| Přispěvatelé: |
Toulouse Biotechnology Institute (TBI), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), INSA de Toulouse, Arnaud Cockx, Sylvie Gillot |
| Popis: |
Oxygen supply in biological reactors represents an important part of the energy consumption of the wastewater resource recovery facilities. Understanding the coupled impact of surfactants and rheological behavior of the fluid has been identified as essential to optimize aeration in such tanks. As in situ measurements being unlikely in activated sludge (in particular of bubble size), the aim of this PhD work was to measure precisely governing parameters of oxygen transfer in a bubble column with model fluids, and to model observed phenomena to better understand and to interpret them.First, a comprehensive 1D-model coupling hydrodynamic and oxygen transfer model was developed. It was confronted to three datasets of experiments in bubble columns with clear water from the literature, selected for their broad range of bubble diameter, gas superficial velocity and water height. The impact of hydrostatic pressure on hydrodynamic parameters (gas superficial velocity, bubble diameter, gas hold-up) is not negligible and has to be systematically accounted for along column height to reproduce accurately experimental mean gas hold-up results. Likewise, the bubble drag law choice has to be adapted to the water quality of the considered dataset (high or low contamination effects). Due to gas-liquid mass transfer, a significant oxygen concentration depletion in the gas has been highlighted, and must be taken into account to correctly interpret oxygen mass transfer coefficient measurements.Then, a parallelepiped bubble column was built, in order to carry out local bubble size distribution measurements, gas hold-up and oxygen transfer measurements, with model fluids, a liquid height of 2.9 m and low gas hold-up values ( |
