Influent concentrations and removal performances of metals through conventional and advanced municipal wastewater treatment processes

This comprehensive study aims at quantifying the wastewater concentration and removal efficiency of 23 metals and metalloids through 9 full-scale biological plants and 3 additional treatment processes. The metals investigated are Li, B, Al, Ti, V, Cr, Fe, Ni, Co, Cu, Zn, As, Se, Rb, Mo, Ag, Cd, Sn, Sb, Ba, Tl, Pb and U. Particulate and dissolved metals were measured using 24 h composite samples at each treatment stage. In influents, total concentrations of Cd, Sb, Co, Se, U, Ag, V are below a few mg/l, whereas at the other extremity Zn, B, Fe, Ti, Al are in the range of 0.1 to >1 mg/l. We demonstrate that conventional biological processes are efficient to remove most metals, with the exception of B, Sb, Li, Rb and Mo, due to their low adsorption capacities. The additional removal efficiency by tertiary treatment has been studied.