The use of ozone and high silica zeolites to enhance refractory compounds removal

This work investigates the removal of organic pollutants from water through a three-phase process combining adsorption onto hydrophobic zeolites and in situ oxidation by ozone gas. Zeolites are aluminosilicates with various crystalline structures – and especially different pore sizes - which offer a great selectivity, profitable to organic pollutants separation in a complex matrix like natural water. They are highly resistant to chemical agents as acids, bases or oxidising agents such as ozone. Moreover, high silica zeolites have a high adsorption capacity for organics. Ozone is known to be a powerful oxidising agent able to react with various organic compounds. Its action – either direct or indirect - leads to the decomposition of organics into smaller molecules that are generally biodegradable. Previous studies have shown that organics adsorbed onto zeolites could be oxidised by ozonated water faster than in bulk water because of a micropore concentration effect (Fujita et al, 2004 and Sagehashi et al, 2005). In the gas phase, Monneyron et al (2003) showed that high silica zeolites could catalyse ozone decomposition into radical species and that adsorption properties were not significantly modified after exposition to ozone. Hence it is expected that zeolites saturated with organics could undergo regeneration by ozone without degradation of their structures or decrease of their adsorption capacities. The present work showed that high silica zeolites could efficiently adsorb nitrobenzene from water although their capacity stayed beyond that of activated carbon, except at low concentrations. The adsorption capacity depended on the zeolite structure and the Si/Al ratio. Adsorption isotherms could be well described by Langmuir or Freundlich models. As regards the three phase coupled process, the adsorbent could be efficiently regenerated during an ozonation step consisting in bubbling ozone through a suspension of saturated zeolite in a nitrobenzene solution at equilibrium. The initial adsorption capacity was quickly recovered and, continuing the treatment, the adsorption capacity of the zeolite was even increased. This may be due to the cleaning of zeolites pores by ozone (Pic et al, 2005). Yet traces of template molecules could probably remain from the zeolite synthesis process. Until now the catalytic effect of the zeolites has not been evidenced in the liquid phase. Therefore future work will focus on the conditions in which the oxidation kinetics can be enhanced in the presence of zeolites through a concentration effect, and to what extent

Adsorption of Nitrobenzene from Water onto High Silica Zeolites and Regeneration by Ozone

This work investigates the removal of nitrobenzene (NB), a model pollutant from water, by combining adsorption onto zeolites and regeneration with ozone. The adsorption equilibrium isotherms of NB onto zeolites enabled the best adsorbent to be selected and zeolites with a high Si/Al ratio were the most efficient. The adsorption capacity depended on the Si/Al ratio and on the pore size. In a sequential process coupling adsorption and oxidation by ozone, NB was completely removed from water and the initial adsorption capacity of the zeolite was totally restored. Although no catalytic effect was noticed, the adsorption produced locally high concentrations, thus enhancing the oxidation rate for NB

Oxidation of nitrobenzene by ozone in the presence of faujasite zeolite in a continuous flow gas–liquid–solid reactor

This work investigates the oxidation of nitrobenzene (NB) by ozone in the presence of faujasite zeolite. Experiments were carried out in a gas–liquid–solid reactor were ozone transfer and NB oxidation took place at the same time. Three configurations of the reactor were compared: empty, filled with inert glass beads and filled with faujasite pellets. First, ozone transfer coefficient (kLa) and decomposition rate constant (kC) were determined for each configuration. In presence of solid, kLa was 2.0 to 2.6 times higher and kC was 5.0 to 6.4 times higher compared to the empty reactor. Then, the various configurations were evaluated in terms of NB removal and chemical oxygen demand (COD) decrease. The faujasite reactor showed higher removal of NB and decrease of COD compared to other configurations under the same conditions suggesting that the faujasite increases the oxidation rate of NB. Oxidation of NB in presence of faujasite also proved to be limited by the transfer of ozone from the gas to the liquid phase

Etude d’un procédé hybride couplant\ud adsorption sur zéolithes et oxydation par l’ozone.\ud Application au traitement d’effluents aqueux industriels

Cette étude a pour objet un nouveau procédé de traitement des effluents aqueux\ud industriels chargés en matière organique et difficilement traitables par voie biologique. Ce\ud procédé hybride couple l’adsorption sur des zéolithes hydrophobes et l’oxydation par l’ozone\ud au sein d’un unique réacteur.\ud La première partie de cette étude concerne les interactions binaires entre les différents\ud éléments du procédé : la molécule cible, les adsorbants et l’ozone. Cette étude permet\ud d’améliorer la compréhension des mécanismes fondamentaux ; différentes méthodes de mise\ud en oeuvre du procédé hybride sont alors envisagées et étudiées dans une seconde partie. Les\ud paramètres choisis pour évaluer les différentes configurations sont les vitesses d’élimination\ud de la molécule cible et de ses sous-produits ainsi que la consommation d’ozone. Dans toutes\ud les configurations, les vitesses d’élimination augmentent et la consommation d’ozone diminue\ud par rapport à un procédé d’ozonation en absence de zéolithe. Le procédé hybride peut être\ud configuré selon deux méthodes : une méthode séquentielle comportant une phase d’adsorption\ud suivie d’une phase de régénération de l’adsorbant par l’ozone et une méthode dans laquelle\ud l’effluent aqueux et l’ozone sont introduits simultanément et en continu à travers un lit fixe de\ud zéolithe.__________________________________________________This study investigates a new hybrid process to degrade organic species in an industrial\ud wastewater which is not suitable for biological treatment. This hybrid process consists of\ud adsorption onto hydrophobic zeolites and oxidation with ozone in a single reactor.\ud The first part of this study concerns the binary interactions between the different\ud components of the process: the target compound, the adsorbents and ozone. This study leads\ud to a better understanding of the fundamental mechanisms. This information is then used in the\ud second part of the study in which different configurations for the hybrid process are\ud investigated. The parameters used to evaluate the process are the removal rate of the target\ud compound, the removal rate of the by-products and the ozone consumption. In all the\ud configurations the removal rates are enhanced and the ozone consumption is decreased\ud compared with ozonation in absence of zeolite. The hybrid process can be configured in two\ud ways: a sequential method consisting of an adsorption stage followed by a regeneration stage\ud using ozone; and a continuous method in which the target compound and the ozone are\ud simultaneously introduced into a fixed bed of zeolite

