Activated sludge and clarifiers: wastewater treatment plants in North Carolina
63 plants · 74% of the state · 107 MGD reported by 29 plants
Klarifi identifies 63 publicly owned wastewater treatment plants with activated sludge and clarifiers in North Carolina, 74% of the 85 plants in the state (107 MGD reported by 29 plants). The largest is Neuse River Resource Recovery Facility in Raleigh at 47.06 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 | 47.06 | NC0029033 | Feb 2025 | 1 |
| 2 | Irwin Creek Wastewater Treatment Plant | Charlotte | 10.99 | NC0024945 | Oct 2028 | 0 |
| 3 | Town Of Cary - North Cary WWTP | Cary | 5.91 | NC0048879 | Feb 2028 | 0 |
| 4 | Town Of Cary - South Cary WWTP | Apex | 5.1 | NC0065102 | Apr 2028 | 0 |
| 5 | New Bern Waste Water Treatment Plant | New Bern | 4.91 | NC0025348 | Jun 2027 | 0 |
| 6 | Mason Farm WWTP | Chapel Hill | 4.48 | NC0025241 | Jul 2030 | 0 |
| 7 | Triangle WWTP | Durham | 4.35 | NC0026051 | Apr 2027 | 3 |
| 8 | Johnnie Mosley Regional WRF | Kinston | 3.46 | NC0024236 | Jan 2029 | 32 |
| 9 | City Of High Point | Thomasville | 3.05 | NC0024228 | Feb 2026 | 0 |
| 10 | Siler City WWTP | Siler City | 2.1 | NC0026441 | May 2027 | 21 |
| 11 | Graham WWTP City Of | Graham | 1.9 | NC0021211 | May 2026 | 10 |
| 12 | Central Johnston County WWTP | Smithfield | 1.5 | NC0030716 | Mar 2026 | 2 |
| 13 | Contentnea Metropolitan Sewerage District | Grifton | 1.44 | NC0032077 | Nov 2025 | 0 |
| 14 | Sgwasa WWTP | Butner | 1.36 | NC0026824 | Oct 2030 | 0 |
| 15 | Tarboro WWTP | Tarboro | 1.35 | NC0020605 | Sep 2029 | 0 |
| 16 | Cherokee WWTP | Cherokee | 1.25 | NC0052469 | Apr 2030 | 10 |
| 17 | Sam'S Branch WRF | Clayton | 1.23 | NC0025453 | Mar 2030 | 4 |
| 18 | Oxford WWTP | Oxford | 0.99 | NC0025054 | Sep 2030 | 2 |
| 19 | Little Creek Resource Recovery Facility | Zebulon | 0.92 | NC0079316 | May 2030 | 2 |
| 20 | Hillsborough WWTP Town Of | Hillsborough | 0.89 | NC0026433 | Jan 2030 | 1 |
| 21 | West Stanly WWTP | Oakboro | 0.54 | NC0043532 | Jan 2029 | 46 |
| 22 | Eagle Road WWTP | Cramerton | 0.53 | NC0006033 | Jan 2027 | 0 |
| 23 | Newport WWTP | Newport | 0.36 | NC0021555 | Jul 2030 | 0 |
| 24 | Kenly Waste Water Treatment Plant | Kenly | 0.25 | NC0064891 | Apr 2023 | 0 |
| 25 | Pinetops WWTP | Pinetops | 0.15 | NC0020435 | Sep 2029 | 26 |
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 September 11, 2026.