How the plastic recycling process works

From soda bottles to styrofoam, here’s how goods get (hopefully) reborn

How to recycle plastic

Many people diligently sort their home plastic waste, from iced coffee containers to berry baskets, but companies and governments aren’t really holding up  their end of the recycling bargain. The EPA puts the U.S.’s recycling rate at around 9%, but one 2022 report argues that around 5% of plastic is actually recycled stateside.1 In 2021, Americans discarded 51 million tons of bags, bottles, and wrappers—only 2.4 million tons of this waste was recycled.

It can be tough to collect and sort plastic, and some products (like those that involve mixes of materials that melt at varying temperatures) are difficult to recycle with current methods (learn about plastic recycling problems). Due to these challenges, much of our plastic ends up in landfill, which is currently a far cheaper and more practical solution for companies and municipalities. 

Still, by learning precisely how the process works and what role we play, consumers can make things a bit easier for recycling centers down the line.

How to recycle different plastics

From the moment plastic hits your blue recycling bin, it embarks on a lengthy journey with multiple potential outcomes (read about how many times plastic can be recycled). Ideally, it gets turned into new material that can re-enter the market—but more often, it heads to a landfill where it can take centuries to break down. To help ensure things get done properly for recyclable plastics, it’s important to know plastic recycling numbers.

Which plastics are readily recyclable?

Plastic #1: PET (Polyethylene Terephthalate)

This is one of the most widely used (and recycled) plastics, and it often makes its way into products like beverage bottles and food containers along with textiles such as clothes and bedding. The recycled bottles are often melted down into fibers for insulation materials or turned back into the original product (if it’s clean enough by the time it arrives at a recycling facility). See how to recycle plastic bottles.

Plastic #2: HDPE (High-Density Polyethylene)

This is another popular polymer, and it’s typically used for items like cosmetics and food packing along with outdoor furniture. HDPE can be commonly recycled by being shredded and melted down into pellets to make new products like bottles and furniture.

One 2022 report argues that around 5% of plastic is actually recycled stateside.

What plastics are only sometimes recyclable?

Plastic #3: PVC (Polyvinyl Chloride)

This versatile plastic is used across a range of industries, including building, transportation, electronics, and health care. It’s super durable and can last a long time, so it makes up about 20% of all plastic manufacturing around the globe. At home, you’d likely find it in things like furniture, shoe soles, credit cards, and backpacks. It’s challenging to recycle PVC, because it contains toxic additives that can release hydrochloric acid, which can damage recycling equipment and harm workers. 2

Plastic #4: LDPE (Low-Density Polyethylene)

LDPE comes from the same chemical building blocks as HDPE, but it has more loosely packed molecules so it tends to be softer, thinner, and more flexible. Most of this plastic is made into a thin film that can be used for plastic bags, such as the ones used to collect produce at the grocery store. Though only some facilities accept it, this plastic can be shredded, melted and turned into pellets to manufacture new items—but it’s known to get tangled in recycling machinery in that shredding step, which can significantly slow down the overall process.3

Which plastics are not readily recyclable?

Plastic #5: PP (Polypropylene)

This plastic can be turned into fibers for things like upholstery, carpets, and clothing, along with flexible food packaging. It was long considered tough to recycle until 2022, when the North American packaging recyclability labeling system known as How2Recycle announced it was placing the plastic into the “widely recyclable” category. But Greenpeace quickly condemned this decision, since less than 30% of Americans have access to recycling systems that accept it.

Plastic #6: PS (Polystyrene)

Polystyrene—which you may know as styrofoam, its trademarked name from the company DuPont—is often used as an insulation material for construction. When in the form of expanded polystyrene foam, which is made by heating up and inflating small polystyrene beads, it’s typically used to make packaging for food like meat and eggs. 

Polystyrene has gotten a bad rap in recent years because it’s tough to recycle. That’s because expanded polystyrene foam is lightweight, bulky, and hard to clean, so most curbside programs don’t accept it. Once it hits a landfill, it can take more than five centuries to break down, sending toxic chemicals into the environment in the meantime.

So far, 11 states and Washington, D.C. have passed bans against polystyrene in food and beverage containers. Washington and Oregon also prohibit the material in other items, like packing peanuts and coolers. And in recent years, demand for polystyrene has declined due to slowing demand.4

#7: The misfits

The #7 refers to other miscellaneous kinds of plastics that are lumped into one group, including nylon, fiberglass, polylactic acid made from plants, and acrylic plastic (which is often used to make products like lenses, acrylic nails, paint, and LCD screens). These are typically made of a mix of plastics or materials that can’t be easily recycled. Acrylic, for example, can be dangerous to recycle because it involves adding molten lead.

The plastic recycling process

Mechanical recycling

Mechanical recycling is the most common form, and it’s pretty much exactly as it sounds. Materials are ground down into the component parts, and hopefully reconstituted into new wares.

