Questions for PhD qualifiers: Bioprocess EngineeringPROBLEMS FROM BIOPROCESS ENGINEERING SHULER AND KARGI CHAPTERS – 3, 7, 9 and 10 Q1. The hydrolysis of urea by urease can be described by Michealis-Menten kinetics with the maximum reaction rate Vmax = 5 moles/l-min and Km = 0.05 M. Determine the time required to consume 90% of the initial urea concentration (S0), when (i) S0 = 10 moles and (ii) S0 = 0.1 mole? Q2. Evaluate the pH value at which the maximum enzymatic rate occurs for the below pH dependent mechanism for a given substrate concentration of S0 assuming Haldane’s approach? Q 3. Enzyme inhibition kinetics: The following data was obtained for an enzyme ‘E’ for a fixed substrate concentration S0 Substrate concentration Inhibitor concentration v/vmax The outlet stream contains 3 g/L of Lactose. bulgaricus on lactose (S) in milk is given as follows: 0.S0 (mM) 50 0 0. If alpha=0. Determine the concentration of biomass at t=2h assuming quasi steady state. F=200ml/h.4 P 1 10 where P is the lactic acid concentration. Q1. bulgaricus produces lactic acid only while it is growing.2 S Will the organism spoil the chemostat operation through contamination? Q2.3 1/hr. S0 = 100g/l. Lactobacillus bulgaricus is used to ferment milk to yogurt. Yx/s=0. bulgaricus. Another organism has contaminated the fermentation.6 Determine the enzymatic rate as a fraction of vmax for a substrate concentration of 10mM and an inhibitor concentration of 25 mM. A chemostat (CSTR) is operated for the preproduction stage. It is known that L.1g/l. The growth rate of L.75 25 10 0. In a fed batch culture operating with intermittent addition of glucose solution.32S 0. It is known that YX/S = 0. X0=50 g/l Find V0 (initial volumn). The growth rate of the organism is represented by Monod’s kinetics. when the system is at quasi-steady state. Ks=0. .5 and YP/X = 2 for L. The feed stream has a substrate concentration of Sf. V =1000 ml. mumax=0. where the input to the reactor is sterilized milk with 5 g/L of lactose. Fed-Batch Operation: A fermentor is operated as a fed-batch process.2g/g Determine the concentration of product at t=2h assuming P0=0.5g/g. whose growth rate is given by 0.9 50 10 0. Determine the feed flow rate for the process and determine the final biomass concentration? Assume Yx/s as the yield coefficient? Q3. values of the following parameters are given at time t=2 h. The substrate concentration is kept constant in the reactor at S. Determine the dilution rate. Find the cell concentration in the centrifuge effluent. The outlet stream contains 3 g/L of . beta=1 and YX/S = 2 g/g [Marks 3. The yield coefficient Y X/S = 0.5] Q2 Chemostat Operation: Lactobacillus bulgaricus is used to ferment milk to yogurt. Q2. In a chemostat with cell recycle. The value of C is 1. Glucose concentration in the feed is S0=10g. amount of substrate consumed. where the input to the reactor is sterilized milk with 5 g/L of lactose. the feed flow rate and culture volumes are F=100ml/h and V=1000ml. The growth rate of L.21/h. alpha = 2. The kinetic constants of the organisms are mumax=0.4 g dw cells/g glucose.2 s 0 . bulgaricus on lactose (S) in milk is given as follows: 0.Q4.6 1 40 .5] Q3. respectively. non growth associated constant.5 s s 2 50 Methanol concentration in the feed solution is 100 g/L with an initial cellmass of 20 g/L and an initial volume of reactor of 500L. Yx/s =0. Determine the final volume and cellmass concentration for operating a fed batch reactor at maximum growth rate in the reactor.5 and the recycle ratio is 0. Find the cell concentration in the recycle stream. The system is operated under glucose limitation and the yield coefficient.4 P 1 10 where P is the lactic acid concentration. It is known that L.7. A methanol utilizing strain has a specific growth rate given by: 0 . The system is at steady state. bulgaricus produces lactic acid only while it is growing. A chemostat (CSTR) is operated for the preproduction stage. growth related product formation constant. [Marks: 3. product and biomass formed to maximize (a) product productivity and (b) Biomass Productivity for an organism with the following growth parameters: P 0. Ks=1g/l.5g/g. Find the substrate concentration in the recycle stream Find the specific growth rate of the organisms. Lactose.2 S Will the organism spoil the chemostat operation through contamination? Justify your solution with an explanation.32S 0. Consider the following reaction sequence: S + E (ES)1 (ES)2 P + E Develop a suitable rate expression for the product formation (dP/dt = k4(ES)2) assuming quasi-steady state approximation? . Q1. Another organism has contaminated the fermentation.5 and YP/X = 2 for L. It is known that YX/S = 0. bulgaricus. whose growth rate is given by 0.