Question

A town has an existing horizontal flow sedimentation tank with an overflow rate of $17m^3/day/m^2$, and it is desirable to remove particles that have a settling velocity of $0.1mm/sec$. Assuming the tank as an ideal sedimentation tank, the percentage of particles removal is approximately equal to

• A. $30\%$
• B. $90\%$
• C. $50\%$
• D. $70\%$

Answer 1

The correct option is C $50\%$

Given surface overflow rate

$V_0=17m^3/day/m^2$

$\Rightarrow V_0=\frac{17\times {10}^3}{24\times 60\times 60}$

$=0.196mm/sec$

$\eta =\frac{V_s}{V_0}\times 100=\frac{0.1}{0.196}\times 100$

$=50.82\%\simeq 50\%$