First Photos of New Location

In today’s update we bring the first photos of the S.C.R.A.P. Lab as it is being reconstructed!

Check out the photo essay below from the construction site:

Driveway leading to the S.C.R.A.P. Lab. The fabric structure has been placed over the dried slab
Front of the building
Inside: The first fabric layer without insulation, exposing the scaffolding. Installation of electric conduit has begun
View from the back: To the left of the composting facility where the soil is currently disturbed will eventually be a small shelter cover shed for storing our carbon feedstock

The ComPOSTer: Fall Semester Update

Welcome back to campus for the new academic year!

It is great to see everyone back again while continuing measures to prevent the spread of covid.

This summer we received our municipal permit to begin the reconstruction of our composting facility on Washington Rd near Princeton’s solar field (see circled area on the map below)

This week the concrete was poured to create the slab and by mid-September the fabric structure will be re-erected and then we will reassemble the composting system inside (more updates and pictures to come). The operational restart is still tentative but will happen sometime this semester, likely in mid/late October.

In other composting news:

  • New Jersey’s food waste diversion legislation, will go into effect this October. The bill mandates establishments (e.g. hospitals, prisons, schools, restaurants, supermarkets) that generate 52 or more tons of food waste annually must arrange for separate recycling if an authorized facility is located within 25 road miles. It will also create a market development council to assist in generating demand and finding markets for finished compost.
  • At the national level, H.R. 4443 COMPOST Act was recently introduced in Congress to provide critical infrastructure and financial support for the composting industry.  As currently written, this legislation has three main goals:
    • Establish a USDA-led grant and loan guarantee program to provide $200 million in funding per year through 2030 for compost equipment, siting, and systems needed to expand compost facilities accepting food scraps, both public and private.
    • Provide funding for collection programs and development of markets for finished compost
    • Recognize compost as a conservation practice which will make compost use an eligible reimbursement item for farmers who use compost to improve soil and sequester carbon.

The ComPOSTer will continue to follow and provide updates on these and other related legislation.

Th ComPOSTer: Interview with Professor Xinning Zhang

Our faculty Q&A series wraps up with an update from Professor Xinning Zhang, an environmental microbiologist jointly appointed in the Department of Geosciences and the High Meadows Environmental Institute. This month, the ComPOSTer interviewed Dr. Zhang to learn more about how her lab is extending its research in microbial metabolism and biogeochemcical cycling on the Princeton campus, and how it relates to environmental justice.

Xinning Zhang, Assistant Professor of Geosciences and at the Princeton Environmental Institute
Professor Xinning Zhang; Photo from Princeton University Dept. of Geosciences

What are the main questions that your research group is asking about the composting process and how is the S.C.R.A.P. lab involved?

The Zhang lab is broadly interested in understanding the role of microbes in decomposition and greenhouse gas cycling within man-made and natural environments.  As the environmental and human health harms of using industrial fertilizers to promote plant growth have become clear, many communities, including the University and the township, are exploring compost as a nutrient rich amendment to soils in place of industrial fertilizers.

Working with the S.C.R.A.P. lab, members of the Zhang group (Gabrielle D’Arcangelo ’21, Galen Cadley ’21, Dr. Jared Wilmoth) have been studying the microbial decomposition of food and garden waste into compost and greenhouse gases like carbon dioxide and methane with the aim of optimizing Princeton University’s aerobic digester for producing nutrient rich compost with low net greenhouse gas emissions. Specifically, we would like to determine (a) who the main microbial actors are in the compositing process, (b) how these microbes work together to make healthy compost, and (c) how microbes and their activities respond to changes in the composition of incoming food waste flows and environmental characteristics like aeration levels and temperature.

Gabby D’Arcangelo ’21 and Calvin Rusley ’20 during the summer of 2019 collecting feedstock samples from the composter for microbial rDNA sequencing

What have been the preliminary findings to-date and the next steps in the research?

