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16 MLD of water is flowing through a 2.5 km long pipe of diameter 45 cm. The chlorine at the rate of 32 kg/d is applied at the entry of this pipe so that disinfected water is obtained at the exit. There is a proposal to increase the flow through this pipe to 22 MLD from 16 MLD. Assume the dilution coefficient, n = 1. The minimum amount of chlorine (in kg per day) to be applied to achieve the same degree of disinfection for the enhanced flow is
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- 60.50
- 44.00
- 38.00
- 23.27
Correct Option: A
We know, tcn = k
where C is the concentration and n is the direction coeff.
t is time required to kill organism.
Here n = 1
t = | ||
V |
where, L = length of pipe
V = velocity of flow
t = | = | ||
V | Q/A |
t = | ||
Q |
L = | ||
Q |
where, W = weight of disinfectant/day
Q = discharge/day
t1Cn1 = t2Cn2
× | = | × | × | |||||
Q1 | Q1 | Q2 | Q2 |
∴ W2 = | × W1 | |
Q²1 |
= | ![]() | ![]() | ² | × 32 = 60.5 kg/d | |
16 |