Which of the following provides the best evidence that cell-signaling pathways evolved early in the history of life?

TLS Online TPP Program

#Question id: 14218

#Section 5: Bioprocess Engineering and Process Biotechnology

In CSTR system at steady rate  

TLS Online TPP Program

#Question id: 14219

#Section 5: Bioprocess Engineering and Process Biotechnology

A waste-water stream of F = 1 m3 /h with substrate at 2000 mg/l is treated in an upflow packed bed containing immobilized bacteria in form of biofilm on small ceramic particles. The effluent substrate level is desired to be 30 mg/l. The rate of substrate removal is given by the following equation

                   

By using the following information, determine the required height of the column (H). k = 0.5 h-1, X = 10 g/l, Ks = 200 mg/l, L = 0.2 mm, α = 100 m2 /m3 , A = 4 m2 , η = 0.8

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TLS Online TPP Program

#Question id: 14220

#Section 5: Bioprocess Engineering and Process Biotechnology

A value of kLa = 30 h^-1 has been determined for a fermenter at its maximum practical agitator rotational speed and with air being sparged at 0.5 l gas/l reactor volume-min. E. coli with a qO2 of 10 mmol O2/g-dry wt-h are to be cultured. The critical dissolved oxygen concentration is 0.2 mg/l. The solubility of oxygen from air in the fermentation broth is 7.3 mg/l at 30⁰C.

What maximum concentration of E. coli can be sustained in this fermenter under aerobic conditions?

TLS Online TPP Program

#Question id: 14221

#Section 5: Bioprocess Engineering and Process Biotechnology

E. coli have a maximum respiration rate, qO2max, of about 240-mg O2/g-dry wt-h. It is desired to achieve a cell mass of 20 g dry wt/l. The kLa is 120 h-1 in a 1000-l reactor (800 l working volume). A gas stream enriched in oxygen is used (i.e., 80% O2) which gives a value of C* = 28 mg/L. If oxygen becomes limiting, growth and respiration slow; for example,

                                     

   where CL is the dissolved oxygen concentration in the fermenter. What is CL when the cell mass is  at 20 g/l?

TLS Online TPP Program

#Question id: 14222

#Section 5: Bioprocess Engineering and Process Biotechnology

A stirred-tank reactor is to be scaled down from 10 m3 to 0.1 m3. The dimensions of the large tank are: Dt = 2 m; Di = 0.5 m; N = 100 rpm.Determine the dimensions of the small tank (Dt , Di , H) by using geometric similarity?

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TLS Online TPP Program

#Question id: 14223

#Section 5: Bioprocess Engineering and Process Biotechnology

A furnace wall is constructed of firebrick 15-cm thick. The temperature inside the wall is 700⁰C the temperature outside is 80⁰C. If the thermal conductivity of the brick under these conditions is 0.3 W m-1 K^-1, what is the rate of heat loss through 1.5 m2 of wall surface?