Abstract:

This study quantified the environmental footprint of recycled polypropylene （PP） used in lunch box production by applying a life cycle assessment framework integrated with the circular footprint formula. The assessment evaluated impacts including global warming potential （GWP）， abiotic fossil resource depletion （ADPf）， human toxicity potential （HTP）， ozone depletion potential （ODP）， acidification potential （AP）， and eutrophication potential （EP）. The results for the recycling process， from waste lunch boxes to regenerated PP particles， were determined as follows： 1.837 kg CO₂⁃eq （GWP）， 39.766 MJ （ADPf）， 4.218 kg 1，4⁃DB⁃eq （HTP）， 3.275E⁃08 kg CFC⁃11⁃eq （ODP）， 0.006 kg SO₂⁃eq （AP）， and 0.002 kg PO₄⁃eq （EP）. The initial waste lunch box collection was the dominant contributor， accounting for 84.0 % to 94.9 % of each impact category， while electricity consumption contributed 1.60 % to 14.0 %. Compared to virgin PP processing， the GWP of recycled PP was 49.5 % lower. Normalization analysis revealed that GWP， ADPf， and HTP together constituted 85.2 % and 88.1 % of the total environmental load in Scenarios A and B， respectively. Sensitivity analysis demonstrated that the choice of allocation method significantly influences the results. The cut⁃off allocation method yielded the lowest environmental impacts for the recycled product， whereas the 50/50 allocation method was found to potentially overestimate impacts for secondary materials.

Key words: recycled plastics, carbon footprint, lunch box recycling, life cycle assessment, sensitivity analysis