The water-nutrient cycle

The average adult eats about a ton of food per year. In the industrial world, the majority of that food gets from farm to plate in trucks. Almost all of the nutrients in all that food passes through the people, and passes through their toilets. Where we live on Cape Cod, most of those nutrients then go into their septic tanks, and some of it goes into the groundwater and eventually into the coastal waters. The rest is trucked away as septage to a sewer.

We think it’s crazy to put all those waste nutrients into water, and then at a high cost try to remove them from the water again, or even to try to remove only one of them (nitrogen). And it’s ecologically wrong to waste all those nutrients: they should be recycled them back to an agricultural or natural ecosystem.

The following slideshow is our presentation “Let No Waste Go To Waste”, a call for an ecologically-based water, nutrient and energy management scenario. It focuses on Cape Cod, but the lessons can be applied anywhere in the world.

Pause and continue the slideshow using the buttons on the sides of the image.

Eco-toilets: an elegant solution

An eco-toilet is a toilet that uses either very little water or none at all, while recovering a majority of human “waste” nutrients. There are many kinds of eco-toilet systems— home-made ones as well as commercially available brands— and new, better systems are constantly being developed.


While conserving precious water, energy and material resources, eco-toilets recover nutrients essential for sustainable agricultural systems. As they become adopted on a wider scale, they may prove to be the best solution to turn the polluting liability of human waste into nature’s most important assets: clean water and nutrients.

New, commercial versions of composting toilet designs have recently been developed that are cheaper, smaller, more sanitary, and more user-friendly than older commercial models. We have tested variety of eco-toilet systems to come up with a design that we think is the best available on the market today. This Hybrid Urine-Diverting, Composting Eco-Toilet system combines a urine-diverting toilet from Sweden with the most practical bin composting system from Vermont. The result is no water use, low energy, safe recovery of all nutrients. Please visit our sister site, the Cape Cod Eco-Toilet Center, to find out more.

 Evolution of waterless composting toilet systems


Waterless composting toilet systems were introduced to the US in the 1960’s with the large Clivus Multrum. The technology has gradually evolved to be smaller, easier to maintain, and more pleasant to use.

The most advanced system provides better sanitation for the user than a flush toilet, and a high level of sanitation during maintenance.

  • User Experience – Separett toilet is waterless, urine-diverting and contains a visual baffle to avoid view of chute. Systems are odorless; fans constantly pull air from the bathroom down into the toilet, eliminating all odors.
  • Less Exposure to Pathogens – Multiple-bin systems require no contact with residual material during use or during periodic maintenance.   Compost is not moved or removed from bin until composted for 2 years, which eliminates all pathogens.
  • Energy Efficient – Multiple-bin systems use 4 watts per bin for continuous ventilation and aeration.
  • Better Aeration of Compost – best systems constantly move air through the entire volume of compost material.
  • Urine Diversion – In early systems, urine flows through the compost and accumulates as excess liquid (leachate) at the bottom. Urine-diverting composting toilets directs the urine to a storage container for later nutrient recycling.
  • Better Resource Recovery – More nitrogen is recovered with urine diversion than when if composting urine and solids together. When composting urine and solids together, more nitrogen is lost in the ventilation air.

EcoDrum: the Final Solution

Once your composting toilet bin is full, the question remains: what to do with the final product? Public health guidelines call for the compost material to be buried at least six inches underground, and may be used as fertilizer for non-edible trees, shrubs and grass. (Remember: commercial fertilizers like Milorganite are actually dried sludge from Milwaukee’s sewage treatment plant!)

Though this solves the “problem” of what to do with your compost, it doesn’t complete the food-nutrient cycle. We think the EcoDrum is an ideal system to finish the compost so it can become, without question, a safe and potent fertilizer for food crops.

EcoDrum slide

The Green Center began investigating the EcoDrum rotating composter in 2007 and since then we have promoted it as an ideal method of recovering and recycling a variety of waste nutrients on Cape Cod.

