Introduction of nanofiltration in a production process of fermented organic acids

Nanofiltration in a production process of fermented organic acid

Investigation of nanofiltration as a purification step for lactic acid production processes based on conventional and bipolar electrodialysis operations

Nanofiltration was investigated for usability in a specific lactic acid production process based on conventional and bipolar electrodialysis operations. Industrial fluids, corresponding to two potential integration levels and coming from an existing installation, were investigated. The commercially available DK nanofiltration membrane was used and performances in terms of lactate/lactic acid recovery rate and purification efficiency are reported. Nanofiltration was able to efficiently remove magnesium and calcium ions from a sodium lactate fermentation broth before its concentration and conversion by electrodialysis (first potential integration level). Maximum impurities rejections and lactate recovery were obtained at maximum transmembrane pressures. Mg2+ and Ca2+ rejections were 64±7 and 72±7%, respectively and lactate recovery rate reached 25±2 molm−2 h−1 for P = 20 bar. Sulfate and phosphate ions were also partially removed from the broth (40% rejection). At the invert, chloride ions were negatively retained by the membrane and were consequently more concentrated in the permeate. Nanofiltration also led to a nearly total decolouration of the fermentation broth. On the other hand, sulfate and phosphate rejections obtained from the filtration of a converted broth containing the lactic acid under its neutral form (second potential integration level) were also satisfactory, i.e. 47±5 and 51±5%, respectively. High recovery rates were observed in that case, i.e. 48±2 molm−2 h−1 at 20 bar. It indicated that NF could also be used as final purification step in the process

Production processes of fermented organic acids targeted around membrane operations: design of the concentration step by conventional electrodialysis

Organic acids are increasingly used for various industrial applications. Their production is mainly achieved by fermentation. Precipitation or extraction stages, which generate big amount of effluents, are then traditionally used to get the acid in a suitable form. To lower the impact on the environment, the implementation of cleaner operations are investigated. In this context, a complete process targeted around membrane operations for clarification, concentration and conversionwas studied. The present paper is devoted to the study of the concentration step, carried out by conventional electrodialysis (EDC). A model, based on the description of the solute and solution fluxes through the membranes is developed. Dedicated procedures are proposed to determine the different contributions, i.e. electromigration and diffusion, to these fluxes so as to feed the model. This approach is then applied to the concentration of sodium lactate solutions. The preponderance of electromigration is thus demonstrated as well as the existence of a maximum achievable concentration, the predicted value of which is confirmed experimentally. Comparison between EDC of sodium and ammonium lactate solutions shows that the counter ion has negligible influence on the transport of lactate. The influence of the membrane characteristics is also drawn from comparison with previously published results. Finally, the predictions of the model are compared with the experimental results concerning the concentration of a fermentation broth and a good agreement is stated. The approach proposed in this paper can be used as well to design EDC concentration of any other organic acid salt than lactate

Ouaga 2007 : habiter, peupler, socialiser par les mobilités

Ce rapport dresse un panorama des mobilités et migrations qui traversent, forment et dynamisent Ouagadougou en 2007, date de l’enquête dont il présente les résultats. Il engage une observation des diverses mobilités formant la ville, observation qui sera actualisée en 2009 dans le cadre d’un projet plus large incluant d’autres capitales sahéliennes (Bamako, Niamey), avec la promesse de comparaisons instructives sur les évolutions urbaines de la sous-région. Dans cette étude, les migrations internationales sont centrales, mais elles sont replacées aux côtés des mouvements internes et des pratiques de multirésidence ou des migrations temporaires. En arrière-plan de l’analyse de ces mouvements, analyse déclinée selon l’âge, le sexe, l’éducation et le travail des individus, s’impose un questionnement sur les logiques de l’installation et du peuplement en ville. Dès lors, les migrations apparaissent comme une composante de la vulnérabilité urbaine, du caractère informel du travail. En effet, l’intensité des flux migratoires qui traversent et font la ville infléchit sa composition sociale et spatiale et ainsi son futur

Nanofiltratio of glucose and sodium lactate solutions Variations of retention between single- and mixed-solute solutions

