The effect of road salt on the metal binding ability of adsorptive media

Abstract

The first part of this study included stormwater sampling from highway bridges. The second part of the project evaluated media to remove metals in the presence of salt. Media tested included eleven adsorptive materials. Batch tests were conducted with three levels of salt (none, 2.5, 5 g/L NaCl) mixed with a standard combination of metals (Cu, Zn, Pb, Ni, Cr) based on the values found in highway bridge runoff sampled. The third part was a column study designed to represent field conditions. Three media were tested with the same stormwater treatments. Effluent was compared based on salt levels and media type to identify the media with the best ability to absorb metals in the presence of salt. It was determined that Imbrium 10, a mixture of aluminum and iron oxides and fine sand, had the highest absorption capacity for zinc and copper in the presence of salt.