Life cycle assessment of plastic packaging recycling embedded with responsibility distribution as driver for environmental mitigation

Life cycle assessment modelling of multi-cycle recycling systems is challenging. There is still nei-ther consensus on applying allocation approaches nor a one-size-fits-all solution. This study pro-poses an allocation approach embedded with the responsibility distribution of stakeholders rather than the standard approach, which is assessed based on stages. It is applied to the case study of plastic packaging recycling and compared to simple and economic allocation cut-off methods. A total of four multiple recycling or cascade utilisation scenarios are assessed, consist-ing of the linear system (disposal), mechanical recycling, waste to energy and chemical recycling, for at least one of the cycles. Scenario 2, with mechanical recycling as the end-of-life manage-ment in all three multiple cycles, has the lowest overall GHG emissions (similar to 4.8 t CO2eq/t plastic packaging) regardless of allocation method, even after considering deducted savings due to the degraded quality along the cycles. The simple cut-off method could not drive the selection in the first cycle toward the recycling alternatives (Scenario 2-4) with overall lower emissions as the GHG saving from utilising recycled resources are accounted for in the second cycle. Regarding eu-trophication potential, as the burdening impact of disposal is significantly higher, recycling op-tions accounted for following the simple cut-off method are preferable even when the burdening effect is entirely embraced by the first cycle without the unburdening accounting. Economic allo-cation cut-offs provide a better incentive to recycle in the assessed cycles. However, the standard accounting is by stages such as material production, product manufacturing, recycling and dis-posal. It is unclear whose responsibility, either the raw material producer (MP), the product man-ufacturer (PM) or the consumer (C). The proposed method with defined responsibility (e.g. 6.2 t CO2eq/t by MP; 2.9 t CO2eq/t by PM; 0.5 t CO2eq/t by C in Scenario 1) is more effective for envi-ronmental mitigation strategies (e.g. taxation and incentives, deposit refund scheme) of the plas-tic life cycle. The scenarios assessment serves as a stepping stone to optimise the allocation among the identified stakeholders in future work according to local conditions.