Projects
Groundwater contamination is a great risk to the environment. Designing modern landfills is a solution made to contain the contaminants and prevent further leakage through the soil. Hydraulic conductivity of soils affects many geo-environmental processes as well as design parameters, and is mostly dependent on fluid viscosity, grain-size distribution, and void ratio of the porous medium. Due to dipole properties of water molecules in a porous medium, any electric field will align molecules to the direction of the field. An alternating electric field oscillates individual water molecules and incites a change in water flow patterns through the porous medium. In this study the effect of electromagnetic waves (EM) on the hydraulic conductivity of soils is investigated.
This research emphasizes on the goal of studying “remote directive electromagnetic stimulation of transport mechanisms to enhance soil remediation.” Alternating electric fields can oscillate water dipole molecules, which can in turn stimulate mechanisms such as airflow, seepage, microbial activities, desorption, and volatilization. Several soil remediation technologies use injection of air into soil to enhance microbial activities for bioremediation and volatilization of organic contaminants for soil cleanup.
Recent research has also shown a strong potential to mitigate liquefaction by air sparging. Air, however, does not easily flow in saturated soils. Increasing air injection pressure will create air channels within high porosity zones for easy airflow. These channels are preferential paths for flow of the majority of the injected air. The size, spacing, and formation of these air channels cannot be controlled successfully and rapidly. The air diffusion rate between these channels is extremely slow. There is a need for enhancement of air delivery between these channels.
Use of electric current has become popular to enhance remediation processes. However, electric current will find preferential paths of relatively higher electrical conductivity. In sandy or even highly conductive lossy clayey soils, relatively higher conductivity zones are the same high porosity zones, previously taken by air channels. Therefore, these technologies leave low electrical conductivity zones of small pores untouched. EM waves can oscillate water dipole molecules, which can in turn, stimulate and enhance different transport mechanisms (e.g., air diffusion rate between air channels), and increase hydraulic conductivity, and control the size of air channels.EM waves propagate better in zones of low conductivity (low porosity zones (untouched by the previously mentioned methods). In addition, sources of EM waves are antennas that can be designed to operate from aboveground (in the most versatile and remote way), be directive (i.e., designed to input more power in desired directions), and input more energy into desired locations (using constructive radiation patterns).
The heating effect due to oscillation by an EM field can also be controlled more easily than the one due to electric current, by low voltage high frequency waves. This project will be a breakthrough in enhancement of soil remediation technologies, and reach areas of soil not reached by other methods. Developing such a system needs a thorough study of necessary basic knowledge about the interactions among EM waves, oscillation of water molecules, and transport mechanisms. Effect of variations in frequency and power level on enhancement of different transport mechanisms and microbial activities need to be studied. This study is essential for developing theoretical models necessary to simulate and study the above-mentioned interactions.