Environmental Impacts of PET Chemical Recycling: A Case Study on Alkaline Hydrolysis and Systemic Evaluation

Abstract

Polyethylene terephthalate (PET) is one of the most widely used polymers, but its durability and versatility generate significant end-of-life challenges. While mechanical recycling remains the predominant option, its limitations in quality loss and ability to treat complex waste streams highlight the need for complementary solutions. Chemical recycling offers the potential to regenerate virgin-quality PET and handle waste fractions not suitable for mechanical routes, yet its environmental performance is still to be fully explored. This study presents comprehensive insights into an innovative chemical recycling process for PET, consisting in microwave-assisted alkaline hydrolysis. An attributional Life Cycle Assessment (LCA) was conducted to quantify the environmental impacts associated with the innovative system and to provide a comparison with virgin and biobased PET. Scenario analysis investigates the replacement of the fossil fraction of the electricity mix with renewable energy. An analysis of the complementarity between chemical and mechanical recycling in the European market has been carried out to implement a systemic approach. Results highlight substantial reductions in greenhouse gas emissions when renewable energy is adopted, but also show trade-offs in biobased PET scenarios. The combined use of chemical and mechanical recycling emerges as essential to maximize circularity while minimizing environmental burdens, underscoring the need for systemic, multitechnology strategies in PET waste management.