New facility photos and Congress briefing on “forever chemicals”

Progress at 300 Washington Rd.

New updates include the installation of an exhaust fan and the pouring of the concrete pad for the adjacent wood shed

An exhaust fan was installed in the left front vent of the facility. The fan will improve air circulation into and out of the building, which we found is especially needed in hot weather
Concrete pad for the foundation of the wood shed that will store the carbon feedstocks for composting operations. A smaller “hoop” structure will cover the footprint

Jaffé briefs Congress on “forever chemicals”

Peter Jaffé
William L. Knapp ’47 Professor of Civil Engineering
Professor of Civil and Environmental Engineering

Meanwhile… Testifying before Congress, Professor Peter Jaffé called on the federal government to support research into and mitigation of chemicals called PFAS, or “forever chemicals” because of the time they take to break down in the environment. Earlier this year, the ComPOSTer interviewed Dr. Jaffé about his research to mitigate PFAS contamination and to remove the chemical from groundwater and the environment. Dr. Jaffé recommended that Congress direct more funding into research on the forever chemicals, arguing that a better understanding of their impacts will help with mitigation.

Read more about Dr. Jaffe’s testimony and find the full briefing here:

In Context: PFAS & Compost

In a recent BioCycle column, Dr. Sally Brown shows how the biggest risk of exposure to PFAS comes from direct exposure pathways to dust, cosmetics, cookware and packaging (including the food that touches both). As a result, PFAS ends up inn compost but concentrations are much lower than those in many household products. Dr. Brown argues that the manufacturing of products with PFAS should be restricted to prevent the direct exposure to these chemicals, instead of restrictions being placed on down-stream sources of PFAS like compost. The compostable food packaging industry is currently testing and developing viable alternatives that don’t include PFAS so these chemicals don’t end up in composts in the first place. However they are currently not widely available or in limited supply.

2-yr old compost, new design features and other reconstruction updates!

This month we’ve made significant progress on the reconstruction of the composting facility. Check out the photo essay below to see and hear about several new and exciting design and infrastructure improvements (and some well-aged compost)!

Pictured above: The new site on a crisp fall morning.
Foreground: On-going landscape grading work
Background: The outline and beginning construction of a covered storage space for our carbon source, and behind that the electric equipment for the facility
The composting system was completely reassembled last week. The digestion vessel and loading hopper are now stationed on top of elevated slabs which will allow our receiving receptacle trailer to fit completely under the screener on the off-loading end. Next up: Cleaning all the debris and dust accumulated in almost 2 years of storage
Nearly 2-year old compost!
This compost “brick” was found inside of the composting system . Because of the emergency shutdown during spring 2020, some of the food scraps and wood shavings remained, and they ended up naturally decomposing

More updates to come in December. We are getting closer to a “power on” date and hope to resume composting operations in January of the New Year.

Have a happy and healthy Thanksgiving holiday!

Relocation Update, Webinar & More

In this ComPOSTer, we provide an update on our facility relocation and highlight an interesting upcoming webinar on Wasted Food Solutions and more composting-related current events.

SCRAPPY on the move

Efforts are underway to move the composting system into the reconstructed facility. Pictured above is a forklift transporting “SCRAPPY” from its storage location to the facility where it will be placed on the elevated slab below

Wasted Food Solutions Webinar

Join this virtual workshop co-hosted by the Center for EcoTechnology (CET) and New Jersey Composting Council (NJCC) to learn about strategies for implementing wasted food prevention, donation, and diversion programs in businesses in the food service sector. Although specific to New Jersey and its Food Waste Law, participants will leave with an understanding of the next steps for building wasted food management into their operations and gain access to digital resources and guidance documents. All attendees will also have access to free one-on-one support from CET, which will take place in the last hour of the workshop.


In the News

The Global Methane Pledge was introduced recently as an ambitious plan to slash global methane emissions 30 percent by 2030.

The pledge is a big step for limiting the potent greenhouse gas, but critics are quick to point out that the pledge fails to address limiting emissions from the largest source of methane globally — agriculture.

