Repeat Problem 5-5 assuming a three-column system in series and operation of the “lead”...

Repeat Problem 5-5 assuming a three-column system in series and operation of the “lead” column until the bed is exhausted. Assume the total out-of-service time is three hours.

Problem 5-5

A pilot scale ion exchange column was used to develop design data for a softening system for the Village of Dolomite. The data are shown below. The design flow rate is 7,000 m³/d. The design final hardness is 120 mg/L as CaCO₃ . Regeneration is to be once per day. The manufacturer’s operating capacity to breakthrough is 50%. Assume a two-column system and that there is no leakage before breakthrough. Use the mass balance technique to determine the mass of resin that will be required.