Multidimensional Sustainability Assessment of Chemical Valorization Pathways for PET Waste: A Literature-Based Early-Design-Stage Index Including Technology Readiness

Abstract

Inadequate waste-management practices have led to significant environmental impacts, requiring the development of sustainable valorization alternatives. The exponential growth of plastic waste represents a major challenge that must be addressed through coordinated global strategies. Among polymers, polyethylene terephthalate (PET) is one of the most produced and used worldwide, mainly for food and beverage packaging. It offers significant opportunities for the implementation of circular economy practices due to its inherent properties. Chemical processes can effectively return PET to its original components by molecular transformation, facilitating its reintegration into the production cycle. This study established a sustainability assessment for the chemical valorization of PET waste, incorporating technological, economic, environmental, and social dimensions with their corresponding indicators, all based on data compiled from a comprehensive literature review. The technological dimension was defined to allow the decision-maker to compare the technological readiness level (TRL) of each pathway. A Sustainability Index (SI), using selected indicators, was developed and applied to evaluate seven chemical valorization pathways. The sustainability assessment identified the top three alternatives in a base case: glycolysis as the most sustainable pathway (SI = 0.20), followed by basic hydrolysis (∼0.22) and microbiological degradation (∼0.25). Additionally, a sensitivity analysis was conducted by varying the level of importance of the dimensions, revealing the most influential factors for each valorization pathway. These findings underscore the potential of these alternatives to address the complex challenge of PET waste management, offering more sustainable solutions compared to conventional practices such as landfilling or incineration.