State of nutrient management infrastructure of lagoons wastewater systems serving small communities in the U.S

Lagoon wastewater treatment systems remain the backbone of sanitation in many small U.S. communities, yet their treatment technologies and nutrient management performance remain poorly characterized. Using publicly available federal and state datasets supplemented by permit reviews, this study evaluated the existing nutrient management infrastructure for municipal lagoon wastewater systems serving communities with less than 10 000 residents. Of all lagoon systems identified, approximately 69% of facilities operate at less than 0.1 million gallons per day. Non-aerated lagoons accounted for about 61% (2512 facilities), while aerated systems were present in 1697 facilities. Nutrient permitting was inconsistent throughout the U.S., where parameters such as total nitrogen (TN) and total phosphorus (TP) were frequently monitored but seldom subject to enforceable limits, constraining performance benchmarking and compliance comparability. Effluent data (2020-2024) showed moderate organics and suspended solids control but substantial variability in ammonia, TN, and TP, with many facilities exceeding limits typical of nutrient-sensitive watersheds. Facilities with nutrient-specific upgrades including moving bed biofilm reactors and fixed-bed attached growth reactors, consistently achieved low effluent ammonia and TN while chemical precipitation provided the most reliable TP reduction. Life cycle assessment of the operations phase indicated higher carbon and eutrophication footprints for facultative and aerated lagoons, whereas targeted nutrient management upgrades balanced nutrient removal and energy efficiency, lowering environmental impact profiles. The findings of this study underscore the need for improved influent data collection efforts and nutrient permitting as a driver for compliance. Priorities for practice include leveraging routine monitoring datasets to bolster compliance oversight and integrating decision-making frameworks.