Bioprocess Engineering

, Volume 6, Issue 1, pp 63–69

Integration of continuous production and recovery of solvents from whey permeate: use of immobilized cells of Clostridium acetobutylicum in a flutilized bed reactor coupled with gas stripping

  • N. Qureshi
  • I. S. Maddox

DOI: 10.1007/BF00369279

Cite this article as:
Qureshi, N. & Maddox, I.S. Bioprocess Eng. (1990) 6: 63. doi:10.1007/BF00369279


An investigation was performed into the operation of an integrated system for continuous production and product recovery of solvents (acetone-butanol-ethanol) from the ABE fermentation process. Cells of Clostridium acetobutylicum were immobilized by adsorption onto bonechar, and used in a fluidized bed reactor for continuous solvent production from whey permeate. The reactor effluent was stripped of the solvents using nitrogen gas, and was recycled to the reactor. This relieved product inhibition and allowed further sugar utilization. At a dilution rate of 1.37 h−1 a reactor productivity of 5.1 kg/(m3 · h) was achieved. The solvents in the stripping gas were condensed to give a solution of 53.7 kg/m3. This system has the advantages of relieving product inhibition, and providing a more concentrated solution for recovery by distillation. Residual sugar and non-volatile reaction intermediates are not removed by gas stripping and this contributes to high solvent yields.

List of Symbols

C kg/m3

Lactose concentration in reactor effluent

Cb kg/m3

Lactose concentration in bleed stream

Cc kg/m3

Lactose concentration in whey permeate feed

Ci kg/m3

Lactose concentration at reactor inlet

Cp kg/m3

Lactose concentration in condensed solvent stream (=0)

Cr kg/m3

Lactose concentration in recycle line (Cb=Cr)

ΔC kg/h

Amount of lactose utilized during certain time period

D h1

Dilution rate of reactor, Fi/D=F/D

F dm3/h, m3/h

Fi = Rate of feed flow to the reactor

Fbdm3/h, m3/h

Rate of bleed

Fc dm3/h, m3/h

Rate of feed of whey permeate solution

Fp dm3/h, m3/h

Rate of concentrated product removal

Fr dm3/h, m3/h

Rate of recycle of stripped effluent to the reactor

Pl %

Percent lactose utilization

Rl kg/(m3 · h)

Overall lactose utilization rate

Rp kg/(m3 · h)

Overall reactor (solvent) productivity

Rsl kg/h

Rate of solvent loss

S kg/m3

Solvent concentration in reactor effluent

Sb kg/m3

Solvent concentration in bleed

Sc kg/m3

0; Solvent concentration in concentrated whey permeate solution

Si kg/m3

Solvent concentration at inlet of reactor

Sp kg/m3

Solvent concentration in concentrated product stream

Sr kg/m3

Solvent concentration in stripped effluent, Sr=Sb

ΔS kg/h

Amount of solvent produced from ΔC amount of lactose in a particular time

ds′/dt kg/(m3 · h)

Rate of accumulation of solvents in the stripper

t h


V dm3, m3

Total reactor volume

V1 dm3, m3

Liquid volume in stripper


Solvent yield

Copyright information

© Springer-Verlag 1991

Authors and Affiliations

  • N. Qureshi
    • 1
  • I. S. Maddox
    • 1
  1. 1.Biotechnology DepartmentMassey UniversityPalmerston NorthNew Zealand

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