Question

A city is going to install the rapid sand filter after the sedimentation tank. Use the following data:
Design loading rate to the filter = 200 $m^3/m^2/d$ ;
Design now rate = 0.5 $m^3/s$
Surface area per filter box = 50 $m^2$
The number of filters required shall be

• A. $4$
• B. $6$
• C. $8$
• D. $3$

Answer 1

The correct option is B $6$

Surface area required

$=\frac{\text{Design flow rate}}{\text{loading rate}}$

$=\frac{0.5\times 86400m^3/d}{200m/d}$

$=216m^2$

Number of filter required

$=\frac{\text{Surface area required}}{\text{Surface area per filter}}=\frac{216}{50}$

= 4.32
= 5 filters

One additional filter is provided so that maintainance of filter should be carried without providing any overloading on any filter so, number of filters = 5+1= 6 filters.