A fluidized-bed, immobilized-cell bioreactor is used for the conversion of glucose to ethanol by Z. mobilis cells immobilized in k-carrageenan gel beads. The dimensions of the bed are 10 cm (diameter) by 200 cm. Since the reactor is fed from the bottom of the column and because of CO₂ gas evolution, substrate and cell concentrations decrease with the height of the column. The average cell concentration at the bottom of the column is X₀ = 45 g/l, and the average cell concentration decreases with the column height according to the following equation:

                             

where Z is the column height (cm). The specific rate of substrate consumption is q_S = 2 g S/g cells . h. The feed flow rate and glucose concentration in the feed are 5 l/h and 160 g glucose/l, respectively.

Determine the ethanol productivity (g/l . h) if YP/S = 0.48 g ethanol/g glucose.

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TLS Online TPP Program

#Question id: 14262

#Section 5: Bioprocess Engineering and Process Biotechnology

The BOD5 value of a waste-water feed stream to an activated-sludge unit is S0 = 300 mg/l, and the effluent is desired to be S = 30 mg/l. The feed flow rate is F = 2× 10^7 l/day. For the recycle ratio of α = 0.5 and a steady-state biomass concentration of X = 5 g/l, Use the following kinetic parameters:

 

calculate Required reactor volume (V). 

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TLS Online TPP Program

#Question id: 14263

#Section 5: Bioprocess Engineering and Process Biotechnology

The BOD5 value of a waste-water feed stream to an activated-sludge unit is S0 = 300 mg/l, and the effluent is desired to be S = 30 mg/l. The feed flow rate is F = 2× 10^7 l/day. For the recycle ratio of α = 0.5 and a steady-state biomass concentration of X = 5 g/l, Use the following kinetic parameters:

 

calculate Biomass concentration in recycle (Xr).

TLS Online TPP Program

#Question id: 14264

#Section 5: Bioprocess Engineering and Process Biotechnology

The BOD5 value of a waste-water feed stream to an activated-sludge unit is S0 = 300 mg/l, and the effluent is desired to be S = 30 mg/l. The feed flow rate is F = 2× 10^7 l/day. For the recycle ratio of α = 0.5 and a steady-state biomass concentration of X = 5 g/l, Use the following kinetic parameters:

 

calculate Hydraulic residence time

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TLS Online TPP Program

#Question id: 14265

#Section 5: Bioprocess Engineering and Process Biotechnology

For the activated-sludge, the specific growth rate of cells is given by 

 

The following parameter values are known: F = 500 l/h, α = 0.4, ɣ = 0.1, Xe = 0, V = 1500 l, Ks = 10 mg/l, µm = 1 h-1 , kd = 0.05 h-1 , S0 = 1000 mg/l, Y M X/S = 0.5 g dw/g substrate. Calculate the substrate concentration (S) in the reactor at steady state. -------------------------

TLS Online TPP Program

#Question id: 14266

#Section 5: Bioprocess Engineering and Process Biotechnology

For the activated-sludge, the specific growth rate of cells is given by 

 

The following parameter values are known: F = 500 l/h, α = 0.4, ɣ = 0.1, Xe = 0, V = 1500 l, Ks = 10 mg/l, µm = 1 h-1 , kd = 0.05 h^-1 , S0 = 1000 mg/l, Y M X/S = 0.5 g dw/g substrate.. Calculate the cell concentration in the reactor. 

TLS Online TPP Program

#Question id: 14267

#Section 5: Bioprocess Engineering and Process Biotechnology

In a trickling biological filter, the BOD value of the feed stream is S_0i = 500 mg/l with a feed flow of F = 10³ l/h. The effluent BOD value is desired to be S₀ = 10 mg/l. The following kinetic parameters for the biocatalysts are known: r_m = 20 mg/S/l .h and K_s = 200 mg S/l. The biofilm thickness is L = 0.1 mm. The cross-sectional area of the filter is A = 2 m² , and the biofilm surface area per unit volume of the bed is a = 500 cm² /cm³ . Assume that dissolved oxygen is the rate-limiting substrate and the diffusion coefficient of oxygen is D_O2 = 2 × 10^-5 cm² /s. Determine the required height of the bed. You can assume first-order bioreaction kinetics?

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