The Bronx Zoo knows conservation. Since it opened its gates to the public in 1899, the Zoo, under the direction of its parent organization, the Wildlife Conservation Society (WCS), has continually worked to fulfill the Zoo’s mission “to advance the study of zoology, protect wildlife, and educate the public.” Historically, the Bronx Zoo’s conservation efforts have focused on protecting wildlife and educating the public. The Zoo was instrumental in saving the American Bison from extinction at the turn of the 20th century. Over the years, it has played a major role in protecting a variety of other endangered and threatened species, including snow leopards, lowland gorillas, and Chinese alligators—to name a few. And of course, the Bronx Zoo recognizes that education is a crucial element in ensuring the continued protection of these species and their eco-systems, so, as early as 1929, they started creating a variety of education programs that now reach schoolchildren and teachers in all 50 states and 15 countries.

More recently, the Bronx Zoo has expanded its mission of conservation and education to include its facilities. In the fall of 2006, the Zoo finished work on its new Eco-Restroom at the Bronxdale Gate entrance, which was designed to accommodate more than half a million visitors annually. The Eco-Restroom replaces an older restroom building which according to Jon Dohlin, the Zoo’s Project Manager for Capital Construction, had fallen into disrepair and had been closed due to concern over its failing septic system’s potential to pollute the Bronx River.

For these reasons, the WCS and the design team decided the new restroom should be an example of how to manage human waste sustainably, conserve resources, and prevent pollution. It was determined that key to reaching these aims was to use composting toilets and greywater irrigation systems for the project. This means that the Eco-Restroom is not connected to the City’s sewer system. Instead, toilet waste is collected in the compost system and water from sinks and drinking fountains (greywater) is used to irrigate plants outside the structure. The resulting model of sustainability sharply contrasts with the problems associated with big city sewage treatment systems, such as New York’s.

With its population expected to increase by around one-million over the next 25 years, to over 9 million, New York’s sewage treatment problems will only become more acute. According to the environmental group Riverkeeper, “More than 27 billion gallons of raw sewage and polluted stormwater discharge out of 460 combined sewage overflows (CSOs) into New York Harbor each year,” from the Bronx and from locations throughout the city.  In fact, the city’s sewer system—which in many places manages a combination of sewage and stormwater—was designed to overflow in the wake of heavy rainfalls. This means raw sewage is discharged into surrounding waterways where it makes beaches unsafe for swimming. In April, New York City Mayor Michael Bloomberg announced plans to spend $10 billion to improve the system’s ability to manage heavy flow periods without dumping untreated sewage. But because end-of-the pipe solutions, like treatment plants, are slow to get created and expensive, he acknowledged that a significant portion of the funding needs to go toward implementing solutions that will address the problem by keeping wastewater from entering the sewers in the first place, including “greening our streets, expanding our bluebelts, [and] promoting green roofs.” The problem of sewage treatment plant capacity encouraged the New York City DEP, which manages New York’s sewage treatment plants, to fund the purchase of the Eco-Restroom’s composting toilets and greywater system.

But as good as the Mayor’s plan may be, at the Bronx Zoo they’re really getting to the root of the sewage treatment problem. Since the compost toilets at the Zoo are completely independent of the sewer, they offer no opportunity for human waste to be mixed with toxic waste substances from industry, which are regularly dumped into the sewer, and which remain in the sludge end-product of the sewage treatment plant. Sludge (sometimes given the nicer-sounding name “biosolids”) is used as fertilizer for food crops or is added to potting soil or compost sold at the local garden store! Heavy metals and chemicals, such as dioxin, are kept out of the compost toilet and its fertilizer end-products.

The Eco-Restroom’s Clivus Multrum Compost Toilet Systems include 14 foam-flush toilet fixtures, 4 waterless urinals, and 10 composters—which are maintained by the manufacturer. The foam-flush fixtures use just 3 ounces of water and a drop of bio-compatible soap to flush waste down a conventional drainpipe to the composters below. In the composter, solid and liquid wastes are separated and transformed, through natural biological decomposition, into a solid, topsoil-like compost and a potent liquid fertilizer. In total, these systems have the potential to save over 1,000,000 gallons of water per year, as compared to conventional low-flow toilets.

The Clivus Multrum Greywater Irrigation System collects water from the restroom’s non-toilet fixtures in a small tank in the basement and sends it into an 80’x 20’ flower garden. The greywater is distributed through buried half-round pipes into the garden’s root zone, where plants use the water and the small amount of nutrients contained in the water from soap. Because greywater is used for plant irrigation and toilet wastes are contained in the composters, there is no pollution discharge, as is the case in buildings with septic systems.

In addition to composting toilets and greywater systems, the Eco-Restroom uses a rainwater harvesting system to keep stormwater onsite and out of the sewer. Janine Sutton, a representative from Edelman Sultan Knox Wood Architects, the firm responsible for design of the Eco-Restroom, says the system collects rainwater from the roof in large barrels and redirects it into the garden so that it can be used by plants instead of running off into storm drains. And besides addressing wastewater issues, the designers also included technologies designed to cut energy use and built in an educational component as well.

The Eco-Restroom saves energy by making optimal use of natural daylighting through the positioning of four 30-foot skylights. Supplemental light (though rarely needed) comes from high-efficiency CFL bulbs, and a radiant floor heating system cuts energy use even further. And Sutton adds, “Besides being a restroom, it’s also an exhibit.” In addition to the various ‘green’ building technologies, visitors to the Eco-Restroom will also notice a variety of signage designed to explain the technologies and educate people of all ages about the environmental issues that the Eco-Restroom seeks to address.

The Eco-Restroom, though, is not a one-off example of green building at the Zoo. Dohlin says they are currently at work on two more eco-friendly buildings—both of which will go for LEED certification. The new Lion House building will go for LEED Gold and the Center for Global Conservation, which will house the WCS international department and function as a conference center, will go for Silver. Such commitment as shown by the WCS to sustainable building practice demonstrates its concern not just for wildlife but for the entire animal kingdom.