The ComPOSTer: Meet this semester’s new assistants

Good evening all,

As we head into Thanksgiving, I just wanted to convey my gratitude to the team of student assistants who make the daily to weekly cross-campus trek to participate in the food scraps composting demonstration project.

Composting can be a very labor intensive process, so having a hardworking and dedicated team is key to success! This semester we are lucky to have 8 regular student assistants, 3 of whom are new to the project.

Hear in their own words why each wanted to join the S.C.R.A.P. Lab team:

Name and Class Year: Christian Hernandez ’22
Concentration: Molecular Biology
Hometown: Manvel, TX
Why you decided to join the team: As a small farmer and composter myself, I want to participate in how composting can work at a larger scale as well as just maintain some fitness through physical labor.
Name and Class Year: Julia Herrle, ’19*23
Concentration: MPA, International Relations
Hometown: Wexford, PA
Why you decided to join the team: I’m passionate about improving food security and sustainability of food systems. Reducing food waste is an important part of this, and I’m excited to learn more about composting at Princeton!
Name and Class Year: Chloé Vettier, GS
Concentration: French Literature
Hometown: Paris, France
Why you decided to join the team: because I want to support sustainable initiatives on campus – and I really miss my composter in Paris!

Weekly Data: 11/8 – 11/21

Happy Thanksgiving!


The ComPOSTer: Welcome Back & Compostable Coffee Pod Testing

Hi all,

The S.C.R.A.P. Lab has been back up and running for the past week since everyone returned from Fall Break.

One of the latest efforts we are testing is collecting and composting spent compostable coffee pods and their packages from departments making the switch from single-use disposable coffee cups. Made popular by Keurig about 15 years ago, these “K-Cups” have contributed to society’s growing plastic waste problem. In 2014, Keurig sold enough K-Cups that if placed end-to-end, would circumnavigate the globe 10.5 times. The majority of these ended up in landfills.

Since then Keurig has responded by creating recyclable K-Cups, but these are still energy intensive to make and there is no guarantee that the cups will actually be recycled. Consumers have to place them in recycling bins and not all recycling centers have the correct sorting technology to properly recycle them. Furthermore, more and more recycling centers across the U.S. have stopped accepting the type of plastic (#5) used to make these K-cups due to China’s import ban on plastic waste.

So… where composting facilities exist, the more sustainable option is a coffee pod made of compostable* materials and packaging like these from Wolfgang Puck Co.

These compostable pods are used in coffee machines such as NEWCO’s CX Touch.

Carola Gerbick removes a bin of spent coffee pods from the coffee machine.

The S.C.R.A.P. Lab is currently partnering with the Psychology and Geosciences departments to test the compostability of different types of  branded pods and packages claiming to be “100% compostable” inside of the in-vessel composting system.

If all goes well, we will try to advance this best practice across other campus departments.

*Look for “compostable”, not “biodegradable”, to ensure that the materials break down in a reasonable amount of time and don’t release metal residues. For assurance, pursue products that have been certified by the Biodegradable Products Institute (BPI). 

Weekly Data: 11/1 – 11/7

Last week we started to gradually re-fill the composting system so there wasn’t any compost to off-load. We expect to begin off-loading again at the end of this week.

Total Food Academic


/Event Collection

Campus Center/Cafes Wood Shavings (BA/CS) % BA/CS Compost Off-Loaded GHG Emissions Saved (MTCO2-eq)
11/1 – 11/7 2,967 333 2,634 1,026 35% 0
Cumulative (lbs) 142,250 3,718 138,532 46,162 32% 136,200 42

The ComPOSTer: Fall Break Plans

Hi all,

Leaves are turning on campus, midterms are over, and students have started to depart campus for Fall Break.  Which means that the S.C.R.A.P. Lab will also be getting a rest and will be temporarily shut down during this time. In preparation, the team focused on gradually emptying the compost from the system’s vessel over the last week.

