The Plastic Recycling Process
Recycling is a complex, reverse supply chain that begins in millions of households when an empty container is tossed in a bin. Understanding the process is the first step in improving it.
A Fascinating and Complex Journey
In 2022 over 5 billion pounds of plastic packaging was recycled in the U.S., driving jobs and revenue, reducing natural resource extraction and greenhouse gas emissions, and helping the country move towards a circular economy. But how did those 5 billion pounds of plastic get recycled? What happens after someone tosses that plastic bottle or container into the recycling bin? Scroll down to follow this amazing journey.
Step 1: The Recycling Bin
Whether a container is placed in a curbside recycling bin, a public recycling bin at the airport or dropped off at a community recycling center, this is where it starts.
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When the right material gets into the recycling bin, that material gets recycled. It’s important that we all know what can and cannot be recycled in our community. Check your community recycling website, use RecycleCheck with your zip code, or follow these general guidelines:
- In most communities, #1 PET bottles, #2 HDPE bottles, and #5 PP containers can be recycled.
- Empty any remaining food/product, rinse if necessary, and put caps back on bottles.
- Do NOT recycle plastic bags or any flexible films (e.g., shrink wrap, zip lock bags) in curbside bins unless a program specifically calls for them. Those should be collected and returned to store drop-off locations.
Step 2: Haulers
Haulers collect post-consumer materials from the curbside recycling bins, and take it to a material recovery facility (MRF)
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Occasionally haulers use one truck to collect both recycling & trash. In this situation, it may look like a garbage collector is tossing carefully separated items into the same big pile. But there is actually a divider in the truck, and trash goes on one side and recycling on the other. Materials stay separate so that those recyclables can be sorted and reprocessed into new materials, and avoid the landfill.
Step 3: Material Recovery Facilities (MRFs)
MRFs sort through all the recyclables and divide them into categories like aluminum, paper, and different types of plastic. The goal is to sort and bale each material so that it can be sold to the correct market.
TIPPING FLOOR
All the recyclables are tipped out of the trucks onto the floor in a giant pile, and then loaded onto a conveyor belt to start their journey. This is a mix of plastic, paper, metal, glass and more.
PRE-SORT
The materials on the conveyor belt then go through pre-sorting, where MRF workers pull out non-recyclable materials which could be anything from electrical cords to food to bowling balls.
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These items are called contaminants, and they do not belong in the recycling system. They not only increase the cost of recycling but can also injure workers and damage machinery. This is why it’s important that residents and businesses follow guidelines of what can and cannot be recycled. It’s also a reason to avoid “wishcycling,” which is when people put the wrong materials into the recycling bin, hoping they will be recycled instead of trashed.
Workers also remove a lot of plastic bags. Plastic bags should not be combined with other recyclables. They should be collected separately and returned to special drop-off locations, often located at grocery stores and other retail locations. Plastic bags get caught in machinery and need to be cut out with knives multiple times a day, leading to safety, productivity, and profitability challenges.
MATERIAL SORTING
Next comes a series of steps to sort materials first by size and shape, then material type.
Large cardboard is pulled off the conveyor first, and then the flat, 2D paper materials float over the screens while the 3D containers fall down through the screen.
Metals are sorted out based on their magnetic (steel) and conductive (aluminum) properties.
Glass is crushed and then sifted, so that anything smaller than two inches will fall through, while the rest of the material continues down the sort line.
Plastic is sorted into types (PET, HDPE and PP are the most common) using optical sorters.
In this example, the optical sorter is programmed to look for PET plastic. When the sensor sees a PET bottle, a puff of air is released and moves the bottle over the divider while the rest of the material falls down.
Though the optical sorters are relatively effective, in-person quality control is still needed to sort out contaminants.
Some MRFs have installed robotic arms to sort plastic or other materials, particularly in the quality control area.
BALING
After the plastic is sorted, it is baled into compressed 1000-1500 lb rectangular blocks and wrapped with wire. The bales are sold to recyclers (commonly referred to as reclaimers), who will process the material into recycled plastic.
MRF’s decisions around what they can economically accept and process are based on their revenues and costs, just like any other business. The revenue from the sale of bales needs to cover the costs of sorting and processing those materials. The value of recyclable materials fluctuates and depends on many external issues including the price of oil, material shortages, and other economic factors.
APR creates model bale specifications for plastic, to support both the MRFs selling bales and the recyclers buying them.
Step 4: Recyclers
CUTTING BALES
The bales are cut apart, and the material is pushed onto a conveyor belt.
MATERIAL SORTING
Although the recycler is starting with pre-sorted bales, it’s important to do another sort to remove any lingering contaminants—such as glass or small metals. The material will be sorted into 3 streams: the intended plastic (high value), missorted plastic containers (medium value), and waste (negative value.) The amount of sorting and pre-processing depends on the type of plastic being recycled and the intended end-use.
GRINDING
The material then goes into an industrial grinder, where it will be cut up into small pieces, called flake.
WASHING
The flake is then washed in hot water and detergent-solution to remove surface dirt and dissolve any adhesives used to attach labels.
FLOAT/SINK TANK
Next, the material goes into a large tank of water to separate different types of plastic. Some plastics float and some sink. For example, caps attached to a soda bottle travel with the bottle during the sorting phase but are separated during grinding. The caps, often made of HDPE plastic, float to the top of the float-sink tank while the bottle, made of PET, sinks to the bottom of the tank. This separates the different types of plastics so they can be processed and recycled.
RINSING & DRYING
The separated flake is rinsed again and air dried.
ELUTRIATION
Some plastic packaging incorporates thin layers of other materials to increase product shelf life. These thin layers can delaminate during the washing process. In order to remove and capture these, the flake is passed through an airstream.
DECONTAMINATION
If the material will be used for food-contact packaging, it will go through a decontamination process using vacuum and heat under low oxygen levels. This is required to receive a Letter of No Objection (LNO) from the U.S. Food & Drug Association for food packaging.
MELTING & FILTERING
The flake is then melted in an extruder, filtered to remove small solids, and processed with special equipment to turn it into pellets.
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Sorting and recycling plastic packaging is a very intricate process. This is why it is critical for companies to think about designing packaging for recyclability from the start.
- The APR Design® Guide is a free, self- service tool that is widely recognized as the authority on how to design plastics packaging for recyclability in North America.
- APR Design® Recognition provides third-party validation that a component or packaging has met the highest criteria for recyclability according to the APR Design® Guide.
Step 5: Manufacturers
When companies choose post-consumer resin (PCR) for packaging, they are choosing to reduce virgin plastic production. This means less natural resource extraction and a significant decrease in energy use. According to APR’s 2018 life cycle analysis, when virgin plastic is replaced by recycled content, the energy saved can be as much as 70%.
When individuals, companies and governments choose to buy items made with recycled plastic vs. virgin plastic, it creates the pull-effect we need to keep our recycling system going. There must be demand for recycled products for all the companies along the supply chain to participate. Choosing products made with recycled plastic is critical.
And don’t forget, once you’re done with that plastic product– if it’s recyclable, and your program accepts it– throw it in the recycling bin when empty. And the process starts all over again…