Step 1: Collection

To kick off the process, consumers set out their used plastic on the curb or take it to a drop-off center. Around 91% of the U.S. population has access to curbside recycling or drop-off recycling programs, down from 94% in 2016.5 Our plastic waste is hauled away by either a private company or a government service.

Step 2: Sorting

Once it arrives at a recycling facility, plastic must be separated into various plastic types. That’s because the various types of polymers melt at different temperatures and don’t tend to mix well to make new products. They may also be sorted by properties like use, thickness and color.

Facilities employ a range of sorting techniques, including hand-picking non-recyclable and clearly dirty items. Some centers may use magnets to get rid of metals, for example, or high-tech optical sorting machines with sensors that measure the varying wavelengths that reflect off these plastics to distinguish between them.

Step 3: Washing

Next, plastics need to be washed to get rid of stuff like adhesives, food waste, and labels—all of which could contaminate the recycled byproducts. 

Step 4: Shredding and resizing

To turn these polymers into new products, they need to be shredded into smaller pieces by specialized machines. At this point, the smaller pieces can be put right into asphalt or sold as a raw material.

Step 5: Identification and separation of plastics

At this point, facilities check for density and thickness of plastics. They test for the former by floating the plastic pieces in a basin of water, where the more dense particles sink and the less dense ones float. For the latter, facilities will put the shredded plastic in a wind tunnel, where skinnier pieces fly up and thicker ones remain below them. Recycling centers may check the melting point during this step, too.

Step 6: Compounding 

During this final step, facilities send plastic through a machine called an extruder. This gizmo melts and cuts the plastic into small pellets, which are then sold to companies to be re-melted and made into new plastic products.

Around 91% of the U.S. population has access to curbside recycling or drop-off recycling programs, down from 94% in 2016.

Chemical recycling

While most of the country’s recycling relies on mechanical systems, which crushes plastic and melts it, Paschalis Alexandridis, a professor in the department of chemical and biological engineering at the University at Buffalo in New York says we can expect lots of progress in chemical recycling. This group of techniques use chemicals and/or high heat to turn plastics back into their building blocks called monomers. The processes create higher-quality recycled products compared to mechanical recycling. These methods include pyrolysis, or the heating of plastics in an oxygen-free environment, and hydrolysis, where water molecules break down certain plastics with the help of an acid or a corrosive compound like sodium hydroxide between around 200 to 300 degrees Fahrenheit.

The U.S. only had eight chemical recycling facilities as of 2022, with two under construction and 12 more proposed. Overseas, a few cosmetics companies have begun selling or researching plastic products made through chemical recycling. Industry-funded research has claimed these processes produce lower greenhouse gas emissions than new plastic production.6

Chemical recycling comes with significant downsides, though. Environmental advocates have pointed out that these technologies can use lots of energy and generate hazardous waste. Pyrolysis can also release nine times more greenhouse gas emissions than mechanical recycling.

How to recycle plastic at home

Can I recycle plastic bags, wraps and films?

These can’t go into your curbside recycling bin. But some retail stores will collect them if they have a How2Recycle Store Drop-off label, according to How2Recycle, the labeling system used for U.S. plastic products.

Can plastic bottles and caps be recycled?

This depends on your local recycling program, so you should check with your city to make sure. It used to be harder to recycle bottles with the caps on, but recycling tech has since improved—these two components separate in a facility’s water bath. Some beverage bottles will therefore instruct you to recycle them with the cap on.  

Can polystyrene foam, or styrofoam be recycled?

While styrofoam is technically recyclable, your local recycling facility probably can’t get the job done. This site can help find a recycling center that accepts polystyrene. 

Can plastic containers, cups, and utensils be recycled?

For containers and cups, it depends on the type of plastic these items are made of and whether your local recycling program accepts it. Most municipal services will take plastics #1 and #2, and a growing number now take #5. 

Utensils may not be labeled individually, so unless you have the original packaging it’s impossible to know which type of plastic they’re made from and therefore whether it’s recyclable.

Shape also matters. For example, the plastic clamshell containers often found at grocery stores, given out with restaurant leftovers, or used to seal new products present a logistical nightmare for recycling facilities. While they’re often made of highly recyclable PET plastic, they’re tricky to sort after they flatten out and may have food residues or sticky labels.

With any piece of plastic that you ate or drank from, it’s important to clean off all food and drink residue before tossing it in your blue bin to make it easier for facilities down the line. Take a look at our guide about microplastics in food.

Can you recycle plastic furniture?

If the furniture is made from a widely recyclable type of plastic like #1 or #2, you can check if your local program accepts large items like furniture. If not, you can try to find specialized facilities in your area that will.

Can you recycle plastic toys?

