title: Enhancement of oxygen mass transfer and gas holdup using palm oil in stirred tank bioreactors with xanthan solutions as simulated viscous fermentation broths.
abstract: Volumetric mass transfer coefficient (kLa) is an important parameter in bioreactors handling viscous fermentations such as xanthan gum production, as it affects the reactor performance and productivity. Published literatures showed that adding an organic phase such as hydrocarbons or vegetable oil could increase the kLa. The present study opted for palm oil as the organic phase as it is plentiful in Malaysia. Experiments were carried out to study the effect of viscosity, gas holdup, and kLa on the xanthan solution with different palm oil fractions by varying the agitation rate and aeration rate in a 5 L bench-top bioreactor fitted with twin Rushton turbines. Results showed that 10% (v/v) of palm oil raised the kLa of xanthan solution by 1.5 to 3 folds with the highest kLa value of 84.44 h(-1). It was also found that palm oil increased the gas holdup and viscosity of the xanthan solution. The kLa values obtained as a function of power input, superficial gas velocity, and palm oil fraction were validated by two different empirical equations. Similarly, the gas holdup obtained as a function of power input and superficial gas velocity was validated by another empirical equation. All correlations were found to fit well with higher determination coefficients.
authors.affiliation: Faculty of Chemical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor, Malaysia.
authors.forename: Suhaila
authors.initials: S
authors.lastname: Mohd Sauid
authors.affiliation: Faculty of Chemical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor, Malaysia.
authors.forename: Jagannathan
authors.initials: J
authors.lastname: Krishnan
authors.affiliation: Faculty of Chemical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor, Malaysia.
authors.forename: Tan
authors.initials: T
authors.lastname: Huey Ling
authors.affiliation: Faculty of Chemical Engineering, Manipal International University, 71800 Nilai, Negeri Sembilan Darul Khusus, Malaysia.
authors.forename: Murthy V P S
authors.initials: MV
authors.lastname: Veluri
mesh_terms: D019149:Bioreactors; D003470:Culture Media / Q000378:metabolism*; D005285:Fermentation / Q000502:physiology*; D005740:Gases / Q000378:metabolism*; D008296:Malaysia; D008970:Molecular Weight; D010100:Oxygen / Q000378:metabolism*; D000073878:Palm Oil; D010938:Plant Oils / Q000378:metabolism*; D011135:Polysaccharides, Bacterial / Q000378:metabolism*; D012996:Solutions / Q000378:metabolism
chemical_list: D003470:Culture Media; D005740:Gases; D010938:Plant Oils; D011135:Polysaccharides, Bacterial; D012996:Solutions; D000073878:Palm Oil; D010100:Oxygen; C002563:xanthan gum