Activated sludge and clarifiers: wastewater treatment plants in Arizona
24 plants · 43% of the state · 166 MGD reported by 14 plants
Klarifi identifies 24 publicly owned wastewater treatment plants with activated sludge and clarifiers in Arizona, 43% of the 56 plants in the state (166 MGD reported by 14 plants). The largest is 91st Avenue WWTP in Tolleson at 83.69 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 Arizona
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | 91st Avenue WWTP | Tolleson | 83.69 | AZ0020524 | Apr 2028 | 2 |
| 2 | 23rd Avenue Wastewater Treatment Plant | Phoenix | 35.19 | AZ0020559 | Jun 2029 | 2 |
| 3 | Pima County - Ina Road WWTP | Tucson | 29.75 | AZ0020001 | May 2027 | 3 |
| 4 | Yuma, City Of - Figueroa Ave WPCF | Yuma | 7.28 | AZ0020443 | Aug 2028 | 13 |
| 5 | Town Of Prescott Valley - WWTP | Prescott Valley | 2.69 | AZ0025381 | Feb 2027 | 0 |
| 6 | Tolleson WWTP | Tolleson | 2.1 | AZ0020338 | Feb 2031 | 28 |
| 7 | Buckeye WWTP | Buckeye | 1.91 | AZ0025313 | Oct 2030 | 1 |
| 8 | Cottonwood WWTF | Cottonwood | 1.02 | AZ0024716 | Apr 2027 | 17 |
| 9 | American Gulch Wastewater Treatment Plant | Payson | 0.79 | AZ0020117 | Apr 2027 | 0 |
| 10 | City Of Somerton - WWTP | Somerton | 0.74 | AZ0026603 | Dec 2029 | 0 |
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 Arizona
Activated sludge and clarifiers in other states
Activated sludge and clarifiers in Arizona: 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 · Centrate · Ozonation · all terms