  • The pledge only promises to incentivize “the deployment of improved manure management systems, anaerobic digesters, new livestock feeds, composting, and other practices.”
  • In the U.S., the Biden administration plans to pose direct restrictions on the oil and gas industry, but only voluntary adoption measures with the agriculture sector.
  • Meanwhile, environmental justice groups believe the solution lies in transitioning away from the large-scale livestock operations that are one of the biggest contributors of methane emissions. These facilities dump manure into large “lagoons” which creates unsafe air and groundwater in the disproportionately Black, Latino, Indigenous, and white rural surrounding communities.

As an alternative solution, New Jersey Senator Cory Booker reintroduced the Farm System Reform Act, which imposes a moratorium on these industrial facilities and creates federal financial assistance for farmers to transition to pasture-based dairy and hog farming. 

Read more: There’s a major gap in the new methane pledge: Agriculture

NOTE: If managed properly, grass-fed animal operations can be a more sustainable option and healthier to nearby communities, however the scientific community is still in debate over whether pasture-raised systems (in particular beef), are consistently more climate-friendly than industrial beef.

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: Interview with Professor Daniel Rubenstein

Professor Daniel Rubenstein is the Class of 1877 Professor of Zoology in the Department of Ecology and Evolutionary Biology. Last month, I interviewed him about the intersections between food, agriculture, and the environment and how these topics related to environmental justice.

Professor Daniel Rubenstein
Photo Source: Department of Ecology and Evolutionary Biology

Interview edited for length and clarity

Q: Why are you interested in food, agriculture, and the environment?

A: I’m a behavior ecologist and what that means is you look at how the environment shapes animal behavior. So you’re looking at how changes in environmental factors, ecology, climate, etc. affect different species and in different environmental contexts. I’m interested in unraveling those patterns and I use a lot of modeling and comparative analysis to try to find general rules.

The species that I have studied most extensively are the equid, or the horses, zebras, and the wild asses. They’re all very closely related evolutionarily because they’re all the same genus. There are very few species left on the planet (only seven) and are not particularly numerically abundant anymore anywhere but they’re widely distributed.

Now, when they cover the planet, everyone who is a farmer who has livestock cattle, sheep, and goats believes that every grass blade in the environment belongs in the belly of their livestock and when they see horses, zebras, or wild asses eating the vegetation, they are very unhappy. And they want them gone and so they persecute them and cause the extinction of these equids. Since I study them and people consider them vermin, I got involved in farming. I needed to talk with the pastoral people and the commercial ranchers who didn’t like the animals that I studied. In order to find out why they persecuted them, I started doing experiments to demonstrate that in fact there’s not so much competition between them. It’s actually mutualism because the equids can eat the stems in the straw that the cattle find difficult to eat and therefore they open up the grasslands, take away the negative foods, stimulate the growth of the good, highly nutritious foods as long as there’s moisture in the soil and therefore benefit the cattle. And so the “vermin”, all of a sudden now are facilitating the growth of the cattle and the cattle — by feeding with their tongue — are stripping away the larvae that parasitize the guts of the equids and so as a consequence, there’s a joint mutualism using different currencies.

And so this experience made me interested in farming and I teach a course on agriculture, human diets, and the environment, precisely to talk about these issues and other issues like where did farming come from? Why did it supplant hunter-gathering (which was a perfectly good lifestyle)? How do you deal with the fact that you have no nitrogen in your soils or water? What are the resulting impacts on biodiversity? I set up the course so that the students would need to play with and analyze farming data to really sink their teeth into what evidence exists that explains how different types of farming have different impacts on the landscape, lead to different productivities, profits, and also to different distributions. Who can afford organic foods? If you’re poor, you can’t. And so now you have a social equity issue as well playing into it. 

Q: How does the S.C.R.A.P. Lab relate to your course?

We received a grant from the university to examine different farming practices on several farms around Princeton. In the summer, we put out sensors in the field to measure metrics like evapotranspiration which is a measure of plant metabolism via water intake. If the water is going up through the plants it means the plants are photosynthesizing so via evapotranspiration you know how hard the plants are working effectively in terms of productivity. The students in the class pick different projects so they can compare commercial industrialized farming with organic farming,  biodynamic farming, or precision agriculture which puts the artificial fertilizer in places where plants appear are needed rather than blanketing the landscape. 

