Pardon the delay! Over the past year and a half, we wrapped up our second year of research into compostable product collection and processing. We’re excited to share final results-starting with Part I: Upstream collection – featuring audit data from our education campaign and infrastructure upgrades at the point of toss
As we shared in our last post, a baseline audit of the Frist Food Gallery showed that over 60% of landfill waste could be composted—mostly food scraps and compostable dining products.
In response, our Dining team partnered with procurement and suppliers to streamline product offerings and switch to certified compostables. We also redesigned the toss zone, adding a compostables bin and deploying student and staff ambassadors to guide diners. Once the ambassadors stepped back, we reinforced sorting with signage featuring real item examples above each bin.
The results? A third-party audit showed that landfill waste was cut by more than half! Our overall waste diversion percentage jumped from 4% to 56% as shown in the data charts below:
Additionally, over 50% of the compostable stream was diningware—proof that packaging swaps matter.
Contamination in the compost stream started at 20%, but we’ve since halved that to 10% thanks to further improvements: motion-sensor compactor bins, a large banner advertising the collective impact, and permanent 3D wall signage:
Still, our goal is 5% contamination or less. This spring, we surveyed diners to understand sorting pain points. One big insight? The condiment station near the toss zone was causing congestion. So, with guidance from the Kahneman-Treisman Center for Behavioral Science, we’re relocating it and redesigning the area with a “decision tree” layout—compost on one side, landfill on the other—to encourage more mindful sorting.
While we wait for these changes, stay tuned for the next post in our series where we’ll dive into the composting process itself and what we learned about compost quality.
In today’s post, the comPOSTer takes a look back at the fall semester happenings at the S.C.R.A.P. Lab:
In the Fall we received the results from our spring baseline audit of everything consumers were putting in trash and recycling at retail dining. We selected the largest venue – Frist Gallery – and one of the smaller cafes (Shultz) on campus as representative locations. Over the course of two days in mid-April, our Campus Dining and Sanitation staff helped us collect and transport the waste materials so they could be audited by our contractor, MSW Consultants.
Figure 4-2 (shown below) compares the recoverability of refuse from the Frist Campus Center and the Shultz Café. Key takeaways include:
Most of the food waste (average of ~35%) from each location was loose, this amounted to 100 lbs. over two days (“Food Waste/Compostable” columns)
Another ~30% of items across the two locations consisted of items “Eligible for Conversion to Compostable Alternatives” Uncertified paper items such as commercial soft drink cups, french fry “boats,” and uncoated paper plates were the biggest culprits.
In sum, over 60% of items going to the landfill have the potential to be diverted to composting in the two retail dining locations.
The goals of the fall semester were to:
Replace traditional petroleum-based plastic packaging with certified compostable packaging
Provide collection receptacles for compostable items and change the behavior of diners to encourage proper sorting
Investigate how adding the compostable products affects the composting process
First, our Campus Dining team worked with our food supplier to streamline the number of disposables that are offered in retail dining while also swapping out products for the compostable alternatives. Working mainly with Eco-Products, we identified two different types of certified compostable products:
Molded fiber (consisting of paper or sugarcane) – typically plates, “clamshell” containers, and bowls like the tan ones shown below
Polylactic acid (“PLA”) – which is a plastic substitute made from fermented plant starch (usually corn) – typically utensils and cold cup lids
Or a combination of both (e.g. hot coffee cups or soup containers that are fiber-based but have PLA coatings)
In October, we began to transition some of the single-use packaging to the compostable alternatives and began collecting them during meal hours with the help of bin monitors to ensure a contaminant-free stream.
Diningware collected by bin monitors. The bowls and clamshells are made out of molded fiber sugarcane and the utensils consist of PLA
For two weeks we loaded the food scraps and compostables using the standard way (shredded by the composter’s built in shredder). We had a transition week during fall break and then two weeks after that we pre-shred the compostables through a chipper prior to being loaded in the hopper as part of the exercise on investigating the impact of size reduction. Throughout the Zhang lab researchers and students in the first year seminar course monitored exhausts gases and compost quality.
Chipper rental used to pre-shred the compostables
The shredded compostables after being processed by the chipper
In mid-December the students presented their posters with preliminary findings on how adding the compostable products affected the exhaust gas profiles and nutrient (particularly nitrogen) cycling.
