Nitrifying and denitrifying bacterial communities in advanced nitrogen-removal onsite wastewater treatment systems

Document Type


Date of Original Version



Advanced N-removal onsite wastewater treatment systems (OWTS) rely on nitrification and denitrification to remove N from wastewater. Despite their use to reduce N contamination, we know little about microbial communities controlling N removal in these systems. We used quantitative polymerase chain reaction and high-throughput sequencing targeting nitrous oxide reductase (nosZ) and bacterial ammonia monooxygenase (amoA) to determine the size, structure, and composition of communities containing these genes. We analyzed water samples from three advanced N-removal technologies in 38 systems in five towns in Rhode Island in August 2016, and in nine systems from one town in June, August, and October 2016. Abundance of nosZ ranged from 9.1 ? 103 to 9 ? 108 copies L-1 and differed among technologies and over time, whereas bacterial amoA abundance ranged from 0 to 1.9 ? 107 copies L-1 and was not different among technologies or over time. Richness and diversity of nosZ-but not amoA-differed over time, with median Shannon diversity indices ranging from 2.61 in October to 4.53 in August. We observed weak community similarity patterns driven by geography and technology in nosZ. The most abundant nosZ-and amoA-containing bacteria were associated with water distribution and municipal wastewater treatment plants, such as Nitrosomonas and Thauera species. Our results show that nosZ communities in N-removal OWTS technologies differ slightly in terms of size and diversity as a function of time, but not geography, whereas amoA communities are similar across time, technology, and geography. Furthermore, community composition appears to be stable across technologies, geography, and time for amoA. Copyright c

Publication Title, e.g., Journal

Journal of Environmental Quality