Biological sewage treatment, like electricity, power generation, telephones, and mass transit, has been a key technology and a major part of the urban infrastructure since the late nineteenth century. But sewage treatment plants are not only a ubiquitous component of the modern city, they are also ecosystems--a hybrid variety that incorporates elements of both nature and industry and embodies multiple contradictions. In Hybrid Nature, Daniel Schneider offers an environmental history of the biological sewage treatment plant in the United States and England, viewing it as an early and influential example of an industrial ecosystem. The sewage treatment plant relies on microorganisms and other plants and animals but differs from a natural ecosystem in the extent of human intervention in its creation and management. Schneider explores the relationship between society and nature in the industrial ecosystem and the contradictions that define it[: the naturalization of industry versus the industrialization of nature; the public interest versus private (patented) technology; engineers versus bacterial and human labor; and purification versus profits in the marketing of sewage fertilizer.] Schneider also describes biotechnology's direct connections to the history of sewage treatment, and how genetic engineering is extending the reaches of the industrial ecosystem to such "natural" ecosystems as oceans, rivers, and forests. In a conclusion that shows how industrial ecosystems continue to evolve, Schneider discusses John Todd's Living Machine, a natural purification method of sewage treatment, as the embodiment of the contradictions of the industrial ecosystem.