Development of a compartment model based on CFD simulations for mixing description in bioreactors

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(2), 517-522

Understanding and modelling the complex interactions between biological reaction and hydrodynamics is a key problem when dealing with bioprocesses. It is fundamental to be able to accurately predict the ... [more ▼]

Understanding and modelling the complex interactions between biological reaction and hydrodynamics is a key problem when dealing with bioprocesses. It is fundamental to be able to accurately predict the hydrodynamics behaviour of bioreactors of different size and its interaction with the biological reaction. CFD can provide detailed modelling about hydrodynamics and mixing. However, it is computationally intensive, especially when reactions are taken into account. Another way to predict hydrodynamics is the use of "Compartment" or "Multi-zone" model which are much less demanding in computation time than CFD. However, compartments and fluxes between them are often defined by considering global quantities not representative of the flow. To overcome the limitations of these two methods, a solution is to combine compartment modelling and CFD simulations. Therefore, the aim of this study is to develop a methodology in order to propose a compartment model based on CFD simulations of a bioreactor. The flow rate between two compartments can be easily computed from the velocity fields obtained by CFD. The difficulty lies in the definition of the zones in such a way they can be considered as perfectly mixed. The creation of the model compartments from CFD cells can be achieved manually or automatically. The manual zoning consists in aggregating CFD cells according to the user's wish. The automatic zoning defines compartments as regions within which the value of one or several properties are uniform with respect to a given tolerance. Both manual and automatic zoning methods have been developed and compared by simulating the mixing of an inert scalar. For the automatic zoning, several algorithms and different flow properties have been tested as criteria for the compartment creation. [less ▲]

Trehalose as a stress marker of the physiological impact of mixing on yeast production: scale-down reactors and mini-bioreactors investigations

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14

Evaluation of a set of E.coli reporter strains as a physiological tracer for the monitoring of the bioreactor hydrodynamic efficiency

Conference (2009, October 14)

Development of an original approach to evaluate effects of surfactants, biomass and pollutants on the scaling-up of a two-phase partitioning bioreactor.

Poster (2009)

CFD-based Compartment model for the description of the heterogeneities experienced by microorganisms in bioreactors

Poster (2009)

Effect of surfactants and biomass on the gas/liquid mass transfer in an aqueous-silicone oil two-phase partitioning bioreactor using Rhodococcus erythropolis T902.1 to remove VOCs from gaseous effluents

in Journal of Chemical Technology & Biotechnology (2009), 84

BACKGROUND: The two-phase partitioning bioreactor (TPPB) has become a new strategy in the context of waste gas treatment. However, the impact of biomass and surfactants on gas/liquid (G/L) mass transfer ... [more ▼]

BACKGROUND: The two-phase partitioning bioreactor (TPPB) has become a new strategy in the context of waste gas treatment. However, the impact of biomass and surfactants on gas/liquid (G/L) mass transfer needs to be better evaluated because the impact of these factors on the mass transfer coefficient “ ” and the interfacial area “ ”, respectively, remains misunderstood. RESULTS: Our study showed that, firstly, the surfactant extract produced by Rhodococcus erythropolis reduced the surface hydrophobicity of the biomass. Secondly, an optimal concentration appeared to exist for both of the components, respectively 0.5 g.L-1 and 0.7 g.L-1 for biomass (B) and surfactant extract (SE) when the global mass transfer coefficient ( ) of oxygen was measured in a silicone oil/water TPPB. However, the combination of B and SE was found to induce a negative synergism. In particular, SE improved the interfacial area “ ” by increasing the bubble diameter, while B reduced it as soon as a concentration of 1g.L-1 was exceeded. By contrast, the SE acted negatively on the , while B improved it overall. CONCLUSION: Better consideration is needed of the effect of biotic components in order to understand the phenomenon of G/L mass transfer in a TPPB. The behaviour of biomass growth and surfactants may strongly influence the mathematical models suggested in the literature. [less ▲]

Physiological response of yeast to process perturbations : a mini bioreactor approach

in New Biotechnology (2009), 255

Développement d'une méthode d'analyse de l'expression génique par PCR en temps réel pour l'étude de la production de lipases par Yarrowia lipolytica

Conference (2008, October 26)

Investigation of the effect of different extracellular factors on the lipase production by Yarrowia lipolityca on the basis of a scale-down approach

in JOURNAL OF INDUSTRIAL MICROBIOLOGY & BIOTECHNOLOGY (2008), 35(9), 1053-1059

The influence of three extracellular factors (namely, the methyl oleate dispersion in the broth, the dissolved oxygen variations, and the pH fluctuation) on the lipase production by Y. lipolytica in batch ... [more ▼]

The influence of three extracellular factors (namely, the methyl oleate dispersion in the broth, the dissolved oxygen variations, and the pH fluctuation) on the lipase production by Y. lipolytica in batch bioreactor has been investigated in different scale-down apparatus. These systems allow to reproduce the hydrodynamic phenomena encountered in large-scale equipments for the three specified factors. The effects of the extracellular factors have been observed at three distinct levels: the microbial growth, the extracellular lipase production, and the induction of the gene LIP2 encoding for the main lipase of Y. lipolytica. Among the set of environmental factors investigated, the dissolved oxygen fluctuations generated in a controlled scale-down reactor (C-SDR) have led to the more pronounced physiological effect by decreasing the LIP2 gene expression level. The other environmental factors observed in a partitioned scale-down reactor, i.e., the methyl oleate dispersion and the pH fluctuations, have led to a less severe stress traduced only by a decrease of the microbial yield and thus of the extracellular lipase specific production rate. [less ▲]

Environnemental oscillations occurring in small and large-scale bioreactors during an Escherichia coli BL 21 fed-batch culture

Poster (2008, May)