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TLS Online TPP Program

#Question id: 14329

During exponential phase in batch culture, the growth rate of a culture is proportional to the concentration of cells present. When Streptococcus lactis bacteria are cultured in milk, the concentration of cells doubles in45 min. If this rate of growth is maintained for 12 h, what is the final concentration of cells relative to the inoculum level?

#Section 5: Bioprocess Engineering and Process Biotechnology
  1. 6.54×104 x0     
  2. 2.95×104 x0             
  3. 5.2 ×105x0  
  4. 4.0  ×105x0
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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 S0i = 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: rm = 20 mg/S/l .h and Ks = 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 DO2 = 2 × 10-5 cm2 /s. Determine the required height of the bed. You can assume first-order bioreaction kinetics?

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TLS Online TPP Program

#Question id: 14268

#Section 5: Bioprocess Engineering and Process Biotechnology

An activated-sludge waste treatment system is required to reduce the amount of BOD5 from 1000 mg/l to 20 mg/l at the exit. The sedimentation unit concentrates biomass by a factor of 3. Kinetic parameters are µm = 0.2 h-1 , Ks = 80 mg/l, kd = 0.01 h-1 , and Y M X/S = 0.5 g MLVSS/g BOD5. The flow of waste water is 10000 l/h and the size of the treatment basin is 50,000 l. What is the value of the solids residence time?