Study of Flow Pattern in Jet Clarifier for Removal of Turbidity by Residence Time Distribution Approach

This study aims to determine the performance of the jet clarifier for turbidity removal and its mechanisms for proposing the optimal operating conditions and design criteria. The experiment were performed continuously using a pilot scale jet clarifier with the volume of 243 L. Effects of liquid flow rates, types of liquid phase, and sludge blanket heights on turbidity removal efficiency were investigated. Moreover, the residence time distribution (RTD) study was carried out to investigate the flow pattern. The results indicated that the jet clarifier can effectively reduce the water with the efficiency of 80% under the optimal condition. The RTD results suggested that the flow pattern in the jet clarifier corresponded to the design as the plug flow and mixed flow conditions were found in the coagulation and the flocculation/sedimentation zones, respectively. The presence of the sludge blanket can reduce the bypass and recirculated flows. Besides, the increase of flow rate resulted in the increase recirculation in the tank. It can be suggested that the jet clarifier can be used for removing turbidity in the water treatment. The hydrodynamic in the reactor, which relates to flow pattern in the reactor, is one among the important factors in a jet clarifier

Study of Aeration and CO2 Absorption Using Filtration Membranes in Terms of Physical Properties and Mass Transfer Parameters

Hollow fiber membrane contactor is nowadays one of the alternative absorption processes for conventional bubble columns. In this work, the performances of microporous hollow fiber membranes for aeration and CO2 absorption were investigated. The membranes used in this work were adapted from filtration membranes which are significantly cheaper than conventional absorption membranes. The effects of operating variables such as average pore sizes, gas flow rates, liquid flow rates, amounts of hollow fiber membrane, and concentrations of chemical solution on the gas-liquid absorption rate were determined. For oxygen-water absorption, the overall mass transfer coefficient (kLa), which corresponding to the absorption rate, increased with the increase of membrane porous diameter. The kLa was also enhanced with the increase of the liquid flow rate and the number of membranes while the gas flow rate was rarely influent. For carbon dioxide absorption, the increase in liquid flow rate and the carbon dioxide concentration resulted in higher mass transfer rate. Moreover, adding sodium carbonate in absorbent improved the kLa value up to 2.2 folds, comparing with physical absorption. The comparison between membrane contractor and bubble column indicated that the utilization of filtration membranes had more efficiency comparing to bubble column due to its high surface area and adaptability when operating with the same size

The performance of surfactant mixtures at low temperatures

Optimising detergency at lower temperatures is of increasing interest due to environmental and economic factors, and requires a greater understanding of the effects of temperature on the adsorption of surfactant mixtures at interfaces. The adsorption properties of surfactant mixtures and biosurfactant/surfactant mixtures have been studied at room temperatures and at temperatures below ambient using surface tension and neutron reflectivity measurements. For the ternary surfactant mixture of octaethylene monododecyl ether, C12E8, sodium dodecyl 6-benzene sulfonate, LAS, and sodium dioxyethylene glycol monododecyl sulfate, SLES, the surface tension at the air-water interface increases with decreasing temperature. In contrast, there is a notable reduction in the increase in the surface tension with a decrease in temperature from 25 °C to 10 °C for the 5 component rhamnolipid/surfactant mixture of the mono-rhamnose, R1, and di-rhamnose, R2, with C12E8/LAS/SLES. The associated neutron reflectivity data for the ternary C12E8/LAS/SLES mixture and the significant observation is that the 3, 4, and 5-component mixtures containing rhamnolipids in conjunction with the other surfactants show changes in composition and adsorbed amounts of the individual components which are close to the experimental error. However the significant observation is that the neutron reflectivity data indicate that the improved surface tension tolerance at lower temperatures is associated with the dominance of the rhamnolipid adsorption in such mixtures. Hence the introduction of the rhamnolipids provides a tolerance to the adverse effects associated with reduced temperatures, and a potential for improved detergency at relatively low temperatures

Synthesis of Stable Iron Oxide Nanoparticle Dispersions in High Ionic Medi

A novel one-pot method was developed in this work to synthesize and disperse nanoparticles in a binary base fluid. As an example, stable magnetite iron oxide (Fe3O4) dispersions, i.e., nanofluids, were produced in a high ionic media of binary lithium bromide-water using a microemulsion-mediated method. The effects of temperature and precursor concentration on morphology and size distribution of produced nanoparticles were evaluated. An effective steric repulsion force was provided by the surface functionalization of nanoparticles during the phase transfer, supported by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The formed nanoparticles exhibited a superior stability against agglomeration in the presence of high concentrations of lithium bromide, i.e., from 20 to 50 wt.%, which make them good candidates for a range of novel applications

Etude du transfert de masse gaz-liquide dans une colonne à bulles et à pulvériser avec ajout de milieu solide

