Operational Framework to Quantify Quality of Recycling across Different Material Types

Many pledges and laws are setting recycling targets without clearly defining quality of recycling. Striving to close this gap, this study presents an operational framework to quantify quality of recycling. The framework comprises three dimensions: the Virgin Displacement Potential (VDP); In-Use Stocks Lifetime (IUSL); and Environmental Impact (EI). The VDP indicates to what extent a secondary material can be used as a substitute for virgin material; the IUSL indicates how much of a certain material is still functional in society over a given time frame, and the EI is a measure of the environmental impact of a recycling process. The three dimensions are aggregated by plotting them in a distance-to-target graph. Two example calculations are included on poly(ethylene terephthalate) (PET) and glass. The results indicate that the recycling of bottle and container glass collected via a deposit-refund system has the lowest distance-to-target, at 1.05, and, thus, the highest quality of recycling. For PET bottles, the highest quality of recycling is achieved in closed-loop mechanical recycling of bottles (distance to optimal quality of 0.96). Furthermore, sensitivity analysis indicates that certain parameters, e.g., the collection rate for PET bottles, can reduce the distance-to-target to 0.75 when all bottles are collected for recycling.

Automated summary

Many recycling targets lack a clear definition of recycling quality. This study proposes an operational framework that quantifies recycling quality using three dimensions: Virgin Displacement Potential (VDP), In-Use Stocks Lifetime (IUSL), and Environmental Impact (EI). The framework is applied to PET and glass, showing that bottle and container glass recycled through a deposit-refund system has the highest quality, while closed-loop mechanical recycling of PET bottles achieves the highest quality. Sensitivity analysis demonstrates that improving collection rates could greatly enhance recycling quality.