You are designing a reactor that uses chlorine in a PER or CMFR to de-stroy pathogens in water. A minimum contact lime of 30 min is required to reduce the pathogen concentration from 100 pathogens L-1 to below 1 pathogen L-1 through a first-order decay process. You plan on treating water at a rate of LOOD gal min-1 .
(a) What is the firssorder decay rate constant?
(b) What is the minimal size (in gallons) of the reactor required for a plug Row 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 treatment objective stated that "no discharge an ever be greater than 1 pathogen L-1 ?" (Explain your reasoning.)
(e) If the desired chlorine residual in the treater water after it leaves the reactor is 0.20 mg L-1 . and the chlorine demand used during treatment is 0.15 mg L-1 , what must be the daily mass of chlorine added to the reactor in grams?