Science of Water : Concepts and Applications

Water Treatment Calculations 393
Solution:
Calculate the lb/day chlorine dosage:
chlorine, lbday Hypochlorite, lbday
% available chlorine
100
x lbday chlorine
40 lbd hypochlorite
0.65
(0.65)(40) x
26 lbday chlorine x
Then calculate mg/L chlorine, using the mg/L to lb/day equation and fi lling in the known
information:
Example 10.116
26 lbday chlorine ( x mgL chlorine)(1.10 MGD)(8.34 lbgal) 26 lbd x
(1.10 MGD)(8.34 lbgal) 2.8 mgL chlorine
Problem:
A fl ow of 2,550,000 gpd is disinfected with calcium hypochlorite (65% available chlorine). If 50 lb of
hypochlorite are used in a 24-h period, what is the mg/L chlorine dosage?
Solution:
The lb/day chlorine dosage is:
The mg/L chlorine dosage required is:
x lbd chlorine
50 lbday hypochlorite
0.65
x 32.5 chlorine
( x mgL chlorine)(2.55 MGD)(8.34 lbgal) 32.5 lbday CALCULATING HYPOCHLORITE SOLUTION FEED RATE
x 1.5 mgL chlorine
Liquid hypochlorite (i.e., sodium hypochlorite) is supplied as a clear, greenish-yellow liquid in
strengths from 5.25 to 16% available chlorine. Often referred to as “bleach,” it is, in fact, used for