Béatrice Balannec - Academia.edu (original) (raw)

Papers by Béatrice Balannec

Food Technology and Biotechnology, 2011

To describe a microbial process, two kinds of models can be developed, structured and unstructure... more To describe a microbial process, two kinds of models can be developed, structured and unstructured models. Contrary to structured models, which take into account some basic aspects of cell structure, their function and composition, no physiological characterization of cells is considered in unstructured models, which only consider total cellular concentration. However, in spite of their simplicity, unstructured models have proven to accurately describe lactic acid fermentation in a wide range of experimental conditions and media. A partial link between cell growth and production, namely the Luedeking and Piret model, is mostly considered by the authors. Culture pH is the main parameter to be considered for model development. Acidic pH leads to inhibitory concentrations of undissociated lactic acid, the main inhibitory component, which causes cessation of growth and then production. On the other hand, pH control at optimal value for LAB growth allows to overcome product inhibition (b...

In the recent year’s one can observe a growing interest in lactic acid production, which plays an... more In the recent year’s one can observe a growing interest in lactic acid production, which plays an important role in various applications in food, pharmaceutical and textiles industries More recently, lactic acid fermentation has received much attention because of an increasing demand for new bioengineering materials such as biodegradable polymers and the recent rise in the cost of petroleum, which is usually used as feed stock for production of lactic acid in conventional chemical processes. For a better understanding of the fermentation process and its optimization, a model is of a great help. Owing to the complexity of structured models, unstructured models can be preferred and have proven to accurately describe lactic acid fermentation in a wide range of experimental conditions and media. The aim of this work was to develop an unstructured model based on the experimental results of lactic acid fermentation using Lactobacillus helveticus growing on whey permeate supplementation. T...

The building sector accounts for 40% of the world’s energy consumption especially for air-conditi... more The building sector accounts for 40% of the world’s energy consumption especially for air-conditioning and refrigeration. Furthermore, cold production is associated with hot air flowing out of the condensers responsible for the urban heat island effect. The proximity of buildings and their cooling equipment creates hot outdoor environment provoking higher cooling needs and lower performance of the air-conditioners. This waste heat might be used for fresh-water production using membrane distillation. The objective of this study is thus to couple an AGMD unit with a heat pump for the simultaneous production of cold and fresh water by desalination. The work presented here deals with the experimental characterization of an AGMD pilot plant with a view to its coupling with a heat pump. Based on the experimental results a model was developed to predict AGMD performance. The experimental work was focused on operating conditions compatible with the use of a heat pump to heat the feed water....

La croissance demographique mondiale entraine une augmentation des besoins en froid commercial et... more La croissance demographique mondiale entraine une augmentation des besoins en froid commercial et domestique, en rafraichissement ou climatisation ainsi qu’en eau potable. Dans l'objectif d’un developpement social et industriel durable, il apparait indispensable pour certaines populations, en particulier dans les sites isoles, que de nouveaux systemes economes en energie pour la production d'eau potable soient developpes. L’objectif general est de coupler une thermofrigopompe (TFP) a une unite de distillation membranaire pour la production de froid et le dessalement de l’eau de mer (figure 1). La technique utilisee pour le dessalement est l’AGMD, air gap membrane distillation. C’est un procede thermique et membranaire (figure 2) base sur la creation d’un gradient de pression de vapeur genere par un gradient de temperature de part et d’autre d’une membrane microporeuse hydrophobe. Une etude de caracterisation experimentale de l’AGMD est effectuee sur une installation pilote. ...

Thanks to its unique features, membrane distillation (MD) has been particularly applied for desal... more Thanks to its unique features, membrane distillation (MD) has been particularly applied for desalination but also for niches applications with feed solutions containing a mixture of volatile molecules. For such solutions, the complex interplay of the solutes and solvent physicochemical and operating parameters makes it challenging to predict the separation efficiency by MD. There is thus a need for a better understanding of the behavior of volatile compounds in MD as well as the influence of their physicochemical environment. This study aimed at investigating the influence of different operating parameters on rejection efficiency of air-gap MD towards carboxylic acids (formic, acetic and succinic acids). Acid rejection was found to be highly dependent on the carboxylic acid structure. In addition, it increased with the acid concentration, which could be related to the formation of acid dimers in the feed solution. This behavior is opposite to what is classically observed for pressur...

Chemical Engineering Science, 2018

Separation and Purification Technology, 2018

Journal of Membrane Science, 2018

Industries Alimentaires Et Agricoles, 2002

Les eaux de procedes de l'industrie laitiere, generees par les phases de demarrage, d'equ... more Les eaux de procedes de l'industrie laitiere, generees par les phases de demarrage, d'equilibrage, d'interruption et d'arret des equipements contribuent significativement aux pertes non accidentelles de matiere premiere, a la consommation d'eau et a la production d'eaux residuaires. Le traitement de ces effluents a la source permettrait de valoriser les composants du lait recuperes et de produire une eau reutilisable pour des usages specifiques. Les separations a membranes, osmose inverse (OI) et nanofiltration (NF) en particulier, sont des operations pertinentes pour traiter ces effluents. Une etude comparative des performances (permeabilite, selectivite) de differentes membranes (01 et NF) est realisee en filtration frontale sur un effluent laitier modele. Des experimentations en OI tangentielle sont realisees pour valider les resultats obtenus et determiner l'influence des conditions operatoires (FRV, vitesse d'ecoulement tangentiel, pression transmembranaire).

