Demonstrating microwave assisted pyrolysis for green recovery of plastics

Plastic is an incredibly useful material. This has been emphasised during the Covid-19 crisis, which has seen a dramatic surge in plastic use. This ranges from PPE equipment such as face masks and acrylic screens at supermarket checkouts, to single use plastic bags in home shopping deliveries. This came at a time where climate change and the need to protect our environment from plastic contamination were forefront in the minds of the public, businesses and government. Unfortunately, much of this waste cannot be recycled using existing technologies.

This project will trial a new enhanced recycling technology called microwave assisted pyrolysis, or MAP. MAP uses microwaves to heat up plastic waste until the point where it breaks back down into the oil from which it was first formed. This oil can then be refined and made into brand new, high quality plastics. Because MAP breaks the plastic back down into oil, MAP can even be used on dirty degraded plastics, removing the impurities and making it suitable for new food packaging. This is something which we simply cannot do at the scale we need to using traditional recycling methods.

Microwaves are great for doing this because, unlike other technologies that heat plastic from the outside in, it heats all of the plastic at the same time. This makes the process much faster, and helps the material heat evenly rather than getting too hot in places which can produce char. Even better, it doesn't matter if the plastic is wet or has left over food on it - this actually helps the microwaves do their work. This means we get a better quality product out, and more of it, and that means that we can produce more new plastic from it and save more carbon in the process.

MAP has been developed by an engineering company in North Yorkshire called Sylatech. They have already built a MAP machine that can process about 18kg of plastic waste per hour. That's the weight of around 1800 plastic water bottles! Together with Enva, one of the companies that sorts and recycles the UK's waste; Lucite, the world's biggest producer of acrylic (used in those plastic screens at the supermarket checkout) who wish to develop a circular economy for acrylic, and supported by experts in microwave pyrolysis and plastics chemistry from the University of Nottingham we will test this technology on real plastic waste to assess its ability to solve the plastics problem. The results from this work will enable us to determine, what plastics MAP can recycle, the recipe for doing that as efficiently as possible, how much carbon it saves compared to sending those plastics to landfill or incineration, and what it costs to run. Ultimately that will mean that we can develop this technology faster, turn the tide on plastic, and help with a green recovery of the UK economy!