title: Hydrodynamic characteristics of immobilized cell beads in a liquid-solid fluidized-bed bioreactor.
abstract: This study examined the hydrodynamic characteristics of a liquid-solid fluidized-bed bioreactor using elastic particles (PVA gel beads) of various diameters as carriers. The drag coefficient-Reynolds number, velocity-voidage, and expansion index-Reynolds number relationships observed during fluidization of PVA gel beads in a fluidized bed in our experiments were compared with the published results. Predictions made from previous correlations were examined with our new experimental findings, revealing the inadequacy of most of these correlations. Thus, new correlations describing the above-mentioned relationships are suggested. The drag coefficient of immobilized cell beads is larger than that of free cell ones at the same Reynolds number because the surface of the immobilized cell beads is rougher. For multiparticle systems, the correction factor, f(epsilon), is a function of the falling gel bead properties (Reynolds number) as well as the fluidized gel bead properties (Archimedes number), and depend strongly on the bed voidage (epsilon). A new simple relation was developed to predict easily the epsilon value from 0.5-0.9 at 4,986 < A(r) < 40,745 or 34 < Re(t) < 186. For all the immobilized cell beads used in this study, the prediction error of the bed voidage was less than 5% at epsilon > 0.5. The prediction equations in this study can be further applied to analyzing the hydrodynamic characteristics of a fluidized-bed reactor using similar entrapped elastic particles as carriers.
authors.affiliation: Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan 300, Republic of China. jywu@mx.nthu.edu.tw
authors.forename: Jane-Yii
authors.initials: JY
authors.lastname: Wu
authors.forename: Kuo-Cheng
authors.initials: KC
authors.lastname: Chen
authors.forename: Chun-Ting
authors.initials: CT
authors.lastname: Chen
authors.forename: Sz-Chwun John
authors.initials: SC
authors.lastname: Hwang
mesh_terms: D040981:Acinetobacter baumannii / Q000502:physiology / Q000648:ultrastructure; D016980:Aeromonas hydrophila / Q000502:physiology / Q000648:ultrastructure; D001422:Bacterial Adhesion / Q000502:physiology*; D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000379:methods*; D002465:Cell Movement / Q000502:physiology; D018914:Cells, Immobilized / Q000502:physiology; D020604:Comamonas testosteroni / Q000502:physiology / Q000648:ultrastructure; D003198:Computer Simulation; D006090:Gram-Negative Bacteria / Q000502:physiology* / Q000648:ultrastructure*; D044085:Microfluidics / Q000379:methods*; D008863:Microspheres; D008954:Models, Biological; D011142:Polyvinyl Alcohol; D013045:Species Specificity
chemical_list: D011142:Polyvinyl Alcohol