Thermal Effects of Microwaves in Contaminated Soil Remediation

Microwave heating is one of the major treatment approaches for remediating contaminated soil, and the underlying thermal effects are worth studying. This study established a microwave reaction chamber model to simulate this heating process. The results show that the microwave power and frequency significantly influenced the electric field strength in the reaction chamber and the temperature distribution in the soil sample. The temperature distribution through numerical simulation was generally consistent with the experimental results of color-changing silica gel and infrared thermography, thereby verifying the reliability of the model simulation. In a microwave thermal effect experiment using diatomaceous soil, increasing the water content to 10% was found to increase the maximum temperature by 30 degrees C. The effective power and temperatures for microwave remediation differed according to the type of contaminated soil. The optimum removal rate for xylene-contaminated soil was achieved at a microwave power of 500 W, whereas that for nitrobenzene-contaminated soil required power of 750 W. Based on the contaminated soil degradation experiment, equipment for the continuous microwave treatment of contaminated soil was designed in simulation to verify the temperature at which the contaminated soil could be degraded. The research results provide a theoretical basis for the microwave remediation of contaminated soil.