Oxidation ditches: wastewater treatment plants in Pennsylvania
46 plants · 6% of the state · 229 MGD reported by 43 plants
Klarifi identifies 46 publicly owned wastewater treatment plants with oxidation ditches in Pennsylvania, 6% of the 790 plants in the state (229 MGD reported by 43 plants). The largest is Northeast WPCP in Philadelphia at 153.22 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 Pennsylvania
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Northeast WPCP | Philadelphia | 153.22 | PAL026689 | Dec 2030 | 0 |
| 2 | City Of Allentown Wastewater Treatment Plant | Allentown | 31.66 | PA0026000 | Sep 2007 | 0 |
| 3 | Reading STP | Reading | 14.02 | PA0026549 | Apr 2028 | 9 |
| 4 | Hanover Boro STP | Mcsherrystown | 4 | PA0026875 | Dec 2027 | 2 |
| 5 | Warren City WWTP | Warren | 2.19 | PA0027120 | Oct 2022 | 4 |
| 6 | Elizabethtown STP | Elizabethtown | 2 | PA0023108 | Apr 2027 | 7 |
| 7 | Ephrata STP | Ephrata | 1.92 | PAL027405 | Dec 2030 | 18 |
| 8 | Punxsutawney Boro STP | Punxsutawney | 1.43 | PAL020346 | Dec 2030 | 2 |
| 9 | Harvey Avenue STP | Doylestown | 1.14 | PA0021172 | Apr 2027 | 0 |
| 10 | Berwick Mun Auth | Berwick | 1.14 | PAL023248 | Dec 2030 | 3 |
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 Pennsylvania
Oxidation ditches in other states
Oxidation ditches in Pennsylvania: 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 · Filter press · FOG · all terms