Correct option is B
The
detention time in a sedimentation tank is the time that water spends in the tank to allow suspended particles to settle down. For
coagulated raw water, the particles are made heavier through coagulation, and they settle more quickly than uncoagulated particles.
Detention Time:
·
For coagulated raw water:
· The detention time is typically
2 to 4 hours, as the process is aided by the coagulation of particles.
· This is sufficient to allow effective sedimentation of flocculated particles.
·
For plain sedimentation (without coagulation):
· The detention time is generally longer, often
4 to 8 hours.
