Quick Reference Data
DO targets, pH ranges, loading rate benchmarks, unit conversions, and chemical data — organized for field use.
[ Dissolved Oxygen ]
Operating Ranges by Process Zone
| Process Zone | Target DO (mg/L) | Notes |
|---|---|---|
| Aeration Basin (Nitrification) | 2.0 – 4.0 | Minimum 2.0 for full nitrification |
| Aeration Basin (General) | 1.5 – 3.0 | Below 1.0 risks filamentous growth |
| Anoxic Zone (Denitrification) | < 0.2 | DO inhibits denitrification |
| Anaerobic Zone (EBPR) | < 0.05 | Critical for phosphorus release |
| Secondary Clarifier Effluent | 4.0 – 8.0 | Higher DO indicates good aeration |
| Digester (Anaerobic) | 0 | Strict anaerobic conditions required |
[ pH Targets ]
Operating Ranges by Process
| Process | pH Range | Notes |
|---|---|---|
| Activated Sludge | 6.5 – 8.5 | Optimal range for biological activity |
| Nitrification | 7.2 – 8.0 | Below 6.8 significantly inhibits nitrifiers |
| Denitrification | 6.5 – 8.0 | Less sensitive to pH than nitrification |
| Anaerobic Digestion | 6.8 – 7.4 | Below 6.5 = acid phase; above 8.0 = inhibited |
| Chemical Phosphorus Removal | 5.5 – 7.0 | Alum optimal around 6.0–7.0 |
| Effluent Discharge (typical) | 6.0 – 9.0 | Varies by permit |
[ Loading Rate Benchmarks ]
Design & Operational Targets
| Parameter | Typical Range | Units |
|---|---|---|
| F/M Ratio (Conventional AS) | 0.2 – 0.4 | lbs BOD / lb MLVSS / day |
| F/M Ratio (Extended Aeration) | 0.04 – 0.1 | lbs BOD / lb MLVSS / day |
| MCRT (Nitrification) | 10 – 20 | days (varies with temp) |
| MCRT (Conventional) | 5 – 15 | days |
| SVI (Good Settling) | 80 – 150 | mL/g |
| SVI (Bulking) | > 200 | mL/g |
| Surface Loading Rate (Clarifier) | 400 – 800 | gpd/ft² |
| Solids Loading Rate (Clarifier) | 20 – 30 | lbs/day/ft² |
| VS Loading Rate (Digester) | 0.1 – 0.3 | lbs VS/day/ft³ |
| Digester Detention Time | 15 – 30 | days |
| VSR (Anaerobic Digestion) | 38 – 55 | % (Class B minimum 38%) |
[ Unit Conversions ]
Common Wastewater Conversions
| From | To | Factor |
|---|---|---|
| MGD | GPM | × 694.44 |
| MGD | CFS | × 1.5472 |
| MGD | L/s | × 43.813 |
| MGD × mg/L | lbs/day | × 8.34 |
| mg/L | lbs/MG | × 8.34 |
| ft³ | gallons | × 7.481 |
| acres | ft² | × 43,560 |
| °F | °C | (°F − 32) × 5/9 |