While there is insufficient sample consistency to make any firm conclusions, preliminary findings of the microbial community analysis have identified Lactobacillus and Acetobacter to be the most dominant bacterial groups (indicating a rapid uptake of simple sugars), followed by Clostridium and Chitonophaga (complex carbon degradation), and less than 1% of methane-producing organisms, the most dominant being the oxygen-intolerant hydrogen gas consumer, Methanobacterium.

An accumulation of the latter category or “methanogens” was found during a power outage and when on-loading/off-loading of material was halted. These results indicate that to avoid increased methane emissions, compost materials should not be allowed to sit for long durations (> a couple days) in the composter, particularly in the back end of the unit where oxygen-free conditions favoring microbial methane production easily develop.

Future work will aim at evaluating whether increases in aeration frequency and/or changes in food waste/bulking agent composition will further reduce composter methane levels. However it is important to note that even optimally working municipal waste composts can contain anaerobic pockets allowing the presence of about 1% methane-producing bacterial species, so these results are consistent with those found in other composting operations.

Why is this research important and how does it relate to environmental justice?

The application of industrial fertilizers leads to numerous environmental problems, most notably the eutrophication of water supplies with detrimental effects on water quality, fisheries health, and greenhouse gas emissions. Unfortunately, these environmental harms are disproportionately borne by people of color in lower income neighborhoods. We hope that our work with the S.C.R.A.P. lab on the science behind composting will aid in weaning our food and landscaping system off industrial fertilizers to promote environmental health and justice.

Interview edited for length and clarity

Looking forward to 2021

Dear friends of the S.C.R.A.P. Lab,

Thank you for your loyal following during this unusual year of hardship and sorrow due to a global pandemic and acts of national racial injustice. Usually the last ComPOSTer of the year serves as an ode to the past year, but I think we can all agree that we rather leave 2020 behind. Still, with the New Year only several hours away, the ComPOSTer takes a moment to look back on the (brief) composting highlights of 2020, but more importantly, what is to come in the New Year. We are optimistic about 2021!

2020 Year in Review

January – March : Started off the year strong, just where we left off after our first full calendar year of operations. We converted 14 tons of food scraps into nutrient-rich compost before COVID-19 forced our facility to shutdown early in Mid-March.

April: Debuted a new video highlighting the behind the scenes processes and the people involved in the journey from food scrap to compost


June: Began the study of compost application on campus farmland

August – December:

  • Launched a faculty Q&A blog series led by Wesley Wiggins ’21
  • Began site planning for SCRAPPY’s new location along Washington Rd. south of Lake Carnegie

Other 2020 Highlights:

The S.C.R.A.P Lab was featured in…

  • A combined 10 presentations, webinars and tours
  • Campus as Lab projects:
    • Faculty-sponsored research projects: 3 active
    • Junior papers/senior theses: 2 completed
    • Student course projects: 1 completed


Re-construction of our composting facility at our new home will begin early next year with operations expected to resume in Spring 2021. We will continue to engage our students as operational assistants, albeit under new social distancing and other covid-related guidelines. Otherwise we plan to pick-up where we started on our operational and research efforts, including:

  • Expanded compostables collection in the food gallery of Frist Campus Center
  • Integration of research efforts with operational testing of different feedstocks and recipes
  • Testing of new food scraps collection and drop-off systems to expand reach across campus

See you in the New Year!

The ComPOSTer: State of Organics in New Jersey: Legal Updates

Happy Holiday Season!

