When recycling took off in the United States in the early 1990s, the environmentally conscious were instructed to sort their recyclables into separate bins. Paper went into one bin, plastic in another, glass sorted by color into another bin. By the end of the decade, however, technology that allowed single-stream recycling was developed.
At last, even the laziest among us had no excuse to avoid recycling.
Under the single-stream recycling system, all recyclables go into a single bin. At the recycling plant, recyclables are loaded onto a conveyer belt and pushed off in response to certain stimuli: Magnets lift iron-based metals from the belt; puffs of air blow paper from the line, and so on<.