Microbiome 9, Article number: 116 (2021)
Background: Microorganisms in urban sanitary sewers exhibit community properties that suggest sewers are a novel ecosystem. Sewer microorganisms present both an opportunity as a control point for wastewater treatment and a risk to human health. If treatment processes are to be improved and health risks quantified, then it is necessary to understand microbial distributions and dynamics within this community. Here, we use 16S rRNA gene sequencing to characterize raw wastewater bacterial communities in a five-year time series of wastewater treatment plants in Milwaukee, WI; 77 wastewater treatment plants across the United States (US); and in Milwaukee residential sewers.
Results: In Milwaukee, we find that in transit from residences to WWTPs, the human bacterial component of wastewater decreases in proportion and exhibits stochastic temporal variation. In contrast, the resident sewer community increases in biomass and cycles seasonally, assembling into two distinct states each year. Wastewater bacterial communities from other northern US cities follow temporal trends that mirror those in Milwaukee, but southern US cities have distinct community compositions and differ in their seasonal patterns.
Conclusions: Our findings provide evidence that environmental conditions associated with seasonal change and climatic differences related to geography predictably structure the bacterial communities residing in below-ground sewer pipes.
PRJNA597057: Wastewater temporal and spatial meta-analysis