Environmental impact assessment of waste electronic and electric equipment (WEEE) management practices in developing countries through leaching tests

Abstract

Increasing quantities of domestic and imported waste electronic and electric equipment (WEEE) stimulates a rapid development of informal recycling activities in developing countries. This economically driven recycling, oftentimes based on open burning or acid-base treatment, followed by open dumping of the residues, does not usually fit environmental and public health requirements. For the underlying research, the hypothesis was formulated that the specific conditions of dumping of residues from informal recycling activities are enhancing the leaching of hazardous substances into the ground- or surface water. Hence, this paper aims at identifying major influencing factors that affect leaching behaviour of heavy metals from WEEE components and assess environmental impact of informal WEEE recycling and dumping practice. A set of leaching tests were carried out with a homogenized sample of printed circuit boards from personal computers. The results of the study show that the concentrations of Pb, Zn, Cd, Ni and Cu leached from the test material, is higher than the Dutch standard of heavy metals reference value in soil. In addition, under the toxicity characteristics leaching procedure (TCLP) extraction test, 6879 ± 1342 mg/kg dissolved organic carbon (DOC) was measured. It was also confirmed that the leachability of Pb and Cd exceeds the regulatory limit of TCLP. Lead was the predominant heavy metal to leach from the waste material and 5617±739 mg/kg Pb was released by the standard pH-controlled leaching test. The column leaching test results suggested that high amount concentrations of heavy metals released were washed out before a liquid to solid (L/S) ratios of 5. Similarly, from the column leaching trend 99.3% of DOC was leached in the lower L/S ratios of (upto L/S ratio of 2). The standard pH controlled test results indicated that heavy metals were highly mobile in the acidic pH ranges.

Key words: Printed circuit boards (PCBs), e-waste, leaching tests, heavy metals, dissolved organic carbon (DOC).