For years I have rinsed plastic bottles and metal cans, flattened cereal boxes, and bagged up newspapers for recycling. Every once in a while – when the accumulation of bags of stuff to recycle gets to be too much in the way – I take them to the closest recycling bins (there are several around town). One bag goes to the newspaper bin, one to the aluminum/tin cans bin, and usually several bags go to the mixed plastics (we consume a lot of dairy products, most of which come in recyclable plastic containers).
A few months ago I saw a large blue trash-can type container at the public library, with an explanation that in March, these containers would be distributed throughout the city for curbside recycling. It also explained that residents would be able to put all their recycling in this one container – glass, plastic, metal, cardboard, paper.
Our 65-gallon container was delivered a couple of weeks ago, though it will be another couple of weeks before the first recycling pickup. Right on the lid is a list of what is OK to put in and what is not (pretty much the same as previously, except that now it includes telephone books, which if they were accepted before I didn’t know it). I’ve filled it about halfway so far, though I haven’t yet gone through our (large) collection of phone books to discard the older ones.
While it’s very convenient for me, I couldn’t help wondering how all the different types of recycling will get sorted out. Years ago I had read that one reason curbside recycling wasn’t used in more municipalities was that the cost savings of recycling was more theoretical than real. One reason was that it was very labor-intensive to sort out all the different kinds of materials, especially since – despite the acceptable/not acceptable lists – people put in all sorts of “not acceptable” stuff anyway.
I could imagine how some of the sorting could be done automatically. Some metals can be picked out by magnets – but not aluminum cans. Glass is certainly heavier than plastic, though I couldn’t visualize just how that would work in terms of automated sorting. But with all this stuff going in one container, there had to be a way to sort it out without people reaching into a mess of broken glass and jagged metal cans.
I found an article that describes how single stream recycling works.
The plant uses a variety of sorting devices, including screens, magnets and ultraviolet optical scanners that trigger blasts of air to separate plastic bottles from the rest of the items, as well as spinning, star-shaped plastic devices that separate newspaper from cans and bottles by pushing the paper higher up an inclined screen so the heavier, smaller cans and bottles tumble down to a lower level. Glass is sorted by color and crushed, while plastic is shredded into small chips.
Since the article is from over three years ago, no doubt the technology has only improved since then.