A wastewater treatment plant must disinfect its effluent before discharging the wastewater to a nearby stream. The wastewater contain 5.5 x 1^5faecal coliform coliform – forming units (CFU) per liter. The maximum permissible faecal coliform concentration that may be discharged is 3000 faecalcoliform CFU/L. It is proposed that a pipe carrying the wastewater be used for disinfection process. Determine the length of pipe required if the linear velocity of the wastewater pipe is 0.85 m/s. Assume that the pipe behaves as a steady-state plug flow system and that the reaction rate constant for destruction of the feacal coliform is 0.22 per min.
A wastewater treatment plant must disinfect its effluent before discharging the wastewater to a nearby stream. The wastewater contain 5.5 x 1^5faecal coliform coliform – forming units (CFU) per liter. The maximum permissible faecal coliform concentration that may be discharged is 3000 faecalcoliform CFU/L. It is proposed that a pipe carrying the wastewater be used for disinfection process. Determine the length of pipe required if the linear velocity of the wastewater pipe is 0.85 m/s. Assume that the pipe behaves as a steady-state plug flow system and that the reaction rate constant for destruction of the feacal coliform is 0.22 per min.
Given data:
Initial concentration of California colony (Co) = 5.5 x 105 CFU/L.
Maximum California concentration discharged © = 3000 CFU/L
Velocity (V) = 0.85 m/s
Reaction rate constant (k)= 0.22 min-1
Consider reaction rate (A steady state plug flow first order system) equation for PFR:
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