Material flow analysis and modelling of the feedstock potential for recycling polystyrene

Global plastic production has recently experienced dramatic growth, which is expected to accelerate. To reduce the environmental impacts related to plastic production and consumption, European policies call for increased plastic recycling. Polystyrene is a main commodity plastic with good recyclability; however, today, recycling levels for polystyrene are lower than those for other commodity plastics. To promote plastic circularity and increase polystyrene recycling, this study investigates feedstock availability for polystyrene recycling, using Finland as a case study. Key waste streams containing polystyrene are explored: municipal solid waste, plastic packaging waste, construction and demolition waste, as well as waste from electrical and electronic equipment. A spreadsheet-based material flow model was developed to estimate the extraction of polystyrene from waste streams in different scenario simulations. Data entered into the model was collected via literature review supported by expert interviews. This model can be applied to other regions by tailoring the input data. The results show significant potential for polystyrene recycling by implementing collection schemes for polystyrene at construction sites and by extracting polystyrene from separately collected plastic packaging waste and waste electronics, as well as by introducing industrial post-sorting of residual municipal solid waste. The findings indicate the potential of more than 10 thousand tonnes of polystyrene as feedstock for recycling, of which up to 5.2 thousand tonnes originate from the construction sector, 2.6 thousand tonnes from separately collected plastic packaging waste, 1.8 thousand tonnes from waste from electrical and electronic equipment, and 3.2 thousand tonnes from residual municipal solid waste. It can be concluded that there is significant potential for polystyrene recycling in Finland, which is partly driven by European recycling targets. However, a major obstacle for plastic recycling is related to the lack of data related to plastic waste flows.