The biotech solution that recycles trickier plastic waste
The world produces 460 million tonnes of plastic annually(opens in new window), with only 9 % recycled and the rest landfilled or incinerated. In Europe, where the total plastic waste produced in 2021 was 16 million tonnes(opens in new window), recycling rates remain around 35 %(opens in new window), with most plastic combusted (42 %) for energy or landfilled (23 %). This results in plastics leaking into the oceans and the food chain. Current mechanical recycling facilities especially struggle with mixed plastic waste, multilayers, blends and additives, relying on easy-to-sort and relatively clean waste streams, while the chemical solutions under development require more energy, increasing CO2 emissions. “This is an urgent problem; by 2050 it is estimated that plastics production and incineration could release emissions equivalent to over 600 coal plants annually,” notes Cristiano Varrone(opens in new window) from the EU-funded UPLIFT(opens in new window) project. Applying novel biochemical upcycling technologies and eco-designs, UPLIFT has been developing a more sustainable plastic packaging value chain for the food and drink sector. “Our unique solution breaks down mixed plastic waste into monomers, then microbial processes upcycle these into more renewable plastics and additives,” says Varrone from Aalborg University(opens in new window), the project host.
A novel biorefinery for eco-polymers
Using a combination of advanced pretreatments, enzymes, microorganisms and greener chemical catalysts, UPLIFT’s novel depolymerisation process can handle the mixed plastic waste that can’t currently be recycled properly. Tests identified the best enzymes for breaking down polyester polymers into their constituent monomers, in mild conditions – low temperatures, without harsh chemicals. This depolymerisation process was augmented by novel and benign chemical catalysts. The project’s significant breakthrough was its plastic biorefinery approach, which combines plastic-derived monomers with bio-based fermented building blocks. Genetically engineered microorganisms upcycle these plastic-derived monomers and other residues into compounds such as polyhydroxyalkanoates(opens in new window) (PHAs), to produce eco-polymers, more carbon-neutral and easier to recycle. After testing the depolymerisation of pure commercial plastics, focus shifted to more challenging post-consumer plastic waste, including polyethylene terephthalate(opens in new window) (PET) bottles, trays and mixed plastic waste. The project achieved pilot-scale enzymatic depolymerisation of 25 kg of real plastic waste, as well as the production of novel bio-based building blocks in a 1 500 litre reactor. UPLIFT scaled up its most effective processes to produce 10-20 kg of PHA- and polylactic acid(opens in new window) based bio-upcycled eco-polymers, compounded into new packaging materials (including flexible films, rigid trays and bottles). “However, despite the environmental benefits, large-scale adoption of novel eco-polymers remains challenging and the cost is still too high to be competitive with conventional technologies,” adds Varrone.
Supporting the transition to a more circular economy
Between 2010 and 2022, the volume of plastic packaging waste in Europe increased by about 29 %(opens in new window). Meanwhile, half of the plastic collected for recycling is exported for treatment in countries outside the EU. As China now restricts imports of plastic waste, more will likely be incinerated or end up in landfill, compromising the EU’s circular economy(opens in new window) ambitions. This is especially concerning when about 22 million tonnes of plastic(opens in new window) reached soils, rivers and oceans in 2019, and with both plastic leakage and emissions from plastics lifecycles set to at least double by 2060. UPLIFT’s innovation could contribute to the EU Waste Framework Directive’s(opens in new window) ambition of reaching a minimum of 65 % (by weight) of municipal waste being reused and recycled by 2035. With a patent on chimeric enzymes already secured, the team is now working to optimise processes, reducing the cost of upcycling and eco-polymer production.