On Princeton University-owned farmland, we’re also interested in top-down pressures of herbivores eating the maize or soybean since the farmers leasing the land predicted that 30% of their crops were disappearing due to deer. So we sent out experiments to test whether that in fact was true by fencing off some of the lands with an electric fence at the same time that we are assessing the bottom-up factors (e.g. soil fertility). And that’s where the composter comes in. We can apply artificial fertilizer, which is what the farmers currently do, or we can have the soil additions be the compost. Each of these has different effects on the outgassing of CO2 as well as energy inputs. It turned out that the main cause of the loss of food was the herbivores or the deer but the nutrients do matter. We will be examining the effects further along with cover crops as well. 

Q: Why is it important that we study the intersections between these three fields at Princeton University?

A: I think it’s important for us to study it on campus because we all bring slightly different perspectives to the notion of how plant productivity in general operates. One of the things about food is that students love food. It becomes a touchstone, a magnet that brings people into understanding – well, what am I eating? Is it healthy? What impact is my diet having? Everyone has strong beliefs about this. Some say “I’m a meat-eater because humans evolved to be meat-eaters”. Others say “I’m going to stay as an omnivore”. And others say that the footprint is too great, therefore, I’m going to become vegetarian, in fact, I’m going to become vegan. And so people come in with these really strong beliefs. It turns out there’s no perfect way to eat. That each one of these diets has issues and difficulties in one way or the other.  When you do a life cycle analysis with all of the inputs, it turns out that what you think is the best type of farming often has hidden costs that you don’t appreciate. So there’s a lot of issues and my course brings out these issues to force people to rethink their beliefs. 

Others who are biogeochemists and genomicists can really look at biology or chemistry and bring in the understanding of different breeds, different genetics, and the relationship between the genetics of the plants vs the insects and pests. So when you can start to look at genomics, you can start thinking about ways in which you can build better plants that get into GMOs (Genetically Modified Organisms). Crop engineering has very low impacts on the environment, both in terms of maintaining biodiversity and in managing water and gas production, but brings up issues questioning if GMOs are healthy for you and others, so there are unintended consequences. And the more we can bring knowledge to dealing with these trade-offs and preconceived notions, we start to make better decision-makers by sharing the knowledge with students and colleagues.

Even if we can’t agree on the right answer, the more information we can give students, the more skills we can give them to think through these wicked problems which are not easy to solve. That’s why the introductory, environmental nexus course was created which was based on the four pillars of Climate, Food, Water, and Biodiversity. We had to make sure in the Environmental Studies program that there were upper-level courses to build upon the themes that were being introduced in the foundational courses. And so that’s how my course arose, and then there are other courses such as history and literature courses that deal with farming, diets, and self-worth. We’re trying to think about putting together a food certificate program that would bring these together going forward.

Q: How is the work that you are doing related to environmental justice?

A: The justice implications are very real. Organic produce is much more expensive. If I go to the supermarket, I can get an ear of sweet corn for 30 or 50 cents depending on whether it’s on sale. If I go to an organic farm or a farmers market, that same ear of corn is going to cost me 75 cents or even $1, and that’s much more expensive. If you’re limited on money and you want to eat natural foods you’re going to go buy food at the grocery store and not at the organic farm. And there may be pesticides on that food. Are you washing it carefully enough? If not, then you’re ingesting chemicals that will impact your health. The organic farmer would have grown it without chemicals or a different set of chemicals that are deemed to be safer for you than the ones they use in industrial agriculture. So right away, the limits in your income and the ability to get out to a community-sponsored agriculture location are very, very different.

When I conduct different livestock rearing experiments in Kenya’s 55,000-acre, Mpala Conservancy, we open them to the pastoral herds in the community and hire the children as the herders. They’ll live at Mpala, earn some cash, and in doing this new type of herding they are seeing the difference in the growth and health of their cattle. I can publish a paper on it and do a community presentation, but the telegraph from child to father is much faster and much more effective. By participating, you take ownership of the experience and you can spread it much faster because you become an ambassador. 

At Princeton, we hope to create a farm and invite kids from Trenton and Ewing, who may not have really healthy diets and engage them in actually growing and tasting vegetables. In doing so, they may experience something novel, and probably compel them to switch their diets. But most importantly, we will give them the crops to take back and sell within their communities. And that’s our belief that if we bring kids from urban centers and bring them into farming, not that they’re going to be farmers in the future, but they will start to appreciate and become aware that diet is something they can choose if they have access.

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.