Researchers at AMBER, the SFI Research Centre for materials science at Trinity College Dublin and BEACON Bioeconomy Research Centre, the Science Foundation Ireland (SFI) funded Research Centre led by University College Dublin have discovered a blend of biodegradable plastic that completely degrades under typical home-composting conditions. Their research was published today in the prestigious American Chemical Society journal Environmental Science & Technology.
Of the hundreds of millions of plastic bottles, films and cartons produced everyday in the world, it is estimated that fewer than 15% end up being recycled, with most destined for landfills or littering our environment. Ireland is not immune to this problem with more than 80% of Irish coastal areas and inland waterways polluted with plastic litter, causing issues for people and wildlife. Plastic waste ends up in our environment as a result of poor recycling options. One potential solution to this problem is the introduction of biodegradable plastics. Biodegradable plastics do exist and offer new waste prevention and management options which has the potential to fight against litter and environmental damage but until now no one had studied the conditions under which biodegradable plastics decompose.
The research was a collaboration between Professor Kevin O’Connor, BEACON and UCD’s School of Biomolecular & Biomedical Science, Dr Ramesh Babu AMBER Investigator, and European collaborators on EU funded projects (SYNPOL and P4SB). The collaborative team studied 15 different biodegradable plastics and mixtures of these plastics to see which had the most potential to biodegrade across a range of different environments – including standard home composting and industrial composting facilities where current brown bin material are taken. The research team tested blends of biodegradable plastics because often plastic packaging is made of a blend of plastics. They found that blends of biodegradable plastics can create new possibilities for managing plastic waste. Polylactic acid (PLA) is one of the well adopted biodegradable plastics on the market, but it requires high temperatures for breakdown and is not home-compostable. But surprisingly, a blend of PLA and polycaprolactone (PCL) degraded completely under typical home-composting conditions.
Professor Kevin O’Connor, BEACON Bioeconomy Research Centre and UCD’s School of Biomolecular & Biomedical Science, said: “Imagine putting your waste plastic packaging into a household composting bin that breaks down the plastic and produces compost for your garden or into your brown bin so waste collection companies are able to mix plastic with unavoidable food waste and produce biogas to run their fleet or power your home, that’s the future this study suggests.
Dr Ramesh Babu, AMBER and TCD’s School of Physics, said: “Going forward we will see massive shift in use of biodegradable polymers and our research opens up new and exciting possibilities that biodegradable plastics offer to society. We have shown for the first time that you can blend plastics together to make them more biodegradable but still keeping the strength and performance of the plastic. This opens up huge opportunities to create novel sustainable plastics that perform in multiple positive ways for society.
Dr Tanja Narancic, UCD’s School of Biomolecular & Biomedical Science and BEACON, a co-author on the publication said “Apart from providing opportunities to return carbon to soil as compost and to create clean energy (biogas), biodegradable plastic can be managed with other organic waste, rather than separated, making management easier.”
This research establishes new possibilities for waste management because if such biodegradable plastics were introduced as packaging and collected in the standard household brown bin this disposal treatment would result in their safe biodegradation and production of useful large scale by-products such as compost which can be used to grow plants, or biogas which can be used directly as fuel or upgraded to natural gas-quality biomethane, a renewable energy.
However, Professor O Connor warns that the study also found that “only two of the 15 biodegradable plastics tested, polyhydroxybutyrate (PHB) and thermoplastic starch (TPS), broke down completely under standard soil and water conditions. Therefore, biodegradable plastics are not a panacea for plastic pollution and post-consumer biodegradable plastic must be managed carefully to avoid pollution and bring benefit to society.”
The paper entitled “Biodegradable plastic blends create new possibilities for end of life management but they are not a panacea for plastic pollution” is available online: https://pubs.acs.org/doi/10.1021/acs.est.8b02963