First Sights of Compost! (November 2022 update)

One month of restarted full-scale operations is in the books!

6,620 lbs. of uneaten, recovered food was composted in the month of November and we had our first compost off-load session this week as the vessel reached its operational capacity:

Compost building up in the screener during off-load mode
Water vapor as compost emerges from inside of the vessel, representing the temperature difference between the vessel (where it is 100s of degrees F) to the facility (under 60 degrees F)
Compost loaded into the trailer where it will be sent to our soil recycling yard and stockpiled until it is used for landscaping projects on campus. We will continue to off-load compost regularly, two times per week, as long as we continue to load material.


  • Food scraps and compostables recovery at the Orange & Black Ball
  • Staff training
  • Introduction to Sabrina Fields, our new Grad Compost Coordinator, who will be assisting with food scraps recovery efforts in departments across campus

Pumpkin Composting, NJ Organics Summit & Full Operations Resume! (October 2022 update)

Welcome back! We hope everyone had a safe and fun Halloween.

Spooky season here at the S.C.R.A.P. Lab started off with servicing pumpkin carving events. We offered our small bins for the collection of pumpkin seeds and “guts” as the pumpkins were being carved.

We are not at the point where we can track down all of those pumpkins for composting on campus, but if you would like to compost your pumpkin at home, you can read: How to Smash & Compost your Jack-O-Lanterns

Later in the month, Gina attended the New Jersey Composting Council’s Organics Waste Management Summit. It is a wonderful annual event where composters, state and municipal officials, and more, gather to learn and network from each other. This year, some topics included: permitting barriers to composting operations; considerations for compostable product usage, PFAS management; and compost microbiology.

Speaking of PFAS, Peter Jaffé’s work on PFAS remediation was recently highlighted by the University in the below video:


852 lbs.

The total amount of material composted at the S.C.R.A.P. Lab in October

On Nov. 1st, the S.C.R.A.P. Lab started to receive and process the recovered, uneaten food from the Frist Campus Center and Campus Cafes. We thank our contractor, Organic Diversion, for filling in during the time that SCRAPPY has been offline.

Our monthly totals will now be much higher going forward. Meet the new student team who helps make all of the magic happen.

Until next time!

How to expertly fold pizza boxes for composting and more (September 2022 Recap)

Dear readers,

Can you guess how many pizza boxes are collapsed in the below?

The last few weeks in September flew by, and while the S.C.R.AP. Lab is not yet at full operations, we are ramping up gradually, especially as we begin this year with a new crop of student assistants (bios coming soon!) and equipment.

Read more about the equipment, our successful resumption of collecting compostable materials from the annual Facilities Appreciation Picnic, and yes, the answer to the pizza box question, below:


Loading Lift Arm

We sought a new Toter lifter after realizing that our existing lifter proved to be undersized and unable to handle the excess strain from heavier and more liquid-filled Toters of wasted food.

After a year plus of research and confirming the correct specs as we designed the new facility, we settled on the Solus Group Dumpmaster, which offers a more efficient, safer, and adaptable design.

Stairwell & Platform

We sought an easier way to observe and access the loading hopper for addressing shredder jams and dumping smaller bins. This stair system was a perfect cost-effective option.


Similar to the last event in 2019, we used bin monitors to help Facilities staff properly sort materials. With reusable cups and sporks offered, nearly all of the materials from the event were compostable. In total, we collected and diverted 133 lbs. of material from the landfill which included molded fiber plates, food scraps, and napkins (collected in the bags below), as well as a few trays of uneaten food. Coincidently this total was within a few pounds of the same amount collected in 2019. But with more people attending in 2022 vs 2019, this means that each person wasted less food!


739 lbs

The total amount of material composted at the S.C.R.A.P. Lab in September (includes coffee grounds, food scraps, pizza boxes, and serviceware)

Did anyone guess 41?


Stay tuned for updates on the following:

  • New Team Members
  • Pumpkin Composting
  • Frist/Cafes collection start date

Saving a Seat for the Bottom-Feeder

Happy first day of classes to the Princeton community!

To ring in the start of the ’22-23 academic year, we’re featuring a Q&A with Sessina Dani ’23 who examined Princeton’s composting habits and the ways that people think about composting. Hear what she had to say about our composting system and the “bottom-feeder” organisms that make composting possible:

How did the S.C.R.A.P Lab help you learn more about composting at Princeton?

