How Princeton Is Taking Composting to the “Next Level”

Some eco-minded people at Princeton University view their small, New Jersey campus as a microcosm for the larger world—a place to vet sustainability solutions that could potentially be scaled and used in communities beyond their “bubble.”

They are leveraging the Ivy League school’s capacity as a research institution to see how they might improve composting practices, beginning on their campus, but aiming to gain knowledge they can share with other institutions and communities.

“We use the campus as our lab to study and demonstrate potential solutions to sustainability challenges and looked at composting because of the problems we were seeing in our region,” says Gina Talt, project manager, Office of Sustainability Princeton University.

New Jersey and surrounding states’ facilities were struggling to stay on top of odor and contamination. Some of them eventually shut down, forcing communities to scramble to find homes for their organic waste and prompting conversations around decentralized compost systems so economic and environmental benefits were more likely to stay local.

Princeton decided to pilot an in-vessel system; it was small enough for their early project, yet there was potential to scale. The rotary drum system has a 5,000-pound-per-week capacity of food waste, which comes from the dining halls.  It’s affectionately called SCRAPPY, a name that’s caught on with staff and students.

“We are under capacity but have room to expand, which is the next hanging fruit that we want to pilot. How can we bring in more feedstock? How can we collect organics like we do trash and recycling?” Talt says.
Part of what she and her team are working on is piecing together a behavior puzzle, which has to do with helping people understand what to put in the bins to mitigate contamination.

The student population turns over about every four years, so that’s the available window to reinforce good practices. The transitory environment and a diverse population has led to confusion around recycling rules.

“So, it’s a communication challenge, and we have to start slow and purposefully,” Talt says.

“You can have a lot of signage, but sometimes they just see a hole where they can discard waste. I think on a busy campus that’s more likely to happen,” she says.

The Sanitation staff and dining facility workers have been key to making the logistics work. Dining hall scraps from the kitchen and uneaten food are tossed in bins, moved to loading docks, picked up, and sent to the facility. Student volunteers are involved in the next steps, rolling bins onto the scale; figuring out how much weight they will process; and determining the ideal ratio of carbon (in this case wood pellets) to food scraps. There’s no shortage of helping hands. The students don’t mind getting their hands dirty or smelly. It’s a way they can have an impact on campus, Talt says.

Incoming loads spend a week in the vessel and come out as a stable product, ready for use. But since it’s used for horticulture with specific design aesthetics to meet, it’s cured for several months, with other vegetative materials mixed in to create different blends.

While Princeton focuses on this project, it’s expanding its work with a grant from the New Jersey Department of Environmental Protection (DEP). The grant funding is to study the collection and recycling of compostable bioplastics and to better understand what type of compostable service ware can break down in the university’s process.

“We’ve done basic testing in the past, adding different compostable products to the mix, like fiber, polylactic acid (PLA), and bamboo. But now we want to do a robust analysis in partnership with researchers to collect information that we can share at conferences and write white papers about,” Talt says.

The Sustainability Office will work with a professor in Geosciences and her freshman class in the fall of 2023, studying samples to figure out how to optimize the university’s process and to learn what happens when they add different compostable plastics.

“Our baseline is using fiber-based compostable products that degrade well, but if we introduce PLA and other materials how does that change the profile of the compost?” Talt asks.

Princeton is one of a number of New Jersey universities and colleges working to develop organic recycling programs that can be used to demonstrate compost processes and applications – and it’s one of several to tap into New Jersey DEP’s grant to do so.

Rutgers, Kean, and Bergen Community College have also been awarded over the last several years, focusing on objectives such as expanding organic capture and diversion; learning how to work effectively with multiple feedstocks; and setting up micro bins to compost different materials from multiple locations, rather than from one centralized site.

New Jersey Composting Council has supported the schools in their grant projects, whether with research, project management, or in other areas, believing engaging with them aligns with the nonprofit industry group’s interests.

There is a plethora of technologies out there and opportunities to do composting at different scales, says Isaac Bearg, vice president New Jersey Composting Council.

“We want to show [multiple stakeholders] it can be done responsibly: DEP who permits facilities; universities who may purchase technologies; composters who may accept [more or different] materials; and residents near compost facilities,” he says.

Why partner with the higher education community, a long-time focus of the regional Composting Council?

"We work with universities because of their interest in doing good, as well as their capability to research, adjust methodology, and report their findings,” says Jairo Gonzalez, president of the New Jersey Composting Council.

“With them we can build case studies that will help us motivate generators of organic waste, and change policy to make organic recycling a more common good.”