The Weekly BioDIGESTer (12/3): Welcome Scully Co-op!

We start off this week’s BioDIGESTer by welcoming the Scully food cooperative (Scully Co-op) to our list of partnering venues which already includes Frist Campus Center and campus cafes. Although the co-op is only expected to generate a small amount of kitchen scraps, the partnership represents a pilot effort to capture food scraps from residential settings on campus.

See below for last week’s operational statistics, and expect to see Scully Co-op’s contribution to the weekly totals in the coming weeks!

Weekly Data: 12/3 – 12/7

Food Wood shavings (BA/CS) %
Compost Off-loaded
Week Totals (lbs.) 3,338 1,032 31% 3,000
CUMULATIVE (lbs) 29,993 8,852 30% 20,500

The Weekly BioDIGESTer: 11/26

In this week’s bioDIGESTer, we welcome you into December with an article featuring a Guest Commentary from FOR Solutions and our contribution Case Study on the biodigester. Read more on pages 60 and 61 of Waste Advantage Magazine’s December edition:

Weekly Data: 11/26 – 11/30

Lastly we  highlight operational data from the last week of November. We processed slightly less than usual due to limited dining hours over Thanksgiving break weekend. We also off-loaded half the amount of compost to compensate for the lower volume of food scraps over the last two weeks.

Food Wood shavings (BA/CS) %
Compost Off-loaded
Week Totals (lbs.) 3,305 1,000 30% 1,500
CUMULATIVE (lbs) 26,655 7,820 29% 17,500


The Weekly BioDIGESTer: 11/19

In addition to the weekly operational statistics, this week’s bioDIGESTer shares an article highlighting the  project’s dual goal in serving as a teaching and learning tool as well as an opportunity for critical study through the Campus as Lab program. 

Weekly Data: 11/19 – 11/21 (Thanksgiving week)

With Frist Campus Center being closed most of the week for Thanksgiving recess, we only had two load/off-load sessions v.s. our normal three per week. Accordingly, last week’s load of food scraps was about 1/3 less than in previous weeks.

Food Wood shavings (BA/CS) %
Compost Off-loaded
Week Totals (lbs.) 2,275 687 30% 3,000
CUMULATIVE (lbs.) 23,350 6,820 29% 16,000

CAMPUS AS LAB: Biodigester as a teaching tool and area of study

Students and staff touring biodigester

Students in the class “Investigating an Ethos of Sustainability at Princeton” take a tour of the campus biodigester. The biodigester is one of many models across campus that allow students in the class to learn about global issues through a local lens by examining the sustainability initiatives and challenges at the University. Photo by Nicole Guglielmo

From the piece:

“If we evaluate the feasibility of a biodigester at the University, we can share our knowledge with other organizations seeking solutions to food waste,” Weber told the class. “A system like this also is an example of Princeton’s campus-as-lab approach, providing research and teaching opportunities for faculty and students.”

Full article:


The Weekly BioDIGESTer: 11/12

In this week’s bioDIGESTer, we present the weekly statistics from the last three operational sessions, and highlight our team of student operational assistants! In their own words, learn more about why they consistently make the cross-campus trek to take part in this initiative.

Data: Similar to prior weeks, we continued to load ~3,500 lbs. of food scraps into the system and off-load an equal amount in finished compost over a week’s worth of operations.

Food Wood shavings (BA/CS) %
Compost Off-loaded
Week Totals (lbs.) 3,565 1,071 30% 3,000
CUMULATIVE (lbs.) 21,075 6,133 29% 12,500

Meet the Team!








Name: Daniel Tjondro ’20
Major: Civil & Environmental Engineering
Hometown: Queens, NY
Why I was interested in assisting: To reduce food waste on campus by repurposing it into nutrient-rich soil.









Name: Ezra Zinberg ’21
Major: Computer Science
Hometown: Teaneck, NJ
Why I was interested in assisting:  I want to do what I can to reduce waste and make Princeton a place that lives up to our highest environmental ideals

Name: Frederick Hagen-Gates ’22
Major: Mechanical & Aerospace Engineering
Hometown: Woodbridge, VA
Why I was interested in assisting: I needed a campus job and this seemed like a good idea.
Name: Gregory Smith ‘21
Major: Computer Science
Hometown: Philadelphia, PA
Why I was interested in assisting: I  am fully supportive of Princeton’s extensive sustainability efforts and want to do my part. Additionally, working with the biodigester team has helped me to stay conscious of the sheer amount of food we collectively waste, motivating me to make environmentally conscious decisions at all times.






