The concept of a plastic item being “recyclable” is complex, often creating a gap between public perception and the operational reality of waste processing facilities. The vast majority of plastic produced globally is not actually recycled. This low rate highlights that the Resin Identification Code (RIC) only indicates the polymer’s chemical makeup, not whether local infrastructure can economically process it. Understanding non-recyclability requires examining the material’s chemistry, its physical form, and the economic systems governing its end-of-life management.
Plastic Types That Are Rarely Accepted
Certain polymer types are widely excluded from municipal recycling programs due to their chemical properties and low reprocessing value. These plastics, despite having a Resin Identification Code, are considered contaminants by many Material Recovery Facilities (MRFs).
Polyvinyl Chloride, or PVC (RIC #3), contains chlorine. When subjected to the high temperatures used in standard recycling, it releases hydrogen chloride gas, which is corrosive to machinery. Even a small amount of PVC mixed into a batch of other common plastics like PET or HDPE can contaminate the entire load, making the resulting material unusable.
Polystyrene (PS), designated as RIC #6, is rarely accepted, especially in its expanded foam state (Styrofoam). The foam is composed of up to 95% air, making it extremely bulky relative to its weight. This high volume-to-weight ratio means that collecting, transporting, and storing the material is not economically viable for most municipal programs.
Plastics labeled RIC #7, or “Other,” represent a diverse category, including multi-material laminates and bio-plastics. This variety makes them unrecyclable through conventional means, as MRFs are designed to sort pure streams of specific polymers. These items cannot be easily sorted by optical scanners and are often automatically rejected.
Physical Structures That Cannot Be Processed
A plastic item’s physical form can render it non-recyclable in curbside programs, even if it is made from a technically recyclable polymer. Automated sorting machinery relies on size and density and struggles to handle certain shapes and configurations.
Plastic films and bags, often made of recyclable polyethylene (#2 or #4), are a primary physical contaminant. These flexible materials wrap around the rotating screens and sorting equipment within a Materials Recovery Facility (MRF). This tangling causes mechanical failures, forces frequent and costly shutdowns for manual clearing, and endangers workers. Consequently, these films are almost universally banned from single-stream recycling bins.
Packaging made from multiple fused materials, such as multi-layer pouches for snacks or coffee, presents a structural barrier. These hybrids combine different plastics, sometimes with layers of foil or paper, to achieve properties like airtightness. Since the layers cannot be easily separated and melt at radically different temperatures, processing them via mechanical recycling results in a low-quality, unusable material.
Small, three-dimensional items also present a problem because they fall through the sorting screens designed to separate larger containers. Items like plastic straws, small caps, and blister packs are too diminutive for the machinery to capture. Items with non-plastic components, such as pumps with metal springs or scrub brushes with embedded metal wires, can also cause severe abrasion and wear in the processing equipment, leading to their rejection.
Systemic Reasons for Non-Recyclability
Non-recyclability is frequently a result of economic and logistical barriers within the waste management system, regardless of the plastic’s intrinsic properties. Since recycling is an industrial process, it must be economically sound to be consistently practiced.
Contamination is a significant systemic hurdle that can downgrade or ruin large quantities of otherwise recyclable material. Food residue, liquid, or non-recyclable materials mixed into a bale of plastic reduce the quality of the final product and increase processing costs. For example, a container of liquid or uncleaned food residue can contaminate an entire load of valuable plastic containers.
A lack of end-market demand for the recovered material also limits what is truly recyclable. If there are no buyers willing to purchase the processed plastic flakes or pellets, the facility must stockpile the material or send it to a landfill. This is often compounded by the fact that producing virgin plastic is frequently cheaper than processing recycled material, especially when global oil prices are low.
The high cost-to-value ratio is a constant economic pressure on Material Recovery Facilities (MRFs). The expense of collecting, sorting, cleaning, and reprocessing plastic often exceeds the revenue generated from selling the final recycled product. This economic reality means that even technically recyclable plastics that require extensive cleaning are often deemed non-recyclable in practice.
Responsible Disposal of Unrecyclable Plastics
For plastics that cannot be placed in the curbside bin, options exist for responsible disposal that divert material from landfills. The first step is to correctly place truly non-recyclable, contaminated items, such as food-soiled plastic containers, into the regular trash to avoid contaminating other streams.
Specialized drop-off locations are often available for plastic films and bags. Many large grocery or retail stores provide collection bins for clean and dry plastic films. These are then baled and sent to dedicated facilities for processing into items like composite lumber. These store drop-off programs handle materials that municipal sorting equipment cannot process.
Alternative, localized collection schemes also exist for plastics that are difficult to recycle. Companies like TerraCycle offer free or paid mail-in programs for highly specific waste streams, such as multi-layer snack packaging or coffee capsules. These specialized services partner with manufacturers to ensure a viable end-market for materials that the traditional municipal system is not equipped to handle.