You are designing a reactor that uses chlorine in a PFR or CMFR to destroy pathogens in water. A minimum contact time of 30 min is required to reduce the pathogen concentration from 100 pathogens/L to below 1 pathogen/L through a first- order decay process. You plan on treating water at a rate of 1,000 gal/min.
(a) What is the first-order decay rate constant?
(b) What is the minimum size (in gallons) of the reactor required for a plug flow reactor?
(c) What size (in gallons) of CMFR would be required to reach the same outlet concentration?
(d) Which type of reactor would you select if your treat- ment objective stated that "no discharge can ever be greater than 1 pathogen/L"?