While awareness of the environmental problems caused by plastic waste is growing, there is no sign that the amount being produced globally is decreasing – in fact, quite the opposite is true.
About 2.3 million tonnes of plastic were created in 1950, but the figure now is around 450 million tonnes and there are forecasts that it could double by the middle of the century.
Finding improved ways to sort plastic waste into its various types is key if recycling rates are to increase, not least because it makes the recycling process more financially viable.
Teams from Cycled Technologies, a company with a base in the UAE, and Khalifa University in Abu Dhabi are working on a method, operated by artificial intelligence, which they believe could help create a breakthrough when it comes to recycling plastic waste.
A prototype using the technology is located at the Masdar Institute Field Station, a research centre operated by Khalifa University.
Detailed images enable the AI system to identify the type of plastic that the waste is made of.
“The equipment contains the camera for detection, and a sorting mechanism,” said Dr Ayoola Brimmo, Cycled Technologies’ co-founder and chief operating officer.
“We have used a variety of mechanical arms, multi-axis rollers and pneumatic manipulators for sorting. The camera and sorting device are both connected to the main controller board.”
The device has a vent through which waste enters before it is taken by a conveyor belt to be compressed.
The technology employs near infrared (NIR) spectroscopy, with samples identified according to how they absorb or scatter near infrared light.
NIR spectroscopy is well established in plastics sorting and advocates say it is fast, non-destructive and able to identify numerous types of plastic.
The system can identify polypropylene or PP (which may be used for bottles, food packaging and yoghurt pots), high density polythene or HDPE (used for shampoo bottles and bleach bottles, among other things) and polythene terephthalate or PET (used for food packaging and bottles, for example).
Keeping costs down
A key advantage of the Cycled Technologies and Khalifa University system is, Dr Brimmo said, its low cost, which means that it can be used in community settings.
“What we’re doing right now is something that’s been done in big industrial facilities for over 10 or 15 years. But it’s never been financially viable on a small scale. Now it’s more viable, it’s now making sense financially,” he said.
Dr Brimmo, who has worked with Dr Khalid Askar at Khalifa University to develop the technology, said that the method employed, which is still in a trial stage, is almost 100 per cent accurate.
A 2022 Organisation for Economic Co-operation and Development (OECD) report stated that twice as much plastic waste is now being created, compared with two decades earlier.
The quantities are eye watering: In the US, for example, 221kg of plastic waste is generated by every person each year, while in European OECD member countries the figure averages 114kg.
“Even though plastics damage the environment and don’t disintegrate for many decades, use of plastic is exponentially increasing,” said Amit Goyal, distinguished professor in the Department of Chemical and Biological Engineering at the University of Buffalo in New York.
“It’s not easy to replace plastic products for many applications. We have to find better ways of recycling plastic.”
Damaging impact of plastic waste
Improving recycling rates may help to reduce the quantities of plastic that enter the natural environment.
According to the UN Environment Programme, between 19 million and 23 million tonnes of plastic waste find their way into rivers, lakes and the sea every year.
Millions of animals die after becoming entangled in plastic or because of starvation, which often happens when material remains in the stomach so that creatures do not feel the need to eat.
Many camels in the UAE have died because huge lumps of plastic waste have accumulated in their stomachs.
Consuming plastic has also been shown to lower the reproduction rates of some animals.
Aside from reducing the problem of plastic pollution, Dr Brimmo indicated that recycling plastics had a climate impact too.
Research suggests that producing a given amount of recycled plastic creates 30 per cent to 80 per cent fewer carbon emissions than generating the same quantity of virgin plastic.
Among the other researchers developing new ways to sort plastic is Prof Goyal, who is working on the use of “bar codes” that indicate what type of plastic an item is made of. Similar to Cycled Technologies’ approach, the method makes use of AI and robotics.
“When you go to the grocery store and fill your cart, at the checkout you scan the bar code and get the final bill,” Dr Goyal said. “What if there was a similar bar code that magically applies to every plastic product?”
The transient thermal bar code (TTB) technology employs molecular fingerprinting – the unique pattern of a molecule’s chemical structure – to identify seven types of plastic.
“The system knows what kind of plastic product it is … This will hopefully reduce contamination in the sorting process, which is essential to increasing recycling rates,” Prof Goyal said.
With such new approaches being developed, Prof Goyal, whose technology is undergoing trials at a laboratory scale, is “very optimistic” that higher recycling rates could be achieved.
“I see no fundamental hindrance,” he said. “In a couple of years we should be in a position to roll this out.”
