
2. Stimulation of the microbial degradation of contaminants
   • improving soil permeability
   • increasing vapour pressure and mobility of the contaminants
   • taking advantage of strip effects
3. thermal support in soil vapour extraction
   • improving soil permeability
   • increasing vapour pressure and mobility of the contaminants
   • taking advantage of strip effects
   • thermal support in soil vapour extraction
   • Enhance thermo-desorption of contaminants

Advantages

• The method can be applied in a wide range of temperatures from –20 °C to more than 400 °C
• The in-situ heating of soil by applying electromagnetic energy in the radio frequency (RF) range permits the removal of contaminations located deeply in the underground or beneath sealed areas.
• The method facilitates the application of other treatment techniques especially at low to medium temperatures: e.g. microbial degradation, and soil vapour extraction

Advantages compared to other methods (e.g. heating by hot air or water vapour):

• The heat is produced directly in the soil.
• For heat transfer no additional media are needed that could be contaminated.
• The heat transfer is not limited by surface or boundary barriers.
• Variable heating rates and temperatures
• In contrast to other methods, RF heating can be applied in cohesive materials.

In-situ application of RF heating – detailed information is available in German only.