Although being championed as the emerging potential solution to the escalating plastic waste crisis, advanced recycling technologies for plastics, including pyrolysis and gasification consume substantial energy consumption, emit hazardous pollutants, and have limited effectiveness in converting waste into new plastic materials.
A UK-based firm named Mura Technology aims to revolutionise this by introducing an innovative approach. Their technology employs supercritical temperatures in heated water to break down the molecular bonds of waste plastics, as opposed to the conventional practice of combusting the plastic itself. Set to open later this year, Mura Technology’s inaugural commercial-scale plant in Wilton on Teesside will kickstart operations by recycling an initial annual volume of 20,000 tonnes of plastic waste. This includes items like films, pots, tubs, and trays- materials that currently face disposal in landfills or through incineration.
The company claims the process creates a ‘true circular plastics economy’ because the oils derived from the waste can be used to produce new food-grade plastic, with no limit to the number of times it can be reprocessed.
Geoff Brighty, the UK company’s chief sustainability officer, told a recent conference in London that Mura’s HydroPRS technology works in a similar way to pyrolysis, which is the thermal processing of a substance in the absence of air. But instead of applying heat directly to plastics, it heats water under supercritical conditions to crack the polymeric material in plastic back into short-chain hydrocarbons. “You aren’t creating a char or a waste material, meaning we have very high conversion efficiencies (high 80s or maybe even low 90s) and you are putting less energy into the system,” said Brighty.
A lifecycle assessment by the European Commission’s Joint Research Centre this year found that HydroPRS had a global warming potential about 50% lower than pyrolysis, and 80% lower than incineration. Researchers at the University of Warwick, found that the process doesn’t create the same harmful byproducts, such as dioxins, “and helps to maximise higher product yields” of recycled plastics.
“By diverting plastics from energy from waste,” Brighty said, “we estimate a net saving of 1.8 tonnes of CO2 for every tonne we process.”
The system is tolerant of mixed, contaminated plastic waste, including polystyrene and agricultural plastic waste.
“Millions of tonnes of plastic waste in this country go to incineration each year,” Brighty said. “We want to change that. The point is to complement the existing mechanical recycling infrastructure by diverting it away from energy from waste.”
Besides producing different grades of plastic, one byproduct of the process is a heavy wax residue, the result of stripping off the waxes in waste plastic packaging.
“It’s effectively a bitumen binder that can be used to decarbonise road-making,” said Brighty.