Pressure fields in an industrial UF module: effect of backwash

International audienceno abstrac

Determination of Pressure and Velocity in a Dead-End Inside-Out Membrane Module Used in Drinking Water Production

International audienceno abstrac

Pressure fields in an industrial UF module: effect of backwash

International audienceIn the last decade, membrane manufacturers have improved their ultrafiltration module to raise the production of drinking water in order to meet an increasing demand. The usual process used is an inside-out filtration in dead-end mode. In this configuration, the energy consumption is limited by outside-in backwashes. Raising the permeability of the membranes lead to an increase in module compactness and strongly modify the driving force in the module. This study presents a computational fluid dynamics (CFD) model to predict the pressure and velocity field in the hollow fiber network (HFN) taking into account several parameters as the geometry of the module, the inlet pressure, gravity, and temperature. For the industrial tested module configuration, results shown that hollow fibers work in a homogeneous way in filtration mode but a great heterogeneity appear during the backwash. All the results have been validated compared with experimental values

Combining a Commercial Mixer with a Wall-Tube Electrode Allows the Arbitrary Control of Concentrations in Protein Film Electrochemistry

Protein film electrochemistry is a technique in which an enzyme is immobilized on an electrode in a configuration that allows following the changes in turnover frequency as a response to changes in the experimental conditions. Insights into the reactivity of the enzyme can be obtained by quantitatively modeling such responses. As a consequence, the more the technique allows flexibility in changing conditions, the more useful it becomes. The most commonly used setup, based on the rotating disc electrode, allows easy stepwise increases in the concentration of nongaseous substrates, or exposure to constant concentration of dissolved gas, but does not permit to easily decrease the concentration of nongaseous substrates, or to change the concentration of dissolved gas in a stepwise fashion. To overcome the limitation by mass transport of the substrate toward the electrode when working with fast enzymes, we have designed another kind of electrochemical cell based on the wall-tube electrode (WTE). We demonstrate here that by using a system combining two syringe pumps, a commercial mixer, and the WTE, it is possible to change the concentration of species in a stepwise fashion in all directions, opening new possibilities to study redox enzymes. As a proof of concept, this device was applied to the study of the electrochemical response of the cytochrome c nitrite reductase of Desulfovibrio desulfuricans