title: Ultrasonic and mechanical soil washing processes for the removal of heavy metals from soils.
abstract: In order to determine the optimal operating conditions of full-scale soil washing processes for the removal of heavy metals, the effect of high-power ultrasound on the conventional mechanical soil washing process was investigated in a large lab-scale 28kHz sonoreactor. The soil samples were obtained from an abandoned railway station site in Seoul, Korea, which was contaminated with Cu (242.7±40.0mg/kg), Pb (441.3±49.8mg/kg), and Zn (358.0±35.7mg/kg). The treated concentrations of three heavy metal species in each process were compared with the regulation levels. It was found that higher performance, satisfying the regulation levels, was obtained in the ultrasonic/mechanical process due to the combined effects of macroscale mixing and microscale sonophysical effects. Moreover ultrasound played a more important role in less favorable conditions for the mechanical washing process (less acidic or less washing liquid conditions). Considering the application of the ultrasonic/mechanical soil washing process in real contaminated sites, the optimal conditions for the reactor with the bottom area of 15×15cm2and the input ultrasound power of 250W were determined as follows: (1) the amount of soil per an operation was a 300g; (2) the ratio of soil and liquid was 1:3; (3) the concentration of acidic washing liquid was 0.5M HCl.
authors: School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 136-701, Republic of Korea.
authors: Beomguk
authors: B
authors: Park
authors: Department of Environmental Engineering, Kumoh National Institute of Technology, Gumi 730-701, Republic of Korea. Electronic address: yson@kumoh.ac.kr.
authors: Younggyu
authors: Y
authors: Son
keywords: Heavy metals; Soil remediation; Soil washing processes; Sonophysical effects; Ultrasound