Session 10

Do the benefits of avoiding the use of virgin materials outweigh extra efforts for recycling into high-grade products? A case study of plastic waste recycling into a green roof tile
Sophie Huysveld1, Karen Van Kets2, Sara Hubo2, Kim Ragaert2, Jo Dewulf1
1Department of Sustainable Organic Chemistry and Technology, Ghent University, Belgium; 2Department of Materials, Textiles and Chemical Engineering, Ghent University, Belgium

Recycling gives second life to waste, thereby avoiding the use of virgin materials. In case of more difficult to recycle plastic fractions (e.g. the sink fraction after float-sink separation of post-consumer packaging waste), the recycled material is still mainly used in low-grade thick-walled products, e.g. street poles and benches, because of technical challenges. For waste suppliers, this can be an economic barrier to seek business opportunities with recycling companies, i.e. when the return from selling the waste seems not worth the effort of establishing a recycling value chain. Consequently, the waste might be incinerated and, thereby, ending the material’s life. Recycling into high-grade applications on the other hand may require extra efforts before the waste stream is technically suitable to be used. These processing steps lead to additional resource consumption, which may question the environmental benefits of recycling. There is a need to investigate whether the benefits of avoiding the use of virgin materials outweigh extra efforts for recycling into high-grade products. Calculation of the recyclability benefit rate indicator, i.e. the ratio of the environmental savings that can be achieved from recycling the product over the environmental burdens of virgin production followed by disposal(1), fits this purpose. This study’s objective was to apply this indicator to a case of plastic household waste recycling into a high-grade application, comparing to an incineration scenario. We focus on the difficult to recycle sink fraction, which is used to produce a green roof tile. The recycling chain is subdivided in two main parts. First, shredding, depollution, float-sink separation, drying, wind sifting and milling into granules. The second part includes steps to further process the sink fraction granules, i.e. PVC and aluminium removal, drying and injection moulding. Results will be presented at the conference.