Oxidation ditches: wastewater treatment plants in North Carolina
36 plants · 43% of the state · 26 MGD reported by 17 plants
Klarifi identifies 36 publicly owned wastewater treatment plants with oxidation ditches in North Carolina, 43% of the 83 plants in the state (26 MGD reported by 17 plants). The largest is Town Of Cary - North Cary WWTP in Cary at 6.11 MGD.
Oxidation ditches are ring-shaped activated sludge reactors with long retention times, common at plants between 0.5 and 10 MGD. They are recognisable from the air by their looped channels and rely on surface aerators or brush rotors, which are frequent replacement and energy-efficiency projects.
The largest oxidation ditch plants in North Carolina
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Town Of Cary - North Cary WWTP | Cary | 6.11 | NC0048879 | Feb 2028 | 0 |
| 2 | New Bern Waste Water Treatment Plant | New Bern | 5.17 | NC0025348 | Jun 2027 | 0 |
| 3 | Triangle WWTP | Durham | 4.53 | NC0026051 | Apr 2027 | 3 |
| 4 | Siler City WWTP | Siler City | 2.26 | NC0026441 | May 2027 | 20 |
| 5 | Contentnea Metropolitan Sewerage District | Grifton | 1.52 | NC0032077 | Nov 2030 | 0 |
| 6 | Sam'S Branch WRF | Clayton | 1.42 | NC0025453 | Mar 2030 | 4 |
| 7 | Sgwasa WWTP | Butner | 1.38 | NC0026824 | Oct 2030 | 0 |
| 8 | Little Creek Resource Recovery Facility | Zebulon | 1.05 | NC0079316 | May 2030 | 3 |
| 9 | Oxford WWTP | Oxford | 0.9 | NC0025054 | Sep 2030 | 2 |
| 10 | Newport WWTP | Newport | 0.37 | NC0021555 | Jul 2030 | 1 |
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
Oxidation ditches in other states
Oxidation ditches 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: Oxidation ditch · Activated sludge · Biological nutrient removal · Lift station · Inflow and infiltration · all terms