L’électrodialyse (ED) est principalement basée sur l’action spécifique des membranes échangeuses d’ions (MEIs) et est largement répandue en industrie agroalimentaire pour la stabilisation tartrique des vins, la désacidification et le traitement des jus de fruits, la déminéralisation du lactosérum ou l’élimination et le fractionnement des protéines du lait. Le colmatage organique, accentué par la complexité de composition des effluents alimentaires et leur richesse en composés phénoliques, représente un facteur majeur de limitation de l’efficacité des procédés et des performances des MEIs. Ce phénomène provoque une diminution de la sélectivité de membranes, une augmentation de leur résistance électrique et réduit le rendement énergétique du procédé conduisant à des pertes économiques en industrie. Cette étude consiste principalement à étudier le décolmatage de MEIs par procédés chimiques et biologiques. Des lots de membranes échangeuses de cations (MECs) et d’anions (MEAs) neuves (1 lot de MEC et 1 lot de MEA) et usées (3 lots de MECs et 2 lots de MEAs) à différentes durées d’utilisation en ED dans l’industrie agroalimentaire –application confidentielle- ont été étudiés. L’ensemble des échantillons ont préalablement été caractérisés pour détermination des paramètres physicochimiques (capacité d’échange (CE), épaisseur (Tm), conductivité électrique (km), angle de contact (θ), teneur en eau (WC) ainsi que la fraction volumique de la solution inter-gel (f2) résultant de l’exploitation du modèle microhétérogène), de structure et morphologiques par spectroscopie IR-TF, microscopie optique, microscopie électronique à balayage et mécaniques par essais de traction. Les effets directs et indirects (causés par les opérations de lavage régulières en industrie) du colmatage ainsi que l’anisotropie des propriétés mécaniques de membrane ont été mis en évidence. Des méthodes de nettoyage non agressives et respectueuses de l’environnement ont été expérimentées en mode statique en ex-situ : Solutions salines (NaCl à 35 g.L-1 et eau de mer reconstituée), solution hydro-alcoolique (mélange eau-éthanol 12%, pH=3,5) et solutions biologique utilisant 3 catégories d’agents enzymatiques (Rohalase BX-BXL, β-glucanase / Corolase 7089, endo-peptidase / Tyrosinase, polyphenol-oxydase) dont les conditions opératoires d’activité enzymatiques optimale ont été déterminées. L’évolution de CE, km, θ et f2 ont été suivis en fonction de la durée de nettoyage. Les solutions salines ont un effet négligeable sur le nettoyage en profondeur mais restent efficaces pour le nettoyage de surface. Cependant, l’application de la solution hydro-alcoolique et des solutions d’enzymes se sont avérées être efficaces pour le décolmatage interne et externe et parviennent à rétablir significativement les paramètres suivis. Il a été démontré que les composés phénoliques, principaux constituants des effluents traités, sont en majeure partie responsables du colmatage des MEIs. Ceux-ci forment des nanoparticules colloïdales denses, non perméables aux ions dans les méso- et macropores des MEIs et ne pénètrent pas dans ses micropores. Une modification du modèle microhétérogène selon cette hypothèse a permis de fournir une interprétation adéquate du km et de modéliser la modification structurale de la phase inter-gel engendrée par les mécanismes de colmatages de polyphénols et expliquer les raisons de diminution du facteur f2app. Une méthode d’extraction utilisant un mélange de solvants (25%V/V, acétone/méthanol/isopropanol/eau) a été mise au point et a permis d’extraire certains composés phénoliques de différents lots de MECs et MEAs usées et ont été identifiés par chromatographie liquide à haute performance. Il a été démontré que les interactions entre les composés phénoliques et la matrice polymère étaient principalement régies par l’empilement des cycles aromatiques et des interactions électrostatiques du type CH-pi et pi-pi ainsi que les liaisons hydrogènes / Conventional electrodialysis (ED) is mainly based on the specific action of ion exchange membranes (IEMs) and is widely used in food industry for tartaric stabilization of wines, deacidification and treatment of fruit juices, demineralization of whey or elimination and fractionation of milk proteins. The organic fouling, accentuated by the complex composition of the food effluents and their richness in phenolic compounds, represents a major limitative factor of the process efficiency and the IEMs performance. This phenomenon causes