I was writing a paper on our relationship with composting organisms as a campus and as individuals for an anthropology class entitled “We Were Never Alone: Multispecies Ecologies in the Anthropocene,” taught by Professor Agustin Fuentes. I wanted to learn more about how Princeton University as a broad entity, and as a sum made of its parts, was conscious of and interacted with the composting organisms that sustainable food systems often rely on. Therefore, learning about the S.C.R.A.P. Lab was not only central to the research question but also my first introduction to Princeton’s composting system

What was your biggest takeaway from your research?

My research was focused on an anthropological lens, and it helped me gain a deep appreciation for composting organisms and other decomposers in the wild and inside our bodies. I had no idea the breadth of services that composting organisms offer and how that compares to their roles in the wild. I want to be really mindful of how and what I feed a compost pile and how to care for our composting friends like I care for my own digestive bacteria.

What do you think Princeton students should know about the university’s composting strategy?

I think more students should know that the composting system exists and that that is the purpose of the food chutes [in the dining venues]. I chose this term project because I was curious about how prevalent the composting system was in the periphery of students’ minds, and I found that there were even some dining employees that didn’t know what the food chute was really for. I think learning about the Forbes Garden really illuminated how full-circle our food system can be, and how awesome it could be if all students knew about and paid attention to how they interact with their campus’s food system, including the composting system.

What did you enjoy most about your project and work through the S.C.R.A.P lab?

I had an awesome time talking to students and Gina! I actually got inspired to intern at the Zhang lab this summer, which is the lab that works on sequencing the microbes in the compost pile because it was really awesome to learn about how interdisciplinary composting research could be. Although I didn’t work on the S.C.R.A.P. lab this summer, I enjoyed learning more about how microbes participate and fuel nutrient cycling. I think the Campus as Lab initiative is a great opportunity for students to learn about sustainability in their everyday practices here on campus, like mealtime. I’m really excited to learn more about Princeton’s composting system and get involved with the S.C.R.A.P. lab this fall!

Interview conducted by Abby Van Selous, Office of Sustainability summer intern

Fall Semester Composting Update

While we have not yet started composting wasted food from Princeton’s retail dining venues, we have begun small-scale food scraps collection, by restarting coffee ground pick-ups at the Coffee Club!

Photo credit: The Coffee Club

Summer ’22 Updates: DEP grant, Youth Inclusion tour & Operation status

Dear ComPOSTer community,

The Dog Days of Summer are officially here. We hope everyone is staying cool and safe during this heat wave. It’s been awhile since the last post, but this summer has been a productive, exciting, and fun one at the S.C.R.A.P. Lab. Check out our latest news below:

NJDEP Research Grant!

We are excited to share that Princeton University is a grant recipient of the New Jersey Department of Environmental Protection (NJDEP)’s FY21 Recycling Enhancement Award (REA) Research Grant Program! Starting in 2023, we will be partnering with the New Jersey Composting Council, professor Dr. Xinning Zhang, and our other campus partners to study and test innovate new methods for using, collecting, and recycling compostable plastic products.

Specific objectives include:

1. Assessment of how well several types of compostable plastic products break down in the in-vessel system and subsequent piles or windrows (i.e. can they completely disintegrate/become unrecognizable?)

2. Evaluation of the effectiveness of using a chipper-shredder machine to reduce material size as a pre-processing tactic to make the composting process more efficient

3. Understanding the impact that the addition of compostable plastic products has on composting emissions, microbial communities, and compost nutrient density (both with and without pre-processing)

4. . Implementation and evaluation of infrastructure and messaging strategies to increase diversion and recycling rates of the compostable plastics and wasted food.

NJDEP Youth Inclusion Initiative

The Office of Sustainability recently hosted a tour for youth as part of an intensive NJDEP program to introduce young professionals across New Jersey to careers in environmental justice and sustainability. At the first stop at the S.C.R.A.P. Lab, we had a great time interacting with the youth, demonstrating the lifter, passing around compost, and overall sparking their enthusiasm around composting! Two more groups will visit later this summer.

Gina Talt explaining how the auger transports shredded food and wood into the composting system
Group photo!

Operations Restart Update

It’s been a long road due to the pandemic and our facility relocation, but after a 2+ year hiatus, we are happy to announce that the S.C.R.A.P. Lab is now up and running and will begin to accept wasted food from Princeton’s retail dining venues at the start of the Fall 2022 semester! We hope you will continue to follow us in our next composting chapter.

