The Thinking Minority

For years now, I've dutifully checked every plastic piece of trash for the right set of numbers to figure out if I could recycle it. Our trash service collects one through four, along with our other recycling, all in one bin. We are advised to rinse plastics first and to remember to remove bottle tops, which frequently are made from a different kind of plastic than the primary container.

We perform this civic service at home for two reasons. First, putting stuff in the recycling bin keeps it out of our regular trash, so we don't need to take the big barrel out every week. We just put out the recycling bin, which is easier to lug around since it’s filled with empty cans, plastic bottles, glass jars, and newsprint. Second, I have felt strongly the importance of taking care of the environment, limiting pollution, and limiting our use of non-renewable natural resources. Plastics are a petrochemical product, meaning that producing them requires using oil and/or natural gas, and I recall from chemistry classes that manufacturing plastic, and sometimes even recycling it, can produce noxious chemical fumes. I don’t want all of that crap in the air I breathe, and I don’t want large chunks of plastic in the wild where it can do physical and chemical damage.

The silence of the empty office produces some rather interesting, non-sequiter thoughts. Today, I wondered (possibly aloud), "what do the numbers mean?" Then, "if the numbers mean something, why can I mix them all in one bin?" And this: "what if recycling plastic doesn't really help the environment?”

Quickly, everyone – to the Internet!

There are a lot of leftist treatises on the importance of recycling plastic. The most extreme I’ve seen so far recommends that we stop using plastics entirely. Frankly, I think that’s both useless and stupid. Useless, because plastics are ubiquitous – clothes, furniture, cell phones, car parts, circuit boards, carpet, building materials, containers of every variety, printed materials, and hundreds (perhaps thousands) of other products are made from plastic. If all consumers stopped using plastic wrap to save their leftovers, I doubt the plastics industry would blink.

Boycotting plastic is also stupid. Many of those products – the ones that could exist before plastic, anyway – would be made of some other natural material (like wood) if it weren’t for the abundance of plastic, and so would cost several times what they do now. Plastic makes our world less expensive. It also makes it safer; when was the last time you worried about dropping a two-liter soda bottle? They used to be glass, and they used to shatter quite well. Now they’re plastic, and if you drop one, you might spill some soda, but you won’t shred your feet.

In any case, if you wade through the propaganda, you can find some useful facts. First of all, the numbering system has an explanation (albeit a little complex). Each number represents a different plastic resin, and each resin has different properties. In the first place, some plastics melt when exposed to heat (thermoplastic), and some resist melting (thermosetting). For example, most of you probably have non-stick pots or pans that can go in the oven (and all can be used on top of the stove). The non-stick coating is plastic (usually Teflon, or PTFE – polytetrafluoroethylene), but it doesn’t melt. But don’t try cooking anything in a plastic milk jug. The Intermediate Technology Development Group, a “charity which works with poor communities to develop appropriate technologies” has an explanation in their technical brief.

Since the easiest way to recycle plastic is to shred it into pellets, then melt the pellets and extrude or mold new objects, plastics that resist melting can be a big problem. Plastics one through six (PET, HDPE, PVC, LDPE, PP, and PS) are all thermoplastic, and according to the ITDG brief, make up about 80% of the world’s plastics. But these plastics melt at different temperatures, so the recycling process has to be different for each different type of plastic. The problem gets worse when hardeners or other reinforcing agents (like fiberglass) are mixed with the plastic.

Assume for the moment you’re recycling only PET (1) and HDPE (2). PET melts at 250C, HDPE at 130 (482 and 266 Fahrenheit). While the plastics don’t have to be (and shouldn’t be) entirely melted for recycling, they do have to be heated to the point where they are soft enough that they can be molded into new objects. It’s difficult to heat plastic evenly, because it is not a good conductor of heat. There’s also a narrow range of temperatures at which it is safe to work with plastic (too hot, and it gives off fumes and can char; too cold, and it doesn’t work). So PET and HDPE have to be separated before they can be recycled. Because other contaminants (like food clinging to containers) interfere with the softening process (and can contaminate the final product), they have to be removed as well.

From what I can tell, although there are some pretty sophisticated ways to sort plastics through machinery (using X-rays and fluoroscopes), this part of the process is mostly done by hand.

So apart from helping the environment, recycling plastic employs trash workers whose job it is to sort plastic by color and number. Any manual process is prone to human error, so it’s anyone’s guess as to how many bales have to be resorted or thrown away because of mistakes.

So I’ve answered my first two questions, but the last one will require more investigation and lots of math.