Students in FRS 115: Decomposing the Science of Composting prepare samples for CO2 respiration, a key metric for determining compost stability
Meanwhile, we transitioned most packaging products to compostable alternatives and rolled-out 24/7 collection containers for consumers in the Frist Gallery. We took an agile approach and tinkered with the space based on direct feedback from diners and their observed behaviors. See our evolution below:
1st iteration: A large banner connecting the effort to the S.C.R.A.P. Lab and campus sustainability efforts. Instructional signage is above each type of receptacle. We used our Toters and experimented with spray-paint on the front to try to catch diners’ attention. One of the Toters was left open, another had a motion sensor lid on top of the opening.
2nd iteration: We quickly realized that the addition of the orange banner and green Toters were not enough to catch diners’ attention. The instructional signage did not stand out enough. Thus we physically taped each of the items to the wall above the container where they should respectably be placed. This intervention caught people’s attention and correct sorting became more likely after people studied the wall.
3rd iteration: We separated the different sets of containers to make the distinction clearer between landfill and compost
4th iteration: The Toters were unfamiliar to diners (mostly students) so instead we “hot roded” one of the landfill containers and transitioned it to a compost container using bright green tape and green outline text. The bright colors further caught diners’ attention and led to more conscious engagement with sorting. We also removed the motion-sensor lid since it was difficult for diners to understand and we found it was not necessary with the other interventions
MSW Consultants came back to campus to perform the follow-up audit. Results are pending but quick observations included:
About a 10% contamination rate (by weight)
30% loose food
The remaining ~60% are certified compostable products that were loaded into SCRAPPY and treated as a carbon or “brown” source for the system (consistent with earlier audit results)
We will continue to modify and enhance the sorting area to improve diversion and lower contamination rates, but so far we are okay with the level of contamination.
We sort out any contaminates at the facility and sometimes get a good laugh at what we find
Happy first week of classes to the Princeton community!
In celebration of the start of the ’23-24 academic year, we look back at the summer happenings at the S.C.R.A.P. Lab:
OPERATIONS
After a taking a break from mid-May through June, the S.C.R.A.P. Lab was back in operation on a limited schedule after July 4th through the end of August. We processed on average a half of a ton per week (about half of what we process during the busier academic semesters).
RESEARCH
The rest of the time was focused on research and course planning tied to our DEP compostables testing grant. The next phase of our grant studying bioplastic composting will happen this fall in conjunction with FRS 115: Decomposing the Science of Composting: How To Turn Waste into Resource. In preparation, we met with Prof. Zhang and her lab team to test out the sampling protocol for the class:
Dr. Shannon Haynes of the Zhang Lab trials gas sampling techniques
Locations where gas samples will be collected (three ports along the vessel)
Gas sampling from the exhaust pipe
The tube above is connected to a Picarro device which tracks real-time continuous measurements of the exhaust gases
Picarro output: Spikes in Nitrous Oxide, Carbon Dioxide, Methane, Ammonia and Water Vapor tend to occur right after aeration of the vessel. We will report our findings on the significance of these trends by the end of the semester
ENGAGEMENT
We also had a tour with the US Composting Council and engaged a group of first-year students for a work day.
Giving a tour to participants in a Compost Operations Training Course hosted in New Jersey. “SCRAPPY” was one stop of several that the group made of local facilities in the Garden State in early August. Photo courtesy of the Compost Research & Education Foundation
For our final post of ICAW, we share updates on our DEP grant project to study and test innovate new methods for using, collecting, and recycling compostable plastic products.
As part of our assessment on how well several types of compostable plastic products break down in our composting systems (SCRAPPY followed by piles or windrows), we first need to better understand our post-consumer retail waste stream. Our goals are to:
streamline and cut down on the number of single-use serviceware items (The fewer kinds of serviceware, the easier it is to encourage proper recycling)
pick better product alternatives that are certified compostable (preferably PFAS free too) so we can test them in our systems
So our first step in this journey was to conduct a waste audit of everything consumers were putting in trash and recycling at retail dining. We selected the largest venue – Frist Gallery – and one of the smaller cafes on campus as representative locations. Over the course of two days in mid-April, our Campus Dining and Sanitation staff helped us collect and transport the waste materials so they could be audited by our contractor, MSW Consultants.
While we are still waiting for the full audit results, we share some details and preliminary findings in the photo essay below (trigger warning for anyone who doesn’t want to see the food waste):
Above: Audit sorting table. Contents of bags were dumped here and individual items were identified by MSW staff and placed into the appropriate sorting bin. Bins get weighed after so we know the material breakdown (by weight) of the entire stream
Sorted certified compostable bowls that are already compostable in SCRAPPY
Sorted UNCERTIFIED compostable serviceware that has the potential to be compostable in SCRAPPY if swapped for an alternative
Certified compostables and organics from the audit that were sent for composting at SCRAPPY
Overall we captured a lot of waste – 250 lbs alone of organics (wasted food & molded fiber compostable serviceware that we know composts well) went to SCRAPPY directly after the sort across both days.
