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A horizontal flow primary clarifier treats waste water in which 10%, 60% and 30% of particles have settling velocities of 0.1 mm/s, 0.2 mm/s and 1.0 mm/s respectively. What would be the total percentage of particles removed if clarifier operates at a surface overflow rate (SOR) of 43.2 m³/m². d?
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- 43%
- 56%
- 86%
- 100%
Correct Option: B
SOR = 43.2 m³/m²d
| = | mm/s | |
| 24 × 60 × 60 |
= 0.5 mm/s
30% particles has settling velocity more than SOR. So, it will settle particles with velocity lower than SOR, that will settle equals to its ratio with SOR.
| ∴ % particles removed = 30% + 60% × | + 10 % × | = 56 % | ||
| 0.5 | 0.5 |
