Kate Porterfield, a University of Vermont graduate, tests unpackaged food waste for microplastic contamination. Her Casella-funded research examines the sustainable use of this waste to produce biogas and improve resource recycling in Vermont. (Photos: Sarah Hobson, Kate Porterfield)
UVM researchers are working with Casella to uncover the suitability of packaged food waste for organic recycling.
Vermont business magazine More than a third of Vermont food waste is still packaged – a difficult situation when it comes to the mandatory diversion of food waste from landfills under the state’s new universal recycling law. Law 148 banned food waste from landfills from July 2020.
Researchers from the University of Vermont (UVM) are collaborating Casella waste systems to test the efficiency of a new unpacking system at the company’s recycling facility in Williston.
“It is very exciting for us to bring this technology to our home state,” said John W. Casella, Chairman and CEO of Casella Waste Systems, Inc, to bring it to better use and to conserve natural resources. “
Casella has funded two UVM students to conduct this sustainable waste management research. Assistant Professor Eric Roy and two of his PhD students are examining whether food waste, once separated from its packaging, can be used for anaerobic digestion and composting.
As an alternative to composting, leftovers are broken down by microorganisms in the oxygen-free containment of an anaerobic fermenter, often in combination with milk fertilizer. This creates biogas, a clean, renewable energy source. In addition to biogas, liquid and solid fermentation residues are produced during anaerobic digestion, which are usually applied to fields as fertilizer, used as litter or composted.
But what happens if the separated food waste still contains small packaging particles – mostly plastic? The manufacturer of the unpacker claims it is 95 to 99 percent effective in isolating food from its containers. This leaves a small amount of microplastic that can get into the environment if the food waste is incorporated into the soil as digestate or composted.
“Casella is very proactive in determining how well its repackaging line is performing to maximize environmental benefits and minimize costs,” said Roy, a member of the UVM faculty on both Rubenstein School of Environment and Natural Resources and the College of Engineering and Mathematics (CEMS). “We’re trying to collect data that can guide food waste management in Vermont and beyond into the future.”
Casella and the researchers are focusing on two main streams of packaged food waste: pre-consumers – usually large quantities of packaged but unsaleable products from food manufacturers – and post-consumers, which may contain packaging or other contaminating materials. Roy and his students test both streams of unpackaged food waste. They quantify its value for biogas production and composting as well as its plastic pollution.
“I was able to sit down with the folks at Casella and ask research questions about our common concerns and interests in relation to the environment and waste management,” said Kate Porterfield, a PhD student at CEMS who investigates the suitability of de-packaged food waste for use in the Biogas production.
Porterfield began her research at the facility in January 2021, the day Casella ran its first load in the unpacker. She watched the operators load packaged food waste into the hopper, where rotating paddles broke the packaging open without breaking it. The separated food waste passed through sieves and the packaging was lifted out for recycling or landfill. Porterfield collected samples of food waste after the separation process for laboratory testing.
Casella’s support has enabled Porterfield and Roy to break new ground in measuring plastics in food waste. Porterfield is working on methods with which the abundance of microplastics can be isolated and quantified quickly and easily. Marine researchers are doing similar work to study plastic in the oceans.
Porterfield uses an instrument called the Automated Methane Potential Test System (AMPTS 2), a laboratory-scale anaerobic fermenter that runs through 15 soft drink-sized bottles of food waste at a time. Every time a sample produces methane, a computer records gas bubbles and creates a graph of biogas production. This will help researchers find out how efficiently food waste can be converted into biogas.
After the organic waste has fermented, small pieces of plastic can be easily removed with a fine-meshed sieve. Porterfield counts the particles under a microscope to see how much plastic is contaminating the organic matter. She then uses Fourier Transform Infrared (FTIR) spectroscopy to classify the polymers of plastics isolated from the laboratory digestion.
“Once we have identified the types and amounts of contaminating plastic, Casella and others in the industry can go upstream to food manufacturers or waste suppliers to find ways to remove unwanted packaging or other contaminating materials,” said Roy.
“Our results are hugely important to the Vermont Universal Recycling Law, which required this type of research,” said Porterfield. “There is so much we don’t know about food waste use, especially the effects of plastic pollution.”
UVM Master’s student Sarah Hobson will study unpackaged food waste, composting and plastic contamination. In the fall of this year, she began her two-year course at the Rubenstein School with a Casella-funded Sustainable Materials Management Fellowship.
“Can compost that contains microplastics be safely used in the environment?” Said Hobson. “This is still a new area of study and we are trying to better understand the life cycle of plastic in food waste.”
“We are proud to partner with a leading sustainability institution like UVM and to offer UVM students meaningful research opportunities that advance our industry,” said Casella. “Seeing how research has real impact in real time is very powerful, and we are grateful for the ongoing partnership and shared commitment of UVM to advance sustainable solutions for the environment.”
As a guide to their work, Hobson will use participatory action research to learn firsthand what they know and what questions they have about plastics in food waste and compost from farmers, compost producers and compost users.
Roy and his PhD students bring their research to the classroom to engage up to 50 students each year on projects that become trial runs.
“Students are thrilled to see that they are at the limit of new knowledge and involved in actionable science that can be used to improve the environment,” said Roy.
In Roy’s Advanced Ecological Design course last spring, a team of students performed anaerobic digestion experiments with unpackaged food waste and developed methods for separating microplastics.
“Working with Kate Porterfield and my group has been by far the funniest, highest-level learning project I’ve ever participated in,” said Garrett Dunn, a bachelor’s degree from UVM. “The most important aspect was how we decided to work on a fairly new research discipline in waste management. This made the learning experience really unique from any other class. “
This fall, a larger group of students will learn about the carbon cycle and food waste management through similar experiments in Roy’s Ecological Design and Living Technologies class. These practical learning experiences take place with the support of Casella in a new Eco-Design Makerspace in the Aiken Center on the UVM campus.
About the University of Vermont
The University of Vermont has worked to advance humanity since 1791. The strengths of UVM correspond to the most urgent needs of our time: the health of our societies and the health of our environment. Our size – large enough to offer a wide range of ideas, resources, and opportunities, yet intimate enough to enable close mentorship between faculty and students across all degrees – enables us to explore these interrelated topics through cross-disciplinary research and pursue collaboration. Providing our students with an unparalleled educational experience and ensuring their success is at the heart of what we do. As one of the first land grant universities in the country, UVM advances Vermont and society at large through the discovery and application of new knowledge.
UVM comes from Latin Universitas Viridis Montis (in English, University of the Green Mountains).
Learn more about Casella, a regional solid waste, recycling and resource management company headquartered in Rutland, Vermont.
Video describing Casella’s Williston unpacker facility and the research partnership between Casella, the University of Vermont and local food manufacturers
You can also see it here: https://youtu.be/0qFhQe9frgM
Source: BURLINGTON, Vt. – UVM 10.15.2021