Table 2 Operating parameters in the water treatment plant
Process | Designed contact time (min) | Coagulant (aluminum sulfate) concentration (mg L−1)a | Ozone dosage (mg L−1)a | Actual contact time (min) | Backwash frequency |
|---|---|---|---|---|---|
Pre-ozonation | 3 | – | 0–1.0 | 3.4 | – |
Flocculation | 20 | 20–30 | – | 23 | – |
Sedimentation | 120 | – | – | 137 | – |
Sand filtration | 30 | – | – | 34 | 24–48 h |
Post-ozonation | 12 | – | 0–1.5 | 14 | – |
GAC | 12 | – | – | 14 | 5–10 days |