Australia’s coffee habit produces a lot of grounds and a lot of cups that go to landfill. An engineering student wants to close the loop and recycle coffee grounds into biodegradable plastics.
“Australians consume six billion cups of coffee every year, and the coffee grounds used to make these coffees are used only once and then discarded,” said Dominik Kopp, a Macquarie University PhD student.
“In Sydney alone, over 920 cafes and coffee shops produced nearly 3000 tonnes of waste coffee grounds every year.”
Although some of this can be recycled into products like mulch, the majority ends up in landfill. The same goes for most takeaway coffee cups, which can’t be recycled as they are lined on the inside with a thin plastic film.
Getting a coffee fix
Kopp saw an opportunity to tackle both problems. He has helped develop a method that uses discarded coffee grounds as the base for a biodegradable plastic with applications as diverse as compost bags, medical sutures and food storage containers – including coffee cups.
His method converts the sugar in coffee grounds – primarily mannose – into lactic acid, which can then be used to produce the biodegradable plastics.
“Lactic acid can be used in the production of biodegradable plastics, offering a more sustainable and environmentally friendly alternative to fossil fuel derived plastics,” Kopp said.
Kopp’s process differs from comparable industrial production of lactic acid from corn, where sugars are fermented with microbes. His process required developing a synthetic pathway, which meant manipulation of DNA sequences to produce an enzyme that acts as a natural catalyst to transform the sugar. The resulting lactic acid acts as the base material for polylactic acid (PLA) biodegradable plastics.
Kopp’s method was inspired by a metabolic pathway that is thought to exist in an evolutionarily ancient organism, which lives in hot and extremely acidic environments.
Waste not
Kopp’s work was done under the supervision of Associate Professor Anwar Sunna, who leads a synthetic biology and nanobiotechnology research group at the university. Their group looks for “new ways to convert biowaste – whether that be agricultural, garden, paper or commercial food waste – into valuable raw materials that can be used to produce high-value compounds in more environmentally friendly ways,” Sunna said.
Kopp’s work won him the Early Career Award for Applied Biocatalysis/Nanobiotechnology at the European Congress on Biotechnology in Geneva.
It remains to be seen how much coffee it would take to produce a single coffee cup and whether it is more efficient than current processes. Kopp plans to further refine the process with an eye on commercial production.