GATE Civil Engineering (CE) 2018 Shift 2 Solved Paper

Question : 48 of 65

Marks: +1, -0

At a small water treatment plant which has 4 filters, the rates of filtration and backwashing are

200 {m}^{3} {/} {d} {/} {m}^{2}

and

1000 {m}^{3} {/} {d} {/} {m}^{2}

respectively. Backwashing is done for 15 min per day. The maturation, which occurs initially as the filter is put back into service after cleaning, takes 30 min. It is proposed to recover the water being wasted during backwashing and maturation. The percentage increase in the filtered water produced (up to two decimal places) would be______

Your Answer:

Validate

Solution:

Let total area of filters be

1 {m}^{2}

Water used for backwashing

=1000 × \;{15}/{24 × 60}=10.4166 {m}^{3}

Water used for maturation

=200 × \;{30}/{24 × 60}=4.166 {m}^{3}

Total water wasted for backwashing and maturation

=10.4166+4.166=14.58 {m}^{3}

Water to be treated by filtered

=200 × \;{24}/{23.25}=206.45 {m}^{3}

/ day

\%

increase in filtered water produced

=\;{14.58}/{206.45} × 100=7.06 \%

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