Activated sludge and clarifiers: wastewater treatment plants in Louisiana
44 plants · 17% of the state · 137 MGD reported by 39 plants
Klarifi identifies 44 publicly owned wastewater treatment plants with activated sludge and clarifiers in Louisiana, 17% of the 259 plants in the state (137 MGD reported by 39 plants). The largest is South Wastewater Treatment Plant in Baton Rouge at 33 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 Louisiana
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | South Wastewater Treatment Plant | Baton Rouge | 33 | LA0036412 | Jun 2029 | 20 |
| 2 | Jefferson Parish Department Of Sewerage- East Bank WWTP | Elmwood | 20.66 | LA0066630 | Jul 2028 | 0 |
| 3 | Baton Rouge, City Of | Scotlandville | 11 | LA0036439 | Jul 2029 | 30 |
| 4 | Sewerage & Water Board Of New Orleans Westb Ank Sewage | New Orleans | 10.13 | LA0038105 | Nov 2029 | 1 |
| 5 | Jefferson Parish Department Of Sewerage- Marrero WWTP | Marrero | 6.19 | LA0042048 | Oct 2026 | 5 |
| 6 | Monroe, City Of (wpc Cntr) | Monroe | 6.09 | LAL038741 | Dec 2030 | 78 |
| 7 | Plant B | Lake Charles | 5.74 | LAL036366 | Dec 2030 | 73 |
| 8 | Red River Wastewater Treatment Plant | Bossier City | 4.48 | LA0053716 | May 2028 | 0 |
| 9 | Northeast Wastewater Treatment Plant | Bossier City | 3.76 | LA0065978 | Mar 2026 | 0 |
| 10 | Ruston, City Of- Northside Wastewater Treatment Plant | Ruston | 3.22 | LA0036323 | Jun 2028 | 81 |
| 11 | Slidell, City Of | Slidell | 2.95 | LA0047180 | Sep 2030 | 3 |
| 12 | Shreveport North Regional WWTP | Shreveport | 2.71 | LAL042188 | Dec 2030 | 42 |
| 13 | Denham Springs Wastewater Treatment Facility | Denham Springs | 2.39 | LAL045730 | Dec 2030 | 207 |
| 14 | Lafayette Consolidated Government - East WWTP | Lafayette | 2.36 | LAL036382 | Dec 2030 | 1 |
| 15 | St. Charles Parish Council--Destrehan WWTP | Destrehan | 2.27 | LA0073539 | May 2027 | 0 |
| 16 | Thibodaux, City Of- Wastewater Treatment Facility | Thibodaux | 2.1 | LA0032948 | Jul 2029 | 77 |
| 17 | Jennings, City Of- WWTP | Jennings | 1.61 | LA0041769 | Oct 2025 | 16 |
| 18 | Bridge City Wastewater Treatment Plant | Bridge City | 1.59 | LA0042064 | Feb 2031 | 14 |
| 19 | St. Charles Parish Council | Hahnville | 1.43 | LAL073521 | Dec 2030 | 2 |
| 20 | Plaquemines Parish Government- Belle Chasse WWTP | Belle Chasse | 1.34 | LA0044032 | Jun 2030 | 14 |
| 21 | Sewerage District #1 Of Iberia Parish & City Of New Iberia- Tete Bayou WWTP | New Iberia | 1.27 | LA0065251 | Apr 2027 | 108 |
| 22 | Bastrop Main Wastewater Treatment Facility | Bastrop | 1.23 | LAL020443 | Dec 2030 | 394 |
| 23 | Gretna City Of Wastewater Treatment Plant | Gretna | 1.17 | LA0041262 | Aug 2028 | 10 |
| 24 | Youngsville Wastewater Treatment Facility | Youngsville | 1.17 | LA0055328 | Apr 2018 | 32 |
| 25 | Lafayette Consolidated Government - Northeast WWTP | Lafayette | 1.16 | LAL036391 | Dec 2030 | 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 Louisiana
Activated sludge and clarifiers in other states
Activated sludge and clarifiers in Louisiana: 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.