Effectiveness of WEEE mechanical treatment: separation yields and recovered material toxicity

Waste Electrical and Electronic Equipment (WEEE) is one of the fastest growing waste flow in developed countries. Although it is being regarded as an urban stock due to its composition in terms of valuable materials, the presence of hazardous substances raises great concern for their possible adverse effects on both human and environmental health. This work focuses on assessing the distribution of toxic materials after WEEE mechanical processing. Both input waste and output flows were sampled at a full-scale plant and characterised by their chemical-physical composition and toxicological response. The NOAEL concentrations were also estimated for each analysed flow. Experimental results showed that the mechanical selection process was efficient in removing the plastics from the metallic scraps, mainly aluminium and copper. However the latter output fractions were characterised by a higher potential toxicity than the input waste. This outcome suggests the need for further improvement of separation yields, in order to reduce the interactions among the hazardous substances affecting the toxic response of recovered materials. The content of these substances in electrical devices should also be lowered, so that the identification of NOAEL concentrations, evaluated in the present study as a first attempt in this direction, could be a suitable strategy.