Bioprocess design 7.5 ECTS Ladokcode: TK741D The exam is given to: Bioprocess design ExamCode: Date of exam: 2017-05-29 Time: 09:00-13:00 Means of assistance: It is an open-book exam. Calculators, books and notes are allowed. Attn: No material can be shared between the students. No computer or mobile phones can be used.

Total amount of point on exam:: 40 Requirements for grading:

Additional information:

Next re-exam date:

The marking period is, for the most part, 15 working days, plus up to 5 working days for administration, otherwise it’s the following date: Important! Do not forget to write the ExamCode on each paper you hand in. Good Luck! Examiner: Mohammad Taherzadeh Phone number: 033-435 5908

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Exam in: Bioprocess Design (Open book exam)

1) Draw a PFD for process of biodiesel production as complete as possible according to the following

process description (5 hp). In this process vegetable oils react with methanol to form fatty acid methyl esters (which are called biodiesel) according to the following equation:

The catalyst for this reaction is usually potassium hydroxide. In this process, the catalyst is first dissolved in methanol to form a solution which is called methoxide. The vegetable oils as well as methoxide solution are sent to a stirred tank reactor where biodiesel is formed. The reaction products are transferred to a separator where the glycerol which has a higher density is separated from biodiesel. The obtained biodiesel contains some unreacted methanol and therefore is sent to a distillation unit where methanol, which is more volatile, is separated from biodiesel. This methanol is then reused in the process. Biodiesel is then sent to an adsorption unit where the remaining catalyst is absorbed on ion exchange resins and a pure biodiesel is obtained.

2) An enzyme has the following kinetics constants (5hp):

Where k1= 109 M-1s-1, k-1=4.4×104 s-1, and k2=103 s-1.

a) Calculate the Mickaelis Menten constant for this enzyme. b) At an enzyme concentration of 10-6 M, if substrate concentration is 10-3 M, calculate the initial

rate of enzymatic reaction.

3) The following graph has been obtained in a bacterial batch culture. Ks for this bacterium is 80 mg/l. Consider the weight of one cell to be 2×10-12 g. (20hp)

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This bacterium converts two third of substrate carbon (base on the weight) to biomass. Glucose is used as a substrate for this microorganism. The following biological reaction is happened:

𝐶#𝐻%&𝑂# + 𝑎𝑂& + 𝑏𝑁𝐻, → 𝑐𝐶/./𝐻1.,𝑁2.3#𝑂%.& + 𝑑𝐻&𝑂 + 𝑒𝐶𝑂& This microorganism is used in a continuous chemostat with recycle process with a reactor working volume of 400 l. In this process, sterile feed containing 10 g/l glucose is entered at a flow rate of 1000 l/h. Recycle stream with flow rate of 10 l/h and a recycle biomass concentration 5 times as large as in the reactor exit is used in this process.

a) Determine the maximum specific growth rate of biomass. b) Determine the biomass yield as Yx/s (g cell /g substrate) and Yx/O2 (g cell/g oxygen). c) Determine the biomass and substrate concentrations at the outlet of the reactor. d) Determine the biomass productivity in the process (g/l.h) e) Calculate the rate of oxygen consumption in this process (kg/h)

4) A fixed tube heat exchanger is designed for the following operating conditions: (10hp) Process fluid in tubes requires cupper MOC Shell side utility (cooling water) requires carbon steel MOC Heat transfer area = 80 m2 Operating pressure (both shell and tube) = 65 barg Considering CEPCI = 397 for 2001 and CEPCI = 556.8 for 2017:

a) Determine the bare module cost of the heat exchanger in year 2001. b) Estimate the price of the heat exchanger in year 2017.

Good luck! Buena suerte! Bonne chance! Viel Glueck ! よい運! Lycka till! موفق باشید! الحظّ السّعید

Mohammad Taherzadeh/Akram Zamani/Abas Mohsenzadeh

Heat Exchanger