Now we will be able to better understand our waste composition and how we can divert as much as possible toward recycling/composting over the next few months when we revamp the waste sorting area in Frist over the summer and fall. Stay tuned for more progress updates!
For today’s ICAW post we are pleased to share a Q&A about home composting with Tania Althoff who is a Project Manager in the Office of Capital Projects at the University.
Read more about Tania’s journey to composting, her process, and advice to those looking to start:
Why were you interested in starting to compost?
I like to make plant-based meals and salads with different fruits and vegetables, and I realized how much food waste I was throwing in the trash. I wanted to “recycle” these food scraps to make something useful for my garden and yard. Also, I joined an organic community garden this year and this opportunity became a great motivator for starting my own system!
Tell us about your composting system
I have a dual chamber tumbler that sits outside. I turn it occasionally to aerate it and add water to keep it moist. Also, I use a metal bin to collect scraps in the kitchen. I’ve been collecting all plant scraps like pepper stems, potato peels, broccoli or kale stalks, etc. and also egg shells, coffee grounds, newspaper, and leaves. Having just started the system recently, it’s still “brewing” so I don’t have usable compost just yet. It’s a slow process but I’m hopeful I’ll have compost for use later in the growing season!
Any advice for others looking to start composting at home?
Just do your research! There’s so much information out there about how to get started composting at any scale, as well as the different types of home composting options available. Make sure to learn about the balance of nitrogen and carbon that’s required for any system. Good luck!
Thanks Tania!
Don’t forget to visit our Resources pages to learn more about composting basics and find a home composting system suitable for you. For more inspiration, revisit last year’s home composting Q&A with Ted Borer
Tune in for one more post tomorrow for a project update on our DEP grant
During the pandemic, SCRAPPY was relocated from Princeton to West Windsor Township. This March, we held a “relaunch” ribbon cutting ceremony to formally (re)-introduce the West Windsor and greater Princeton University community to our food scraps demonstration composting project. A photo essay of the event is below.
All photos courtesy of Jared Flesher, Communications Specialist with the Office of Sustainability
Despite the rainy spring day, about 50 attendees came out for the ceremony. Opening remarks were given by VP of Facilities, Kyu Whang, Office of Sustainability Director, Shana Weber, and Food Systems Project Manager, Gina Talt ’15
After remarks, Kyu Whang does the honor of cutting the ribbon
Next Gina leads the group on a facility tour
Curious attendees take a look of the loading hopper
Gina explaining the compost off-loading process to West Windsor Township Council President, Andrea Mandel. Not pictured, compost giveaways to all attendees, packaged in reusable Stasher bags
Following the facility tour, we also raffled off a home composting system. Sarah Williams of the Molecular Biology Department was the lucky winner and the ComPOSTer will follow-up with her to hear about her experience with it.
To learn more about home composting options, visit our Resources page and stay tuned for tomorrow’s post for a home composting Q&A with Facilities staff member, Tania Althoff.
Our first commemorative post highlights project updates from March and April.
During this time we….
Reached a big milestone of processing 100 tons of uneaten, non-recoverable food (for the 2 years that scrappy has been operational, not counting offline time during the pandemic)
Expanded our team by creating new roles to enable more event and bin pick-ups.
Sabrina Fields ‘GS joined the team as a Graduate Compost Coordinator, assisting with food scraps collection efforts in academic departments. Prior to coming to Princeton, Sabrina was at the University of Chicago’s Harris School of Public Policy, where she helped coordinate an effort to reinstitute compost in the Keller Center building as students returned to in-person learning. Being her first experience with composting outside of a residential composting program, she learned a lot about how important the education and behavioral aspects of larger-scale composting programs are.
Victoria Koretsky ’26 joined the team as a Compost Concierge Driver. Victoria drives around campus in our minivan and picks-up smaller buckets and bags of pizza boxes from a few centralized locations on campus, helping to free up time for our operational team
We also welcomed three new student team members to the operational crew. Check out their full profiles here
OPERATIONAL UPDATES – MARCH & APRIL
As the weather warmed and we entered the busy part of the spring semester without any pauses in operations, our monthly totals have jumped to the highest they have been since the pandemic.
With Sabrina’s and Victoria’s help, we were able to capture a greater amount of food scraps from non-dining venues by beginning new partnerships with the Center for Policy Research on Energy and the Environment, the Real Food Co-op, as well as working with our student Eco-Rep team to collect compostables at various events across campus.
