Nutrient removal: US wastewater treatment plants
178 plants in 11 states · 348 MGD reported by 172 plants · 18 planning upgrades
Klarifi identifies 178 publicly owned wastewater treatment plants with nutrient removal in the United States (348 MGD reported by 172 plants). The largest is Southwest WWTP in Springfield, MO at 30.9 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
84 plants
28 plants
24 plants
19 plants
14 plants
4 plants
1 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 October 26, 2026.
Wastewater terms: Biological nutrient removal · Tertiary treatment · Activated sludge · Oxidation ditch · Anaerobic digester · all terms