Analysis of heavy metal contents by using poly aluminum chloride water treatment residuals and their implications for land application

Abstract

Twenty four poly aluminum chloride water treatment residual (PACl-WTR) samples were analyzed for some important heavy metals using ICP-OES apparatus. Results showed that heavy metal contents of poly aluminum chloride water treatment residuals in the wet season were higher than those in the dry season. The order of magnitude in the residual metal concentrations of poly aluminum chloride water treatment residuals was Al > Fe > Mn > Ni > Zn > Ba > Cu > Cr > Pb > Co > Sb > As > V > Cd. Aluminum concentrations in poly aluminum chloride water treatment residuals were found lower than those levels in the alum sludge of other studies. Moreover, relatively high concentrations of heavy metals and origin of some metal contaminants such as As, Sb and V may be due to the poor quality of the poly aluminum chloride coagulant. According to the results of this study, the poly aluminum chloride water treatment residuals have the potential to be used on land, but for this purpose, considerations must be taken as to the existing background soil characteristics, particularly, the Cr and Ni concentrations.