ICAW 2022: Why is Soil Biodiversity Important?

Our final post to round out International Compost Awareness Week will tie back to this year’s theme, “Recipe for Regeneration.

So how does compost make our food more nutritious, the air we breathe cleaner, and our climate healthier?

In short, by supporting soil biodiversity through the contribution of organic matter in the form of nutrients and microorganisms (i.e. bacteria and fungi) which are the foundation of a healthy soil food web. Learn more about soil biodiversity’s role in agriculture, climate change, the environment, and human health:

Soil biodiversity and agriculture

Plant Nutrition: Soil microorganisms are both a source and a catalyst for supplying nutrients for plant growth. They make nutrients available to plants through interactions with other soil organisms and abiotic factors such as temperature, pH, moisture content. Nutrients derived from organic matter can reduce the reliance and misuse of synthetic inputs.

Soil biodiversity and climate change

Carbon Sequestration: Soils can either release or store carbon. Healthy soils store more carbon than that stored in the atmosphere and vegetation combined. In addition to applying compost, soil management practices that allow soils to be carbon sinks rather sources include: reduced or no soil tillage/disruption, limiting overgrazing and overapplication of fertilizers and pesticides, keeping the ground covered with cover crops and a diversity of plants.

Soil biodiversity and environmental protection

Ecosystem Services: Soil biodiversity also prevents erosion and bioremediates contaminated soils of heavy metals and toxins

Soil biodiversity and human health

Disease Regulation: Many drugs and vaccines stem from soil organisms (e.g. penicillin), antioxidants from healthy plants stimulate our immune system and contribute to hormone regulation, and studies provide evidence that exposure to soil microorganisms can prevent chronic inflammatory diseases.

Food Production: Soil bacteria and fungi are traditionally used in the production of soy sauce, cheese, wine, and other fermented food and beverages.

Source and to learn more: “The State of Knowledge of Soil Biodiversity: Summary for Policymakers”

ICAW 2022: Composting in the Forbes Garden

Welcome back everyone for another day of celebrating compost!

Today we feature our efforts to restart composting in the campus garden at Forbes College after a hiatus due to the pandemic.

We realized we needed better oversight of the composting efforts in this space to minimize odors, so we hired a student, Jesus Arroyo ’24, to coordinate food scraps drop-offs and to manage the compost pile and tumblers.

Check out our progress so far:

Day 1: Jesus using a pitch fork to pick-up food scraps delivered from a nearby student food co-op
Day 1: Layering the food scraps into our composting pile enclosed by a wire cage. We put a thick layer of wood chips at the base for leachate control
We also pre-mix the food scraps into the wood chips for even distribution. Here we used a ratio of about 2 parts wood to 1 part food. For higher moisture food like shown above, we’ll use a higher ratio of 3:1
Finished pile after Day 1
A few days later – using a temperature probe to monitor compost activity. We’ve managed temperatures in the “steady” (80 – 100 F) to “active” (101 – 130) ranges, but we need to increase our pile size to at least 4ft by 4ft by 4ft to get to the “hot” range (131 – 160 F)
Day 6 after more feedstocks have been added
First Turn: After 3.5 weeks when the temperatures stopped climbing, Jesus mixed the pile to allow microbes to access fresher material and to ensure proper aeration as the pile compacted. The goal will be to get the entire pile to look like the dark brown color in the center
Tumblers! The garden also has several of these to provide extra capacity, however, they can only handle so much. Still, they are a user-friendly option that is great for the new composter

Stay tuned for a video to meet Jesus and to see the work in action!

Thanks for reading!

Check back in for one more post tomorrow!

ICAW 2022: Composting at Home with Ted Borer

Happy 4th day of International Compost Awareness Week!

Today’s post we are pleased to share a Q&A about home composting with Ted Borer.

By day, Ted is an engineer who serves as Princeton University’s Energy Plant Director. He oversees day to day operations and long-term planning to achieve a carbon-neutral campus. Ted is equally as passionate about sustainability in his personal life. He bicycles to work 12 months a year and follows a plant-based diet. His home includes everything from shower drain heat recovery to a chicken coop and an area for composting!

