Evaluation of Pb and Cu contents of selected component parts of waste personal computers

Electronic waste (e-waste) is one of the fastest growing waste streams in the world. The increasing market penetration in developing countries such as Nigeria, replacement market in developed countries and high obsolescence rate, make e-waste one of the fastest growing waste streams. Thirty five (35) units of waste computer central processing unit (CPU) and 24 units of waste computer monitors of different brands, manufacturers, year of manufacture, and model were collected from different electronic repairers’ shops in Ibadan, South-western Nigeria and investigated for the lead and copper contents. The devices were disassembled and the printed wiring boards (PWB) of the CPUs and monitors; and the cathode ray tube (CRT) of the monitor were milled and representative samples digested with a mixture of HNO₃-H₂O₂-HCl and analysed using Atomic Absorption Spectrophotometry (AAS). The results showed very high levels of Cu and Pb in the samples with Cu concentrations ranging from 83100-705300 mg/kg for PWB of CPUs, 39150-630300 mg/kg for PWB of monitors and 73.2-468 mg/kg for CRT. The Pb contents varied from 18060-400650 mg/kg for PWB of CPU, 8460-80850 mg/kg for PWB of monitor and 429-9900 mg/kg for CRT. The results exceeded the Toxicity Threshold Limit Concentration (TTLC) used in characterizing wastes as toxic. The adoption of inappropriate methods in the management of these wastes could result in environmental pollution and human exposure to toxins. Consequently, appropriate measures should be adopted to manage these wastes as hazardous wastes.

Keywords
personal computers; printed wiring board; computer monitor; lead; copper