A Comparison of Mass Transfer Coefficients between Rotating Magnetic Field Mixer and Stirred Tank Reactor

The mass transfer process is the subject of many experimental studies in chemical engineering and also one of the most commonly used processes. Unfortunately, the mechanism of this process is still not fully understood, especially when nonstandard methods of intensification of mass transfer are used. In this investigation, the use of an alternating magnetic field action (AMFs) causing mass transfer was taking into consideration. As a result of the flow of electrically conductive fluid near the alternating magnetic field, electromagnetic forces can be generated within the liquid. These forces arise as a result of interaction between the magnetic field and the electric current. They are responsible for the rotation and consequently cause movement of the fluid on which they act. Therefore, there is the possibility of using these properties in the construction of a nonintrusive mixing stirrer

Analysis of a mixing process induced by a rotating magnetic field by means of the dimensional analysis

The main objective of this work is to study the effect of rotating magnetic field (RMF) on the hydrodynamic conditions in the mixed liquid. The dimensional analysis of Navier-Stokes equations including the Lorenz force allows describing the analyzed process by using the relationships basing on the dimensionless numbers. The comparison between the obtained results and the experimental investigations is carried out. It was found a strong correlation between the velocity field and the magnetic induction or electrical conductivity of fluid

Application of Magnetically Assisted Reactors for Modulation of Growth and Pyocyanin Production by Pseudomonas aeruginosa

Pseudomonas aeruginosa is a producer of desired secondary metabolites, including pyocyanin. Potential uses of this pigment urge a search for improved production methods. Recent trends in bioprocessing show the potential of the use of electromagnetic fields (EMFs) to influence the growth of microorganisms and even modulate the concentration of bioproducts. Here, we aimed at assessing the influence of rotating magnetic field (RMF) and static magnetic field (SMF) on pyocyanin production, growth rate, and respiration of P. aeruginosa. Moreover, exposure time to EMFs (2, 6, and 12 h) and culture volume (10 and 50 ml) were initially assessed. P. aeruginosa was cultivated in magnetically assisted reactors with 5 and 50 Hz RMF (magnetic induction of 24.32 and 42.64 mT, respectively) and SMF (−17.37 mT). Growth kinetics was assessed with Gompertz equation. The viability was tested using resazurin assay, whereas pyocyanin production by chloroform-HCl methodology. The growth of P. aeruginosa was slightly stimulated by exposure to a RMF with 50 Hz (108% related to the control) and significantly by SMF (132% related to the control), while RMF 5 Hz exposure prolonged the time of inflection (in comparison to RMF 50 Hz and SMF). The 6-h exposure to EMFs resulted in the highest pyocyanin production in comparison to the control, indicating a relationship between exposure time and product concentration. Moreover, cultures led in smaller volumes produced more pyocyanin. Our findings show that the use of different EMF types, frequency, and exposition time and volume could be used interchangeably to obtain different bioprocess aims

Single Mathematical Parameter for Evaluation of the Microorganisms’ Growth as the Objective Function in the Optimization by the DOE Techniques

The cultivation of bacteria sets a ground for studying biological processes in many scientific disciplines. The development of the bacterial population is commonly described with three factors that can be used to evaluate culture conditions. However, selecting only one of them for the optimization protocol is rather problematic and may lead to unintended errors. Therefore, we proposed a novel mathematical approach to obtain a single factor that could be used as the objective function to evaluate the whole growth dynamic and support the optimization of the biomass production process. The sigmoidal-shape curve, which is the commonly used function to plot the amount of biomass versus time, was the base for the mathematical analysis. The key process parameters, such as maximal specific growth rate and lag-phase duration were established with the use of mathematical coefficients of the model curve and combined to create the single growth parameter. Moreover, this parameter was used for the exemplary optimization of the cultivation conditions of Klebsiella pneumoniae that was cultured to be further used in the production of lytic bacteriophages. The proposed growth parameter was successfully validated and used to calculate the optimal process temperature of the selected bacterial strain. The obtained results indicated that the proposed mathematical approach could be effortlessly adapted for a precise evaluation of growth curves.DFG, 248198858, GRK 2032: Grenzzonen in urbanen Wassersysteme

Hydrodynamics and Mass Transfer Analysis in BioFlow® Bioreactor Systems

Biotechnological processes involving the presence of microorganisms are realized by using various types of stirred tanks or laboratory-scale dual-impeller commercial bioreactor. Hydrodynamics and mass transfer rate are crucial parameters describing the functionality and efficiency of bioreactors. Both parameters strictly depend on mixing applied during bioprocesses conducted in bioreactors. Establishing optimum hydrodynamics conditions for the realized process with microorganisms maximizes the yield of desired products. Therefore, our main objective was to analyze and define the main operational hydrodynamic parameters (including flow field, power consumption, mixing time, and mixing energy) and mass transfer process (in this case, gas–liquid transfer) of two different commercial bioreactors (BioFlo® 115 and BioFlo® 415). The obtained results are allowed using mathematical relationships to describe the analyzed processes that can be used to predict the mixing process and mass transfer ratio in BioFlo® bioreactors. The proposed correlations may be applied for the design of a scaled-up or scaled-down bioreactors