Two-phase mass transfer coefficient prediction in stirred vessel with a CFD model

Dynamic Single-Use Bioreactors Used in Modern Liter- and m(3)- Scale Biotechnological Processes: Engineering Characteristics and Scaling Up

During the past 10 years, single-use bioreactors have been well accepted in modern biopharmaceutical production processes targeting high-value products. Up to now, such processes have mainly been small- or medium-scale mammalian cell culture-based seed inoculum, vaccine or antibody productions. However, recently first attempts have been made to modify existing single-use bioreactors for the cultivation of plant cells and tissue cultures, and microorganisms. This has even led to the development of new single-use bioreactor types. Moreover, due to safety issues it has become clear that single-use bioreactors are the "must have" for expanding human stem cells delivering cell therapeutics, the biopharmaceuticals of the next generation. So it comes as no surprise that numerous different dynamic single-use bioreactor types, which are suitable for a wide range of applications, already dominate the market today. Bioreactor working principles, main applications, and bioengineering data are presented in this review, based on a current overview of greater than milliliter-scale, commercially available, dynamic single-use bioreactors. The focus is on stirred versions, which are omnipresent in R&D and manufacturing, and in particular Sartorius Stedim's BIOSTAT family. Finally, we examine development trends for single-use bioreactors, after discussing proven approaches for fast scaling-up processes.

Investigating the effect of sparger configuration on the hydrodynamics of a full-scale membrane bioreactor using computational fluid dynamics

A three-phase computational fluid dynamics (CFD) simulation was carried out in a full-scale membrane bioreactor to investigate the effect of sparger configuration on various hydrodynamic parameters.

Challenges in industrial fermentation technology research

Industrial fermentation processes are increasingly popular, and are considered an important technological asset for reducing our dependence on chemicals and products produced from fossil fuels. However, despite their increasing popularity, fermentation processes have not yet reached the same maturity as traditional chemical processes, particularly when it comes to using engineering tools such as mathematical models and optimization techniques. This perspective starts with a brief overview of these engineering tools. However, the main focus is on a description of some of the most important engineering challenges: scaling up and scaling down fermentation processes, the influence of morphology on broth rheology and mass transfer, and establishing novel sensors to measure and control insightful process parameters. The greatest emphasis is on the challenges posed by filamentous fungi, because of their wide applications as cell factories and therefore their relevance in a White Biotechnology context. Computational fluid dynamics (CFD) is introduced as a promising tool that can be used to support the scaling up and scaling down of bioreactors, and for studying mixing and the potential occurrence of gradients in a tank.

A novel airlift reactor enhanced by funnel internals and hydrodynamics prediction by the CFD method

Airlift reactors have been used widely in many industrial processes, but little work has been conducted on such reactors integrated with internals. In this study, a novel airlift reactor with a funnel internal was developed to achieve better flow conditions and advantages in biological processes. The CFD (computational fluid dynamics) simulation method was employed to investigate the effect of the funnel internals on hydrodynamic properties in the reactor. A CFD model was developed for gas-liquid two-phase flow simulation in a bench-scale reactor. Grid-independent simulation results were verified with global-scale experimental data. The results showed that the local or global gas holdup could be enhanced by 15% and that turbulent kinetic energy could be reduced by a maximum of 7.8% when the superficial gas velocity was 1 cm/s. These features are beneficial for applications in stress-sensitive biological processes.

Drawdown of floating solids in stirred tanks: scale-up study using CFD modeling

This work shows development of a scale up correlation using computational fluid dynamic (CFD) simulations for floating solids drawdown operation in stirred tanks. Discrete phase modeling (DPM) simulations were used in conjunction with the lab scale experimental measurements to develop a semi-empirical correlation for the prediction of rate of drawdown of floating solid particles. The rate was correlated to average liquid velocity at the free liquid surface. Since, this correlation is based on a fundamental hydrodynamic parameter, velocity, rather than an operating parameters such as the impeller speed, it can be used for a variety of impeller types and tank geometries. The correlation was developed based on the data obtained from the 2L tank using four different tank designs and was validated against the data obtained from the 10L scale tank. The correlation was further extended to the pilot and the commercial scale tanks ranging from 40L to 4000L scale based solely on the CFD model.