During Fall Break, Gina will be attending the Association for the Advancement of Sustainability in Higher Education (AASHE)’s annual conference and will be co-presenting with several other higher education institutions on a session titled, On-Site Composting: How to Start, Evolve, and Overcome Challenges.

With on-site composting becoming an increasingly important and recognized food waste diversion strategy to meet institutional sustainability goals,  the session will provide useful information and resources so other colleges/universities can assess which processes are best suited to start or grow their own campus composting programs. The S.C.R.A.P. Lab will be featured as one of several case studies that will provide session participants with a better understanding of different composting systems and their associated operations.


See below for the cumulative to-date data going into Fall Break:

Total Food Academic/Residential Buildings Campus Center/Cafes Wood Shavings (BA/CS) % BA/CS Compost Off-Loaded GHG Emissions Saved (MTCO2-eq)
Cumulative (lbs) 139,283 3,385 135,898 45,136 32% 136,200 41

The ComPOSTer: Event Partnerships!

Good evening all,

With the Fall semester in full swing, activity at the S.C.R.A.P. Lab has been heating up. In the last month, we were busy processing an extra 579 lbs. of food scraps and compostable items from 3 major events on campus serving a combined total of around 1,750 people. They were: the First Year Pre-Rade (1,000 people), Graduate College BBQ (250 people), and the Facilities Appreciation Picnic (500 people).

A summary of the event logistics, successes, and lessons learned are below:

At all events, student EcoReps bin monitored Resource Recovery areas to encourage proper sorting and a clean stream of compostable items

  • 0.33 lbs/person  – average weight of compostable material per attendee (range from 0.25 to 0.4 lbs/attendee).
  • The majority of the material – about two-thirds – was compostable serviceware rather than food scraps.  Because of this the volume of the total material recovered was more significant than the weight. The 579 lbs. of recovered material took up the space of about 35 full, large garbage bags!
  • At large events, where attendees have freedom to move around, more material was collected at the permanent outdoor bins rather than the dedicated resource recovery tents, prompting us to shift our strategy mid-event and send more bin monitors to the tentless permanent bins
  • Expect the unexpected: there will likely be materials generated at the event that you didn’t expect to have (e.g. condiment packets brought by caterers). Make sure to inform the bin monitors on where these materials should be placed so they don’t end up in the incorrect stream.
  • Like the bamboo utensils tested earlier this year, the birch utensils also tended to only partially shred and did not compost fully (although they will eventually biodegrade)
  • The paper plates and wood based products should be loaded gradually into the composting system. Loading too many at once can jam the system so it is best to alternate or combine with food scraps when possible
  • Paper plates shouldn’t completely substitute for wood shavings as the bulking agent/carbon source (BA/CS) because they tend to lose their form and mat together under high moisture conditions. When adding one part paper plates per each food and wood bucket pair (equivalent to substituting around 15% of the BA/CS total with the paper plates), we found that the bulk density and free air space of the resulting compost increased and decreased respectively from baseline conditions, indicating a reduction in air flow potential throughout the compost pile. Next time we receive a large load of paper plates, we will reduce their contribution to closer to 10% or lower of the BA/CS.

Lastly, at the Facilities Picnic, we also promoted waste reduction and reuse efforts which should always precede any recycling/composting efforts:

  • Attendees were encouraged to bring their own cup (or were provided with a reusable one)
  • Reusable sporks were also handed out this year. Cleaning stations were provided so that attendees could reuse the sporks throughout the event and take them back for future use. If attendees didn’t want to keep their spork, there were also drop-off containers so that the sporks could be recovered for reuse (see photos below):

Weekly Data (9/13 – 10/10)

Weekly data from the last 4 weeks are below. You’ll notice that the % BA/CS was higher early on and has gradually returned to the usual range of ~33%. In the summer months we were receiving a higher than average moisture content so we needed to compensate with more carbon/wood shavings. Now that the academic year has started, the moisture content has returned to previous levels due to menu changes.

