Living Machines

Putting human waste back in its place: at the bottom of the food chain

One of the articles in Designing A Sustainable Future (IC#35)
Originally published in Spring 1993 on page 37
Copyright (c)1993, 1996 by Context Institute

Pollution problems resulting from the disposal of human waste are relatively new phenomena. For thousands of years, our body wastes were an intricate part of the planet’s natural recycling system, providing food and fuel for the microorganisms at the bottom of the food chain. But with the huge growth in world population and the concentration of that growth in urban centers, human waste has been disconnected from the cycle.

Today our wastes seem to miraculously vanish simply by flushing the toilet. But that’s where the problems begin. Little more than half the solid waste sent through sewage pipes to a primary treatment facility can be removed before discharge. The sludge that is separated – often contaminated with toxic chemicals and heavy metals which are illegally dumped down sewer lines – is sent off to landfills for burial or is burned, polluting the soil and air and wasting the very nutrients that make our wastes a resource. Secondary treatment plants remove more of the sludge, but the effluent discharged is still contaminated by metals, organic chemicals, and viruses.

Septic systems are no better. Today in the US, over one-third of all homes use septic tanks for wastewater disposal. Soil and ground water contamination related to the tanks is common. John Cary Stewart writes in his book, Drinking Water Hazards, "too many septic tanks in a given area overload the natural purification ability of the soil and allow large volumes of wastewater to reach the water table. The denser the population, the greater the likelihood of contamination."

How, then, can communities and individual households hook back into the natural cycle of human waste disposal from which we have become estranged?

Fortunately, several visionaries are setting their sights on answering that question. At the forefront are John Todd and Nancy Jack Todd, husband and wife, and founders in 1981 of the Center for the Restoration of Waters at Ocean Arks International (OAI), a not-for-profit global center for water awareness and action (see IC #25 p. 42).


OAI’s goal is to introduce sustainable alternatives to conventional waste disposal, fuel production, heating and cooling, air purification, and food production. The key to accomplishing these tasks is through ecological engineering. By combining living organisms – chosen specifically to perform certain functions – in contained environments, OAI has created what John calls Living Machines.

A Living Machine’s size, shape, and casing vary according to function. Typically, it involves a series of distinct ecologies each contained within a cylinder. The cylinders communicate through water flowing within connector tubes. Wastes generated by the inhabitants of one cylinder flow through the tubes and become food for the inhabitants of another. In this manner, using sunlight as the primary source of energy, compounds are broken down.

The habitants of each ecology vary depending on what’s in the waste. Toxic compounds from Superfund sites, for example, require a different array of organisms than does human waste. Says John: "A Living Machine is basically a home for a wide variety of organisms, in some cases thousands of species, which serve a function that helps assist human needs."

Using this technology, OAI has created or is in the process of constructing waste treatment plants at more than 10 sites in six states across the US. Their flagship facility, a sewage treatment plant in Providence, Rhode Island, uses snails to break down the heavy metals used by costume jewelry manufacturers. It took researchers nearly a decade to find snails that could thrive in that environment.

Generally, the more concentrated or toxic the substances to be treated, the greater the relative cost benefit of using a Living Machine instead of more traditional treatment methods, John says.

The Todds’ work has won several awards for OAI, including the 1991 Discover Award for technical innovation.


On a smaller scale, OAI recently designed and built a sewage treatment Living Machine inside a Toronto school that not only breaks down waste biologically, but provides an educational tool and a surprisingly attractive display as well.

"When you walk into the central atrium of the school you see this wonderful water sculpture," says John. "The tanks are 14 feet tall then spiral down to about 4 feet in a snail spiral. And then you see the water flowing off to a marsh and from there to a pond. The sculpture is the only sewage treatment plant for the school, and it’s beautiful – it’s a work of art."

Students at the Boyne River school use conventional water-based toilets, but once waste is flushed, it is rapidly digested as it passes through four cells – two with oxygen, two without – each filled with microorganisms. Next, it is pumped up to the highest of the 17 tanks. Here, the students may watch as the water flows through clear tanks first filled with algae, then with higher aquatic rooted plants, and finally with animals including clams, snails, and fish. By the time the wastewater passes through a marsh and pond, it is technically well water and legally drinkable. But no one drinks it – the psychological reaction to doing so is too negative. Instead, most of the water is recycled back up to the toilets. Currently, the school’s Living Machine services the needs of about 300 students a day with a capacity to service 500 more.

Individual homes may soon reap the benefits of OAI’s technology. John is working on a design for a household waste treatment system that recycles the water under a contract with the Canadian Housing and Mortgage Authority. The system will use all of the water internally for the gardens and toilets and showers, but there will be a separate line for the water that’s used for cooking and drinking.

He is cautious about the general acceptance of this new technology. "The biggest blockade to the emergence of living technologies could be the very phenomenon Living Machines are intended to solve, namely, the estrangement of modern cultures from the natural world," John wrote. "Nature is invisible to many people in our culture. It is my hope that the aesthetic and emotional feeling that Living Machines can generate in us will yet carry the day. These machines can be made beautiful and evocative of a deep harmony that is nature."s

John Todd can be reached at The Center for Restorative Waters, Ocean Arks Institute, 1 Locust Street, Falmouth, MA 02540. tel. 508/540-6801.