Anaerobic digesters and biogas: wastewater treatment plants in Maine
23 plants · 27% of the state · 9 MGD reported by 22 plants
Klarifi identifies 23 publicly owned wastewater treatment plants with anaerobic digesters and biogas in Maine, 27% of the 84 plants in the state (9 MGD reported by 22 plants). The largest is Westbrook Waste Water Treatmemt Facility in Westbrook at 2.5 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 Maine
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Westbrook Waste Water Treatmemt Facility | Westbrook | 2.5 | ME0100846 | Jul 2022 | 26 |
| 2 | Old Orchard Beach Wastewater Treatment Facility | Old Orchard Beach | 0.9 | ME0101524 | May 2020 | 11 |
| 3 | Bar Harbor WWTF Main Facility | Bar Harbor | 0.82 | ME0101214 | Jan 2021 | 9 |
| 4 | York Wastewater Treatment Facility | York | 0.67 | ME0101222 | Mar 2030 | 12 |
| 5 | Old Town Wastewater Treatment Facility | Old Town | 0.63 | ME0100471 | Sep 2029 | 2 |
| 6 | Ogunquit Wastewater Treatment Facility | Ogunquit | 0.54 | ME0100986 | Nov 2023 | 8 |
| 7 | Yarmouth Wastewater Treatiment Facility | Yarmouth | 0.44 | ME0100765 | Aug 2022 | 3 |
| 8 | Belfast Wastewater Treatment Facility | Belfast | 0.42 | ME0101532 | Feb 2021 | 0 |
| 9 | Lisbon Wastewater Treatment Facility | Lisbon | 0.37 | ME0100307 | Oct 2029 | 4 |
| 10 | Calais Wastewater Treatment Facility | Calais | 0.34 | ME0100129 | Nov 2021 | 11 |
| 11 | Skowhegan Wastewater Treatment Facility | Skowhegan | 0.31 | ME0100625 | Apr 2031 | 90 |
| 12 | Kennebunkport Wastewater Treatment Facility | Kennebunkport | 0.26 | ME0101184 | Nov 2026 | 27 |
| 13 | Freeport Wastewater Treatment Facility | Freeport | 0.23 | ME0101036 | Feb 2021 | 4 |
| 14 | Bucksport Wastewater Treatment Facility | Bucksport | 0.23 | ME0100111 | Jan 2023 | 9 |
| 15 | Machias Wastewater Treatment Facility | Machias | 0.13 | ME0100323 | Mar 2021 | 2 |
| 16 | Bingham WWTF | Bingham | 0.12 | ME0100056 | Feb 2029 | 29 |
| 17 | Richmond Wastewater Treatment Facility | Richmond | 0.09 | ME0100587 | May 2030 | 8 |
| 18 | Hartland Wastewater Treatment Facility | Hartland | 0.08 | ME0101443 | May 2023 | 0 |
| 19 | Eastport WWTF | Eastport | 0.08 | ME0100200 | Feb 2030 | 2 |
| 20 | Sabattus Sanitary District | Sabattus | 0.06 | ME0101842 | Nov 2021 | 1 |
| 21 | Wastewater Treatment Facility Hulls Cove | Bar Harbor | 0.05 | ME0102466 | Mar 2030 | 5 |
| 22 | Bar Harbor Wastewater Treatment Facility | Bar Harbor | 0.0013 | ME0102474 | Oct 2020 | 1 |
| 23 | Sanford Wastewater Treatment Facility | Sanford | — | ME0100617 | Jul 2023 | 4 |
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 Maine
Anaerobic digesters and biogas in other states
Anaerobic digesters and biogas in Maine: 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.