Each year, Wisconsin is responsible for the production of over 25 billion gallons of milk and 2.5 billion pounds of cheese, according to the Babcock Dairy Plant. With this large-scale dairy production comes the responsibility to manage wastewater. There are a variety of wastewater streams generated from the production of dairy, Director of the Center for Dairy Research and Professor of Food Science John Lucey said. For instance, the washing of any pipes, vats or tanks containing milk in a facility would result in a diluted milk mixture that would require treatment.

Dairy wastewater must be treated to prevent environmental risks. If left untreated, elements like nitrogen and phosphorus can fuel algae blooms and deplete oxygen levels, according to Genesis. These elements undergo oxidation reactions, removing oxygen from surrounding water. This also provides algae with nutrients to grow, increasing oxidation and further reducing oxygen, ultimately starving aquatic life, Lucey said.

Due to the risks untreated dairy wastewater poses, the Wisconsin Department of Natural Resources sets regulations for what may be discharged into waterways. In the past century, many companies have opted to build wastewater treatment facilities on-site to adhere to these set levels, Lucey said. 

But recently, there has been a shift in how dairy byproducts are perceived. Rather than being thought of as the endpoint in the production process, these byproducts may act as the foundational factor for the creation of new marketable materials, Lucey said. Alcohol, acids and polymers for bioplastics can all be created from dairy byproducts through the use of a key component – microbes. At the University of Wisconsin, researchers are exploring how microbes may be used to make these new materials through large-scale pilot projects, according to an article from the Proceedings of the National Academy of Sciences. 

“My kind of mission is to stop talking about this [dairy byproducts] as waste, and to start thinking about this as an opportunity,” Lucey said. 

Assistant Professor of Bacteriology Erica L-W Majumder is one such UW researcher currently exploring this avenue. Her research focuses on how dairy byproducts may be used for the creation of bioplastics. Food processing plants — which make cheese, yogurt or other dairy products — send their wastewater that is full of acid whey to Majumder’s lab. Acid whey contains particularly high amounts of lactose and lactic acid, which microbes like to consume, according to Chemical and Engineering News. Regarding the microbes, Majumder’s lab uses a variant of E. Coli that has been engineered specifically for the production of bioplastics, Majumder said. 

Then, Majumder takes these microbes and dairy byproducts and places them into a bioreactor — a growth vessel allowing researchers to control variables like temperature, oxygen levels and stirring rates, Majumder said. The microbes feed off of the acid whey and naturally produce plastic polymers, like polyhydroxybutyrate, according to PNAS. Majumder and her lab may then collect these microbial cells and open them up. After purifying the polymers that these cells produce, the polymers may be used by plastic companies just like they would if they had been derived from fossil fuels, according to the PNAS article. 

Both Majumder and Lucey feel that microbe-driven, wastewater-repurposing technologies will be the future of the industry.

“It is something where the technology is really close so if the right incentives from all the other factors were in play, it’s something that could happen within a couple of years,” Majumder said. “But, it’s probably not likely to happen that fast.”

While some companies are currently able to make bioplastics from microbes in the country — like Danimer, these industrial processes use sugar feedstocks. So, the challenge is finding a way to replace sugar feedstocks with industrial waste streams, Majumder said. 

Another challenge regarding the implementation of these repurposing technologies relates to cost. In Wisconsin, between 120 and 200 dairy plants are converting dairy products, but many of them are not big enough to afford the necessary waste treatment facilities, Lucey said. Instead, they may choose to ship their waste to municipal waste treatment plants. Companies may refrain from these technologies rather than take on the up-front cost of investing in this sustainable avenue, resulting in higher greenhouse gas emissions. 

But, these technologies are essential for companies to improve their business model and eliminate unnecessary waste, according to PNAS. Not only do waste-repurposing technologies reduce water and air pollution, but they also contribute to a circular economy, which benefits farmers, manufacturers and consumers alike, Lucey said. 

This shift to waste-repurposing technologies is occurring at the UW campus. In partnership with the Wisconsin Cheese Makers Association, the CDR formed the Dairy Business Innovation Alliance, according to the DBIA website. The DBIA is currently funding six different groups at the UW campus working on using these technologies to create butanol, bioplastics, pure elastic gases and food ingredients, Lucey said.

Lucey’s long-term vision is that these technologies will be expanded across various industries so it’s not just cheese byproducts being repurposed, but all industries work toward more sustainable methods of production. 

“This is actually happening,” Lucey said. “That doesn’t mean there’ll be products for tomorrow, because it takes a while to figure out what to do and how to do it … but it has started — companies are interested and research has started, so I’m optimistic.”