While municipal recycling programs don’t usually take plastic toys, the toy company Hasbro collaborates with the recycling company TerraCycle to create a free program that accepts certain kiddo products.

Can single-use plastic products be recycled?

Things like plastic straws, bags and cutlery tend to fall into the cracks of recycling machines—so centers will often reject them.

Can old shoes be recycled?

To sustainably dispose of your old running shoes, you can drop them off at certain stores like Nike and Fleet Feet. You can also buy a box from TerraCycle to fill with old shoes and ship to the company when it’s full for recycling.

Can you recycle compostable or bio-based plastic?

Compostable items aren’t intended for recycling and can cause problems for the recycling stream. You may have a local composting program that can pick up these items, or you can look for drop-off locations near you. As for bioplastics, bio-PET and bioPE can head to regular recycling facilities because they’re chemically identical to their fossil fuel-derived counterparts.7

What happens to recycled plastic and where does it go?

Companies turn recycled plastic pellets into a wide range of products, like food and beverage bottles, carpeting, jackets, crates, and even playground equipment. Often, the plastic used in recycled products end up being lower quality due to previous use and processing at recycling.  Some researchers also worry that recycled plastic used for packaging may contain higher concentrations of hazardous substances like bisphenol A (BPA), a chemical used to make plastics that may disrupt people’s hormones.8

Can I melt plastic and remold it?

While you can technically melt and mold plastic, most experts strongly recommend against it. The process will emit toxic fumes including pollutants like bisphenols and phthalates, which are known to impact human development and our reproductive systems (read about microplastics in humans). Leave that to the professionals, please! 

Can plastic recycling exacerbate microplastic pollution?

Some evidence suggests that recycling can release microplastics into surrounding water and air during the plastic-washing process, but researchers are still figuring it out. One facility in the U.K. may release up to 75 billion plastic particles per cubic meter of wastewater, as reported by a study published in 2023.9

Read this guide: Where do microplastics come from?

Recycling centers can install filters to catch small particles that are larger than 50 microns (each micron is one-thousandth of a millimeter), and the researchers estimated that the facility’s filters could recover just over half of these microplastics released annually. But many microplastics generated during recycling may be much smaller—and it isn’t clear how many of these spew out of recycling centers each year.

Are there benefits of plastic recycling? 

In theory, plastic recycling aims to reduce the greenhouse gas emissions from production of new (also known as virgin) fossil-fuel derived plastic.

Do you know how much oil is used to produce plastic?

Plastic recycling can also reduce the amount of waste that heads to landfills and surrounding ecosystems, which can produce powerful atmosphere-warming methane.10 

Additionally, recycling advocates claim the process can cut down the amount of plastics that reach humans and wildlife, where it may increase the risks of cancer and hormone disruption, among other health impacts.But due to the relatively low recycling rates in the U.S., along with the presence of tiny microplastics nearly everywhere on the planet, it’s currently difficult to mitigate these impacts.

As consumers, we can wield the power of our wallets. We should push companies to use less plastic throughout the supply chain and seek out alternatives to plastic, says Myriam Ertz, a professor of marketing who has researched consumer recycling behavior at the University of Quebec at Chicoutimi in Canada. Shoppers can also pressure companies to start take-back programs and recycle certain products, such as how Nike collects old shoes or Nespresso accepts used coffee pods for recycling.

“This change from companies requires them to adopt a different mentality oriented toward circular economy principles in which products are designed for repair, reuse, decomposition, recomposition, and recycling,” she says.

  1. Circular claims fall flat again, Greenpeace, Oct. 2022. ↩︎
  2. Using waste poly(vinyl chloride) to synthesize chloroarenes by plasticizer-mediated electro(de)chlorination, Nature Chemistry, Nov. 2022. ↩︎
  3. Impact of plastic bag bans on retail return polyethylene film recycling contamination rates and speciation, Waste Management, Nov. 2021. ↩︎
  4. Polystyrene: high prices and slowing demand, Plastics Engineering, Sept. 2015. ↩︎
  5. Centralized study on availability of recycling, Sustainable Packaging Coalition, Jul. 2021. ↩︎
  6. Life-cycle analysis of recycling of post-use plastic to plastic via pyrolysis, Journal of Cleaner Production, Nov. 2023. ↩︎
  7. Bioplastics for a circular economy, Nature Reviews Materials, Jan. 2022. ↩︎
  8. Unpacking the complexity of the PET drink bottles value chain: A chemicals perspective, Journal of Hazardous Materials Advances, May 2022. ↩︎
  9. The potential for a plastic recycling facility to release microplastic pollution and possible filtration remediation effectiveness, Journal of Hazardous Materials Advances, May 2023. ↩︎
  10. Production of methane and ethylene from plastic in the environment, PLOS One, Aug. 2018. ↩︎