We estimate that we recovered and composted over 150 gal of food scraps and 200 pizza boxes from events over the last two months.
8,907 lbs.
The total amount of material composted at the S.C.R.A.P. Lab in March
10,128 lbs.
The total amount of material composted at the S.C.R.A.P. Lab in April
Stay tuned for another post tomorrow recapping our re-launch ribbon-cutting ceremony
Next week, May 7 – 13, is International Compost Awareness Week (ICAW)!
ICAW is the largest and most comprehensive education initiative of the compost industry. It is celebrated nationwide and in other countries each year during the first full week of May. The goal of ICAW is to work together to raise public awareness on why we all should be composting our organics recycling and using compost.
This year’s theme is For Healthier Soil, Healthier Food…Compost! The theme was chosen based on a serious world-wide issue that every nation, unfortunately, experiences: hunger.
One of the initiatives of the United Nations Sustainable Development Goals (SDG), is Zero Hunger: End hunger, achieve food security and improved nutrition, and promote sustainable agriculture.
The chosen 2023 theme best reflects the goal of focusing on how compost can have a role in helping feed the world, by making our soil healthier which produces healthier food.
How does compost help?
By recycling organics into compost and using it on our farmlands we create healthy soils that produce healthier food and higher yields. It also reduces the need for fertilizer and pesticides, improves water quality and conserves water, as well as stores carbon in soil – helping to reduce climate change. Compost not only helps the environment but also helps to decrease food shortages experienced around the world. For Healthier Soil, Healthier Food…Compost!Source & learn more
With Earth Month just wrapping up and in honor of ICAW, the ComPOSTer will post several times during the week. Stay tuned for the following content:
2023 has been off to a great start, beginning with our annual “Black Gold” Behind the Scenes Composting tour of the S.C.R.A.P. Lab for Princeton’s Wintersession.
A diverse group of 15 students, staff, and faculty joined the tour, including an Economics professor, grad students, undergrads, and staff from Facilities to Occupational Health – showing how composting is an activity in which everyone of all backgrounds can engage. It was great to hear that about 1/5 of the group has been composting at home in their backyards which helped foster rich conversation.
Over the course of the 90-min tour, we talked about optimal ways to home compost; composting recipes such as the difference between “greens”/Nitrogen and “browns”/Carbon; compost’s climate impacts; and Gina led a demonstration of the lifter and compost viewing.
Check out some of the sights below:
Presenting a summary of at-home composting solutions which is shown below and can also be found in our Resources section
OPERATIONAL UPDATES
As winter break extended through January, SCRAPPY remained in “auto-digest” mode with compost having a bit longer time to mature inside of the vessel and then we had our first full month of operations once the semester started
8,233 lbs.
The total amount of material composted at the S.C.R.A.P. Lab in February
Committing to reduce methane emissions from the solid waste and wastewater sector by at least 15% by 2030 from 2020 levels and deepen collaboration on waste and agriculture methane measurement and mitigation, including achieving the Global Methane Pledge through trilateral cooperation on methane and black carbon emissions.
Developing a Food Loss and Waste Reduction Action Plan by the end of 2025 outlining efforts to cut food loss and waste in half by 2030.
Happy New Year! We hope all fifty-five of you are enjoying a great start to 2023 !
As with every first post of a new year, the ComPOSTer takes a moment to recap the highlights from the past year, and provide some optimism for the the current year.
Jesus Arroyo’s ’24 Sustainability Story on Why He Composts
We engaged with 30 young professionals through the NJDEP’s Youth Inclusion program to introduce them to careers in environmental justice and sustainability
After a 2+ year hiatus, we were happy to restart composting operations during the Fall 2022 semester, restarting our partnerships with Coffee Club and retail dining. We added a van to our arsenal to enable more food scraps pick-ups, diverted compostable materials from two large events, and altogether composted 5 tons worth of material in 2022.
2023 PLANS
New efforts and/or repeat activities that we didn’t quite get to in 2022:
Hosting a Wintersession Tour to raise awareness of campus composting among the campus community
Holding a re-launch ribbon-cutting ceremony with the greater Princeton community
On-boarding an assistant operational manager
Executing on our DEP grant to study improved ways to collect and recycle compostable serviceware, while engaging first year students in a new seminar called Decomposing the Science of Composting
Launching new graphics and informational signage for the new facility
Continuing to raise awareness about the environmental justice implications of composting when applicable
Thanks for reading and stay tuned for an exciting year for composting!