The major advantages of the EcoDrum composter are:

  • It’s safe. The material is safely contained in the drums – from rain leaching through it, from accidental leaching into the soil, from “vectors of contamination” (insects or animals) that can spread pathogens, pharmaceuticals, and nutients into the environment.
  • It’s modular. The drum can be extended by adding more units together (sealed). Materials can be composted with a longer retention time in a longer EcoDrum. It’s also potentially mobile.
  • It’s effective. The drums are insulated, resulting in higher, more stable temperatures during the composting process. Thermometers and sampling ports can be added to monitor conditions and biological activity, ensuring that composting is thorough.
  • It’s easy. Loading and unloading is simple: new materials are put into the top at one end, and the compost slowly moves to the other end and automatically falls out. Special angled tabs on the inside surface cause the compost to move towards the end with each rotation. The retention time and rate of movement of the compost can be controlled automatically with computerized controls. The turning mechanism is simple and safe.
  • It’s eco-friendly. The EcoDrum can use PV solar electricity to be a stand-alone unit.

EcoDrums can compost more than what remains in your toilet bin. They have been used for food and farm scraps, animal (and in Washington State, human) remains, and more.

Aquaculture: plants and shellfish as nutrient recyclers

Our research on water hyacinths as a biological water treatment tool show that they readily absorb nitrogen and phosphorus from fresh water. The water hyacinths may then be composted in an EcoDrum, creating a potent fertilizer for agricultural production.

In salt water, shellfish aquaculture is a promising and profitable solution.

A solution for Cape Cod

Below are our recommendations for using advanced ecological water and nutrient recycling strategies in the watershed planning and modeling for Three Bays watershed, in Barnstable, Massachusetts.

  • EcoDrum slide

How can we keep Cape Cod waters clean?

An 8-page publication ilustrated by Molly Bang, with support from the Falmouth Climate Action Team, The Green Center, GreenCAPE, Water Alliance, and the Coonamessett Farm Foundation.

Pause and continue the slideshow using the buttons on the sides of the image.

The POOP Manifesto


The following manifesto was submitted by reader Paul Glover of POOP (Proud Of Organic Philadelphia). We think it encapsulates much of our mission, and encourage other readers to get in touch with their ideas.

Excrement is not America’s favorite subject. Flush it and forget it. Toilets are the butt of jokes and the joke of butts.

Yet more than two billion people have no toilet. They shit into rivers and in fields. Millions die every year from poisoned water and land. This toilet crisis endangers not just the Third World. America’s modern cities urgently need sewerage reform. We know that cattle feedlots pollute water, but our cities are human feedlots.

Philadelphia is watered by two rivers. The Schuylkill contains outfall from 100 sewage treatment plants above us. The Delaware contains runoff from 400 sewage treatment plants. Sewage treatment does not remove pharmaceuticals. Plus, industrial goo drains into sewers.

Philadelphians drink, bathe, launder and poop into this water. Then it is poured treated or stinking back into the rivers, sickening people downstream.

Although our sewers are invisible, we might as well be dumping chamberpots on neighbors below.
We smear poop on ourselves too –the sludge that’s spread on farms contains herbicides, insecticides, arsenic, lead, mercury, cobalt and other carcinogens. We grow our food with poisons.

At same time, Philadelphia’s old sewers are cracking and overflowing. Basements fill with shit. Sewer repair is estimated to cost $8-$14 billion.

Perhaps it’s time for a change. What can we do?

The modern sanitation tool is the biodigester toilet,which does not use water. These convert crap into safe, sweet-smelling soil right at home. Then the soil is taken away to rebuild healthy forests and fields. Since soil is the food of food, this clean fertilizer can be used in urban and rural greenhouses and farms, as other countries do.

There is cultural resistance to composting, of course. We’d rather talk about recipes than receptacles. Or diets rather than diarrhea. Local institutions may resist as well, since hundreds of Philadelphia jobs and multimillion-dollar contracts also keep this game rolling.

Yet hundreds more jobs can begin here, to manufacture, install and repair compost toilets, then to recycle and/or sell nutrients.

At full flush, composters are a key tool for rebuilding our cities and suburbs toward balance with nature, creating new jobs, reducing infrastructure expenses, making our rivers clean enough to swim in, and repairing public health.

We begin with whoever is ready to begin.

Further reading…

%d bloggers like this: