Activated sludge and clarifiers: wastewater treatment plants in Iowa
83 plants · 11% of the state · 196 MGD reported by 78 plants
Klarifi identifies 83 publicly owned wastewater treatment plants with activated sludge and clarifiers in Iowa, 11% of the 747 plants in the state (196 MGD reported by 78 plants). The largest is Water Pollution Control Facility in Cedar Rapids at 39.59 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 Iowa
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Water Pollution Control Facility | Cedar Rapids | 39.59 | IA0042641 | Aug 2030 | 15 |
| 2 | Davenport Wastewater Treatment Plant | Davenport | 25.36 | IA0043052 | Jun 2026 | 0 |
| 3 | City Of Sioux City STP | Sioux City | 14.01 | IA0043095 | Jan 2031 | 10 |
| 4 | Fort Dodge City Of STP | Fort Dodge | 11.42 | IA0044849 | Dec 2030 | 0 |
| 5 | Iowa City, City Of (south) STP | Iowa City | 8.98 | IA0070866 | Jul 2030 | 11 |
| 6 | Council Bluffs City Of STP | Council Bluffs | 8.21 | IA0036641 | Aug 2031 | 0 |
| 7 | Clinton WWTP | Clinton | 6.52 | IA0035947 | Jun 2031 | 12 |
| 8 | Burlington, City Of (wwtp) | Burlington | 5.79 | IA0043079 | Jan 2027 | 4 |
| 9 | Mason WWTP | Mason City | 5.13 | IA0077305 | May 2029 | 6 |
| 10 | Cedar Falls City Of STP | Cedar Falls | 4.83 | IA0036633 | Dec 2029 | 0 |
Plants planning activated sludge and clarifiers upgrades
These plants report activated sludge and clarifiers as a planned process in the EPA Clean Watersheds Needs Survey: the earliest public signal of a project.
| Facility | City | Avg flow (MGD) | NPDES permit | Expires |
|---|---|---|---|---|
| Park View Water Co | Eldridge | 0.21 | IA0062561 | Jun 2028 |
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 Iowa
Activated sludge and clarifiers in other states
Activated sludge and clarifiers in Iowa: 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 · WWTP · Biosolids · all terms