Before the Thanksgiving break, I attended the New Jersey Composting Council’s annual Organics Waste Summit on November 19th. Included in the topics of the virtual event were legal updates around the state of organics in New Jersey. Read on for highlights:

First, some background:

  • To achieve NJ’s goal of reducing statewide emissions 80% by 2050 (from 2006 levels) , emissions from the waste sector must be reduced by 15%
    • Waste management was the largest source of non-energy GHG emissions in both 2006 and 2018.
    • In 2018, GHG emissions from waste management was over 5 million metric tons CO2e as shown below:
Source: 2018 Statewide Greenhouse Gas Emissions Inventory, New Jersey Department of Environmental Protection

Updates on Recent Organics Recycling-Related Laws & Regulations

Aimed to directly or indirectly advance progress toward the “80×50” goal:

  • New Jersey Protecting Against Climate Threats (NJ PACT) – Signed January 2020: Directs the Department of Environmental Protection (DEP) to make sweeping regulatory reforms to reduce emissions and adapt to climate change.
  • Commercial Organics Recycling Mandate – Signed April 2020; Regulations Pending; Stakeholder Meetings Anticipated Early/Mid 2021; Mandate Effective October 2021: Establishments (e.g. hospitals, prisons, schools, restaurants, supermarkets) in the state that generate 52 or more tons of food waste annually must arrange for separate recycling if an authorized facility is located within 25 road miles. 
  • Exemptions to Solid Waste Regulations for Small-Scale Food Waste Recycling Activities – NJDEP Stakeholder Meeting November 2020; Proposal Anticipated Early 2021: Aimed to make regulations easier to comply with for those looking to start micro/community-scale composting operations
  • Environmental Justice Legislation – Signed September 2020; Stakeholder Meeting October 2020 (with additional meetings anticipated); Proposal Anticipated Early/Mid 2021: Aimed to prevent new environmentally damaging projects (e.g. landfills) from siting themselves in “burdened communities,” Learn more, including how to participate on the NJDEP EJ website
  • Cannabis Legislation – pending after NJ voters approved a ballot question to legalize recreational marijuana in November 2020: Given that waste processing of cannabis residue needs to happen in-state, regulations and processes must be outlined to make sure the residue is diluted and sterilized as is most commonly required by governments in other states where cannabis is legalized. If the residue is combined with organic material, the resulting feedstock can be safely composted by effectively reducing levels of THC in discarded marijuana.

The ComPOSTer: Zero Waste & Composting Tips for Events

Happy November!

We take a quick break from our faculty Q&A series to share our recent contribution to the U.S. Composting Council’s Soilbuilder’s blog with a post on

Event Composting: A strategy for achieving a clean stream of compostables

We’ll be back again in 2 weeks. Remember to VOTE if you haven’t already. You can find your local polling location here.

The ComPOSTer: Studying compost use on campus farmland – project update

Continuing our review of Campus as Lab efforts, this post will provide an update on a project examining the environmental and economic implications of transitioning campus agricultural land from conventional to sustainable farming practices.

The project, led by Professor Daniel Rubenstein and assisted by me, involves engaging undergraduate students in measuring the relative importance of different soil amendments (including S.C.R.A.P Lab compost!) and weed control methods on crop productivity, soil health, and profit. Additionally, our team is analyzing the impact of low-cost fencing in reducing crop damage from deer overgrazing.

The ultimate goal of the project will be to develop a set of recommendations on how the University can farm in a more environmentally responsible and cost-effective way as the current industrial model of growing a rotation of corn and soybeans using fossil-fuel based inputs is carbon intensive, degrades soils, and pollutes waterways. Alternative and more sustainable practices that we are testing include diversifying the crop rotation, using natural soil amendments like compost, and ensuring ground cover over the winter with a cover crop in order to increase the soil’s ability to supply nutrients to crops without relying on excess use of chemical inputs.