Read more about Ted’s composting journey and process, as well as his advice for new backyard composters below:

Ted Borer pictured with his 3-bin composting set-up.
  1. When did you start composting and why?

My wife and I started composting in 1989. Compost bins were one of the first things I built when we bought our first house. There were a lot of trees and shrubs and we both enjoy gardening. We wanted to manage our yard waste and food scraps and re-incorporate them into the gardens.

  1. What do you compost?

Yard waste and non-meat, non-fat food scraps: Sticks, branches, leaves, garden weeds, bark from firewood, sawdust, sometimes grass clippings, poultry and rabbit bedding/waste, food scraps with no meat or dairy.

Ted using a chipper-shredder machine to grind up large pieces of wood into smaller pieces to reduce material size to enable hot composting
  1. What benefits have you’ve seen as a result of composting or applying compost?

First is joy! It’s really fun to see the temperature rise and fall as I change the carbon/nitrogen (brown/green) balance or mix up the piles, or run things through a chipper/shredder to break them down and aerate them, or add water. It’s a fascinating process to observe. It’s part of an endless cycle of life-death-decay-renewal.

Second, it reduces the amount of waste that leaves our property. Ideally, I’d like nothing organic to leave our property. We have a ways to go before achieving that goal. But we certainly don’t get rid of any yard waste and essentially zero food scraps. It’s too valuable.

Third, like much of this area, our yard has very little topsoil and is mostly clay and shale. By mixing in finished compost, I can lighten any soil and plants will grow better in it. Lighter soil absorbs more water instead of letting rain sheet-flow into a creek; taking nutrients downstream with it. When I top-dress or mulch shrubs with compost, they grow faster and are more healthy.

Ted’s active compost pile. Ted uses a temperature probe to ensure hot composting (i.e. when temps are between 131 – 160 F, the range needed for at least 3 days to kill off pathogens)
  1. What advice do you have to anyone looking to start composting at home?

You don’t have to do everything all at once. Starting composting can be done with little time and effort – but it grows over time as you learn more! Maybe start with kitchen scraps and leaves and a small “compost tumbler”. But, be aware that composting works better and is more stable the larger you go. I built a three-compost-bin system and use a pretty large chipper-shredder to manage all our yard waste and animal bedding. The bins are 48” x 48” x 48”. I cycle from bin-to-bin as the compost breaks down.

If you do want to start on a small scale, learn about vermiculture! A tiny pile of kitchen scraps in the back yard is not a “composting system”. It will just attract animals.

Get a book like: Let It Rot!: The Gardener’s Guide to Composting (Third Edition) (Storey’s Down-To-Earth Guides): Campbell, Stu: 9781580170239: Books:

Thanks for reading!

Stay tuned for another post on backyard composting tomorrow, featuring the Forbes Garden!

ICAW 2022: Facility Updates

Happy International Compost Awareness Week!

Our first celebratory post is an update on the status of the composting facility.

The facility has passed all inspections – building, electric, plumbing – and we are currently working on preparing SCRAPPY and the facility to restart operations.

Check out the improvements we have made to the composting system based on lessons learned from our first 1.5 years of operation:

Screener Upgrades:

To prevent the build-up of compost inside of the off-loading screener and to improve the rate at which compost is off-loaded from the composting system, we’ve installed a screener with more openings and with larger access doors

Old screener with the end panel having smaller access doors and no openings
New screener with larger access doors and mesh wire openings on the end panel

HOPPER Upgrade:

Because we process bulkier and solid items (e.g. large watermelon rinds), we have installed a wider and stronger agitator mechanism to facilitate the movement of food to the shredder below.

Old agitator with two narrow flaps
New agitator with one, but wider and more durable flap that covers the entire width of the hopper

Thanks for reading!

Stay tuned for the next two posts on solutions for home composting!

ICAW 2022 Preview: Recipe for Regeneration

Next week, May 1 – 7, is International Compost Awareness Week (ICAW)!

Just as a chef pulls together the best ingredients to create the perfect recipe, the 2022 theme, Recipe for Regeneration: Compost, focuses on the crucial role recycling our food scraps and yard trimmings plays by creating compost, which when added to soil results in a recipe that makes our food more nutritious, the air we breathe cleaner, and our climate healthier overall.

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:

  • SCRAPPY Updates
  • Composting in the Forbes Garden
  • Composting at Home Q&A with Ted Borer
  • Why is Soil Biodiversity Important?