a decrease in the selectivity of membranes, an increase in their electrical resistance and reduces the energy efficiency of the process leading to economic losses in industry. This study mainly consists in studying the IEMs cleaning by chemical and biological methods. Two batches of new membranes (cation- (CEMs) and anion-exchange membranes (AEMs)) and five batches of used ones (3 CEMs and 2 AEM) with different durations of use in ED units in food industry -confidential application- have been studied. All the samples have been previously characterized to determine their physicochemical parameters (ion-exchange capacity (IEC), thickness (Tm), electrical conductivity (km), contact angle (θ), water content (WC) and the volume fraction of the inter-gel solution (f2) resulting from the study of the micro heterogeneous model), structure and morphology by FTIR spectroscopy, optical microscopy, scanning electron microscopy and mechanical by tensile strength tests. The direct and indirect effects (caused by the regular cleaning operations in industry) of fouling as well as the anisotropy of the membranes mechanical properties have been highlighted. Non-aggressive and environmentally friendly cleaning methods have been experimentally tested in ex-situ static mode: Saline solutions (35 g.L-1 NaCl and reconstituted seawater), hydro-alcoholic solution (12% water-ethanol mixture, pH = 3,5) and biological solutions using 3 categories of enzymatic agents (Rohalase BX-BXL, β-glucanase / Corolase 7089, endo-peptidase / Tyrosinase, polyphenol oxidase) whose operating conditions of optimal enzymatic activity have been determined. The evolution of IEC, km, θ and f2 were followed in function of the cleaning duration. Saline solutions have a negligible effect on intern cleaning but remain efficient for extern cleaning. However, the application of the hydro-alcoholic solution and enzyme solutions have been found to be efficient for both intern and extern cleaning and led to significant recoveries of the studied parameters. It has been shown that phenolic compounds, the principal constituents of treated effluents, are mainly responsible for MEIs fouling. Apparently, they form dense colloidal nanoparticles not permeable for ions within membrane meso- and macropores, not penetrating into micropores. A modification of the micro heterogeneous model under this assumption allowed an adequate interpretation of km and the modelization of structural modifications of the inter-gel phase generated by the fouling mechanisms by polyphenols and explained the reasons why the f2app decreases. An extraction method using a mixture of solvents (25% V/V, acetone/methanol/ isopropanol/water) was developed and made it possible to extract certain phenolic compounds from different batches of used CEMs and AEMs that were identified by high performance liquid chromatography. It has also been demonstrated that the interactions between the phenolic compounds and the polymer matrix are mainly governed by the stacking of aromatic rings and electrostatic interactions of the CH-pi and pi-pi type as well as the hydrogen bonds

No description available.

Cette étude présente les travaux réalisés pour comprendre l'effet de l'aération sur le milieu biologique et sur la filtration dans les bioréacteurs à membranes immergées pour une gamme de paramètres opératoires proche de celles utilisées sur stations réelles. Notre démarche fait le lien entre paramètres opératoires (débit d'aération), hydrodynamique à l'échelle macroscopique (tailles et vitesses de bulles), hydrodynamique à l'échelle locale (contraintes de cisaillement) et propriétés du milieu biologique (taille de flocs et substances polymériques extracellulaires solubles). De moins bonnes performances de filtration à plus forte aération pourraient être expliquées par une plus grande déstructuration des boues sur le court terme. Par ailleurs tout effet d'évolution des boues sur le long terme en fonction des conditions d'aération a été écarté. / This work contributes to the knowledge on aeration for fouling prevention in submerged membrane bioreactors, which represents a great part of energy consumption of the process. More precisely it aims at estimating the impact of aeration on mixed liquor properties for operational parameters range close to those used in full scale plants. Our study links operational parameters (airflow rate), hydrodynamics at macroscopic scale (bubble sizeand velocity), hydrodynamics at local scale (shear stresses), biological