Common Issue with Recycling Plastic Grocery Bags

Plastic grocery bags often end up in recycling bins¹ despite being unsuitable for standard curbside recycling systems. Their inclusion causes significant operational issues at recycling facilities and compromises the quality of other recyclables.

The primary issue with recycling plastic grocery bags is their tendency to wrap around the rotating machinery at Material Recovery Facilities (MRFs)², leading to equipment jams³, facility shutdowns, and contamination of recyclable materials.

How Plastic Bags Affect Recycling Machinery

Plastic bags are lightweight and flexible, which makes them incompatible with automated recycling equipment. Rather than following the intended sorting paths⁴, they get entangled in the rotating shafts, screens, and gears of sorting machines. This results in mechanical failures, overheating, and forced shutdowns, requiring manual removal by workers.

Sorting System Challenges

MRFs use rotating screens—such as trommels or disc screens—to separate materials by size and shape. The process distinguishes between:

• 2D items (e.g., paper): Meant to travel across the surface of screens.
• 3D items (e.g., bottles, cans): Designed to fall through screen gaps.

Plastic bags do not behave predictably in this system. While flat like paper, they are too light and pliable, allowing airflow and mechanical movement to pull them into machinery components, where they tangle and obstruct movement.

Material	Intended Sorting Path	Disruption Caused by Plastic Bags
Cardboard	Travels over screens to the paper sorting line	Can be pulled into the container stream
Plastic Bottles	Falls through screen gaps	Can be trapped by entangled plastic film
Aluminum Cans	Sorted by eddy current separators	Can be blocked or misdirected due to bag tangling
Plastic Bags	Not meant to enter the system	Wraps around components and causes equipment jams

Operational Impacts

• Emergency Shutdowns: A single plastic bag can trigger stoppages across the sorting line.
• Manual Removal: Staff must climb onto machinery using safety gear to cut away tangled film with utility knives—a hazardous and labor-intensive task.
• Equipment Wear: Repeated jams increase mechanical stress, leading to premature failures and costly maintenance.

Why Plastic Bags Are Not Suitable for Curbside Recycling

Curbside recycling systems are optimized for rigid materials like bottles and cans. Plastic bags and other film plastics disrupt this system and reduce the quality of recyclable outputs.

Curbside programs are not designed to handle plastic film. Bags bypass sorting systems, damage machinery, and cause contamination of otherwise recyclable materials.

Contamination Issues

Plastic bags are a common source of contamination, especially for paper:

• Pulping Process: Paper is turned into pulp using water and chemicals. Plastic does not break down and creates "stickies"—small clumps that affect paper quality.
• Rejected Shipments: Excessive contamination leads paper mills to reject entire bales, sending valuable material to landfills instead.

Mis-Sorting Risks

Plastic bags are often misclassified by optical and airflow sorting systems. Their light weight and shape can cause:

• Bags to be blown into incorrect streams.
• Optical sorters to misidentify bags filled with other recyclables.

Item Category	Acceptable in Curbside Bin	Why It Works	Not Acceptable	Why It Fails
Plastics	Bottles, jugs, tubs (#1, #2, #5)	Rigid shape allows proper sorting	Plastic bags, wrap	Tangles in machinery
Paper	Newspaper, cardboard, mail	Flattens and moves predictably	Soiled/greasy paper	Contaminates paper pulp
Metal	Aluminum & steel cans	Sorted via magnets and eddy currents	Wire, hangers, scrap	Wraps around components

Correct Way to Recycle Plastic Grocery Bags

Plastic grocery bags should not be placed in curbside bins. Instead, they should be collected and returned to designated store drop-off locations⁵.

Proper recycling of plastic grocery bags⁶ involves returning them to retail drop-off bins, commonly located at grocery or big-box stores.

Store Drop-Off System

This system separates plastic film from mixed recyclables:

1. Collection: Consumers collect clean and dry plastic film at home.
2. Drop-Off: Items are placed in designated bins at retail stores.
3. Bundling: Retailers consolidate film into bales.
4. Specialized Processing: Bales are sent to facilities that handle polyethylene (PE) film.
5. New Products: Recycled plastic becomes material for decking, benches, or new bags.

Accepted vs. Unaccepted Film Items

Accepted Items (Clean & Dry)	Unacceptable Items
Grocery and retail bags	Chip bags, candy wrappers
Bread and newspaper bags	Salad bags, frozen food packaging
Dry-cleaning bags	Pet food bags, compostable bags
Reclosable food bags (clean)	Items with food residue
Bubble wrap and air pillows (popped)	Multi-layer laminated pouches
Plastic shipping envelopes (labels off)	Metallized or black plastic

Visit plasticfilmrecycling.org for local drop-off sites.

Impact of Bag Design on Recyclability

Plastic bag design directly influences how easily the material can be recycled.

Designing bags with mono-materials⁷ (e.g., HDPE or LDPE), avoiding certain pigments, and limiting additives improves their recyclability.

Material Composition

Bag Type	Material Example	Recyclability	Reason
T-Shirt Bag	Mono-material (HDPE)	High (store drop-off)	Single polymer is easy to process
Bread Bag	Mono-material (LDPE)	High (store drop-off)	Clean LDPE can be reprocessed
Laminated Pouch	Multi-layer (PET/PE/EVOH)	Very Low	Layers are fused and cannot be separated
Chip Bag	Metallized film	None	Metalized layer interferes with processing

Additional Design Factors

• Color: Optical sorters use infrared light; black plastic is often undetectable, reducing recyclability.
• Recycled Content: Machines must accommodate variability in post-consumer recycled (PCR) materials. Advanced tension control systems help stabilize production.
• Material Innovation: Engineering advances allow production with biodegradable films⁸ or high-PCR content, aligning with sustainability goals.

Conclusion

The main challenge with plastic grocery bag recycling is their incompatibility with standard recycling equipment, leading to mechanical jams and contamination. Effective recycling requires two solutions: consumer use of store drop-off programs and manufacturer focus on recyclable, mono-material bag designs.

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