Total Food Academic/Residential Buildings Campus Center/Cafes Wood Shavings (BA/CS) % BA/CS Compost Off-Loaded GHG Emissions Saved (MTCO2-eq)
9/13 – 9/19 3,158 119 3,039 1,296 41% 3,400
9/20 – 9/26 3,433 201 3,232 1,265 37% 2,200
9/27 – 10/3 3,775 233 3,542 1,357 36% 3,600
10/4 – 10/10 3,324 182 3,142 1,055 32% 4,800
Cumulative (lbs) 136,433 3,157 133,276 44,193 32% 125,600 40

The ComPOSTer: S.C.R.A.P. Lab Turns 1!

“SCRAPPY” – the composting system’s personified nickname

In big news, the S.C.R.A.P. Lab celebrated its 1-year anniversary! We’ve come a long way since that first loading session 365 days ago and want to thank FOR Solutions, our multiple campus partners, and of course our dedicated student assistants in this team effort as we navigated the first year of operations. Now we are in a better place to fine-tune operations in Year 2.

Some of the early highlights of the project over the last year include:

  • 20 students have served as operational assistants (12 currently active), representing 10 different academic disciplines
  • Research
  • 1 Junior Paper, and 1 Senior Thesis planned (so far) for this year
  • 2 Dean for Research Innovation  grants (engaging 6 additional students)
  • 5 courses integrated site visits and/or analysis of the compost
  • High municipal engagement – Many of the town officials, including the Mayor, have toured the facility and have decided to replicate something similar by voting to purchase MetLife Stadium’s unused in-vessel composting system.
  • State government interest: working with Public Affairs we have already had state elected officials visit (with more coming this Fall) so that we can inform the broader legislative process that will incentivize food scraps diversion from landfill for all of New Jersey
  • Partnering with Campus Dining to test different foodservice wares for compostability, and adjusting their procurement practices accordingly
  • Anticipated lawn and grounds maintenance benefits (superior to the existing yard debris composting program), with promising implications for compost “tea”
  • 27 active blog readers – YOU!
  • 5 short videos (see Media page) produced by the Office of Sustainability; 2 videos produced by during the ribbon cutting ceremony in January 2019

Weekly Data (9/6 – 9/12)

See below for last week’s data which can also be viewed in person at the Greenspace in Frist Campus Center (100-level):

Total Food Academic/Residential Buildings Campus Center/Cafes Wood Shavings (BA/CS) % BA/CS Compost Off-Loaded GHG Emissions Saved (MTCO2-eq)
9/6 – 9/12 3,287 123 3,164 1,054 32% 3,600
Cumulative (lbs) 122,743 2,422 120,321 39,220 32% 111,600 36

The ComPOSTer: Welcome Back & Summer Recap

Happy First Day of Fall Semester Classes!

I hope everyone had a relaxing summer! The ComPOSTer will be back on a regular basis with the start of classes, but before we dive into the new academic year, check out what we were up to in the last two months:


Researchers in the Zhang Lab began their “Building Better Compost” study which involves analyzing the gas and microbial profiles along the composting process. The goal of the study is to inform baseline  performance and how it might change by alerting different parameters such as feedstock types and ratios. Stay tuned for results!

Under the guidance of Dr. Jared Wilmoth, Gabby D’Arcangelo ’21 and Calvin Rusley ’20 regularly took feedstock and gas samples along the “compost trail” from when the feedstock first enters the drum, to inside of the drum, and then when it is off-loaded as compost at the end.


I had the opportunity to take a week long compost operations training course with the U.S. Composting Council last month in Ithaca, NY at Cornell University. By engaging in a combination of hands-on activities, lectures, and field trips to different composting operations, I came away with a wealth of knowledge on composting best practices and tools that we will implement and test at the S.C.R.A.P. Lab over the coming year.

