Quality degradation in glass recycling: substitutability model proposal

Area of Science:

• Environmental Science
• Materials Science
• Waste Management

Background:

• Sustainability assessment of waste management requires tools to evaluate material quality degradation during recycling.
• Existing research primarily focuses on plastics, with a gap in models for other materials like glass.
• Glass recyclability is often overestimated, neglecting factors like contamination and colour, leading to inaccurate Life Cycle Assessment (LCA) assumptions.

Purpose of the Study:

• To develop and assess a substitutability model for glass waste.
• To measure the extent of replacement between virgin materials and recycled crushed glass (cullet).
• To incorporate technical quality and market applicability into glass recycling impact assessments.

Main Methods:

• Formulated a substitutability model for glass based on technical quality (impurities, colour) and market demand.
• Applied the model to a European case study on glass waste treatment.
• Compared two scenarios: complete substitution versus substitution accounting for quality degradation.

Main Results:

• Accounting for quality degradation, only 83% of cullet effectively replaces raw materials.
• The benefit of glass recycling decreases by 13-23% across different impact categories when quality loss is considered.
• This contrasts with assumptions of complete one-to-one substitution.

Conclusions:

• Quality deterioration significantly impacts the actual benefits of glass recycling.
• The developed model provides a more accurate assessment of glass recycling sustainability.
• Future LCAs should incorporate material quality degradation for realistic waste management evaluations.