The Weekly BioDIGESTer (1/14)

First Off-Loading of 2019 & Bioware Testing!

We had an exciting first full week operating the biodigester in 2019. Highlights included our first off-loading session as the vessel neared its capacity, and materials testing to help inform our Campus Dining team about types of food service ware that may be composted in our system versus sent to the landfill.

[Composted off-loaded on January 18th]

Henry Wietfeldt ’22 drops one of 50 palm plates into the loading hopper to be shredded before it enters into the rotation vessel. We also tested World Centric plant fiber clamshells, and the Huhtamaki ‘Chinet’ plate. In about a week or so we will be able to tell how well each of the items broke down in the system based on their presence (or lack thereof) in the finished compost.

Click here to watch as shredded pieces of Chinet plates fall from the auger into the input port.

Weekly Data: 1/14 – 1/18

We processed just under 3,000 lbs. of food scraps last week, which is lower than the average of about 3,500 lbs. for a full week. Composting is a great way to return nutrients to the environment to enrich soils and grow healthy plants, but ultimately we want to reduce the amount of food (especially leftover food) from compost whenever we can, so the reduced weight from our campus center and cafes is a win and a metric we will continuously track!

Food Wood shavings (BA/CS) %
Compost Off-loaded
Week Totals (lbs.) 2,986 950 32% 1,250
CUMULATIVE (lbs) 38,884 11,571 30% 29,250

The Weekly BioDIGESTer: 1/7

Welcome to the first weekly bioDIGESTEer of 2019!

In our first (partial) week back in operation since Winter Break, we loaded 2,346 lbs. of food scraps and 727 lbs. of wood shavings into the biodigester, thus maintaining the approximate 3:1 ratio of food to wood given the moisture content of the food scraps.

We didn’t off-load any compost because the vessel was nearly empty after having off-loaded the majority of the compost from the system before Winter Break. It will take about 2 weeks from the first loading session of the New Year on January 7th until we off-load the first batch of compost in 2019 (i.e. when the vessel drum is about 75% full).

Weekly Data: 1/7 – 1/11

Food Wood shavings (BA/CS) %
Compost Off-loaded
Week Totals (lbs.) 2,346 727 31% 0
CUMULATIVE (lbs) 35,898 10,621 30% 28,000



Biodigester Ribbon-Cutting Media Coverage!

Thank you to all who came out yesterday to celebrate the official unveiling of the Princeton University Biodigester Project with us.

If you were unable to attend, see below for several links to media coverage around the event:

Princeton University shows off their ‘Biodigester,’ which turns food scraps into compost in 5 days (

TV clip (6ABC Philadelphia)

Princeton University’s new biodigester makes food scraps sustainable (Princeton University)

KyuJung Whang cutting ribbon in front of biodigester

Ribbon-Cutting Ceremony!

Happy New Year!

To begin 2019, please join us next Tuesday, January 8th, for a celebratory ribbon-cutting ceremony to formally introduce the Princeton University biodigester initiative to the greater community.

See below for additional event details. Hope to see you there!

End of 2018 Summary

With Winter Break in full swing, and the holidays and New Year around the corner, we present a year in review recap of the biodigester project


  • December 20, 2017: The FOR Solutions Model 1000 Composting System is delivered to campus. 
  • April 2018: Installation Acceptance Test completed to insure the correct electrical set-up and proper rotation of the biodigester’s mechanical systems
  • May 2018: Arrival and waterproofing of lifter and other operational items
  • July 2018: System receives UL Certification
  • September 2018: Electric inspection and town code inspections completed
  • September 18, 2018: Biodigester becomes operational with the first loading of food scraps from Frist Campus Center and campus cafes
  • December 2018: Project expands to include food scraps from Scully Co-op
  • December 14, 2018: Last system loading of 2018
  • December 20, 2018: Last off-loading of compost of 2018


  • Over 16 tons of food scraps converted into nutrient-rich compost
  • Engaged 14 undergraduate students as operational assistants
  • 15 presentations/tours
  • 3 related student course reports 


  • Plans to grow project by setting up additional campus food scraps collection locations
  • Project logo!
  • Experimental testing of different compost products (e.g. blends, teas) and applications across campus
  • Cost-Benefit, Life Cycle Analysis and additional research efforts

Happy Holidays and New Year!

Stay tuned for updates in 2019.

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.