There has been an increased focus on special waste types (WEEE, batteries, ink cartridges and cables) in Denmark and abroad, as many of these fractions constitute a special threat to the environment, due to their content of hazardous compounds and valuable resources. Waste Electrical and Electronic Equipment (WEEE) and batteries are some of the special waste types receiving significant focus as hazardous and valuable substances in WEEE and batteries are plentiful. WEEE and batteries, which are not sorted out for recycling
and recovery, do not only imply a loss of materials and metals but could also lead to pollution of other waste streams. In addition to this, there are significant environmental benefits to be obtained when recycling special wastes.
Many of the raw materials found in special waste are in an immediate supply risk for the development of emerging green technologies. The inherent resources in waste have become an obvious focus as a source of these critical raw materials, and the municipal solid waste is considered to be one of the largest potential sources for the recovery and recycling of scarce elements.
Special waste streams should, therefore, be collected and recycled. In particular, precious and scarce metals should be recovered due to environmental as well as sustainability issues.
In Denmark, there are still waste flows that are unaccounted for. One of these flows is the special waste that is being misplaced with residual household waste. Bigum et al. (II) investigated this by conducting a sorting analysis of the Danish residual household waste. The analysis showed that especially small household appliances, lamps, toys, leisure and sports equipment, and portable batteries were frequently misplaced with residual household waste. Misplaced special waste will, in Denmark, be incinerated. This leads to pollution of the surrounding environment with heavy and toxic metals, as well as being a significant source for abiotic resource depletion (Bigum et al., III).
Improvements with respect to the treatment of special waste are necessary. Traditional pre-treatment facilities seem to focus primarily on the traditional
metals such as iron (Fe), aluminium (Al), and copper (Cu), which can be recovered in bulk amounts. Recovery of the precious and scarce metals is to a lesser degree carried out, as these appear in much smaller amounts. Future recovery facilities should, however, aim at recovering these metals, even though they appear in smaller concentrations, as the recovery of these can have larger environmental relevance exceeding that of the traditionally recovered metals (Bigum et al., I).
Life cycle assessments (LCAs) are used as decision-making tools for supporting waste management decisions. LCAs must therefore also be able to incorporate issues related to special waste streams and management. The ability for LCAs to incorporate these issues is crucial for the tool to be able support decisions and to further justify the use of waste-LCAs when decisions are made.
One of these issues is related to special waste being a very heterogeneous waste type. The variation in composition is significant and data availability is scarce, which can make it difficult to include special waste in waste-LCAs. This also means that the environmental aspects connected with the special waste types can be difficult to fully assess, and that the consequences of these may risk being overlooked or underestimated.
The field of environmental assessment of special waste is relatively new, and many issues need to be resolved. One of these issues is the evaluation of resource depletion and scarcity. This area is in need of a much broader consensus and further scientific development in order to ensure that LCA is applicable and accepted as a decision-making tool.
This thesis shows the importance of including a detailed composition of the special waste types, as well as the importance of incorporating the resource depletion of unrecovered elements in waste-LCAs (Bigum et al., III). The thesis also shows that the recycling of metals is of significant environmental importance (Bigum et al., I) and quantifies the amount of special waste types being misplaced with residual household waste (Bigum et al., II). The thesis also concludes that there are still many issues that need to be resolved and suggested which areas need further research in order to improve the field of environmental assessments of special waste types.