Abstract
ABSTRACT Heavy metals contained in electronic waste, if discarded improperly, can become bioavailable after vermicomposting, posing a risk to the environment. Small-scale vermicomposting experiments were carried out with printed circuit boards (PCBs) to investigate the migration of heavy metals (Cu, Pb, Zn, Ni, and Sn) to the final compost, as well as the mobility and bioavailability of these metals. High total levels of Pb, Sn and Cu in samples of manure with electronic waste (MEW) and vegetables with electronic waste (VEW) were detected. Based on the initial metal levels in the PCBs and their concentration in the resulting compost, the order of migration of these metals to the MEW and VEW samples was Sn (23.1 %)>Pb (18.4 %)>Ni (4.63 %)>Zn (0.46 %)>Cu (0.14 %) and Sn (24.3 %)>Pb (23.6 %)>Ni (11.33 %)>Zn (1.76 %)>Cu (0.60 %), respectively. Mobility and bioavailability of these metals in the compost were evaluated by three-stage sequential extraction, where F1 was the exchangeable fraction, F2 the organic fraction and F3 the residual fraction. The bioavailability factor (BF) was calculated by the ratio of the sum of fractions F1 and F2 divided by the total sum of the fractions (F1 + F2 + F3). The highest bioavailability factor (BF = 0.92) was found for Pb, the heavy metal considered the greatest environmental concern in this study, indicating the high mobility and the possibility of becoming bioavailable of this metal.
Highlights
Electronic waste (e-waste) is the name given to residues of obsolete electronic equipment such as televisions, cell phones, computers, and other devices
Mobility and bioavailability of these metals in the compost were evaluated by three-stage sequential extraction, where F1 was the exchangeable fraction, F2 the organic fraction and F3 the residual fraction
The electronic waste (EW) sample was obtained from printed circuit boards (PCBs) of obsolete computers, from which the batteries had been removed
Summary
Electronic waste (e-waste) is the name given to residues of obsolete electronic equipment such as televisions, cell phones, computers, and other devices. The generation of e-waste is on the rise, mainly as a result of technological development that continuously shortens the life of electronic equipment. Cell phones are used for an average period of only 18 months before being replaced, even when still operational (EPA, 2011). Residues from electrical and electronic equipment already account for 8 % of municipal waste and constitute one of the fastest growing waste fractions (Widmer et al, 2005). Brazil is considered one of the largest producers of electronic waste in emerging countries. About 10 to 20 % of the phones produced in Brazil are discarded every year (Oliveira et al, 2012)
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