Hybrid Recycling of Polyvinyl Chloride and Polyethylene Terephthalate: A Life Cycle and Technoeconomic Assessment

With global plastic waste accumulation growing, effective
recycling
approaches are in increasing demand. We propose a recycling system
capable of recovering polyvinyl chloride (PVC), diisononyl phthalate
(DINP), and polyethylene terephthalate (PET) from mixed waste consisting
of tarpaulins and wire harnesses. The system combines selective dissolution
(SD) to extract PVC and DINP and enzymatic hydrolysis to reduce PET
to monomers terephthalic acid and ethylene glycol, which are then
repolymerized. Life cycle assessment shows that recycled PVC (r-PVC)
has lower environmental impacts than virgin PVC in several categories,
including acidification (15% lower), ozone depletion (91% lower),
land use (99% lower), and freshwater eutrophication (29% lower). Despite
these improvements, r-PVC underperforms in key metrics such as climate
change (75% higher), energy demand (37% higher), and carcinogenic
toxicity (1103% higher). Steam production for distillation is the
primary contributor to most impact categories followed by residual
PVC waste treatment and electricity demand. Results also show that
recycled PET underperforms in 24 of 25 impact categories with ozone
depletion being the only improvement relative to virgin PET. The primary
contributor is the physically allocated impact from the SD subprocess
used to separate and recover the PVC and PET individually, indicating
that reductions in this subprocess are necessary for environmental
sustainability. Scenario analyses show that ameliorating these impacts
depends on sustainable steam sourcing and alternative waste disposal
practices for PVC. Technoeconomic analysis reveals that the valorization
process cannot achieve price parity with virgin PVC primarily due
to high wire harness feedstock procurement. Although the system currently
lacks environmental and economic sustainability under current design,
operating, and pricing strategies, this study offers opportunities
for process optimization and establishes a foundational methodology
for developing hybrid plastic recycling systems.