This thesis projected to investigate both hydrodynamics and mass transfer in both spray and bubble columns and comparing their specific power consumptions in order to develop the selection guideline for industrial usages. The results indicated that the bubble column had larger specific interfacial area than the spray column when using a small gas loading rate. At this range of operation, the bubble column yielded a higher overall mass transfer coefficient with the same specific power consumption. However, when operating at high gas loading rate, the spray column was the one better than the bubble column since the bubble column consumed larger power consumption as the pressure drop of the bubble column was mostly due to the gas flow. In addition, this research also studied the effect of the solid phase on the hydrodynamics and mass transfer in the bubble column and spray column. By using the colorimetric method of “red bottle” experiment, it was found that the bubble-particles collision diminished the mass transfer of bubbles because the collision slowed down the bubbles especially for the small bubbles due to the fact that the small bubble simply lost their velocities from the collision. However, there was an advantage of introducing the particles since solid particles could obstruct the rising bubble and reduced its rising velocity. Consequently, the contact time between gas and liquid is increased and resulted in a higher gas hold up, specific interfacial area and thus mass transfer.Cette thèse projetait d’étudier à la fois l’hydrodynamique et le transfert de masse dans les colonnes de pulvérisation et les colonnes à bulles, et de comparer leurs consommations de puissance spécifiques afin d’élaborer la directive de sélection pour les utilisations industrielles. Les résultats ont indiqué que la colonne à bulles avait une surface interfaciale spécifique plus grande que la colonne de pulvérisation lorsqu’on utilise un faible taux de charge de gaz. Dans cette plage de fonctionnement, la colonne à bulles produisait un coefficient de transfert de masse global plus élevé avec la même consommation d'énergie spécifique. Cependant, lorsqu’elle fonctionnait à un taux de charge de gaz élevé, la colonne de pulvérisation était meilleure que la colonne à bulles, car celle-ci consommait une plus grande consommation d’énergie, la chute de pression de la colonne à bulles étant principalement due au débit de gaz. En outre, cette recherche a également étudié l'effet de la phase solide sur l'hydrodynamique et le transfert de masse dans la colonne à bulles et la colonne de pulvérisation. En utilisant la méthode colorimétrique de l'expérience «bouteille rouge», il a été constaté que la collision bulle-particules diminuait le transfert de masse des bulles car la collision ralentissait les bulles, en particulier pour les petites bulles, du fait que la petite bulle perdait simplement leur vitesses de la collision. Cependant, l’introduction des particules présentait un avantage, car les particules solides pouvaient obstruer la bulle en hausse et réduire sa vitesse de montée. En conséquence, le temps de contact entre le gaz et le liquide est augmenté et conduit à une plus grande rétention de gaz, une zone interfaciale spécifique et donc un transfert de masse

One-pot Synthesis of Octyne-Ruthenium on Carbon Nanoparticles

The attempts to manipulate ruthenium nanoparticle by the passivation of π bonds linkage is of interest for many years. That is the way to enhance its optical properties and fluorescence characteristics which can promote the usage for sensor application. Other view, the usage of carbon nanoparticle is governed in many aspects including its fluorescence properties. Therefore, the combination between those two valued nanoparticles was set by conducting the simple synthesis method. With the as-prepared carbon nanoparticles, all other reagents (ruthenium (III) chloride, octyne and Sodium borohydride) were mixed in the same batch. The ratio of carbon substrate, ruthenium (III) chloride and octyne was 10: 1: 3. The particle yielded was then purified and subjected to characterize using some spectroscopy techniques including photoluminescence. The results showed that size of carbon particle before and after ruthenium deposition were 5.0 and 6.3 nanometers, respectively. Octyne was coordinated self-assembly on the ruthenium surface which was 8.1 nanometers in diameter. Moreover, octyne-protected ruthenium on carbon nanoparticles showed the remarkably increasing of fluorescence Intensity. Therefore, the functionalization of carbon nanoparticle with octyne-ruthenium can be a promising strategy to develop a novel complex of ruthenium

Stabilized Oily-Emulsion Separation Using Modified Induced Air Flotation (MIAF): Factor Analysis and Mathematical Modeling

The objective of this work was to study the treatment of oily-wastewater by the combination of induced air flotation and coagulation or the modified induced air flotation (MIAF). Effects of bubble hydrodynamics and mixing were analyzed along with the treatment performance for separation different stable oily wastewaters, including cutting oil, lubricant oil, palm oil. The results suggested the necessity of coagulation for the efficient separation of these emulsions. Different alum concentrations were required for good separation due to the variation of oil concentration. The maximum efficiencies of higher than 85% can be attained under the optimal air flow rate of 0.3 L/min for 10 minutes with appropriate alum dosage. Moreover, the result from factor analysis indicated the importance of coagulant dosage, mean droplet size, and hydrodynamic condition in term of a/G ratio on the treatment performance. Finally, a good correspondence was obtained from the experimental data and the mathematical modeling at which identified the correlation between the treatment efficiency and these key factors with the mean absolute percentage error (MAPE) of at 14%

Relative Effect of Additional Solid Media on Bubble Hydrodynamics in Bubble Column and Airlift Reactors towards Mass Transfer Enhancement

Many researchers have focused on multi-phase reactor development for improving mass transfer performance. However, solid particle addition in gas–liquid contactor for better oxygen mass transfer performance is still limited. Hence, this study aims to analyze the relative effect of different types of local solid media on the bubble hydrodynamic characteristics towards mass transfer enhancement in bubble columns (BCR) and airlift reactors (ALR). This was investigated by varying solid media types (ring, sphere, cylinder, and square), solid loadings (0%–15%), and superficial gas velocities (Vg) (2.6–15.3 × 10−3 m/s) in terms of the bubble hydrodynamic and oxygen mass transfer parameters. The result showed that bubble size distribution in BCR and ALR with additional plastic media was smaller than that without media addition, approximately 22%–27% and 5%–29%, respectively, due to the increase of the bubble breaking rate and the decrease of the bubble rising velocity (UB). Further, adding media in both reactors significantly decreased the UB value. Since media increased flow resistance, resulting in decreased liquid velocity, it can also be the moving bed to capture or block the bubbles from free rising. Therefore, oxygen mass transfer performance was investigated. The oxygen transfer coefficient (KLa) in BCR with solid media addition was enhanced up to 31%–56% compared to a non-addition case, while this enhancement was greater at higher solid loading due to its higher effective surface, resulting in a higher bubble break-up rate compared to the lower loading. In ALR, up to 38.5% enhanced KLa coefficient was archived after adding plastic media over the non-addition case. In conclusion, ring and cylinder media were found to be the most significant for improving KLa value in BCR and ALR, respectively, without extra energy