Analysis of trade-offs of post-sorting plastic packaging

Area of Science:

• Environmental Science
• Materials Science
• Waste Management

Background:

• Increasing recycling rates necessitates improved plastic packaging waste collection.
• Source separation captures significant waste but struggles with misthrows and non-participation.
• Post-sorting of mixed waste is a proposed alternative to increase capture rates.

Purpose of the Study:

• To compare the quality of plastic packaging waste bales from source separation and post-sorting.
• To identify contaminants introduced by post-sorting and assess their impact on recycling.

Main Methods:

• Analysis of plastic packaging waste samples from a single material recovery facility.
• Comparison of bale purity, moisture, dirt, metal, and halogen content between source-separated and post-sorted streams.

Main Results:

• Bale purity was similar for both source-separation and post-sorting.
• Post-sorted bales contained higher levels of contaminants, including prohibited metals (cadmium, lead), moisture, and dirt.
• Elevated concentrations of metals and halogens in post-sorted waste may compromise recycling quality and complicate processes.

Conclusions:

• Post-sorting can supplement source separation by increasing feedstock but introduces contaminants.
• Contaminants in post-sorted waste pose risks to recycling quality and potentially human health.
• Source separation remains crucial and should not be replaced by post-sorting alone.