Below is a photo essay describing the project and progress to-date:

This summer, soybeans were planted on a 5 acre farm plot in 8 sections, each of which received a specific combination of soil amendment and weed control treatments. Each soil amendment-weed control treatment is replicated twice both inside of and outside of the fence, with the exception of the compost-cultivation treatment due to a shortage of compost. Following harvesting of the soybeans in October, a winter cover crop, rye, will be planted in the horizontal strip through the middle of the field.
S.C.R.A.P. Lab compost being applied to plots #5a, 6a, and 7a via a manure spreader, two weeks prior to planting

After planting, a sloping electric fence system with a taller inner fence and shorter outer fence, was constructed in an attempt to keep deer out (deer can jump pretty high, but rather not scale two obstacles at once). Reflective tap was also added as a scare mechanism for both deer and geese.
After a few weeks of growth, the soybeans inside of the fence (on right) are noticeably taller than the soybeans outside of the fence (on left)
Arable Mark devices were set up in each of the treatment plots to measure plant growth and health in real-time. The height and greenness of the plants, measured through a metric called NDVI (or Normalized Difference Vegetation Index), is a good indicator of potential yield

Next Steps:

In a few weeks, the soybeans will be harvested using a yield counter to obtain accurate data on the productivity of each plot. We will conduct statistical analyses to determine the relative effectiveness of fencing, soil amendment, and weed control method on yield. In the spring, we will take soil samples and run the same analyses for initial impacts on soil fertility compared to baseline levels collected earlier this year. We hypothesize that the sections receiving compost and planted with winter rye will have a more favorable soil pH, a higher percentage of organic matter, and optimum levels of nutrients versus the sections that did not receive the compost or rye treatments.

In Other News

Today, September 29th, the United Nations celebrated the first ever observance of the International Day of Awareness of Food Loss and Waste

The ComPOSTer: Event Composting & Alum Profile: Ishy Anthapur ’20

Happy first day of classes!

Princeton’s fall semester officially begins today. Over the course of this semester, the ComPOSTer will provide updates related to the relocation of the S.C.R.A.P. Lab composting facility, and feature a Q&A series with Princeton faculty who are conducting research at the S.C.R.A.P. Lab or on other topics related to composting. But before we head into the new semester, this post will wrap up the unofficial end of summer with highlights from the past month. Read below to learn about event composting and an alum profile featuring former assistant, Ishy Anthapur ’20.

Waste Less Wednesday Zoom Social Series: Composting at Events

Earlier this month, my colleague, Lisa Nicolaison, and I co-hosted a session on Johns Hopkins University’s Waste Less Wednesday Summer 2020 Zoom Social series. Check out the video recording below to hear about Princeton University’s experience hosting low waste events through the collection and composting of food and compostable serviceware.

Alum Profile: Ishy Anthapur ’20

Ishy reflects on her time working at the S.C.R.A.P. Lab and discusses her post-graduation plans. Congrats Ishy!

I worked at the S.C.R.A.P. Lab for the summer of 2019 while I was also doing research on campus for my senior thesis in the EEB department. I learned a LOT about Princeton’s sustainability plan and all the strides forward we’ve made (the S.C.R.A.P. lab being a huge part of that)! I also realized that the campus could be doing a lot more to deal with the amount of food waste in general.

My current plans are to pursue a P55 Fellowship in Boston at the Community Day Charter Public School. The S.C.R.A.P. lab affirmed my belief that community-based projects and services are so important to making an impact in terms of environmentalism and sustainability. I’m looking forward to trying to live as green as possible as I start my new job and my new life as an alum!

The ComPOSTer: Alum Profile – Kiley Coates ’20

This week at the ComPOSTer we take a quick break from Campus as Lab updates to catch up with the second S.C.R.A.P. Lab operational assistant to graduate this spring – Kiley Coates ’20.

Read below about how Kiley’s time working at the S.C.R.A.P. Lab has framed her views of sustainability on different scales and has helped in her transition to the workforce as a lab technician processing COVID-19 test samples.

Kiley’s involvement with the S.C.R.A.P. Lab can’t be overstated – she worked 220+ hours over the course of 10 months and wrote an analysis of the composting process for her senior thesis.

