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CHE 4171: Biochemical Engineering

TUTOTRIAL QUESTIONS (WEEK 2 T1)

Questions

1. Aerobic growth of S. cerevisiae on ethanol is simply described by the following overall reaction.

C2 H 5OH + aO2 + bNH 3 → c(CH1.704 N0.149O0.408 ) + dCO2 + eH 2O

(a) Determine a, b, c and d where RQ = 0.64

(b) Determine the biomass yield coefficient, Yx/s and oxygen yield coefficient Yx/O2

2. Biological denitrification of nitrate-containing waste waters can be described by the following overall reaction.

NO −1

+ aCH 3OH + H

→ bC5 H 7 NO2 + cN 2 + dCO2 + eH 2O

(a) Determine a, b, c, d and e if Yx/s = 0.5 g X / g N

(b) Determine the degrees of reduction for bacteria and methanol

3. Aerobic degradation of an organic compound by mixed culture of organisms in waste water can be represented by the following equation:

C3 H 6 O3 + aO2 + bNH 3 → c(C5 H 7 NO2 ) + dH 2 O + eCO2

(a) Determine a, b, c, d and e if Yx/s = 0.4 g X / g S

(b) Determine the yield coefficients YX/O2 and YX/NH3

(c) Determine the degrees of reduction for the substrate and bacteria and calculate the RQ for

the organism.

4. An aerobic growth of yeast using ethanol as substrate can be described using generalized bioreaction stoichiometry as

Calculate theoretical yields, .