Reducing Urban Water Use Around the World with Compost Toilets

Theodore Roosevelt once noted that "civilized people ought to know how to dispose of the sewage in some other way than putting it into the drinking water." But that's what we're still doing every day.

The one-time use of water to disperse human and industrial wastes is an outmoded practice, made obsolete by new technologies and water shortages. Yet it is still common around much of the world. Water enters a city, becomes contaminated with human and industrial wastes, and leaves the city dangerously polluted. Toxic industrial wastes discharged into rivers and lakes or into wells also permeate aquifers, making water -- both surface and underground -- unsafe for drinking.

The current engineering concept for dealing with human waste is to use vast quantities of water to wash it away, preferably into a sewer system, where it may or may not be treated before being discharged into the local river. The "flush and forget" system takes nutrients originating in the soil and typically dumps them into the nearest body of water. Not only are the nutrients lost from agriculture, but the nutrient overload has contributed to the death of many rivers and to the formation of some 405 "dead zones" in ocean coastal regions. This outdated system is expensive and water-intensive, disrupts the nutrient cycle, and can be a major source of disease and death. Worldwide, poor sanitation and personal hygiene claim the lives of some 2 million children per year, a toll that is one-third the size of the 6 million lives claimed by hunger and malnutrition.

Sunita Narain of the Center for Science and Environment in India argues convincingly that a water-based disposal system with sewage treatment facilities is neither environmentally nor economically viable for India. She notes that an Indian family of five, producing 250 liters of excrement in a year and using a water flush toilet, contaminates 150,000 liters of water when washing away its wastes.

How Lead Gets Into Urban Vegetable Gardens

If you're a vegetable gardener in a lot of older cities, there's a fair chance you have a significant amount of lead in your soil. One common mitigation approach is to build a raised bed and fill it with freshly composted, low-lead soil from elsewhere, right? Maybe not, according to researchers studying the mysterious case of the lead contamination found within raised beds in community gardens in the Boston communities of Roxbury and Dorchester.

"Raised beds are surrounded by a sea of contaminated soil," said Daniel Brabander of Wellesley College. Brabander, his students and colleagues have been studying the lead in 144 backyard gardens in coordination with The Food Project, an organization committed to food security, nutrition and sustainable urban agriculture. Eighty-one percent of the gardens they studied were found to have lead levels above the U.S. EPA limits of 400 micrograms of lead per gram (µg/g) of soil.

To solve that problem, raised wooden beds with freshly composted soil were installed in backyard and community gardens by the Food Project. But the researchers have found that the soil in raised beds that starts with as little as 110 micrograms of lead per gram of soil rose to an average of 336 µg/g of lead in just four years.

Just how this is happening is the focus of a Nov. 1 presentation by Emily Estes at the meeting of the Geological Society of America in Denver.

"We're trying to get a better handle on the mode of transport and the source," said Estes. That means some pretty detailed monitoring and chemical analyses of the minerals in the soils as well as the kind of lead that's in the soil.