Zastosowanie prądów wysokiej częstotliwości i mikrofal do oczyszczania gruntów z substancji ropopochodnych

The paper concentrates on three major items: it gives a review of in situ remediation methods using low-or high-freguency electric currents for heat transmission into the soil,present examples of pilot-scale applications of 60Hz current and radio-frequency radiation to soil cleanup, and discusses the results of laboratory investigations into the remediation of contaminated sand and soil.In the laboratory experiments,electric or electromagnetic energy was supplied to the soil through antennas or electrodes located at the contaminated place.The quantity of the energy absorbed by the soil depended strongly on the dielectric parameters of the aqueous medium,on the mineral components of the sil,and on the contaminants present there.Conversion of radiation of electricity into heat was concomitant with a rise in temperature.When power-line-frequency currents were applied,the process unitized the mechanism of the Joule effect and the principle of ohmic heating. When radiowaves and microwaves were involed,the process followed the mechanism of dielectric heating-simular to the one occuring in microwave ovens.The rise in soil temperature resulted in the desorption or evoporation of organic contaminants into the soil air at a rate which depended on the temperature of the soil.Laboratiry experiments substantiated the utility of microwave heating in the redendiation of contaminated soil.Compared to other remediating methods,microwave heating runs at a very fast rate,yielding high removal of volatile and semi-volatile organics,especially polar contaminants. In the presence of water,the removal of polar and non-polar substances can be described in terms of the steam distillation principle.The cleanup process then runs under steady styate conditions,at a temperature which does not exceed 100 o C. The is of particular importance of the cleanup of organic soil,because overly high temperature may burn the humic substances up.