Managing Heterogeneity in Postconsumer Polymer Waste: A Critical Review of TRL and Scalability of Advanced Upcycling Technologies

While the decarbonization of the chemical industry relies heavily on polymer circularity, current valorization strategies face a critical bottleneck: the intrinsic heterogeneity of postconsumer waste. Unlike idealized laboratory feedstocks, real-world streams contain complex mixtures and additives that severely compromise the thermodynamics process and catalyst stability. This review critically assesses the engineering gaps between laboratory-scale success (TRL 3–5) and industrial implementation (TRL 8–9) for PET, PP, PS, PVC, and PE upcycling. Specifically, the tolerance of these technologies to contamination and mixed feedstocks is evaluated. While conventional mechanical recycling offers significant energy savings (30–80% vs virgin production), its application is limited by material degradation and strict sorting requirements. Consequently, the technological maturity (TRL) and scalability of emerging upcycling routes are analyzed, including the enzymatic depolymerization of PET (TRL 4–5), solvent-based purification of PP (TRL 6), and tandem oxidation of PS (TRL 3–4). Special attention is given to overcoming the “chlorine barrier” in PVC recycling and the economic viability of transforming intractable polyolefin waste into high-value monomers via ethenolysis. It is concluded that achieving a circular economy requires shifting focus from simple waste management to integrated systems combining AI-driven sorting with feedstock-flexible chemical recycling to handle complex, real-world waste mixtures.