18 Plus Closing the Circle · A completed project proposal
From Community Waste to Community Fertilizer: A Sequential Execution Plan
A sequential plan for turning wastewater methane and recovered nutrients into fertilizer for nearby farms, one proven step at a time, without compromising the plant's first job of treating sewage and protecting public health.
The kind of work we do
When the machines do the work, what will you create? 18 Plus Creativity Hub is a place for adults to research, plan, and make something real. This page shows one serious piece of work from that effort: research, a 10-page plan, and a presentation.
It is a completed project proposal — not a finished plant, and not a signed partnership. No agency has received, reviewed, or signed on to it.
Two harvests from one stream
Every day, a city sends a river of waste down its drains. At the wastewater plants that keep neighborhoods healthy, that waste already breaks down in sealed tanks called digesters and gives off methane — a gas many plants capture for power and heat. The question at the heart of this plan is simple: what if that same gas, and the nutrients left behind, could become fertilizer for the farms that grow our food?
Harvest 1: new nitrogen fertilizer
The methane is cleaned, then reformed with steam to produce hydrogen. That hydrogen is combined with nitrogen pulled from ordinary air to make ammonia — the backbone of modern nitrogen fertilizer. The nitrogen comes from the air, not from the waste. The chemistry is mature. Gas from a renewable source does not mean zero emissions, and the finished product still has to be tested, not simply assumed safe.
Harvest 2: 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.
The strongest opening is probably not an ammonia factory at every sewer plant. It is a regional partnership: wastewater utilities recover nutrients and supply cleaned gas; experienced chemical operators make ammonia; farmer cooperatives distribute fertilizer. That arrangement should be compared against a small on-site unit before anyone chooses a path.
Six phases, each with a decision gate
Rather than promising a factory in one leap, the plan lays out six phases. Each one ends in a decision gate — a moment to stop, look at the evidence, and decide whether to go on.
- 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.”
- 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.
- Line up contracts, permits and money (months 9–18). Without putting household sewer bills behind untested technology.
- Build and measure (months 18–36). A full year of reliable, independently measured production — not just a ribbon-cutting.
- Grow what works (years 3–5).
- Connect a regional network (years 5–8). Share testing, processing and distribution so each town doesn't have to rebuild everything alone.
These timelines are planning estimates, not promises.
Where it could start
The plan looks 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, including farm and food-waste gas developers and fertilizer makers such as Yara, which began delivering ammonia made from biomethane in Brazil in December 2024. None of these organizations has been contacted or asked to sign on. They are research candidates only, and the plan says so clearly.
Scale, and the hard part
Using Newtown Creek's measured gas as a worked example, the plan 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 much of that gas may already be 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 chemistry works. The hardest challenge is cost — competing with cheap fossil-fuel ammonia while giving up the gas, heat and credits plants already earn today. That's why the plan 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.
The plan also looks, carefully, at public water-infrastructure loans, bonds, and fair ways farmers and communities could take part. Farmers shouldn't be forced to buy product they can't use, and residents shouldn't carry the losses of an experiment. Those details live in the plan PDF. This page is not an offer to invest, and we make no promises about income.
What's complete — and what isn't
- The research and a 10-page sequential execution plan are complete.
- The article, the plan PDF, and a presentation are live on Rock U Understanding, published November 9, 2026.
- A companion song, Back to the Ground (The Circle Comes Home), is live on the Rock U home player.
- A later outreach to official addresses is planned, but it has not happened. Nobody has been contacted, and nothing has been printed, bound, or mailed.
Please read this plainly.
- Safety comes first. Making fertilizer must never compromise a plant's first job: treating sewage and protecting public health. Pharmaceuticals, heavy metals, and persistent “forever chemicals” like PFAS should be kept out of the loop wherever possible — by testing what comes in and what goes out, and by rejecting contaminated material rather than diluting it.
- No partners have signed on. Named organizations in the plan are research candidates only. Nobody has been contacted.
- Timelines are estimates, not a construction schedule or a promise.
- This is a proposal, not a plant. Completing the research and the plan is the work on offer here.
Read the plan
The full report is the main document: all six phases and their decision gates, the candidate sites, the worked numbers, the government programs and their 2026 limits, and 27 numbered sources.
Optional slide overview: Closing the Circle presentation (PDF) · Public-friendly introduction: Closing the Circle: How Our Community's Waste Could Feed Our Farms (Rock U article #211) · Companion song: Back to the Ground (The Circle Comes Home) (#210), on the Rock U home player.
Related proposal: Philadelphia’s Trash, Chester, and a Net-Positive Path
The plan's closing words capture its spirit: the circle is achievable in pieces. Measure safety, recovery, farmer needs and affordability — then expand only what works.
What we flush away doesn't have to be the end of the story. With care, patience and shared work, it can become the beginning of the next harvest.