Solution :
According to Chick's law
where, t = contact time
c = concentration of disinfectant
k' = lethality coefficient = 4.71
n = dilution coefficient = 1
4 log removal = % removal = 99.99
= 1 - R
= 1 - 0.9999
Now for plug flow reactor contact time,
= 0.01875 days
= 27 minutes
For CSTR,
days
= 5.4 minute
There are 3 reactors, hence total contact time = 3 x 5.4
= 16.2 minute
Or
or
∴ C x t = 1.955
For PFR, min
∴ C = 0.072 mg/L
For CSIR, min
mg/L
∴ Chlorine required for PFR in kg/day
(1 gallon = 3.785 L)
= 18.25 kg/day
Therefore we should go for PFR system.