Nutrient removal: US wastewater treatment plants
102 plants in 11 states · 180 MGD reported by 95 plants · 18 planning upgrades
Klarifi identifies 102 publicly owned wastewater treatment plants with nutrient removal in the United States (180 MGD reported by 95 plants). The largest is Southwest WWTP in Springfield, MO at 25.32 MGD. Each state below links to its own list with every plant.
Nutrient removal takes nitrogen and phosphorus out of the effluent, biologically in anoxic and anaerobic zones or chemically with metal salts. It is driven by permit limits and TMDLs on the receiving water and is the largest upgrade a plant can face, which makes these plants the best-documented market for process equipment and chemicals.
Nutrient removal by state
28 plants
23 plants
20 plants
14 plants
7 plants
4 plants
2 plants
1 plants
1 plants
1 plants
1 plants
The largest plants with nutrient removal in the US
Other treatment technologies
Nutrient removal: questions
Sources and methodology
Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.
Data refreshed September 11, 2026.