ABSTRACT.
The rate at which printed wire boards (PWBs) of obsolete electrical andelectronic equipment (EEE) are being disposed into the environment is questionable. This is because PWB, contain toxic metals at concentrations that could pose human and environmental threats if not properly disposed of. This study investigated the levels of Zn and Pb, in the PWBs extracted from 35 discarded EEE (15 mobile phones, 10 laptops, 5 desktop computers, 3 televisions, and 2 DVD players). The PWBs were separately crushed with Mechanical milling machine and sieved with 2mm sieve to enable effective extraction of the metals aforementioned. All samples were weighed in duplicate making the total of 70 samples. The metals were extracted using EPA method 3051A with reverse aqua regia of ratio 3:1(HNO3and HCl acids respectively). The extracts were analyzed for Pd and Zn levels using atomic absorption spectrophotometric (AAS) technique. The results were compared with the total threshold limit concentration (TTLC) of Pb and Zn, according to the California department of toxic substance control, (DTSC, 2004). This research revealed that the 82.9% of the samples contained high level of Pb above TTLC (1000mg/kg) and 62.3% of the samples contained high level of Zn above TTLC (5000 mg/kg). This research was in agreement with previous studies. PWBs should therefore, be handled and disposed of as hazardous waste.
