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Sorting on the Reboud

Looking at all the recycling bins on curbsides these days you’d think the manufacture of new plastic must be dwindling. Not so-increases in production of virgin plastic packaging outpace the gains in plastic recycling by an order of magnitude. One reason is the difficulty recyclers have in separating various kinds of plastic; if they’re mixed, the whole batch is useless. But researchers at SpectraCode of West Lafayette, Ind., have invented a point-and-shoot device that could solve the problem.

The system shoots a laser beam at the plastic, then analyzes the light reflected from the surface. The distribution of wavelengths serves as a “molecular fingerprint “identifying the type of plastic. The device can distinguish most kinds of plastic in 10 microseconds, which when automated could mean 500 tons of plastic per day in a typical recycling operation. The system’s utility goes beyond plastic: Researcher Ed Grant has used it to distinguish between various kinds of flours and sugars.

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