| advantages | disadvantages |
| Low hydraulic retention time (HRT) and high sludge retention time (SRT) | High bed costs |
| low sludge production | Requires high concentration of dissolved oxygen in biofilm reactors for denitrification |
| high resistant to toxic materials | |
| constant active biological biomass | Congestion problems in the fixed beds |
| Low sensitivity to temperature and amount of sludge production |
|
| nitrification in low temperature |
|
| Removal of high amount of nutrients |
|
| Nitrification and denitrification can simultaneously occur on both exterior and interior sides of a biofilm |
|