Contribution à la mise au point d'application spécifique des hydrocyclones en traitement des eaux

Ce mémoire a permis d'explorer des potentialités originales des hydrocyclones dans le domaine général du traitement des eaux et a montré des possibilités intéressantes d'utilisation de ces séparateurs pour des applications spécifiques. La première application potentielle testée a été le traitement des eaux pluviales. On a montré l'intérêt d'utiliser dans ce cas un hydrocyclone spécifique équipé d'un microdécanteur placé au niveau de la sousverse appelé Grit pot qui permet de cumuler les avantages respectifs d'un hydrocyclone et d'un décanteur sans en présenter les inconvénients respectifs. La deuxième application était quant à elle relative aux potentialités de recyclage de talc utilisé comme agent lestant en traitement biologique et de charbon actif dans une filière de traitement des eaux potables. Dans les 2 applications, on a montré que l'hydrocyclone permet de recycler économiquement aussi bien le talc que le charbon actif. La dernière partie du mémoire, la plus innovante a permis de montrer la viabilité technique d'un procédé d'épuration des eaux hybride intégrant dans un même appareillage 3 procédés unitaires à savoir : coagulation-floculation, flottation à air dessous et séparation centrifuge.The aims of this research are to study the potential of using hydrocyclone in water treatment field and to study the possibility of applying hydrocyclone in some specifics applications. The first specific application is to use the hydrocyclone equipped, at the underflow outlet, with the microdecanter called Grit pot in run-off water treatment processes. This specific hydrocyclone had the advantages of the two processes, hydrocyclone and decanter without presenting their disadvantages. The second specific application concerns the potential of the recycle of talc, which was used as a ballasting additive in biological treatment, and activated carbon, which was used in potable water treatment. In these 2 applications, hydrocyclone showed its high performance and economically recycled of talc as well as activated carbon. The last part of this research, the most innovating part, is to study the technical feasibility of the hybrid process, which integrated in the same reactor with 3 processes: coagulation-flocculation, dissolved air flotation and centrifugal separation in water treatment field.TOULOUSE-INSA (315552106) / SudocSudocFranceF

A Novel Configuration Fluidized Bed Reactor for Nitrate Reduction and Low Strength Anaerobic Wastewater Treatment

In this research, hydrodynamic behaviour in a novel fluidized bed reactor (FBR) was studied by using a residence time distribution (RTD) experiment. The RTD experimental result showed that the liquid flow pattern closed to plug flow behaviour. Moreover, the novel FBR was performed under low hydraulic retention time (HRT) operation (without internal recirculation), and its performance should be further investigated. There are two experimental approaches for wastewater treatment application. The first approach, a novel FBR, was performed for treating nitrate with a denitrification process at COD:NO3- - N of 1:1, 2:1, 3:1, 5:1 and 10:1. The highest nitrate removal efficiency was obtained at 99 ± 1%, with a ratio of COD:NO3- - N of 3:1. In the second approach, a novel FBR was evaluated in low strength anaerobic wastewater treatment. The novel FBR achieved 86 ± 6% of COD removal efficiency at an organic loading rate (OLR) of 5.6 g COD L-1 d-1.In this research, hydrodynamic behaviour in a novel fluidized bed reactor (FBR) was studied by using a residence time distribution (RTD) experiment. The RTD experimental result showed that the liquid flow pattern closed to plug flow behaviour. Moreover, the novel FBR was performed under low hydraulic retention time (HRT) operation (without internal recirculation), and its performance should be further investigated. There are two experimental approaches for wastewater treatment application. The first approach, a novel FBR, was performed for treating nitrate with a denitrification process at COD : NO3- - N of 1 : 1, 2 : 1, 3 : 1, 5 : 1 and 10 : 1. The highest nitrate removal efficiency was obtained at 99 ± 1%, with a ratio of COD:NO3- - N of 3 : 1. In the second approach, a novel FBR was evaluated in low strength anaerobic wastewater treatment. The novel FBR achieved 86 ± 6% of COD removal efficiency at an organic loading rate (OLR) of 5.6 g COD L-1 d-1

Hybrid hydrocyclone process operating with natural water

This research deals with a hybrid hydrocyclone process, involving micro-bubbles injection generated by the dissolved air flotation technique; the micro-bubbles allow the aerated flocs formed by coagulation and flocculation to be separated inside the hydrocyclone. The floc separation is induced by centrifugal force. The lighter phase moves toward the center of the hydrocyclone and the heavier one to the wall. This hybrid process is intended for natural water or industrial raw water and would be performed as an industrial water treatment process. For this study, the hybrid hydrocyclone process was performed under steady state conditions with natural water coming from the river Marne. Efficiencies of 61 +/- 4% for turbidity decrease and 77 +/- 20% for suspended solids removal were obtained. The separation efficiency between the clarified water and the flocs reached 95 +/- 10%. This process achieved continuous operation with 1000 L/h inlet flow. In industrial wastewater treatment, which requires a reliable, compact and efficient process, this hybrid technology shows strong potential, with a significant reduction of the plant footprint. (c) 2012 Elsevier B.V. All rights reserved

VELOCITY MEASUREMENT IN THE HYDROCYCLONE BY OIL DROPLET, DOPPLER ULTRASOUND VELOCIMETRY, AND CFD MODELLING

International audienceTo develop the water treatment process, the hydrocyclone is now used as a unit to operate. Understanding hydrodynamics is a key step to improve the separation process efficiency. Recently, a new simple method called the oil droplet method was proposed by Bamrungsri et al. [Chem. Eng. Res. Design 86, 1263-1270 (2008)] and applied to velocity measurements in a hydrocyclone. The Doppler Velocimetry measurements and computational fluid dynamics (CFD) have been proposed by many researchers as effective for studying the flow field of a hydrocyclone. This work presents a comparison of the experimental results from these two methods along with those obtained from numerical simulations. The numerical calculations of the 3D flow field were performed with FLUENT using the k-epsilon model and the Reynolds stress model (RSM). Measurements and CFD simulations were performed for two hydrocyclone configurations (5 and 10cm diameter). Doppler ultrasound velocimetry data and CFD-RSM results are in close agreement. The oil droplet method is less accurate for the continuous phase velocity profiles but is promising for the validation of Lagrangian tracking simulations

Hydrocyclones

This chapter gives a brief synopsis of hydrocyclones in theory and in practice, including basic design, characterization of performance, models, scale-up and design, as well as monitoring and control of the equipment. The effect of various operational variables, such as pressure drop, cone angle, cyclone diameter, vortex finder and spigot diameters, and solids concentration in the feed on the throughput, cut size, and sharpness of classification of hydrocyclones, is summarized. Both fundamental and empirical models are considered. Numerical solution of first principles models is discussed, with different turbulence models, such as Reynolds averaged Navier-Stokes (RANS) models, large eddy simulation (LES) models, and direct numerical simulation (DNS) models. The Plitt model is considered as a widely used example of empirical models. As an example of the online monitoring of hydrocyclones, the analysis of videographic images of the underflow is discussed, as previously proposed in the literature. This includes the extraction of spray profile variables from image data and online mapping of the data to a process chart, where the normal operating region is delineated by contours following the density