| Description | RBC | SBR |
| External clarifiers and piping | Requires clarifiers & piping (primary & secondary) | Not required |
| Digester | Required | Not required with extended aeration loading |
| Cover/building over reactor | Required | Not required |
| Biomass characteristics | Un-controlled biomass formation No control over the filamentous bacteria |
Improved. Lower SVI. Control over the filamentous bacteria. Desirable balance obtained between zoogloea and filamentous bacteria |
| BOD removal | 80-90% | 90-95% plus |
| Phosphorus removal | Not possible biologically Need chemical coagulation |
Integrated in the sequence. No chemical required |
| Nitrification | Possible if RBC capacity is doubled up with separate treatment units | Integrated in the sequence |
| Denitrification | Not possible or need separate basins with methanol addition | Possible without methanol addition
|
| Sludge age | 0.5 to 3 days | 20 to 30 days |
| Sludge production | 1.0-2.0 lbs/lb BOD removed at its maximum. Primary & secondary unstabilized sludges plus chemical sludge |
0.5-1.0 lb/lb BOD removed at its minimum
|
| Sludge disposal | More sludge to be disposed Chemical sludge generation with potential environmental problems |
Minimum sludge generated No chemical sludge Biological sludge only No disposal problem |
| Chemical feed equipment | required for phosphorus removal | Not required unless as back-up |
| Process characterization | Attached biomass on media | Suspended biomass |
| Treatment status |
|
Advanced treatment
|
| Process classification |
|
|
| Historical status | Extensive history of chronical mechanical
breakages e.g.
|
|
| Process biological pattern | Plug flow | True plug flow |
| Process design modelling | Not available | Available Mass balance approach using specific biokinetic coefficients |
| Equalisation | No equalization provided Equalization recommended |
Self-equalized capacity during peak loads |
| Aerated capacity | Fixed | Variable to accomodate peak loads |
| Controls | Simple (no provess control) Simple automatic timers |
|
| Operation/ maintenance | Several reactors Rotors & drives, bearing, chains Clarifiers & drives Transfert pumps & piping Digesters & aeration equipement |
Simple single tank process Less mechanical equipment Less maintenance |
| Overall cost civil mechanical, operation |
More | Less |
| Power | Process: less Digester: more Overall: less (generally) |
Process: more Digester: less Overall: more (generally) |
