A team of researchers at the University of Washington has discovered a way to turn coffee grounds and reishi mushroom spores into a completely compostable alternative to plastics, using 3D printing technology .
An alternative to plastics: Coffee grounds and reishi mushroom spores
Human-centered design and engineering PhD student at the University of Washington Danli Luo saw the potential in coffee grounds that are usually thrown away. Coffee is rich in nutrients and sterilized during brewing, making it an ideal medium for growing mushrooms. Before transforming into mushrooms, mushrooms form a “ mycelial skin ” that can bind loose substances, creating a strong, waterproof, and lightweight material.
Luo and his team developed a system for converting coffee grounds into a paste called ” Mycofluid ,” which they use to 3D print objects such as packaging materials, vase parts, and small statues. They then inoculate the paste with reishi mushroom spores, which grow and form a mycelial skin around the printed objects, turning them into durable, compostable alternatives to conventional plastics.
We are especially interested in creating systems for people like small business owners who produce products in small batches. We have been working on new material recipes that can replace things like polystyrene with something more sustainable and that can be easily customized for small-scale production.
Luo, the study’s lead author, said.
To create the Mycofluid paste , Luo mixed used coffee grounds with brown rice flour, reishi mushroom spores, xanthan gum, and water. He also built a new 3D print head for the Jubilee 3D printer. The new printing system can hold up to one liter of the paste.
The team printed several objects using Mycofluid : a container for a small glass, three pieces of a vase, two halves of a moai statue, and a two-piece butterfly-sized coffin. After printing the objects, they kept them in a plastic container for ten days to allow the mycelium to form a protective layer around the printed material.
The process is similar to that of home-grown mushroom kits: the mycelium is kept moist while it grows from nutrient-rich material. If the pieces were left in the container for longer, real mushrooms would sprout from the objects, but they are removed after the mycelial skin has formed. The researchers then dried the pieces for 24 hours to stop fruiting.
The finished material is heavier than polystyrene, with a density similar to that of cardboard. After one hour in contact with water, it absorbed only 7% more weight in water and dried to regain its initial weight , while maintaining its shape. It was as strong and resilient as polystyrene and expanded polystyrene foam.
While the team didn’t specifically test the material’s compostability, all of its components are compostable ( and edible ). Since Mycofluid requires relatively homogeneous used coffee grounds, working with it at scale would prove difficult.
We are interested in extending this approach to other bio-based materials, such as other forms of food waste. We want to broadly support this type of flexible development, not just offer a solution to this major problem of plastic waste.
Luo stated.
Study co-author and human-centered design and engineering master’s student Junchao Yang and Nadya Peek, an associate professor at the University of Washington, also participated in the research. This research was funded by the National Science Foundation .
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Source and photos: Washington University