Name : Helena Van Brande ’19
Major: Comparative Literature
Hometown: Thousand Oaks, CA
Why I was interested in assisting: First, as someone interested in farming, composting has always intrigued me. More pressing, however, is that food waste is a terrible part of the food environment on the Princeton campus and also in the food industry at large. One way to ameliorate it is through compost, so that it can be used other than for human consumption, and the biodigester does this much faster than traditional composting. I am looking forward to learning more and being a part of the team!








Name : Henry Wietfeldt ’22
Major: Physics (prospective)
Hometown: New Orleans, LA
Why I was interested in assisting: To help the environment!








Name : Herman Ishengoma ’22
Major: Computer Science
Hometown: Dar es Salaam, Tanzania
Why I was interested in assisting: The position allowed me to get some hands-on experience with recording and studying data in the field. All whilst at the same time making a positive impact to our planet. 









Name : Isabel Koran ’22
Major: Mechanical & Aerospace Engineering (prospective)
Hometown: Norton, MA
Why I was interested in assisting: I want to be a part of a team that is tackling major sustainability challenges at a tangible, local level. I’m excited to have the opportunity to use Princeton’s campus as a laboratory to answer the question that has helped shape my choices for the past several years: What can I do to help develop more sustainable methods of meeting human needs and lessen environmental impact?








Name : Joe Kawalec ’21
Major: Ecology & Evolutionary Biology (prospective)
Hometown: East Brunswick, NJ
Why I was interested in assisting: I wanted to get some hands on experience with data collection and composting, as well as get involved with a great sustainable initiative on our campus.









Name : Kaylin Xu ’22
Major: Undecided
Hometown: Vancouver, Canada
Why I was interested in assisting: I care about sustainability and I also work in the dining hall, so I am just following the compost trail to the biodigester.








Name : Tali Shemma ’22
Major: Physics
Hometown: Hertzlyia, Israel & Dublin, Ireland
Why I was interested in assisting: I think sustainability is one of our most pressing global concerns, and will become even more crucial as the 21st century proceeds. Developing innovative ways to handle our food waste, such as the new biodigester, is a huge part of this; I am very excited to take part in it.








Name : Vincent Yang ’22
Major: Electrical Engineering or Computer Science
Hometown: Philadelphia, PA
Why I was interested in assisting:  I wanted to work a job that had a meaningful impact on the world. In the biodigester operational assistant job, I found an opportunity to work for the benefit of the community, helping to convert Princeton University’s food waste to compost. I also felt that because the biodigester project was a brand-new job opportunity, it would feel like working at a start-up where all my colleagues would be enthusiastic about the work and everyone would be open to new ideas that help to improve the project.








Name : Wesley Wiggins ’21
Major: Geoscience (prospective)
Hometown: Washington, DC
Why I was interested in assisting: To further participate in helping the campus become greener and environmentally-friendly. I also want to learn more about sustainable practices and meet new people

Name : Zoe Rennie ’21
Major: Ecology & Evolutionary Biology
Hometown: San Leandro, CA
Why I was interested in assisting:Interested in substituting potentially harmful synthetic materials with cleaner and organic alternatives

The Weekly BioDIGESTer: 10/29

Inside this week’s bioDIGESTer we feature another a great video by the Office of Sustainability’s Jared Flesher detailing the journey from food scraps to compost, along with our weekly statistics from Fall Break!


Weekly Data: 10/29 – 11/2 (Fall Break week)

With reduced hours and many students off-campus during Fall Break, Frist Campus Center was not as busy as usual. As a result, last week’s load of food scraps was about 500 lbs. less than in previous weeks. However we added an additional off-loading session to compensate for prior weeks so that our ratio of food scraps to compost is closer to the ideal 1:1 ratio*

Food Wood shavings (BA/CS) %
Compost Off-loaded
Week Totals (lbs.) 3,232 953 29% 4,500
CUMULATIVE (lbs.) 17,510 5,062 29% 9,500

*Note that the cumulative food : compost ratio won’t be exactly 1:1 because of the need to fill the system close to the vessel capacity before off-loading begins. In our case, we added nearly 7,000 lbs. of food scraps before our first off-loading of compost.

