Physico-chemical characterisation of material fractions in residual and source-segregated household waste in Denmark

Abstract

Physico-chemical waste composition data are paramount for the assessment and planning of waste management systems. However, the applicability of data is limited by the regional, temporal and technical scope of waste characterisation studies. As Danish and European legislation aims for higher recycling rates evaluation of source-segregation and recycling chains gain importance. This paper provides a consistent up-to-date dataset for 74 physico-chemical parameters in 49 material fractions from residual and 24 material fractions from source-segregated Danish household waste. Significant differences in the physico-chemical properties of residual and source-segregated waste fractions were found for many parameters related to organic matter, but also for elements of environmental concern. Considerable differences in potentially toxic metal concentrations between the individual recyclable fractions within one material type were observed. This indicates that careful planning and performance evaluation of recycling schemes are important to ensure a high quality of collected recyclables. Rare earth elements (REE) were quantified in all waste fractions analysed, with the highest concentrations of REE found in fractions with high content of mineral raw materials, soil materials and dust. The observed REE concentrations represent the background concentration level in non-hazardous waste materials that may serve as a reference point for future investigations related to hazardous waste management. The detailed dataset provided here can be used for assessments of waste management solutions in Denmark and for the evaluation of the quality of recyclable materials in waste.

Contamination in plastic recycling: Influence of metals on the quality of reprocessed plastic

“…The concentrations of all metals, except for As, Fe, Cd and Ti, were within the same order of magnitude as reported in plastic waste samples by Götze et al (2016), whereas the concentrations of As, Fe, Cd and Ti were considerably lower. However, the findings in the review by Bach et al (2008) reported concentrations of Fe as low as 1.3 µg/g in PET mineral water bottles, which is within the same order of magnitude as the lowest Fe concentration measured in this study (3.40 µg/g).…”

“…However, the findings in the review by Bach et al (2008) reported concentrations of Fe as low as 1.3 µg/g in PET mineral water bottles, which is within the same order of magnitude as the lowest Fe concentration measured in this study (3.40 µg/g). The highest measured Cd concentration of 167 µg/g was exceptionally high compared to several other studies (reported in Götze et al, 2016), and it also exceeded the limit value of 0.01% Cd in plastic used for electrical and electronic equipment (EU, 2011a). Nevertheless, Burnley (2007) reported Cd concentration in plastic as high as 388 µg/g; moreover, this high concentration was only measured in a single sample of reprocessed PE plastic from HHW (group 2), which is a sample that also showed remarkably high Pb and…”

“…1D splitting is a mass reduction technique that aims to ensure representativeness of the final sample and reduce errors in sampling when compared to other mass reduction techniques (Dahlén and Lagerkvist, 2008;Lagerkvist et al, 2011). Additionally, it has been used previously for a variety of waste materials, including garden and household waste (Boldrin and Christensen, 2010;Götze et al, 2016). In this study, it was performed on a flat pile of coarsely shredded plastic that was split into equally sized increments, using a plastic box and a shovel.…”

“…Dutra et al, 2014;Cheng et al, 2010) and that has previously also been used for analysis of the total metal content in waste plastic (e.g. Götze et al, 2016). Yttrium and Scandium were added directly as internal standards.…”

“…Where the form of the metals, their hazardousness and exposure influence the potential risk to human health and the environment, the total metal content can be used to identify potential deterioration of material quality, which affects the applicability of the recycled plastic and thereby the circularity (Eriksen et al, 2018). Currently very limited knowledge exists about the fate of metals during plastic recycling, and metal contamination in plastic has been assessed previously only by focusing on one single source of plastic, polymer or metal (Götze et al, 2016;Bach et al, 2012;Romão et al, 2010). Consequently, there is a need to quantify and document the total metal content in conjunction with the plastic material quality, rather than potential health risks, as a first step towards coherently assessing the metal content in plastic collected from various steps in the recycling chain.…”