Traitement avancé de micropolluants organiques dans l'eau par couplage entre adsorption sur charbon actif et ozonation catalysée

Traitement avancé de micropolluants organiques dans l'eau par couplage entre adsorption sur charbon actif et ozonation catalysé

Nitrosamines in pilot-scale and full-scale wastewater treatment plants with ozonation

Ozone-based treatment trains offer a sustainable option for potable reuse applications, but nitrosamine formation during ozonation poses a challenge for municipalities seeking to avoid reverse osmosis and high-dose ultraviolet (UV) irradiation. Six nitrosamines were monitored in full-scale and pilot-scale wastewater treatment trains. The primary focus was on eight treatment trains employing ozonation of secondary or tertiary wastewater effluents, but two treatment trains with chlorination or UV disinfection of tertiary wastewater effluent and another with full advanced treatment (i.e., reverse osmosis and advanced oxidation) were also included for comparison. N-nitrosodimethylamine (NDMA) and N-nitrosomorpholine (NMOR) were the most prevalent nitrosamines in untreated (up to 89ng/L and 67ng/L, respectively) and treated wastewater. N-nitrosomethylethylamine (NMEA) and N-nitrosodiethylamine (NDEA) were detected at one facility each, while N-nitrosodipropylamine (NDPrA) and N-nitrosodibutylamine (NDBA) were less than their method reporting limits (MRLs) in all samples. Ozone-induced NDMA formation ranging fro

Etude d un procédé hybride couplant adsorption sur zéolithes et oxydation par l ozone (application au traitement d effluents aqueux industriels)

Cette étude a pour objet un nouveau procédé de traitement des effluents aqueux industriels chargés en matière organique et difficilement traitables par voie biologique. Ce procédé hybride couple l adsorption sur des zéolithes hydrophobes et l oxydation par l ozone au sein d un unique réacteur. La première partie de cette étude concerne les interactions binaires entre les différents éléments du procédé : la molécule cible, les adsorbants et l ozone. Cette étude permet d améliorer la compréhension des mécanismes fondamentaux ; différentes méthodes de mise en œuvre du procédé hybride sont alors envisagées et étudiées dans une seconde partie. Les paramètres choisis pour évaluer les différentes configurations sont les vitesses d élimination de la molécule cible et de ses sous-produits ainsi que la consommation d ozone. Dans toutes les configurations, les vitesses d élimination augmentent et la consommation d ozone diminue par rapport à un procédé d ozonation en absence de zéolithe. Le procédé hybride peut être configuré selon deux méthodes : une méthode séquentielle comportant une phase d adsorption suivie d une phase de régénération de l adsorbant par l ozone et une méthode dans laquelle l effluent aqueux et l ozone sont introduits simultanément et en continu à travers un lit fixe de zéolitheThis study investigates a new hybrid process to degrade organic species in an industrial wastewater which is not suitable for biological treatment. This hybrid process consists of adsorption onto hydrophobic zeolites and oxidation with ozone in a single reactor. The first part of this study concerns the binary interactions between the different components of the process: the target compound, the adsorbents and ozone. This study leads to a better understanding of the fundamental mechanisms. This information is then used in the second part of the study in which different configurations for the hybrid process are investigated. The parameters used to evaluate the process are the removal rate of the target compound, the removal rate of the by-products and the ozone consumption. In all the configurations the removal rates are enhanced and the ozone consumption is decreased compared with ozonation in absence of zeolite. The hybrid process can be configured in two ways: a sequential method consisting of an adsorption stage followed by a regeneration stage using ozone; and a continuous method in which the target compound and the ozone are simultaneously introduced into a fixed bed of zeolitesTOULOUSE-INSA (315552106) / SudocSudocFranceF

Optimization of the pressure drops in the helium in-module manifolds of the EU DEMO “Optimized Conservative” HCLL Breeding Blanket

In Europe the technology to develop DEMO is being supported by HORIZON 2020 research programme under EUROfusion Consortium. One of the key components that DEMO relies on is a working Breeding Blanket (BB). There are currently four Breeding Blanket concepts being developed in Europe, whose primary purpose is to convert kinetic energy of the neutrons into heat and to transfer this converted heat to a coolant, breed tritium to make plant self-sufficient of fuel and to shield magnets from radiation. This paper describes helium distribution system in the “Optimized Conservative” concept of Helium Cooled Lithium Lead (HCLL) BB, according to the HCLL 2014 Design Description Document. This contains three manifolds to distribute the helium in to several parts of the BB namely the First Wall, Cooling Plates, horizontal Stiffening Plates and the vertical Stiffening Plates. The work mainly focuses on optimization study and reduction of the pressure drops in the helium manifolds. The same is achieved by changing several geometrical parameters to keep the pressure drops under the limit. To achieve the results ANSYS-FLUENT commercial Computational fluid dynamic code is used. The final results include the modified geometry which gives lowest pressure drops for the given mass flow rate