Low-Carbon Valorization of Waste PE Mulch Film: A Carbon Footprint Comparative Analysis of Typical End-of-Life Treatment Pathways

Widespread polyethylene (PE) mulch film application has caused severe farmland plastic pollution and greenhouse gas emissions. To identify low-carbon end-of-life pathways for waste agricultural mulch film, this study established a full life-cycle carbon footprint model comparing three treatment scenarios—incineration, mechanical regranulation, and pyrolysis, each coupled with residue landfilling—under two accounting conditions: with and without carbon-compensation credits from by-product substitution. Using 1 t of waste film as the functional unit and an 8 km2 farmland plot (110.4 t of applied film) as the reference scenario, cradle-to-grave emissions were quantified. Without compensation, regranulation delivers the lowest emissions (519.17 t CO2 eq), 12.02 t CO2 eq below pyrolysis. With compensation credits, pyrolysis achieves the lowest net emission (247.82 t CO2 eq, 248.10 t CO2 eq less than regranulation), but this advantage arises from avoided emissions of product substitution rather than lower direct emissions. The per-tonne carbon footprint ranks pyrolysis (2.24 t CO2 eq) < regranulation (4.49 t CO2 eq) < incineration (5.15 t CO2 eq). A proposed 5400 t/year pyrolysis facility yields an annual net carbon reduction of 1082.16 t CO2 eq. These results inform differentiated disposal strategies for major mulch-film-covering provinces.