Evaluation of Heavy Metal Release from the Disposal of Waste Computer Monitors at an Open Dump

Abstract

Large quantities of waste computer monitors are presently being disposed in Nigeria. As much as 2.4 million units of 'used' computer monitors are imported annually into the country. Significant proportions of these imported devices are non-functioning and are never reused, but rather disposed of at open dumps. This study simulated the breaking of cathode ray tubes at open dumps and assessed the total available metals in the cathode ray tube glass; the printed wiring board and plastic components as well as the ability of rainwater to leach and mobilize the metals through batch extraction using weak electrolytes (CaCl 2 , Ca(NO 3 ) 2 , and H 2 O). The total lead concentration (mg/kg) of the monitor components ranged from 645-2892 (mean 1271918); 11.1-117 (45.644.2) and 3860-4581 (4129290) in cathode ray tubes, plastic and printed wiring board samples respectively. The chromium concentrations in the components were generally <115mg/kg. The extractable Pb from the cathode ray tubes and printed wiring board failed to pass the established limit for leaching tests such as the toxicity characteristic leaching procedure limits used in toxicity characterization of solid waste (5mg/l). High Pb concentrations, 1.3-12% of the total lead, were leached by the weak electrolytes (53.77.74 -24833.3mg/l), and this is between 10-50 times the toxicity characteristic leaching procedure limit. The results of this study reveal the dangers of inappropriate management of computer monitors, especially the disposal at open dumps or with municipal solid waste.