Anaerobic digesters and biogas: wastewater treatment plants in Illinois
93 plants · 14% of the state · 800 MGD reported by 88 plants
Klarifi identifies 93 publicly owned wastewater treatment plants with anaerobic digesters and biogas in Illinois, 14% of the 664 plants in the state (800 MGD reported by 88 plants). The largest is Metropolitan Water Reclamation in Chicago at 281.73 MGD.
Anaerobic digesters stabilise sludge in sealed heated tanks and produce biogas, visible from the air as digester silos and gas holders. Plants with digesters are typically above 5 MGD and are the buyers of mixing, heating, gas handling, cogeneration and dewatering equipment.
The largest plants with anaerobic digesters in Illinois
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Metropolitan Water Reclamation | Chicago | 281.73 | ILL028061 | Dec 2030 | 10 |
| 2 | MWRDGC Terrence J O'Brien Water Reclamation Plant | Skokie | 205.79 | IL0028088 | Jul 2022 | 16 |
| 3 | Sanitary District Of Decatur | Decatur | 34.42 | ILL028321 | Dec 2030 | 1 |
| 4 | Springbrook Water Reclamation Center | Naperville | 20.15 | ILL034061 | Dec 2030 | 0 |
| 5 | Greater Peoria Sanitary And Sewage District | Peoria | 19.22 | ILL021288 | Dec 2030 | 12 |
| 6 | Spring Creek STP | Springfield | 16.41 | ILL021989 | Dec 2030 | 29 |
| 7 | Bloomington Normal WRD -West STP | Bloomington | 16.33 | ILL027731 | Dec 2030 | 0 |
| 8 | Fox River Water Reclamation Dist | Elgin | 13.07 | ILL028657 | Dec 2030 | 50 |
| 9 | Glenbard Wastewater Authority | Glen Ellyn | 11.79 | ILL021547 | Dec 2030 | 27 |
| 10 | Collinsville Wastewater Treatment Plant | Collinsville | 11.53 | ILL028215 | Dec 2030 | 5 |
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 Illinois
Anaerobic digesters and biogas in other states
Anaerobic digesters and biogas in Illinois: 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: Anaerobic digester · Biosolids · Sludge dewatering · Centrate · Biological nutrient removal · Tertiary treatment · all terms