Problem 9. Say you had a 2rd order reaction occurring in a reactor designed and operated as an ideal PER with a detention time of 5 minutes and you obtained 99% destruction of a contaminant with an initial Co of 1000 mg/L. a) What would be the required detention time if that reactor had been designed instead as a CSTR? You should find that for a second order reaction, a PFR is EVEN MORE efficient compared to a CSTR than was found for disinfection (i.e., a first order reaction as you observed in Problem). 8 b) Given that some biological reactions in which carbon is consumed is a pseudo-second order reaction rather than a first order reaction, why are most biological treatment systems such as activated sludge plants designed as CSTRS rather than PFRS? PFRs would be more efficient according to your answer in 9a.

Problem 9. Say yow had a 2rd order reaction occurringin a reactor designed and operated as an ideal PFR with th detention time of 5 minutes and you obtained 99% y lestruction of a contaminant with an inikal Co of 1000 maght a) What would be the required detention time if that reactor had been designed instead as a CSTR? You should find that for a second order reaction, a PFR is EVEN MORE efficient compared to a CSTR than was found for disinfection (i.e,, a first order reaction as you observed in Problem 4 ). b) Given that some biological reactions in which carbon is consumed is a pseudo-second order reaction bather 1 reached than a first order reaction, why are most biological treatment systems such as activated sludge plants designed as CSTRs rather than PFAs? PFRs would be more efficient according to your answer in 9 a