Improvement in the bioreactor specific productivity by coupling continuous reactor with repeated fed-batch reactor for acetone–butanol–ethanol production

Investigation of gas stripping and pervaporation for improved feasibility of two-stage butanol production process

“…The concentratio n of glucose, acetic acid, butyric acid, acetone, ethanol and butanol in the fermentation broth and gas stripping condensate were analyzed with high performanc e liquid chromatography (HPLC) (Knauer GmbH, Berlin, Germany) equipped with a refractive index detector (Setlhaku et al, 2012 ). Samples taken during pervaporation were analyzed by gas chromatograp hy (the detailed procedure is described elsewhere) (Heitmann et al, 2012 ).…”

“…The method of cell cultivation from precultures to reactor has been previously described (Setlhaku et al, 2012 ). The clostridia growth medium used for all the precultures and main fermentation preparati on comprised the following components per liter of double distilled water: yeast extract 5 g; KH 2 PO 4 0.75 g; K 2 HPO 4 0.75 g; NaCl 1 g; MnSO 4 ÁH 2 O 0.01 g; (NH 4 ) 2 SO 4 2 g; MnSO 4 ÁH 2 O 0.2 g; FeSO 4 Á7H 2 O 0.01 g; L-asparagi ne 0.5 g and glucose 60 g. The yeast extract and salts were autoclaved together at 120 °C for 20 min; glucose was prepared and autoclaved separately and mixed into the final medium according to the concentrations above.…”

“…It allows for significant improvem ent of final butanol concentration, volumetric productivity, yield and operation time (Ennis et al, 1987;Gapes et al, 1996;Richter et al, 2012;van Hecke et al, 2012 ). Setlhaku et al (2012) developed a two-stage reactor concept where the first stage is operated continuously and is connected to the second stage operated as a repeated fed-batch. A total of 19.5 g/L ABE and 12 g/L butanol was produced at productiviti es of 1.47 g ABE /L/h and 0.92 g Butanol /L/h, without including any process improvements like in situ product removal, biomass recycle or cell immobilizat ion.…”

“…In this work, the second stage fed-batch fermenter of our twostage process (Setlhaku et al, 2012 ) is integrated with gas stripping. The fermentation broth from the second stage is also fed to a pervaporation unit for butanol removal.…”

Improved Acetone-Butanol-Ethanol (ABE) Solution Analysis Using HPLC: Chromatograph Spectrum Deconvolution Using Asymmetric Gaussian Fit

“…Eurokat H Vertex column (300 × 8 mm, 10 µm, KNAUER, Germany) is another HPLC column used for ABE fermentation broth analysis. Setlhaku et al [23] [24] used this column to quantify the components present in ABE fermentation broths. This column allows performing the HPLC at higher temperatures instead of sub-ambient temperature whereas Amines HPX-87H column for best performance could only operate at low temperatures.…”