Polypropylene is the ubiquitous plastic used in all manner of products from clothing to medical devices, furniture, toys, luggage and packaging. But its popularity is coming at a price: it accounts for 28 per cent of the world’s plastic waste but just 1 per cent is recycled.
Ridding ourselves of plastic waste might soon be easier thanks to researchers from the University of Sydney who discovered that fungi can break down polypropylene, avoiding the need for it to be recycled and remade into new products.
The researchers treated polypropylene with either UV light or heat and then used two common strains of fungi – Aspergillus terreus and Engyodontium album – to biodegrade the plastic, which reduced in volume by 21 per cent after 30 days of incubation and up to 27 per cent over 90 days.
If adopted, the fungi method could help reduce the amount of plastic that ends up in the world’s oceans and rivers. Polypropylene is not easily recycled due to its short life as a packaging material and because it is often contaminated by other materials or mixed with other plastic types, according to the researchers.
Plastic pollution is by far one of the biggest waste issues of our time
“Plastic pollution is by far one of the biggest waste issues of our time. The vast majority of it isn’t adequately recycled, which means it often ends up in our oceans, rivers and in landfill,” the study’s lead author from the University of Sydney’s School of Chemical and Biomolecular Engineering, PhD student Amira Farzana Samat said.
“It’s been estimated that 109 million tonnes of plastic pollution have accumulated in the world’s rivers and 30 million tonnes now sit in the world’s oceans – with sources estimating this will soon surpass the total mass of fish.”
The researchers said they would like to examine other biological processes that fungi and other microorganisms found in plant and soil could carry out.
Other studies have shown that fungi may be able to break down “forever” chemicals such as PFAS, but experts said further research was needed to understand how the process works. There is also speculation that marine fungi may have broken down some of the plastic that has accumulated in the ocean.
The researchers will now study ways to enhance the efficiency in the biodegrading process before seeking to attract investment to commercialise the technology via a small-scale pilot prototype. Future experiments will study how the plastics are being broken down by the fungi and whether they are being metabolised.
Fungi has been shown to biodegrade other types of plastic, including polyurethane in a 2011 Yale University study using the Pestalotiopsis fungi.