Two of the biggest things that we will test to optimize the composting process are 1) pre-mixing carbon into the totes of uneaten food that are especially soupy and 2) adding and/or substituting wood shavings with alternative carbon sources such as straw, wood chips, and soiled food serviceware.

My group’s compost pile that we built using a combination of wood chips, uneaten food, animal manure and bedding (yes you can compost manure!). Left – measuring temperature of the pile on Day 2 ; Right – Steam rising from the pile when it was dissected on the last Day (5)

Field trips to a vermi (worm) composting facility followed by a  facility that composts in 100-ft long aerated static piles.

To-Date Data 

Total Food Academic/Residential Buildings Campus Center/Cafes Wood Shavings (BA/CS) % BA/CS Compost Off-Loaded GHG Emissions Saved (MTCO2-eq)
Cumulative (lbs) 121,540 2,376 119,164 38,830 32% 110,400 36

The ComPOSTer (7/19): Introducing Our Summer Assistants + U.S.C.C. Membership!

Happy Friday everyone,

After learning about the post graduation plans of former S.C.R.A.P. Lab assistant, Helena ’19, this week we will feature profiles of the three students who are serving as operational assistants during the summer. All three are rising seniors who are on campus either to take classes or work on their senior theses:

  1. Name and Class Year: Ishanya Anthapur ’20
  2. Major: Ecology & Evolutionary Biology
  3. Hometown: San Jose, CA
  4. Why you decided to join the team: Working at the S.C.R.A.P. Lab seemed like a great way to learn about the food circulation at Princeton and to reckon with how much extra food waste we generate and what we’re doing to offset that

  1. Name and Class Year: Kiley Coates ’20
  2. Major: Geosciences
  3. Hometown: Fort Mill, SC
  4. Why you decided to join the team: Projects like the S.C.R.A.P. Lab relate heavily to my studies. As a Geosciences concentrator, I want to be able to help solve environmental issues and create a society where we live more sustainably. The S.C.R.A.P. Lab is a great step to not only reduce food waste on campus, but model how this could be applied in other settings.

  1. Name and Class Year: K. Stiefel ’20
  2. Major: Chemistry
  3. Hometown: Flemington, NJ
  4. Why you decided to join the team: For a while I’ve been interested in individual-scale composting, but I’m interested in seeing how the process is effected on larger scales as well. This is the perfect opportunity.

This summer, Princeton University became a member of the U.S. Composting Council (U.S.C.C.), a national non-profit dedicated to the development, expansion and promotion of the composting industry. The membership provides a great opportunity to stay updated on the latest advancements in compost research, policy, standards, and best management practices.

Weekly Data (7/12 – 7/18)

Our processing numbers were up slightly this week as we enter peak summer and the campus cafes start offering outdoor summer BBQs:

Total Food Academic /Residential Buildings Campus Center/Cafes Wood Shavings (BA/CS) % BA/CS Compost Off-Loaded GHG Emissions Saved (MTCO2-eq)
7/12 – 7/18 2,896 66 2,830 982 34% 3,000
Cumulative (lbs) 106,869 2,056 104,813 33,610 31% 93,000 32

The ComPOSTer (7/12): Alum profile + 100,000 lbs. milestone!

Good evening all,

This post features an update from the S.C.R.A.P Lab’s newest (and first) alum – Helena Van Brande ’19!

In between translating poems across three different languages for her senior thesis, and premiering in French theater shows among other activities, Helena worked several hours per week at the S.C.R.A.P. Lab for much of the 2018-2019 academic year and was an invaluable assistant. Although we will miss Helena here in Princeton, she has already used her composting knowledge to advance food scraps diversion efforts in her hometown and soon as a FoodCorps service member. Read more about Helena’s post-graduation plans below:

Helena after installing a Jora composter at her family’s home. 

What are your post-graduation career plans?

