A treatment plant with coagulation, flocculation, sedimentation, and filtration produces...

A treatment plant with coagulation, flocculation, sedimentation, and filtration produces a filtered water with a turbidity less than 0.3 NTU, pH 7, and temperature of 5°C at peak hourly flow of 3.0 mgd. The filtered water is chlorinated in a baffled reservoir with the residence-time distribution as drawn in Figure 7-22. What is the required disinfection by free chlorine of the filtered water? [Answers 25 (mg/l) - min, 90 min, 0.28 mg/l]