Every week, the small plastic bag filled with our collected
plastic and metal tidbits—a partial fossil record of the consuming habits two
American adults—hits the curb beside the cardboard. In my neighborhood, collection
takes place at night to alleviate traffic and ostensibly tamp down crime. It
hasn’t prevented anyone from stealing my recycling bin, but at least most of
the refuse is gone in the morning, never to be seen again. I imagine it
streaming down a conveyor belt at the recycling facility, getting a quick sort
with human hands to separate out the metal, then to a giant crusher where its
packed for shipping to the post-processing facility.
Unfortunately, my efforts to guide the future of anything
stamped with an “arrow triangle” often comes to naught. Plastics, for the most
part, don’t recycle well. Constructed as they are from long chains of large polymer
molecules, are the red-headed stepchild of recycling efforts. Paper? No
problem, just re-pulp. Metal and glass? Add heat. Plastic? Forget it. Big
molecules are harder to mix, and melting the stuff causes it to separate into
various material phases that are difficult to use.
Most plastic is simply sorted by type, heated to remove
impurities and processed as pellets for limited uses (plastic lumber anyone?). Polyolefin
materials (HDPE, LDPE, PP) are the best because they are less expensive to
reprocess, but chemists are starting to getting a handle on much more difficult
types such as PVC. Polyethylene terephthalate (PET) is, of course, the big
culprit for waste, and often the best solution is to simply shred it and find a
way to place it into the biggest product stream for PET: fabrics. Clothing made
from old PET soda bottles is not so unusual anymore.
That’s not to say plastic isn’t great. It saves effort,
time, and untold quantities of paper, wood, and glass. But too much PET is
still making its way into landfills, especially after the last recession made an
early victim of the recycled plastic market. Recycling programs—while invaluable
in keeping plastic out of the conventional waste stream and off the roadside—fool
the public into thinking plastic is a zero-sum consumer product. It isn’t. A one-liter
bottle of water requires several mega-Joules of energy to manufacture, not to
mention three times its volume in water.
One interesting solution is to burn it. Unlike many other
plastics, PET is mostly composed of hydrogen, carbon, and oxygen. Containing
the energy equivalent of soft coal it’s probably no worse to burn if done with
the proper environmental checks. A stopgap solution at best, I suppose. Plant-based
plastics will probably be the future of the industry, and if researchers are
successful, we may be able to extend the life of PET and other plastics
indefinitely.
For now, plastics manufacturers can help out by improving
the labeling system. That familiar “arrow triangle” with the tiny number is
well-nigh useless to the general public. If I knew which plastics would go
straight to the trash mountain, I could save everyone some time by pre-sorting
it.