Helena: “I am going into a year of service with FoodCorps Americorps in Lakeview, Oregon.  I’ll be working with the local community, including the county hospital and local schools, to drive and develop different food-related educative projects. Lakeview, Oregon is a small town in South-East Oregon with a population of less than 2500. Situated in the high desert region, it’s surrounded on all sides by beautiful mountains, lakes, and national parks. I couldn’t be more excited for the opportunity to move to a place like Lakeview and help educate young people about material I am really passionate about. Although I will be in a position to educate, I have no doubt that I will be learning a lot as well.”

How did working at the S.C.R.A.P. Lab prepare and/or develop your interest in pursuing this line of work?

Helena: “Something I will bring with me as a FoodCorps service member is, of course, composting. I have truly loved the time I’ve spent working at the SCRAP Lab with Gina and the other students, even though the work would leave me smelling of rotting and half-digested food scraps for hours. Through Gina, I’ve learned a lot about the chemistry of compost and how important it is to maintain a balance of Nitrogen – Carbon material entering the system, while also keeping an eye on the kinds of food scraps that the university provides us with. Admittedly, these are often less than ideal being cooked, liquid, and/or oily. I hope that I can take some of the things I’ve learned at the SCRAP Lab and scale it down to a manageable size, maybe even institute a few worm farms.

To me, composting is one of the key ways in which we as individuals can directly influence our environment by taking food waste that would otherwise get dumped into the landfill and instead convert it into nutrient-dense soil, which we can then feed back into the earth, replenishing bacteria, microbes, bugs, and rejuvenating soil chemistry and composition. In turn, this process invigorates plant-life, which is incredibly important if we want to keep agriculture sustainable. Although gardening will certainly be a part of my job description in Lakeview, the growing season is quite short due to the high elevation. As a result, my focus will be more on food systems, nutrition, food preparation, and composting.”

We wish Helena the best of luck in her future endeavors. Next week we will feature the three new students who have joined the team for the summer.

Weekly Data (6/27 – 7/11): 100,000 lbs. milestone!

Since the project’s start 10 months ago, the S.C.R.A.P. Lab has converted over 100,000 lbs, or 50 tons, of uneaten food into compost!

Total Food Acad./Resid. Buildings Campus Center/Cafes Wood Shavings (BA/CS) % BA/CS Compost Off-Loaded GHG Emissions Saved (MTCO2-eq)
6/21 – 6/27 2,048 18 2,030 676 33% 2,000
6/28 – 7/5 2,796 38 2,758 895 32% 2,500
7/2 – 7/11 2,254 42 2212 779 35% 2,000
Cumulative (lbs) 103,973 1,990 101,983 32,628 31% 90,000 31

The Weekly ComPOSTer (6/21): More Compost Applications & Audio Journalism

Happy First Day of Summer!

This week we will feature other ways compost from the S.C.R.A.P. Lab is being applied on campus in addition to the departmental garden highlighted in last week’s post.

So what happens when compost is off-loaded from the composting system?

Twice a week after the S.C.R.A.P. lab team rakes off-loaded compost into a trailer bed, our Grounds crew hooks the trailer bed to a truck and transports it to a stockpile yard just south of main campus where the compost is dumped into its own outdoor pile covered with a tarp to prevent nutrient leaching.

Periodically, the Grounds crew will draw compost from the pile and blend it with leaves, soil and other compost generated from the campus. When lab tests indicate that this combined or “blended” product reaches a certain maturity index level, the Grounds crew will use it in one of three ways as a soil amendment on campus:

  1. Mixed into planting mediums during transplantation
  2. Top-dressed on campus lawns after aeration and before overseeding to break up soil that becomes compacted over the year due to foot and vehicular traffic. Aerating soils by perforating it with small holes and then spreading compost allows for better water, oxygen, and nutrient flow to plant roots.
  3. Used to make compost tea: a small amount of compost will be placed in a large mesh “tea” bag which is then steeped in water and aerated in a container to create a brewed, water extract of compost. The process extracts the full diversity of beneficial microorganisms from the compost (plus more if additional ingredients are added), and when applied to soils and plants, it can assist in better plant production, soil structure, nutrient cycling, and less disease incidence. It’s like kombucha but for plants* More on this later!

