Science of Water : Concepts and Applications

394 The Science of Water: Concepts and Applications
bleaching—common household bleach is a solution of sodium hypochlorite containing 5.25% available
chlorine.
When calculating gpd liquid hypochlorite the lb/day hypochlorite required must be converted
into gpd hypochlorite required. This conversion is accomplished using Equation 10.92:
Example 10.117
hypochlorite (lbday) Hypochlorite (gpd)
8.34 lbgal Problem:
A total of 50 lb/day-sodium hypochlorite are required for disinfection of a 1.5-MGD fl ow. How many
gpd hypochlorite is this?
Solution:
Because lb/day hypochlorite has already has been calculated, we simply convert lb/day to gpd hypochlorite
required:
Example 10.118
hypochlorite (lbday) Hypochlorite (gpd)
8.34 lbgal 50 lbday
8.34 lbgal 6.0 gpd hypochlorite
(10.92)
Problem:
A hypochlorinator is used to disinfect the water pumped from a well. The hypochlorite solution contains
3% available chlorine. A chlorine dose of 1.3 mg/L is required for adequate disinfection throughout
the system. If the fl ow being treated is 0.5 MGD, how many gpd of the hypochlorite solution will
be required?
Solution:
Calculate the lb/day chlorine required:
(1.3 mgL)(0.5 MGD)(8.34 lbgal) 5.4 lb day chlorine
Calculate the lb/day hypochlorite solution required:
5.4 lbd chlorine
Hypochlorite (lbd)
0.03
80 lbd hypochlorite