The aim of this work was to investigate NF as a purificatio step, i.e. sugar removal, in the production process of lactic acid from sodium lactate fermentation broth. Experiments were carried out with the Desal 5 DK membrane and solutions of increasing complexity, i.e. single-solute solutions of sodium lactate and glucose and mixed-solute solutions containing both solutes. Concentrations close to those of a fermentation broth were chosen. Experimental results were used to get the variations of the intrinsic retention versus the permeation flu in order to achieve comparisons without the interference of concentration polarization. Quite distinct retentions were obtained for glucose and sodium lactate in single-solute solutions so that the purificatio was expected to be feasible. However, it is pointed out that glucose retention is significantl lower in mixed-solute solutions, i.e. when sodium lactate is present. This decrease is such that the retentions of both solutes become comparable so that any purificatio is unachievable. Experiments were also performed with a salt of a different nature (mineral salt, NaCl). Again, it was found that the presence of NaCl tends to decrease glucose retention. Moreover, the phenomenon is shown to be related to the salt concentration in both cases, i.e. with sodium lactate and NaCl. Some possible explanations of this effect are provided in this paper. Further investigations are still in progress to improve the knowledge of the mechanisms involved

The impact of step-down line extension on consumer-brand relationships: A risky strategy for luxury brands

This paper analyzes the role of the brand concept (luxury vs. non-luxury) in the impact of step-down line extension on consumer-brand relationships. A before-and-after pseudo-experimental study conducted on the Internet among BMW and Peugeot buyers shows that step-down line extension negatively influences the main variables of consumer-brand relationships (e.g., self-brand connections, brand attachment, brand trust and brand commitment) only for the luxury brand BMW. On the contrary, no dilution effects are found for the non-luxury brand Peugeot.vertical line extension, dilution effects; consumer-brand relationships;luxury brands; cars; PSL approach

Modelling of the conversion of weak organic acids by bipolar membrane electrodialysis

Organic acids are increasingly used for various industrial applications. Their production is mainly achieved by fermentation. Precipitation or extraction stages, which generates big amount of effluents, are then traditionally usedto get the acid in a suitable form. Bipolar membrane electrodia lysis (EDBM) can be used to achieve the conversion of the acid salt into its acidic form. Its introduction in replacement of precipitation can significantly lower the environmental impact of the process. This paper is focused on the modelling of the conversion of weak organic acid salts by EDBM The different mass transfer phenomena involved in the system are first identified. A model is then established to get expressions providing the evolution of the product and effluent lines with respect to the operating conditions. The physical meaning of the characteristic parameters involved in the model is also discussed

Influence of isothermal and cyclic oxidation on the apparent interfacial toughness in thermal barrier coating systems

In thermal barrier coatings (TBCs), the toughness relative to the interface lying either between the bond coat (BC) and the Thermal Grown Oxide (TGO) or between the TGO and the yttria stabilized zirconia topcoat (TP) is a critical parameter regarding TBCs durability. In this paper, the influence of aging conditions on the apparent interfacial toughness in Electron Beam-Physical Vapor Deposition (EB-PVD) TBCs is investigated using a specifically dedicated approach based on Interfacial Vickers Indentation (IVI), coupled with Scanning Electron Microscopy (SEM) observations to create interfacial cracks and measure the extent of crack propagation, respectively

Daptomycin > 6 mg/kg/day as salvage therapy in patients with complex bone and joint infection: cohort study in a regional reference center

Background: Even if daptomycin does not have approval for the treatment of bone and joint infections (BJI), the Infectious Diseases Society of America guidelines propose this antibiotic as alternative therapy for prosthetic joint infection. The recommended dose is 6 mg/kg/d, whereas recent data support the use of higher doses in these patients.Methods: We performed a cohort study including consecutive patients that have received daptomycin >6 mg/kg/d for complex BJI between 2011 and 2013 in a French regional reference center. Factors associated with treatment failure were determined on univariate Cox analysis and Kaplan-Meier curves.Results: Forty-three patients (age, 61 ± 17 years) received a mean dose of 8 ± 0.9 mg/kg/d daptomycin, for a mean 81 ± 59 days (range, 6-303 days). Most had chronic (n = 37, 86 %) implant-associated (n = 37, 86 %) BJI caused by coagulasenegative staphylococci (n = 32, 74 %). A severe adverse event (SAE) occurred in 6 patients (14 %), including 2 cases of eosinophilic pneumonia, concomitant with daptomycin Cmin >24 mg/L. Outcome was favorable in 30 (77 %) of the 39 clinically assessable patients. Predictors for treatment failure were age, non-optimal surgery and daptomycin withdrawal for SAE.Conclusions: Prolonged high-dose daptomycin therapy was effective in patients with complex BJI. However, optimal surgery remains the cornerstone of medico-surgical strategy; and a higher incidence of eosinophilic pneumonia than expected was recorded