A framework to assess plastic recycling efficiency of the primary and final processors

Efficient plastic recycling depends on both collection and sorting by the primary processor as well as the processing by the final processor. This study proposes an integrated framework incorporating primary and final processors to evaluate plastic waste recycling efficiency in an industrialized nation from 2012 to 2021. Three original indicators: Primary Diversion Rate (PDR), Efficiency of the Primary Processor (EPP), and Efficiency of the Final Processor (EFP) were proposed to develop a composite efficiency indicator, Efficiency of the Plastic Recycling System (EPRS). Plastics were categorized into three groups: Low (ABS, thermosetting plastic, phenolic resins), Medium (LLDPE, PVC, PS) and High (HDPE, PET, LDPE, PP) based on their cumulative recycled amounts in Canada. The High and the Medium groups showed increasing PDR trends (+5.00<S<+39.00), while the Low group declined, suggesting insufficient diversion. Interestingly, primary processors sorted the Low group plastics more efficiently than the Medium group, with median EPP values of 24.23 % and 15.20 %, respectively. However, EPP trends declined across 18 resin types (-35.00<S < -3.00), indicating worsening sorting and baling performance. In contrast, EFP remained high (78.91 %-80.72 %) and stable (interquartile range: 1.88-4.60) across all groups. Despite this, EPRS remained low (39.42 %-52.81 %) and declined over time, with the sharpest decrease in the Low group. These findings underscore the urgent need to improve diversion rates for the Low and the Medium groups and enhance sorting and baling efficiency to strengthen Canada's overall plastic recycling system.