Urban Runoff Treatment Using Sand Columns Coated with Nanoparticles of Iron Oxide in the Presence and Absence of a Magnetic Field

Increased impervious surfaces in urban areas not only increase runoff volume and peak flow, but also worsen urban storm water pollution. The polluted runoff has many adverse impacts on human life and environment. The purpose of this study was to investigate and compare the efficiency of sand columns coated with nanoparticles of iron oxide in the presence and absence of a magnetic field. In this study, atomic absorption, turbid meter, pH meter and DR5000 were used to measure heavy metals, turbidity, pH, and nitrate/phosphate, respectively. Size and characteristics of nanoparticles were determined by scanning electron microscopy (SEM) while energy dispersive X-ray analysis (EDX) was used to detect the percentage of the components in the sand. SEM and EDX analyses proved that the sand had been successfully coated with nanoparticles of iron oxide (Fe3O4). Results indicated removal efficiency without the magnetic field for turbidity, lead (Pb), zinc (Zn), cadmium (Cd), phosphate (PO4), and nitrate (NO3) to be 90.8%, 73.3%, 75.8%, 85.6%, 67.5%, and 0%, respectively. When magnetic field was applied, removal efficiency for turbidity, Pb, Zn, Cd, PO4, and NO3 was increased to 95.7%, 89.5%, 79.9%, 91.5%, 75.6%, and 0%, respectively. In addition, statistical analyses of data indicated a significant difference between the two columns in removing pollutants. Results of this study indicated that sand columns coated with nanoparticles of iron oxide had a significant efficiency in improving urban runoff quality. Furthermore, magnetic field increased the removal efficiency. Authors believe this approach is simpler and more economical and efficient than other existing methods.