Http Www Theses Fr, 1992

L'objectif de ce travail est de mettre au point et de qualifier un modele de simulation de l&... more L'objectif de ce travail est de mettre au point et de qualifier un modele de simulation de l'adsorption en contre-courant simule, applique a la separation du paraxylene des hydrocarbures en c8 aromatiques. La separation par adsorption en contre-courant simule est une technique complexe derivee de la chromatographie en phase liquide. Deux types de modeles de chromatographie en phase liquide sont donc tout d'abord elabores: ils prennent en compte la dispersion axiale, et l'equilibre phase liquide-phase adsorbee est decrit par des selectivites binaires constantes. Dans le premier modele a etages theoriques l'hypothese de l'equilibre local instantane est faite. Par contre, le second modele de type continu (avec resolution des equations aux derivees partielles par la methode des differences finies) integre une cinetique de diffusion entre la phase liquide interstitielle et la phase liquide presente dans la macro-mesoporosite de la zeolithe. Le modele du contre-courant simule, avec permutation periodique des points d'introduction-prelevement des fluides, est realise sur la base du premier modele a etages theoriques; il permet de decrire le regime transitoire ainsi que le regime pseudo-stationnaire atteint. Trois techniques experimentales sont mises en uvre pour quantifier l'importance relative des differents phenomenes mis en jeu, caler les differents parametres des modeles et tester leur capacite predictive: un dispositif de mesure des equilibres d'adsorption, un montage de chromatographie frontale et un pilote de separation du paraxylene par adsorption en contre-courant simule. Le modele du contre-courant simule a permis d'etudier la sensibilite des performances du procede aux parametres physiques et aux variables operatoires et de tester une variante du schema de procede

The Journal of Physical Chemistry B, 2010

Separation and Purification Technology, 2011

CFD simulation was carried out with the aim to improve the design of a bench-scale nanofiltration... more CFD simulation was carried out with the aim to improve the design of a bench-scale nanofiltration cell and to increase the filtration performances. The laminar fluid flow in the flat circular filtration cell was simulated. Design variables considered were feed chamber thickness, number and distribution of the inlet/outlet pipes, sequential mode inlets, addition of grooves on the top surface of the cell. With the simulated design modifications, the velocity and the wall shear stress could be sharply increased and the size of the recirculation areas could be lowered. Two sequential mode inlets permitted to obtain high velocity and wall shear stress fluctuations in the cell. So, one can expect a sweeping of the membrane surface which should greatly hinder the polarization layer development and membrane fouling. A sharp enhancement of the nanofiltration flux was observed experimentally with the new designed cell, built including the suggested modifications. The addition of grooves on the cell top was simulated and showed intense velocity and wall shear stress fluctuations. The 2D study demonstrated that the groove size and the groove interval play a significant role. So, for small bench-scale cells when the use of retentate spacers is not convenient, the alternative would be to add grooves opposite to the membrane side in order to create velocity fluctuations.

Process Biochemistry, 2009

Physical Review Letters, 2013

Journal of Membrane Science, 2011

Journal of Membrane Science, 2000

This study deals with the estimation of rejection coefficient for small non-charged molecules in ... more This study deals with the estimation of rejection coefficient for small non-charged molecules in an aqueous solution, with reverse osmosis and ultrafiltration membranes in a stirred and an unstirred cell. In a stirred cell with high stirring velocity, the concentration near the membrane is close to the bulk concentration. Rejection is, therefore, known with good precision. On the other hand,

Enzyme and Microbial Technology, 2007

ABSTRACT During lactic acid fermentation, seed cultures are usually carried out without pH contro... more ABSTRACT During lactic acid fermentation, seed cultures are usually carried out without pH control to obtain active cells, while cultures are usually carried out at pH maintained at the optimal value, 5.9, to overcome inhibitory effects. The Luedeking–Piret expression was therefore previously modified by introducing an additional term (i) involving the residual lactose concentration to account for the carbon substrate limitation, responsible for cessation of production during cultures at controlled pH, on one hand; (ii) or involving the undissociated form of the lactic acid, the main inhibitory species, in case of an absence of pH control, namely the usual seed culture conditions, on the other hand. To avoid the use of two different expressions, depending on the culture conditions, a generalised model for production was developed, involving a unique expression taking into account both a nutritional limitation and an inhibitory effect. The nutritional limitation term was modified by introducing the carbon limitation constant, in place of the residual lactose concentration, which varied in absence of pH control, namely in absence of carbon limitation. The model proved to be satisfactory in a large range of culture conditions; and also allow to deduce accurately the growth- and non-growth-associated parts of the production.