Environmental Sanitation

A well is having a diameter of 2 m and depth of water column 6 m. Calculate the amount of bleaching powder (33%) required to disinfect the well. The bluish color change appeared in the 4^th cup of Horrock’s apparatus.

Well diameter = 2 m

Water depth = 6 m

Volume of water in the well = 3.14 x d² x h

                                                         4

                                                =3.14 x 2² x 6

                                                           4

                                                           = 18.84 m³

1m³ = 1000 l

So 18.84 m³ = 18840 litres

Amount of bleaching powder required as per Horrock’s apparatus = 8 g for 455 litres

So for 18840 litres, bleaching powder required is 8 x 18840   = 331.25 g

                                                                                   455