Abstract:

In this paper, the basic physicochemical properties such as the water content, the ash content and the pH value of 7 sludge samples collected from different aluminum-anodizing plants were analyzed, and the chemical compositions of the samples, as well as the contents and leaching characteristics of the heavy metals in the samples, were investigated. The results show that （1） all aluminum-anodizing sludge samples are slightly neutral to mild basic with more than 50% Al₂O₃; （2） the total contents of Cu, Pb, Zn, Ni, Cd and Cr in the 7 sludge samples are of similar distribution; and （3） the contents of Cu, Zn, Ni, and Cr are relatively higher than those of Pb and Cd. Moreover, leaching toxicity tests indicate that the aluminum-anodizing sludge is nonhazardous and the heavy metals in it are significantly different in leaching behaviors, possibly due to their total contents and to the final pH value of the leachate as well.

Key words: aluminum-anodizing sludge, physicochemical property, heavy metal, leaching toxicity, leaching characteristic