Investigation of the Leaching Characteristics of Heavy Metals from Waste Printed Circuit Boards through Column Testing with Simulated Acid Rain

Abstract

Waste printed circuit boards (PCBs) contain various heavy metals; hence, randomly discarded PCBs in open fields induce probable environmental risks when precipitation occurs, particularly acid rain (AR). We applied the column leaching method under simulated AR leaching to study the leaching characteristics of Cu, Pb and Zn in waste PCBs. Cu and Pb were easily leached by AR (pH 2 and 3) but not by distilled water (pH 5.6; CK treatment). By contrast, Zn could be leached readily even in CK treatment. AR with low pH exerted good leaching effects on Cu, Pb, and Zn. The heavy metal contents in the leachates were in the order of Cu > Pb > Zn. The maximum leaching concentrations of Cu, Pb, and Zn were 34.7, 4.06, and 1.15 mg/L, respectively, which are higher than drinking water standard set by the US Environmental Protection Agency. Therefore, waste PCBs can be considered a new source of heavy metal and pose potential environmental risks.