Closing the Circle: How Our Community’s Waste Could Feed Our Farms

A short introduction to the plan “From Community Waste to Community Fertilizer”

Every day, without much thought, a city sends a river of waste down its drains. Most of us stop thinking about it the moment the water swirls away. But at the other end of those pipes, at the wastewater plants that keep our neighborhoods healthy, something remarkable is already happening. In big sealed tanks called digesters, that waste breaks down and gives off methane — a gas many plants already capture and put to work for power and heat.

Here is the question at the heart of this plan: what if that same gas, and the nutrients left behind, could become fertilizer for the farms that grow our food? What if the circle — from table, to waste, to field, and back to table — could actually close?

It sounds like a dream. The full report argues that it is something more practical than that: a real idea, built on real chemistry, that can be pursued carefully, one proven step at a time.

Two harvests from one stream

The report describes two “harvests” that can come out of the same plant.

The first is new nitrogen fertilizer. The methane is cleaned, then reformed with steam to produce hydrogen. That hydrogen is combined with nitrogen pulled from the ordinary air around us to make ammonia — the backbone of modern nitrogen fertilizer. One detail surprises a lot of people: the nitrogen comes from the air, not from the waste. The chemistry is mature and well understood. But the report is honest that gas from a renewable source does not mean zero emissions, and that the finished product still has to be tested, not simply assumed safe.

The second harvest is recovered nutrients. The liquids left in a digester carry phosphorus and some nitrogen. Equipment already in use at some plants can capture these as a crystal called struvite, or as ammonium salts. It doesn’t catch every pound that goes down the drain, but it turns a problem into a product.

Safety comes first — always

Ronnie’s central safeguard runs through the whole plan: keep pharmaceuticals, heavy metals and persistent “forever chemicals” like PFAS out of the loop wherever possible. That means testing what comes into the plant and what goes out, tracking which industries discharge into the sewer, supporting medicine take-back, and rejecting contaminated material rather than diluting it. The report is plain about it: making fertilizer must never compromise the plant’s first job, which is treating sewage and protecting public health.

A plan in six steps, not one leap

Rather than promising an ammonia factory at every sewer plant, the report lays out six phases, each ending in a “decision gate” — a moment to stop, look at the evidence, and decide whether to go on.

1. Choose the right sites (months 0–3). Gather a year of real data on gas, heat and contamination, and be willing to say “don’t convert this one.” 2. Prove it’s safe and pick the best route (months 3–9). Test for contaminants, compare options, and talk honestly with neighbors about odor, traffic and safety. 3. Line up contracts, permits and money (months 9–18). Without putting household sewer bills behind untested technology. 4. Build and measure (months 18–36). A full year of reliable, independently measured production — not just a ribbon-cutting. 5. Grow what works (years 3–5). 6. Connect a regional network (years 5–8), sharing testing, processing and distribution so each town doesn’t have to rebuild everything alone.

These timelines are planning estimates, not promises. That honesty is part of what makes the plan trustworthy.

Where it could start

The report suggests looking first at home: Philadelphia’s Northeast Water Pollution Control Plant, where the Philadelphia Water Department, Philadelphia Gas Works and the Philadelphia Energy Authority are already exploring better uses for the plant’s biogas. It points to New York City’s Newtown Creek plant as a benchmark, because it has strong measured numbers for the renewable gas it produces. It looks at DC Water’s Blue Plains facility as an experienced operating partner, and at a Madison, Wisconsin plant working with Ostara as a model for recovering nutrients.

It also learns from others: farm and food-waste gas developers like Vanguard Renewables and Divert, and fertilizer makers like Yara, which began delivering ammonia made from biomethane in Brazil in December 2024. None of these organizations has been contacted or committed to anything. They are candidates to study, and the report says so clearly.

How big could this be?

Using Newtown Creek’s measured gas as a worked example, the report estimates that a plant of that size could, in principle, produce on the order of 6,800 to 9,700 tonnes of ammonia a year — roughly enough nitrogen, at an illustrative application rate, for something like 82,000 to 103,000 acres of cropland. That’s meaningful. But the report is careful: much of that gas is already committed to other uses, and one city’s waste won’t make a whole region self-sufficient. It’s a real contribution, not a miracle.

The hard part: cost

The chemistry works. The hardest challenge is money — competing with cheap fossil-fuel ammonia while giving up the gas, heat and credits plants already earn today. That’s why the report suggests that recovering nutrients directly may be the smarter first investment, and that partnering with an existing ammonia producer may beat building a small chemical plant from scratch.

Paying for it together

This is where the community comes in. The report walks through water-infrastructure loans like the Clean Water State Revolving Fund, the federal 45V hydrogen credit (with its strict rules), and municipal and green bonds. It also describes ways ordinary people and farmers can take part: farmer cooperatives that buy in and help steer production, multi-year purchase agreements with fair price floors, and community investment through rules like Regulation Crowdfunding. Throughout, it insists on fairness — farmers should never be forced to buy product they can’t use, and residents shouldn’t carry the losses of an experiment.

A circle we can build in pieces

The plan’s closing words capture its spirit: Ronnie’s circle is achievable in pieces. Measure safety, recovery, farmer needs and affordability — then expand only what works.

There’s something deeply hopeful in that. What we flush away doesn’t have to be the end of the story. With care, patience and shared ownership, it can become the beginning of the next harvest.

To go deeper, [read the full report (PDF)](/media/closing-the-circle/from-community-waste-to-community-fertilizer.pdf): From Community Waste to Community Fertilizer: A Sequential Execution Plan — with all six phases and their decision gates, the candidate sites and partners, the worked numbers behind the scale and cost estimates, the government programs and their 2026 limits, and its 27 numbered sources.

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Full report (primary download): From Community Waste to Community Fertilizer: A Sequential Execution Plan (PDF)

Optional slide overview: Closing the Circle presentation (PDF)

Companion song: Back to the Ground (The Circle Comes Home) (#210). Listen in the Rock U song list

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By Ronnie Patterson.

This article was written with AI assistance and reviewed by Ronnie Patterson.