The Weekly BioDIGESTer: 10/22

Welcome back! This week’s bioDIGESTer includes the summary of last week’s data,  a photo essay highlighting the compost off-loading process, and the biodigester’s interactive exhibit at the Frist GreenSpace.

Weekly Data: 10/22 – 10/26

Last week’s data were very similar to the week prior having loaded 3,703 lbs of food scraps and 1,100 lbs of wood shavings into the system.

Food Wood shavings (BA/CS) %
Compost Off-loaded
Week Totals (lbs.) 3,703 1,100 30% 3,000
CUMULATIVE (lbs) 14,278 4,109 29% 5,000

We also off-loaded a trailer bed’s worth of finished compost or around 3,000 lbs. This amount is roughly equal to the amount of food that we added in order to balance out the input-output  equation to prevent over-filling the system (Note: About 25%-30% of the mass of the cumulative feedstock is lost to water vapor which cancels out the addition of the wood shavings).

Herman Ishengoma ’22 assists with off-loading finished compost into the receiving receptacle. Visible is water evaporating from the finished compost as it transitions from a 100+ degrees F environment to ambient temperature on a chilly Fall morning.


Dr. Nick holds a small amount of our best batch of finished compost to date








After two off-loads, the trailer bed is full and is hooked up to a truck and taken by our Grounds crew.

A small amount of compost is salvaged for nutrient analysis testing using a UNIBEST resin capsule which will give us an initial read on the total plant-available nutrients in the compost. Stay tuned for results!

Biodigester at the Frist GreenSpace

The biodigester project is this semester’s featured exhibit  at the Office of Sustainability’s GreenSpace in Frist Campus Center. Stop by the interactive kiosk on the 100-level to learn more about the step-by-step operational process, the University’s  progress and approach toward recycling uneaten food on campus, and class projects and additional research opportunities available via the Campus as Lab program.

The Weekly BioDIGESTer: 10/15

Welcome to the debut of the weekly bioDIGESTer! A new series consisting of weekly project updates and related news around food waste management. Check out what we were up to last week!


Over Monday, Wednesday and Friday, we loaded a cumulative 3,734 lbs. of food scraps into the system along with 1,100 lbs. of wood shavings which serve as a bulking agent/carbon source (Read a previous blog post to learn more about why we add wood shavings).

We are currently testing American Wood Fibers’ mini flake. These wood shavings account for ~30%  of the total weight of the food scraps feedstock in order to adequately account for the moisture level of our food waste stream.

As a result, the 1,500 lbs. of finished compost that we off-loaded was an ideal texture – not too dry and not too wet.

Food Scraps Wood shavings (BA/CS) %


Week Totals (lbs.) 3,734 1,100 29% 1,500


Finished compost after it was off-loaded from the system


Food waste in the news:

A diverse set of strategies will be needed if New Jersey plans to meet a state target of cutting food waste by 50% by the year 2030. The Princeton Biodigester project represents further investigation of the potential of on-site food waste re-purposing through in-vessel composting. Read more about the current legislative and technical landscapes around reducing food waste in New Jersey in this deep dive article from Waste Dive:






The Biodigester is Up and Running!

After a busy summer preparing for the start-up, Princeton University’s biodigester is now operational! Many thanks to our campus partners and FOR Solutions for their on-going support and assistance.

Check out the video below from one of the first loadings and stay tuned for weekly updates as the project progresses!



More Project Updates!

In the last few weeks, we began a series of steps to prepare for our start date in June while also starting campus outreach efforts.  These included a system calibration test performed by FOR Solutions, two tours for the campus community, and the arrival of a  lift arm for loading buckets of the feedstock into the system’s hopper. See the photo essay below!

  1. FOR Solutions performs a calibration test to insure the correct electrical set-up and proper rotation of the biodigester’s mechanical systems

2. Dr. Nick shares his journey into food scraps composting and why he founded FOR Solutions to our Earth Month tour group

3. The lift arm that we will operate in order to dump buckets of uneaten food and wood shavings into the loading hopper

Earth Month Biodigester Tour

Monday, April 30, 2018 – 12:00pm

Tour the Princeton University Biodigester for Earth Month!

Advance reservation is required, please sign up  to reserve your spot.

Tour will start at the Jadwin Gym. There will be a short walk from the gym to the Biodigester site. The tour is approximately 45 minutes to 1 hour long.

Please note that the tour is only open to Princeton University students, staff and faculty.