Activated sludge and clarifiers: wastewater treatment plants in North Carolina
64 plants · 77% of the state · 119 MGD reported by 30 plants
Klarifi identifies 64 publicly owned wastewater treatment plants with activated sludge and clarifiers in North Carolina, 77% of the 83 plants in the state (119 MGD reported by 30 plants). The largest is Neuse River Resource Recovery Facility in Raleigh at 47.05 MGD.
Activated sludge is the standard mechanical process for cities: aeration basins where bacteria consume organic matter, followed by clarifiers that settle the biomass out. These plants are identified by their circular or rectangular clarifiers and by the suspended-growth process code, and they are the main market for blowers, diffusers, clarifier mechanisms and instrumentation.
The largest activated sludge plants in North Carolina
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Neuse River Resource Recovery Facility | Raleigh | 47.05 | NC0029033 | Feb 2025 | 1 |
| 2 | Irwin Creek Wastewater Treatment Plant | Charlotte | 10.55 | NC0024945 | Oct 2028 | 0 |
| 3 | North Durham WRF | Durham | 8.9 | NC0023841 | Jan 2029 | 4 |
| 4 | Town Of Cary - North Cary WWTP | Cary | 6.11 | NC0048879 | Feb 2028 | 0 |
| 5 | Town Of Cary - South Cary WWTP | Apex | 5.96 | NC0065102 | Apr 2028 | 0 |
| 6 | New Bern Waste Water Treatment Plant | New Bern | 5.17 | NC0025348 | Jun 2027 | 0 |
| 7 | Mason Farm WWTP | Chapel Hill | 4.86 | NC0025241 | Jul 2030 | 0 |
| 8 | Triangle WWTP | Durham | 4.53 | NC0026051 | Apr 2027 | 3 |
| 9 | Johnnie Mosley Regional WRF | Kinston | 3.42 | NC0024236 | Jan 2029 | 32 |
| 10 | Central Johnston County WWTP | Smithfield | 2.91 | NC0030716 | Mar 2026 | 2 |
Contacts and project signals for every plant on this list
Klarifi adds verified decision-maker contacts, permit limits, discharge monitoring data and the capital projects planned in each city, filterable by technology, size and compliance record.
Other technologies in North Carolina
Activated sludge and clarifiers in other states
Activated sludge and clarifiers in North Carolina: 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: Activated sludge · Biological nutrient removal · Equalization tank · Biosolids · Filter press · all terms