Compared
Anaerobic vs. aerobic digestion
Both digest wastewater sludge to stabilize it, but differently. Aerobic digestion supplies air so oxygen-using microbes break down the sludge; anaerobic digestion works without oxygen and can produce methane gas that some plants capture for energy. Aerobic is simpler for small plants; anaerobic suits larger ones.
Last reviewed 2026-08-04
| Anaerobic | Aerobic | |
|---|---|---|
| Oxygen | None | Air supplied |
| Gas produced | Methane (can be captured) | Mostly carbon dioxide |
| Energy | Can generate energy from the methane | Uses energy to supply air |
| Best fit | Larger plants | Smaller plants |
| Complexity | Higher | Lower |
The bottom line
Both stabilize sludge and cut its volume. The choice comes down to plant size and whether capturing methane for energy makes sense.
Common questions
- What is the main difference?
- Anaerobic works without oxygen; aerobic supplies air.
- Which makes methane?
- Anaerobic digestion, which some plants capture for energy.
- Which suits a small plant?
- Aerobic digestion, because it is simpler.