All of this information plus more can be heard in an audio-journalism piece that was nicely composed by graduating senior, Angela Mao ’19. For her final class project, Angela captures a sound journey from food scrap to compost. Hear it here:*

*Clarification Notes:

    • Kombucha is a fermented product while compost tea is not, but both share the benefits of introducing beneficial bacteria and in turn supporting healthy “immune” systems– whether in humans or plants
    • The term “compost” is sometimes referred in the piece as the uneaten food that is collected in the dining venues. This is a common misinterpretation of the word. Compost is what is produced after the uneaten food and a carbon source undergo aerobic decomposition.
    • The correct identification of the processing capacity of the FOR Solutions Model 1000 Composting System is “up to 5,000 lbs. of food per week,” rather than “5,000 lbs. at a time.”

Weekly Data: 5/31 – 6/20

As we enter into summer mode with our dining venues on a reduced hours schedule, the total weekly amount of uneaten food processed at the S.C.R.A.P. Lab is about 60% of that during the academic semester.

WEEK Total Food Campus Center & Cafes Academic /Residential Buildings/Events* Wood Shavings (BA/CS) % BA/CS Compost Off-Loaded GHG Emissions Saved (MTCO2-eq)
5/31 – 6/6 2,222 2,160 62 642 29% 2,000
6/7 – 6/13 2,232 2,101 131 772 35% 2,000
6/14 – 6/20 2,375 2,302 73 818 34% 2,000
Cumulative (lbs) 96,875 94,983 1,892 30,278 31%* 83,500 29

* Included in these totals is about 125 lbs. of uneaten food that was recovered from two events on campus

Thanks to all of the friends and alums who came to the S.C.R.A.P.  Lab Reunions tour on the 31st!

The Weekly ComPOSTer (6/7): Compost Applications & Clarification

Happy Friday!

We have an update on how compost from the S.C.R.A.P. Lab is being applied on campus. This week’s update comes from Luiza Wainer and Peter Green who received some of the first batch of compost from 2019 for use in a new community garden for their department. When it came time to apply the compost in their raised bed this spring, they decided to do an experiment  – they split the garden in half and applied compost to one side and not the other. Can you guess which tomato plant in the below picture received the compost application?

Answer: The tomato plant on the right! Although the two plants were planted at the same time, the soil that received compost benefited from the microorganisms and additional nutrients that have supported plant growth and health in the form of a taller and greener plant.

More application updates to come!

Lastly, this post will end with a quick clarification on last week’s mention about the relationship between compost and humus. To clarify: compost and humus are not exactly the same form of matter.

Compost generally refers to a stabilized state of the controlled aerobic decomposition of organic matter when the individual parts of the organic matter are no longer recognizable. It typically occurs outside of the soil system. This is the product that we use as a soil amendment. However compost is technically not completely decomposed as all of the microorganisms are still present and are continuing to decompose the remaining material.

Humus, which is created in the soil system, is found when the decomposition process is fully completed and all of the usable nutrients have been extracted by microorganisms, a process which takes many years.

Weekly Data: 5/24 – 5/30

The S.C.R.A.P. Lab processed less uneaten food over “Dead Week” on campus due to Memorial Day and as most undergraduates left campus for the summer. However, the volume started to increase again on the last day of the loading week with the start of Princeton University’s Reunions weekend.

Total Food Campus Center/Cafes Academic /Residential Buildings Wood Shavings (BA/CS) % BA/CS Compost Off-Loaded GHG Emissions Saved (MTCO2-eq)
5/24 – 5/30 2,164 2,126 38 685 32% 2,000
Cumulative (lbs) 90,049 87,680 1,626 28,046 31% 77,500 27