Up to 3.7 million gallons per day: that’s how much waste milk dairy farmers washed down drains at the height of the Covid-19 pandemic in 2020, according to Dairy Farmers of America. A drop in demand from schools, restaurants and coffee shops meant farms had far more milk than they could sell.
This problem sparked an idea for two professors at the University of Wisconsin, Dr John Obielodan, Professor and Chair of the Department of Mechanical and Industrial Engineering and Dr Joseph Wu, Associate Professor of Chemistry. The pair asked themselves, “‘Why can’t this milk, instead of being wasted, be turned into something valuable?’” They spent the following five years answering that question. The result? A new biodegradable plastic made from waste milk with a use-case in 3D printing.
Dairy proteins become biodegradable plastic with wide-ranging use cases
Obielodan and Wu’s invention received a US patent in October 2025, titled ‘Development of Bio-Composite Materials for 3D Printing Using Milk Proteins.’ The process uses proteins from dairy, such as casein and whey, as the basis for biodegradable plastic. The material is an eco-friendly alternative to petroleum plastic, the non-biodegradable plastic often used in 3D printing.
From medicine to manufacturing, many industries rely on 3D printing methods for production. Obielodan told the University of Wisconsin press that, “Looking ahead, a variety of products could be made using proteins derived from milk. From 3D printing filaments to other engineered materials, the possibilities are wide-ranging.”
A sustainable alternative—or support for the dairy industry?
Creating plastic from leftover milk makes great use of a waste product. What’s more, the process would reduce the production of non-biodegradable plastics, which harm marine life and make their way into human food chains. Emissions from global plastic production will also account for one-fifth of the Earth’s carbon budget by 2050. Obielodan points out that, “Biomaterials offer a more sustainable alternative, turning natural and waste materials into useful polymers with fewer environmental and health risks.” As for 3D printing, the on-demand process creates less waste material than traditional manufacturing, as well as reduces shipping emissions thanks to simplified supply chains.
Wu explained that, “My hope is that [the invention] will help both the 3D printing industry and dairy farmers in Wisconsin.” With dairy farmers under pressure from falling milk prices due to tariffs, a new income stream could provide a significant boost. But, with livestock accounting for 14.5 percent of human-induced emissions, is supporting the dairy industry the best way to help the planet? The invention is undoubtedly a positive way to make use of excess milk rather than pouring it down the drain. But cutting our consumption—both of dairy and plastic—is still the optimum solution for reducing global emissions in manufacturing and beyond.
