Table 4 Summary of PET recycling strategies discussed
PET Recycling Strategy | |||
|---|---|---|---|
Mechanical | Chemical (Methanolysis/Glycolysis) | Enzymatic | |
Strengths | • In some cases (i.e., using high-quality, low-contamination PET), it has the lowest cost and environmental impacts • Infrastructure is already in place | • Can handle contamination and mixed waste strams • Creates new presursors for high-quality PET synthesis | • Enzymes are highly-selective, able to handle low-quality, highly-contaminated waste • Creates direct presursors for high-quality PET synthesis |
Limitations | • Struggles with contaminants, mixed wastes, and some types of PET (e.g., thermoforms) • Downcycling puts a limit on the max number of recycling cycles per material | • Harsh process conditions are resource- and energy-intensive • Requires new infrastructure • Potential issues with product separation and purification | • Has mild reaction conditions, but is water- and energy-intensive, from base/acid additions, required PET pre-treatment, and EG distillation • Requires new infrastructure |
Contexts | • Could be improved by advanced sorting technologies • Can be complemented with chemical recycling for hard-to-recycle materials | • Could be improved through improved catalyst design, reagent recycle, and separations to improve yields and minimize energy and resource use | • Could be improved though enzyme enginering and process innovations (as discussed throughout the text) |
