FLUSH

A remarkable study of how human feces could play a crucial role in a sustainable future.

Nelson, an award-winning science writer with a background in microbiology, believes that human excrement is a valuable resource, and he examines the subject from many different perspectives. The author displays an admirable willingness to investigate personally, and his travels include a reclamation plant in Kenya and a range of treatment facilities in the U.S. The idea of fertilizer derived from feces has been around for a long time, but new research has shown more effective methods for removing the pathogens and utilizing the treatment byproducts—e.g., heat and methane. The water in sewage can be extracted, purified, and returned to the environment. The Blue Plains plant that serves Washington, D.C., puts roughly 3,500 gallons of clean water into the Potomac River every second. Fecal matter, broken down by fly larvae, can also make fuel briquettes, and one ton of briquettes can replace more than 20 trees that would have been used for firewood. Nelson also investigates the medical uses of the bacteria in feces, citing numerous cases of people who have insufficient bacteria in their own gut who have had beneficial bacterial transplants. This is just scratching the surface of a field with a huge amount of potential. The biggest problem with treating feces as a resource is the yuck factor, which probably has roots in diseases like cholera. The attitude has been hard to shift, but with an increasing awareness of resource depletion, it might be changing. Nelson speculates that the future of feces reclamation should include household- or neighborhood-scale plants, and the chapter on new-generation composting toilets is particularly interesting. It all adds up to a fascinating book punctuated with humor and imbued with optimism about the future. “Sometimes,” writes the author, “hope arrives in surprising packages.”

An authoritative, informative, and entertaining book that will change the thinking about what comes out of our bodies.