Efficient Microwave Technology to Immobilize Heavy Metal Copper (Cu) Contaminated Soil by Microwave Energy

Abstract

Using Cu with concentrations up to 250 mg/kg coupled with microwave (MW) irradiation is effective in immobilizing the Cu in both vitrified and nonvitrified soils. Applying 1,080–2,430 kJ MW energy will effectively lower the concentration of 250 mg/kg Cu in the contaminated soil to less than 1.0 mg/L (the detection limit). The critical MW energy is 1,080 kJ for effectively immobilizing Cu in Tai-Kang contaminated soil. A biointake and growing test was also conducted; Chinese-kitam (leafy vegetable) and sprout (stem vegetable) were cultivated in two different types of soil containing 0 and 250 mg/kg Cu, respectively, and the results were compared. The physical appearance of the plants grown in both soils are almost the same. However, the time to reach maturity for plants grown in the soil containing 250 mg/kg Cu is longer buy the Cu content in the mature plant is under the detectable limit. This research shows that microwave can effectively immobilize Cu in both vitrified and nonvitrified soils.