your guide to recyclable items in the United states
Pile of baled aluminum cans (Photo by Evgeny Karchevsky)
Recycling is an important part of waste management and sustainability because using recycled materials often has lower economic and environmental impact than the processes required to make virgin material. For example, using recycled aluminum costs just 5% of what it costs to use freshly produced aluminum! The best way to know what you can and can’t recycle is to know how the process works, so we’ll be taking you through each of the following examples of what items you can and can’t recycle.
Most municipal recycling programs accept the following:
Metals: aluminum, steel, tin, copper
Paperboard: cardboard, paper
Glass
Plastic: PET, HDPE, PP (types 1, 2 and 5)
Common things that can’t be recycled through most recycling programs:
Mixed materials
Plastic bags
Paper cups
Oily paper or plastic food containers
Small pieces of glass or plasitc
Styrofoam
Items you can recycle and how it works
The recycling process in the US is optimized to extract the most valuable and easily separable materials first. That means metals and paper often take precedence over glass and plastic. The stuff you put in your blue bins arrives via truck to the MRF, where it enters a presort station. At the presort station, large items, large pieces of cardboard and plastic bags are removed from the waste stream. Once your recycling hits that conveyor belt it flies down a conveyor belt at amazing speeds, and at those high speeds material gets separated and turned into bales of commodities:
Bales of Recycled Paper (Photograph by Bas Emmen)
Metals - most metals are really hard to make and that makes them really valuable. They are also relatively easy to separate because metals like steel, tin, and copper are magnetic. Aluminum on the other hand is separated by an eddy current. From there, these metals can be shipped off to smelters and made into new material. The properties of metals make them easy to separate, and generally they go through a lot of processing to become what they are, that makes recycling much cheaper and more efficient than using new stuff and the recycling process is optimized to do just that.
Paperboard - paper is less valuable than metal, but still relatively easy to recycle. At the MRF, a series of small spinning blades will flip paper material into a separate recycling stream. From there it gets turned into pulp and then baled for reprocessing. The process is relatively easy, but the main problems with paper are that it’s really easily contaminated and each time it gets recycled the fibers get shorter and shorter. Contamination wise, some oil or even ink in some cases can make paper unrecyclable. Paper is also more valuable if its lighter in color, and it can’t be separated by color at an MRF (that’s why office paper is much more valuable to recycle). The first time paper is used (think office paper), the fibers are very long, but as this fresh paper gets shredded and pulped, the fibers get shorter and shorter (like a paper towel). At a certain point, the fibers are just too short to reuse, and the paper has to be landfilled.
Glass - glass is difficult to recycle through a municipal program because it is difficult to keep it clean. MRFs are equipped to separate glass using density blowers, then crushed into what’s called “cullet” and recycled (hypothetically). The problem is that the mechanism for separating glass is not as accurate as metal or paper, and that means glass often ends up with lots of other material when it gets crushed up into bits. This issue makes the glass that comes out of the recycling process very contaminated (on average about 20%), which means most manufacturers aren’t willing to pay for it (glass is made from sand and therefore extremely cheap to make). Importantly, glass can be recycled profitably but only if its more than 95% free of contaminants.
Plastic - plastic is the problem child of municipal recycling programs. Even though it’s just 13% of what we consume, 90% of is not recycled. Part of the reason is because there are tons of different types of plastics, and new types of plastics are being invented every day! The most common ones for household goods are PET (1), HDPE (2), LDPE (4) and PP (5). At the MRF, a laser spectrometer identifies these plastics while they are flying down a conveyor belt, and air guns shoot them into platforms where they flow into another manual sorting process. Plastic is actually really easy to recycle if its well sorted, it has a low melting point and can be pretty easily remolded into new materials. Pretty cool stuff technologically speaking, except most MRFs don’t separate out each plastic by type. Mixed plastics can’t be recycled efficiently because if you melt them down the plastic they produce is weak (the chemical bonds get all messed up) and can fracture. Until 2018, China recycled all US plastics (half of the plastic in California went to China). Because freight to China, and Chinese labor are much cheaper than US labor, it was economical to sort the plastics in China, turn them back into goods, and then ship them back over to the US. But rising labor prices in China and China’s own growing waste management problem led the government to ban the import of foreign plastics, paper, and scrap. The ban has meant that most US plastic waste gets incinerated, unless municipalities are willing to pay for the plastics to be hand sorted at MRFs.
Items you can’t recycle and why you can’t recycle them
But when it comes to recycling, knowing what not to put in your bin (and why) can be just as important as knowing what goes in it. Most recycling in the US is done at material recovery facilities (MRF), so when you’re recycling keep that in mind. So without further ado, here’s a guide to what items you can and can’t put in your blue bin:
Trash on a beach (Photo by Brian Yurastis)
Mixed materials - lots of packaging includes multiple different kinds of material. Plastic bottles for example, typically have a cap made of a polypropylene (PP), a body made of polyethylene terephthalate (PET), and a paper or LDPE label. The problem is that if you melt all two together, the plastic it produces is weaker and undesirable to manufacturers. Other examples of mixed material include bags of chips or coffee, which have special metal lining on the inside of the bag to keep the products fresh. Some recycling programs will employ manual labor to separate these items, but most small municipalities cannot afford these types of services, so it’s important to make sure whatever you toss in your recycling bin is one type of material.
Plastic bags - plastic bags are typically made from HDPE (bags you get at a grocery store) or LDPE (Ziplocs, plastic packaging bags) and they are technically recyclable, but they aren’t accepted at most municipal recycling programs. Plastic bags are malleable and can get stuck in the mechanisms of a MRF, which can cause the machines to shut down for thirty minutes to an hour, and requires MRF workers to manually fish the bags out. To give you some context, typical MRFs recycle about 220 tons of waste a day so shutting down for thirty minutes can really take a toll on production.
Paper cups - ever wonder why paper cups hold water so well, but if you get any other kind of paper wet it turns into a soggy mess? That’s because paper cups contain about 5% plastic, a thin lining on the inside of the cup that keeps the liquid from turning your morning brew into a pile of mush. That means your paper cups are technically mixed material, and can’t be recycled. The same thing applies to a lot of paper food containers as well so just remember to be wary of anything paper that doesn’t soak when water touches it.
Oily paper or plastic food containers - this could technically go under the mixed materials category, but the cleaning process is a little different so I’m talking about it here instead. Paper with any kind of oil or food on it can’t be recycled into new paper, (but it can be composted) and in fact if the MRF doesn’t get it out in time it can contaminate clean paper when it gets baled into cubes. The same principle is true of plastics, if there’s food or oil on your plastic takeout you have to wash it before it goes in the bin. Sometimes MRFs have resources devoted to cleaning plastics, but most do not. Worse yet, if you’re plastic isn’t clean it can contaminate other things in your recycling bin (like paper).
Plastic straws (small pieces of plastic or glass) - most plastic straws are made of polypropylene, which is technically recyclable, but because waste sits on a big conveyor belt at MRFs, small pieces of plastic like straws can slip through the belt and not make it to the end of the process. For this same reason, small bits of plastic or glass can’t be recycled either.
Styrofoam - is a form of polystyrene (plastic #6) that includes air. Styrofoam can be recycled in some special recycling programs, but it has to be compressed first. Most recycling programs don’t include this process, so it’s best to landfill if you have to get rid of it.
As always, the best way to know for sure is to check with your municipal recycling program!
Here are some additional links if you’re interested to learn more: