Access to basic sanitation is key to a truly regenerative future. (If you don’t agree with that statement yet, check out our article Toilets and Clean Water for All.) The way we provide this service and build these systems gives us with an opportunity to use new technologies that work with natural principles to process wastewater in an ecologically responsible way.
The Omega Center for Sustainable Living is an example of one sustainable method: the Eco Machine™, created by John Todd. The Eco Machine treats all of Omega’s wastewater in seven stages: 1) solid settlement tanks, 2) equalization tanks, 3) anoxic tanks, 4) exterior constructed wetlands, 5) interior aerated lagoons, 6) exterior recirculating sand filter, and 7) dispersal fields, where the now-clean water is put back into the environment. The OCSL can process up to 52,000 gallons of water a day, all powered entirely by solar panels, and using no chemicals. To the casual viewer, it doesn’t look like a wastewater treatment facility, but instead like a greenhouse and garden integrated into the rural landscape of upstate New York.
In contrast to Omega’s rural campus, John Todd worked on a project in Fuzhou, China, a city of 7.2 million people, with an 80 kilometer network of canals where commercial wastewater and sewage was discharged, untreated, on its way to the Minjiang River. This wastewater disposal scenario is typical for many cities in China and India, where a bit over half of the world's population without access to basic sanitation live.
In 2002, John Todd began work on a 600-meter section of the canal. At that time, there were 750,000 gallons per day of untreated wastewater entering the water. The stench alone disrupted nearby temples, schools, and homes, and created health problems. The solution in this case was to install a Restorer, which employs similar technology to the Eco Machine.
The Restorer uses 20 native plant species (12,000 plants total) alongside a central floating walkway in the canal. Todd explains:
Wastewater entering the end of the canal is recycled to the top of the canal for treatment. An anoxic zone at the top of the canal allows for denitrification. The fine bubble aeration system distributes air along the canal from blowers located on a central floating barge. Low-intensity and uniformly distributed aeration circulates the water while forcing it past biologically active zones. The Restorer automatically inoculates the system with beneficial bacteria at two locations. A variety of bacteria species were selected specifically for their ability to aid in sludge and grease digestion, as well as nitrogen removal.
The system has proven to be very successful. It meets the water treatment needs of the city, while improving the aesthetics of the area—all without chemicals, or piping the sewage away to a centralized location for treatment. The project had low up front construction costs, and requires 75 percent less energy to operate than traditional sewage treatment facilities.
Though far from being widely adopted—"Many town engineers are still wedded either philosophically or institutionally to conventional chemical and energy intensive technologies," says Todd—systems using these same principles can work in a wide variety of situations. In this video, he explains the difference between approaches to wastewater management and the conventional, chemical-laden approach:
In addition to the considerations Todd raises in this video, it’s important to consider solutions that are appropriate to a specific site. In places where centralized infrastructure doesn’t exist, it may not make sense to create one in order to pipe sewage to central locations, which can be less efficient, use more energy, and be less resilient in times of stress than a decentralized solution. Instead, tailoring each solution to the local conditions and needs gives us the opportunity to create something new, like the Restorer in Fuzhou, China.
While centralized infrastructure may be the right option sometimes, it has become the primary pattern of development in the last 50 years, even when it might not be the best option. If we want to create a socially and ecologically sustainable and just society, centralized solutions can’t be the only option. The best option—for sewage treatment and any other development—should be one that is low-energy, people-friendly, and environmentally sound.
