While I strive for the highest possible recycling rate, multi-material packaging is one of the most significant challenges. Many items that should be recyclable become a problem for recycling facilities, as even the smallest amount of additional material makes them challenging to handle.
Like many people, I become confused about how to recycle items. If a box has a glossy, water-resistant layer inside or outside the packaging, should I discard it? What about wax coatings on some food boxes? How about metal cans with the plastic layer inside?
While everyone should aim for high recycling rates, it’s important to remember that wishcycling isn’t the solution. It causes more problems for recycling facilities than consumers may realize. Knowing what multi-material items are and how they’re properly handled is essential, and it’s a responsibility we all share.
Not All Items Are Recyclable
An MIT Science Policy Review study found that almost 31% of materials sent to a materials recovery facility (MRF) aren’t recyclable. Contamination in a recycling stream results in more materials being sent to landfills than intended.
One of the most significant issues is the confusion surrounding multi-material products. Items that contain layers of paper fused with a foil interior pose a problem. The paper bag that coffee beans come in should be recycled; however, the foil or plastic layer inside the bag, which keeps moisture out, impacts the recyclability of that item.
The use of multi-material products also helps make packaging lighter. A lighter weight means lower shipping costs and consumption of fewer raw materials during production. That helps keep costs down for consumers. However, the lower price makes recycling more difficult.
Know the Materials
Recycling starts with knowing the materials used in multi-material packaging. This type of material often begins with a layer of paper or cardboard, which is easy to recycle on its own; however, the addition of aluminum foil or plastic complicates the process.
The plastic layer is often one of the following types of plastic.
- #1 – Polyethylene terephthalate (PET)
- #2 – High-Density Polyethylene (HDPE)
- #4 – Low-Density Polyethylene (LDPE)
- #6 – Polystyrene (PS)
Polystyrene isn’t as typical, but it’s essential to consider. The most common use is to have Styrofoam blocks glued into a box to provide cushioning for electronic items, such as computers. If it’s glued, Styrofoam isn’t recyclable, so you must carefully remove all of it before recycling the box.
Key Problems With Recycling of Multi-Material Products
Recycling starts with sorting, but once materials are sorted, they’re processed. This often includes shredding and melting down the materials to form them into new materials. Plastics can be formed into plastic pellets, which are used to create new materials.
While that’s the basics of recycling, it has intricacies that complicate the process. Once you place recyclables in your curbside container, they’re loaded onto a truck that brings them to the MRF. That’s where the complex steps begin.
1. Sorting Is Impossible
Sorters in an MRF use near-infrared (NIR) to identify and sort materials. Items travel on a conveyor belt through the sensors. Those sensors identify the material by analyzing the spectral signature of the infrared light on the object. It scans the results against the database of materials with that specific spectral signature.
When an item contains two or more materials, the sorter doesn’t know what to do. Those items end up in an “other” bin or are ejected directly to a truck for transport to the landfill.
While multi-material packaging can be recycled if the layers are separated, machines often fail to recognize this. It also adds additional steps that sorters don’t do. Carefully separating the layers of material is time-consuming and costly.
2. Recycling Requirements Vary Between Regions
Another complication is that recycling rules vary from one town or city to another. While one city might accept pizza boxes, another doesn’t. Your new hauler may not take batteries, but the city you moved from may have mandated battery recycling. It’s confusing.
When rules vary across the nation, it’s hard for consumers to have clear guidance on what is and isn’t recyclable. If you’re not certain, you may toss them out rather than try to figure it out. Or, you recycle them anyway and wish for the best, which is why it’s referred to as wishcycling.
Having a national system, such as Japan has, would be beneficial, but for now, it’s up to individuals to do as much as they can. If you look at Japan’s system, recycling is sorted by:
- Burnable waste – Items like apparel, diapers, face masks, food waste, paper that cannot be recycled, and vinyl
- Cans – Aluminum and steel
- Glass bottles and containers – Separated by color
- Non-burnable waste – Items like aerosol cans, broken glass, ceramics, and small appliances
- Other plastic materials – Items like plastic bags, coat hangers, food containers, straws, and toothbrushes
- Oversized waste – Items like bicycles, furniture, and large appliances
- PET bottles
- Recyclable paper – Items like books, cardboard, magazines, and newspapers
There are a few extra rules. Items like knives must be wrapped to prevent cuts and labeled as a sharp object. Rules often vary from one prefecture to another, but more sorting is done before items go to an MRF than happens with the standard zero-sort system in the U.S.
3. Materials Have Different Melting Points
Once items are sent to an MRF for recycling, they have to be sorted. This is important as the melting points of materials differ. You can’t process them all at the same temperature, as that would lead to some materials burning while others haven’t properly melted. Others might solidify as the temperature isn’t hot enough.
Look at the different melting points.
- PS – 338 to 536 ºF
- LDPE – 356 to 464 ºF
- HDPE – 410 to 518ºF
- PET – 500 to 536 ºF
When items are mixed and melted at a single temperature, the quality of the recycled material is poor. If the quality of the recycled plastic pellets isn’t good enough, it’s not easy to reuse them. The energy and time spent recycling are wasted.
When there are mixed materials, they need to be carefully separated. Plastic films can become tangled in equipment, making hand sorting ideal, but it’s time-consuming and requires additional workers. Costs increase to the point that it’s cheaper to put them in the landfill. It’s not the right solution, even if it is more affordable and easier.
The Key to Improving Recycling Rates
Recycling multi-material packaging isn’t one group’s problem. It’s not up to consumers or MRFs; it’s also something manufacturers and producers need to address. If everyone teams up and does their part, recycling rates will soar.
Japan’s recycling and waste program is complex, but a town in the Tokushima Prefecture reached 80% of the way towards its zero-waste goal in 2023. It’s possible if everyone does their part.
When you purchase goods, consider where they came from and what happens to them at the end of their life. A circular economy requires thought in what you buy. Goods made with recycled materials are beneficial, but you also need to consider what happens down the road.