Problem

An ion exchange softening plant treats water a flow rate of 150 MGD. The water has the sam...

An ion exchange softening plant treats water a flow rate of 150 MGD. The water has the same characteristics as that listed below. A bypass is used to achieve the desired hardness of 120 mg · L−1 as CaCO3. Determine the bypass flow rate assuming that the total hardness is 2.0 mg · L−1 as CaCO3 after softening.

Chemical Species or Parameter	Concentration (in mg/L as CaCO3 Unless Otherwise Specified)
Calcium (Ca2+)	238.0
Magnesium (Mg2+)	90.6
Iron (Fe3+)	0.7
Copper (Cu2+)	0.02
Sodium (Na+)	56.2
Bicarbonate	198.9
Sulfate	86.4
Chloride (Cl−)	99.7
CO2	25.0
pH (dimensionless)	7.25