Silicon carbide (SiC) membranes in œnology

In a winery, clarification and stabilization steps by crossflow microfiltration are limited by fouling phenomenon which reduces production flows and can alter the aromatic potential of wines, forcing professionals to use several successive filtration steps. The objectives of this industrial-scale study are to (i) introduce SiC membranes at different vinification steps (ii) evaluate the hydraulic and retention performances of SiC membranes and (iii) carry out a comparative study between SiC membranes and polymeric hollow fibers commonly used in the wine industry. It appears that SiC membranes are able to filter diverse matrices with very satisfactory production flow and retention efficiency. This particular process was optimized by developing an efficient regeneration protocol. The clarification and stabilization of the matrices by SiC membranes allowed (i) the production of clear and brilliant wines, (ii) the retention of wine microorganisms, (iii) higher production flows than hollow fibers, while conserving wines interest compounds, (iv) and the filtration of matrices that cannot be processed by hollow fibers

Computational fluid dynamics applied to membranes: State of the art and opportunities

International audienceMembrane filtration has become firmly established as a primary technology for ensuring the purity, safety and/or efficiency of the treatmentof water or effluents. In this paper, we review the improvements that have been achieved concerning the membranes used for microfiltration,ultrafiltration, nanofiltration/reverse osmosis processes during the last decades. More especially, we review the state of the art computational fluid dynamics (CFD) methods applied to membranes processes. Many studies have focused on the best ways of using a particular membrane process.But, the design of new membrane systems requires a considerable amount of process development as well as robust methods. Computational fluiddynamics may provide a lot of interesting information for the development of membrane processes. We review the different ways in which CFDmethods are used to improve membrane performance

Simplified CFD approach of a hollow fiber ultrafiltration system

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Caractérisation de membranes poreuses par techniques optiques

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Optimizing the compacity of ceramic membranes

International audienceThe aim of this study is to increase exchange area or specific area of the membrane unit containing the ceramic membranes in order to achieve a compacity of over 330 m2/m3. Several configurations were studied by varying parameters like the diameter, membrane geometry, and the form of channels (cylindrical, square-section, triangular, hexagonal, etc.). Taking manufacturing constraints into account, several optimized geometries were described, thus allowing the optimization of the filtration area for each module. In this way, membrane compacity was significantly improved. Therefore a substantial increase in the permeate flux was expected and it was important to verify the capacity of the porous media to evacuate such permeate flux. Computational fluid dynamics analysis was used to simulate permeate evacuation as well as the flow-rate of each individual channel in the monolith. The optimal geometries could then be determined as a function of this permeate flow-rate and/or cut-off threshold. The experimental results obtained with water were in good agreement with those obtained by numerical simulation

Ferry oily wastewater treatment

International audienceOver the last decade, membrane filtration has appeared as a rentable and a powerful process for purifying large volumes of wastewater (mostly in the form of bilge water and ballast water) generated by naval and commercial vessels. Ceramic membranes with high resistance to extreme conditions can treat more and more effluents. The aim of this paper is to develop an industrial process that can separate hydrocarbon (HC) from oily wastewater using a membrane process. The purpose is to produce a treated water stream suitable to be discharged in the sea and to reduce the volume of waste stream which must be subsequently treated either onboard or onshore. The separation is accomplished by the combination of a decantation–flotation step and an ultrafiltration step. We have studied the effect of pre-treatment and operating conditions (transmembrane pressure, temperature, oily wastewater concentration, etc.). Having tested several ceramic membranes from the laboratory scale, the process was scaled up and ran in two ferries, with a 300-kDa membrane composed of 19 channels. The process is economically and environmentally attractive: (i) it reduces by a factor of 6 the volume of effluents to be treated onshore, (ii) it rejects a very low HC concentrated (less than 1 ppm) effluent that respects nowdays and future environmental standards, (iii) the regeneration of the membrane is effective after each treatment, (iv) the permeate flux can reach 100 L h−1 m−2 bar−1 and it is possible to produce more than 1500 L h−1 of purified water, (v) it is possible to treat in continuous. This process “Klearsep” has obtained the United States Coast Guard (162050/9051/0), the International Maritime Organisation (IMO MEPC 107 49) and the European (19353/AO EC) accreditations. 7 ferries are equipped with this new process

Application de membranes en carbure de silicium (SiC) à la filtration du vin

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Study of the Effect of Geometry on Wall Shear Stress and Permeate Flux for Ceramic Membranes: CFD and Experimental Approaches

International audienceKnowing how wall shear stress develops at the membrane surface is extremely useful when trying to reduce concentration polarization and fouling. Newly developed as well as manufactured ceramic membranes exhibit various channel geometries (cylindrical, square, triangular, etc). Mass transport characteristics depend on the geometry that conditions hydrodynamic conditions. The goal of this work is to study the influence of the channel geometry on the wall shear stress for various operating parameters (tangential velocity, transmembrane pressure…). Numerical simulations are performed for various inlet velocities for different channel geometries. The wall shear stress along the channel perimeter as a function of the shape and the cross section of the channel are studied. The influence of the geometry on the membrane performances is also studied. The simulated shear stress is employed to correlate experimental results. The results of this comparison show that mass transfer resistance depends on the wall shear stress alone, regardless of the flow rate, the shape or section of the channels

Extraction and purification of high added value compounds from by-products of the winemaking chain using alternative/nonconventional processes/technologies

Grape byproducts are today considered as a cheap source of valuable compounds since existent technologies allow the recovery of target compounds and their recycling. The goal of the current article is to explore the different recovery stages used by both conventional and alternative techniques and processes. Alternative pre-treatments techniques reviewed are: ultrasounds, pulsed electric fields and high voltage discharges. In addition, nonconventional solvent extraction under high pressure, specifically, supercritical fluid extraction and subcritical water extraction are discussed. Finally alternative purification technologies, for example membrane processing were also examined. The intent is to describe the mechanisms involved by these alternative technologies and to summarize the work done on the improvement of the extraction process of phenolic compounds from winery by-products. With a focus on the developmental stage of each technology, highlighting the research need and challenges to be overcome for an industrial implementation of these unitary operations in the overall extraction process. A critical comparison of conventional and alternative techniques will be reviewed for ethe pre-treatment of raw material, the diffusion of polyphenols and the purification of these high added value compounds. This review intends to give the reader some key answers (costs, advantages, drawbacks) to help in the choice of alternative technologies for extraction purposes

Characterization and application of silicon carbide (SiC) membranes to oenology

International audienc