“I worked at the S.C.R.A.P. Lab starting May 2019 and continued there until my time was unfortunately cut short due to COVID in March 2020. The S.C.R.A.P. Lab was a great way of learning about sustainability on a variety of scales. The S.C.R.A.P. Lab itself was a larger-type operation and I was able to learn about how institutions like Princeton could use this machinery to improve their in-house sustainability practices. On smaller scales, I learned a lot about various projects on Princeton’s campus and how to apply them even when I left Princeton (having my own compost pile, using reusable silverware even outside the home, etc.). Gina Talt, my supervisor, was a champion at promoting sustainability in practical ways, recognizing the nuances of environmentalism and the importance of doing what you can, while still acknowledging the class and cultural differences that may limit someone’s ability to participate in sustainable practices. 

After graduating, I started working for LabCorp in Durham, NC in their COVID Lab. My position as a lab technician involves primarily working on the queue of pending samples and ensuring we maintain our turn-around time and process priority samples efficiently. It’s definitely pretty different from my work with the S.C.R.A.P. Lab, but I definitely utilize problem-solving skills I grew during my time with Scrappy.”

Congrats Kiley!

Thank you for being such a dedicated composting champion at Princeton. Best of luck going forward!

The ComPOSTer: Alum Profile – Milan Eldridge ’20

Happy dog days of summer everyone,

In about a month, classes at Princeton will resume, but before we head into the new academic year, the ComPOSTer caught up with one of the S.C.R.A.P Lab’s most recent alumni – Milan Eldridge ’20!

Although relatively new to the team, Milan was a fast learner whose passion for sustainable living made her an invaluable and dedicated assistant who took on multiple shifts even during her last semester at Princeton. Read more about Milan’s experience working at the S.C.R.A.P. Lab in her own words below:

I started working at the S.C.R.A.P. Lab at the beginning of my spring semester during my senior year. After becoming more involved with sustainability on campus, I wanted to continue to explore ways that I could be involved with sustainability within the campus community. I also wanted to learn more about sustainability on a larger scale so that I could carry what I had learned with me after graduation.

During my time on campus, I had seen the university change the company through which they composted. All of a sudden, we weren’t allowed to compost everything we had previously been allowed to compost in the dining halls. Soon, after spending some time in the Frist Late Meal Gallery, I started seeing bins labeled ‘S.C.R.A.P. Lab’. For a long time, I had no clue what the acronym stood for, only that we were meant to put our compost in the bin. After reading more about the S.C.R.A.P. Lab, I thought it would be a great opportunity to expand my knowledge of what the university was doing to combat food waste and help contribute to the goal.

“Sustainability can take many forms and may look different in different places depending on the limitations of each place” Milan Eldridge ’20

While working at the S.C.R.A.P. Lab, I quickly learned that, while the university produces a great deal of food waste, people are willing to do what they can in order to reduce the impact this has on the planet. This ranged from various academic departments keeping compost buckets to student groups like Coffee Club searching for ways to keep their business as sustainable as it could be by searching for a way to compost their used coffee grounds. However, at the same time, there are also people on campus who occasionally get really ecstatic about composting and want to compost everything they receive at late meal, down to the utensils and plastic condiment cups.

Nevertheless, I believe that the Office of Sustainability has been doing a great job on campus in order to educate students about what they can do to live more sustainable lives. I have learned that sustainability can take many forms and may look different in different places depending on the limitations of each place. For example, some products that are marketed as compostable aren’t always easily converted into soil by our composting system and it takes time, dedication, and patience in order to ensure that every member of a community understands the limitations that may be present. All in all, I have learned lessons that I believe will be extremely beneficial in the future as I continue to integrate sustainability into my living habits and encourage others to do the same. 

We wish Milan the best of luck in her future endeavors!

Next week, we will hear from one of our long-standing team members, Wesley Wiggins ’21. Wesley will be the ComPOSTer’s resident blog writer for the next several weeks during which he will use his operational expertise to provide insightful updates on all of the exciting coursework and research happening around the project through our Campus as Lab program.