Etude du colmatage dans un bioréacteur membranaire à recirculation externe utilisé en nitrification partielle

in Proceedings of MEMPRO 3 - Intégration des membranes dans les procédés (2006)

Gas-liquid mass transfer in a circulating jet-loop nitrifying MBR

in Chemical Engineering Science (2005), 60(22 Sp. Iss. SI), 6346-6353

Based on airlift configuration, a novel circulating jet-loop submerged membrane bioreactor (JLMBR) adapted to ammonium partial oxidation has been developed. Membrane technology and combined air and water ... [more ▼]

Based on airlift configuration, a novel circulating jet-loop submerged membrane bioreactor (JLMBR) adapted to ammonium partial oxidation has been developed. Membrane technology and combined air and water forced circulation are adopted to obtain a high biomass retention time and to achieve a separate control of mixing and aeration. This study is intended to determine how gas-liquid mass transfer is affected by operating conditions. In a first approximation, liquid was assumed to be perfectly mixed. A classical non-steady state clean water test, known as the "gas out-gas in" method, was used to determine the gas-liquid mass transfer coefficient k(L)a. Air and recirculated liquid superficial velocities were gradually increased from 0.013 to 0.019m s(-1) and 0.0056 to 0.011 m s(-1), respectively. Subsequently, the gas-liquid mass transfer coefficient kLa varied from 0.01 to 0.02 s(-1). It appears to be influenced by the combined action of air and recirculated liquid flowrates in the range 0.72-1.03N m(3) h(-1) and 0.30-0.58 m(3) h(-1), respectively, for air and liquid. Correlations are proposed to describe this double influence. Experiments were performed on tap water and a culture medium used for the autotrophic growth of nitrifying bacteria, respectively. Oxygen transfer appeared to be not significantly affected by the mineral salt (0.48 g 1(-1)) encountered in this medium. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

Imaging of liquid distribution in reactive distillation packings with a new high-energy x-ray tomograph

in Measurement Science & Technology (2005), 16(11), 2213-2220

We describe a new, high-energy (420 kV), large-scale (0.45 m in diameter, 4 m in height) x-ray tomograph developed to investigate gas and liquid flow through fixed bed like absorption, distillation and ... [more ▼]

We describe a new, high-energy (420 kV), large-scale (0.45 m in diameter, 4 m in height) x-ray tomograph developed to investigate gas and liquid flow through fixed bed like absorption, distillation and reactive distillation columns. The first results obtained with this set-up on test objects (physical phantoms), such as a cylindrical container filled with water or a large diameter structured metallic packing, validate the technique as a quantitative tool for geometrical measurements. Very detailed two-dimensional (21)) and three-dimensional (3D) images of a 0.09 m diameter KATAPAK-SP 12, a reactive distillation packing, are presented. Quantitative information relative to liquid hold-up distribution may be obtained from tomographic imaging performed on an irrigated column packed with this element. [less ▲]

Étude de la texture poreuse d'un matériau polymère cellulaire utilisé en ingénierie tissulaire par microtomographie à rayons X

Poster (2005, October)

Moisture profiles determination during convective drying using x-ray microtomography

in Canadian Journal of Chemical Engineering (2005), 83(1), 127-131

The knowledge of internal moisture profiles which develop during drying is essential for model validation purposes, but they are difficult to determine experimentally. This paper shows that X-ray ... [more ▼]

The knowledge of internal moisture profiles which develop during drying is essential for model validation purposes, but they are difficult to determine experimentally. This paper shows that X-ray microtomography, together with image analysis, provides an accurate, non destructive and easy to use technique to determine moisture profiles. Results reported concern the drying of wastewater sludges whose management is becoming a real environmental challenge. An analysis of the development of moisture gradients at the sample external wall shows an influence of drying operating conditions. Finally, mass diffusion coefficients are estimated from the knowledge of both the moisture gradients and the drying flux. [less ▲]

Integrated adsorbent and process characterization. Application to air separation PSA processes

Conference (2005)

High energy, high resolution x-ray tomography applied to catalytic distillation packings

Conference (2005)

3D imaging of reactive distillation packings with a new high energy x-ray tomograph

in Jong, A.; Takei, M.; William, R. A. (Eds.) et al Proceedings of 4th World Congress in Industrial Process Tomography (WCIPT4), Aizu, Japan, 5-8 septembre 2005 (2005)

Possibilities and limits of application of electrical resistance tomography in hydrodynamics of bubble columns

in Canadian Journal of Chemical Engineering (2005), 83(1), 4-10

Knowing the hydrodynamic regime in which is working a bubble column is of great importance because the regime affects strongly the mass transfer between the phases. To this end, we examine the ... [more ▼]

Knowing the hydrodynamic regime in which is working a bubble column is of great importance because the regime affects strongly the mass transfer between the phases. To this end, we examine the potentialities of an Electrical Resistance Tomography (ERT) device. We analyse cross correlation of electrode pair measurements, of neighbouring pixels and power spectra of averaged pixels within a single plane as well as cross correlations of averaged pixels between two planes, without finding a clear signature of the churn turbulent flow. Variable gas flow rate inputs are used to determine the time resolution of the ERT. [less ▲]

Wastewater sludge convective drying: Influence of sludge origin

in Environmental Technology (2004), 25(9), 1051-1057

This paper deals with thermal drying of wastewater sludges, whose management will become crucial in the forthcoming years. Sludges collected after mechanical dewatering in 5 different WWTPs are submitted ... [more ▼]

This paper deals with thermal drying of wastewater sludges, whose management will become crucial in the forthcoming years. Sludges collected after mechanical dewatering in 5 different WWTPs are submitted to the same convective drying treatment in order to try finding some relations between the drying behaviours, the type of effluent and wastewater treatments. Results show clearly sludge drying remains a particularly complex operation because sludges may exhibit very different behaviours, both from kinetic and texture points of view. Initial moisture content and global composition are not sufficient to explain the different observed behaviours. It is too early to claim one or another type of water treatment has an influence on the drying behaviour. However, the drying rates can be classified in the inverse order of the organic content. Moreover for sludges at the same siccities, the harder the material (rheological properties), the higher the drying rate. Final textural properties can be related to the rheological properties and the internal diffusion limitations lowering the drying intensity. [less ▲]