Wastewater is treated by an activated sludge process in municipal wastewater treatment plants and returned to the environment for use. This treatment process has been used for over a century, and today represents the largest application of biotechnology in the world, yet there has been no effort to map the global activated sludge microbiome.

A study recently published in Nature Microbiology reports the first comprehensive, highly coordinated effort to examine the global diversity and biogeography of this microbiome. “The campaign involved 111 investigators who sampled 269 wastewater treatment plants in 86 cities in 23 countries on six continents,” said Jizhong Zhou, a professor of microbiology at the University of Oklahoma and Berkeley Lab adjunct senior scientist.