Dynamic modelling of an immobilized enzyme bioreactor

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Dynamic experiments provide an excellent means for the determination of crucial process parameters, such as the axial Peclet number, the intraparticle and external mass transfer coefficient and the intraparticle reaction rate constant, in fixed or liquid fluidized bed immobilized enzyme bioreactors. The absence of a complete and comprehensive solution of the model equations in the real time domain, as well as significant advances in the area of statistical mo­ments analysis has rendered the latter approach the dominant one for parameter estimation in fluid-solid reacting systems. Nevertheless, an efficient and easily implementable solution of the model equations in the real time domain, as opposed to the solution in the Laplace domain needed for the statistical moments analysis, opens new possibilities in the design of fixed or fluidized bed bioreactors since, apart from parameter estimation via dynamic experiments, it is suitable for simulation, optimization and control. This paper presents a dynamic model for a fixed or liquid fluid bed immobilized enzyme bioreactor, along with a novel method for the solu­tion of the coupled partial differential equations in the real time domain. Both, the tanks-in­series and the dispersion models have been used to describe the non ideal axial mixing in the reactor. The solution, in its final form, comes in both cases as a system of simultaneous ordi­nary differential equations; this is readily implementable on a computer and can be easily solved by commercially available software packages. Based on this solution, a complete parametric analysis was performed. That analysis revealed the importance of intraparticle and external mass transfer resistances, intraparticle chemical reactio?? and axial dispersion on the transient behaviour of the reactor. Most important, that analysis revealed ways for parameter estimation and system identification via simple dynamic experiments. The design and optimization implica­tions of the study are finally demonstrated by using the derived solution to simulate the perfor­mance of an immobilized urease bioreactor with a recycle loop. Such a configuration is charac­terized by time varying feed concentration and can be used, as part of an extracorporeal artificial kidney device, for the treatment of uremic patients.
Bibliography: p. 81-84.
Papathanasiou, A. (1987). Dynamic modelling of an immobilized enzyme bioreactor (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/11532