Improving Recycling with IR Signature Detection

Improving Recycling with IR Signature Detection

Ever wonder why you are limited to recycling certain kinds of plastic rather than throwing every plastic item you discard into the recycling bin? Much of it comes down to sorting. It is not worth it to some municipalities to invest in expensive sorting equipment and manual sorting if the market for certain kinds of plastics isn’t there. What isn’t worth sorting ends up in landfills. That may change in the future, thanks to something known as IR signature detection.

California-based Rock West Solutions explains IR signature detection as a way of recognizing the identification of a given object based on how it reflects and absorbs infrared light. It is a technology that has been used by the waste management industry for decades to recycle plastics. But it is expensive technology with limited appeal. Hopefully that changes with an invention that debuted in Germany earlier this year.

Better, Less Costly IR

Standard technology calls for automated sorting of recycled plastics using spectrometers and costly IR spectroscopes. As plastics come down the sorting line, they are continuously bombarded with multiple wavelengths of infrared light. Some wavelengths are reflected while others are absorbed. Spectrometers pay attention to all of this.

Based on the data the IR bombardment produces, spectroscopes analyze what kinds of plastics are coming down the line. They can then be separated by way of mechanical arms or quick bursts of air. The system is fairly effective. Unfortunately, it is also rather costly.

A new system recently released in Germany is the brainchild of a high school student who figured out a way to accomplish the same thing using just six infrared diodes and the single sensor. Each of his diodes emits a different IR wavelength, which is then either absorbed or reflected back to the sensor. Based on the light picked up by the sensor, computer software can identify one of eight different plastics.

Key to this system is measuring the intensity of the reflected light. Measuring intensity is what makes it possible to limit the number of wavelengths to six and still get accurate results. Light intensity helps to create interpolation points that can correctly identify certain kinds of plastics without nearly as much effort.

  • What It Could Mean to Recycling

This new form of IR signature detection could mean big things for recycling worldwide if it can be better refined. It’s already great technology as it is but imagine what we could do with it if signature detection could be expanded beyond plastics. Is it possible that infrared signature detection could eliminate the need for manual sorting of recyclables altogether? Perhaps.

It is one thing to identify plastics already separated out from the rest of a load of recyclables. It is an entirely different matter to run that entire load down a line and sort them without any human intervention whatsoever. Automated sorting would be a big deal to global recycling efforts if it could do this.

Getting rid of manual sorting removes one of the biggest inhibitors to cost-effective recycling. As such, automating the entire sorting process increases the financial incentive for recycling. That financial incentive would open up new markets that, in turn, would result in more items being recycled and fewer being thrown into a landfill.

It’s awesome to see high school students take such an interest in practical science. Hopefully, what the 15-year-old student in Germany came up with will eventually go on to revolutionize recycling. Such a simple design in IR signature detection could end up having a huge impact in how we dispose, recycle, and reuse tons of materials.

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