Heavy Metal Removal from Incineration Bottom Ash through Washing with Rainwater and Seawater

Augustine Quek, Wenyu Xu, L

Abstract

The use of incineration bottom ash (IBA) for practical applications requires overcoming the environmental impacts from its use. As IBA contains numerous potential pollutants, especially heavy metals, the use of IBA for practical applications would expose the surrounding environment to risks of heavy metal pollution. One possible, practical way to overcome the problem is pre-treat IBA through washing with naturally collected waters like rain and seawater. Repeated washing with fresh batches of rain or seawater each week over fifteen weeks could reduce heavy metal content by 6-7%. The final concentrations of heavy metals in the wash water were reduced to 27-57% of the initial concentration. However, the reductions varied greatly among the different heavy metals. Only half of the heavy metals analyzed showed a decreasing trend with increasing number of washings for both rain and seawater. Specifically, the final concentrations of all heavy metals in rain water were below the National Environment Agency’s watercourse discharge limits, except for copper, while washing with seawater could reduce all heavy metals below the discharge limits. Antimony and arsenic concentrations did not show decreasing trend with increasing washings with both rain and seawater.