media properties (floc size and soluble extracellular polymeric substances), and filtration performance (transmembrane pressure variations). Hydrodynamics characterisation of two phase flow in membrane module enabled to highlight differences between air/water and air/sludge hydrodynamics with 15-25 % lower bubble velocities in sludge but one order of magnitude higher shear stress (maximal values of 10 Pa). Controlled breakdown of biological media was performed by imposing constant shear stress (range 0,1-10 Pa) to mixed liquor samples. Increase of shear induced a decrease of floc size, and soluble extracellular polymeric substances release. The comparison with shear value obtained by simulation showed that stresses induced by aeration were in the range of mixed liquor destructuration. A pilot campaign showed that wastewater had a stronger impact on the long term on mixed liquor properties, and thus filtration performances, than aeration. However higher transmembrane pressure increase rate observed on pilot for higher airflow at similar wastewater quality could be explained by stronger breakage of biological agregates on short term

Os sistemas que combinam processos biológicos com a tecnologia de separação por membranas, com crescimento biológico em suspensão, Membrane Bioreactor (MBR) e crescimento biológico aderido, Moving Bed Membrane Bioreactor (MB-MBR), se destacam como opções compactas e eficientes para tratamento de esgoto doméstico.Embora esta tecnologia seja muito promissora, ainda apresenta como maior desafio a redução de desempenho das membranas, que é causada por um fenômeno complexo denominado depósito, ou fouling, em inglês. Como forma de melhorar o desempenho e prolongar a vida útil das membranas a adição de nanopartículas de argila durante o processo de síntese tem se mostrado eficiente. O presente estudo teve como objetivo determinar a melhor composição para a síntese de membranas em polietersulfona modificadas pela adição de nanopartículas de argila e avaliar o seu desempenho no tratamento de esgoto sanitário, gerado na moradia estudantil do campus São Paulo da Universidade de São Paulo, em sistemas MBR e MB-MBR. A melhor composição para a síntese das membranas modificadas foi de 4% de nanopartículas de argila e 4% de formador de poros, ambos em relação à massa do polímero utilizado. Essa composição resultou em membranas com permeabilidade média de 293 L.m-2.h-1.bar-1, para água desmineralizada enquanto as membranas sem modificação apresentaram permeabilidade inferior a 50 L.m-2.h-1.bar-1, sendo, portanto, essa composição selecionada para sintetizar as membranas utilizadas durante a operação dos sistemas de tratamento por MBR e MB-MBR. Para efeito de comparação, o estudo foi desenvolvido com membranas modificadas e comerciais, no mesmo reator. Durante a operação do sistema MBR, com membranas modificadas e membranas comerciais, a concentração média de Demanda Bioquímica de Oxigênio (DBO5) na alimentação do sistema foi de 440 mg.L-1 e a eficiência de remoção foi superior a 94%. Quando o sistema MBR passou a operar com concentração de Sólidos Suspensos Totais (SST) superior a 8.000 mg.L-1, condição considerada de equilíbrio, a permeabilidade média das membranas modificadas, normalizada para 20 ºC, foi de 1.166,1 L.m-2.h-1.bar-1, enquanto para as membranas comerciais a permeabilidade foi de 326,7 L.m-2.h-1.bar-1. O fluxo de permeado médio, para o sistema MBR, foi em torno de 6 L.m-2.h-1, tanto para as membranas modificadas quanto para as membranas comerciais avaliadas na etapa de operação em equilíbrio. Com a operação dos sistemas MBR e MB-MBR em paralelo, com as membranas modificadas, concluiu-se que, embora as qualidades dos permeados produzidos tenham sido similares, o sistema MB-MBR apresentou menores pressões de operação e, consequentemente, menor propensão à formação de depósitos. Os ensaios de filtrabilidade demonstram que as membranas modificadas apresentaram menor resistência à filtração que as membranas comerciais para o liquor misto de MBR e MB-MBR, no entanto o liquor misto do sistema MB-MBR apresentou menor resistência a filtração. De modo geral, concluiu-se que a adição de nanopartículas de argila na modificação das membranas resultou em poros mais longos, favorecendo o aumento da permeabilidade das membranas modificadas em relação às membranas comerciais. Quanto a operação dos sistemas MBR e MB-MBR em paralelo, a pressão transmembrana para o sistema MB-MBR foi em torno de 10 vezes menor que a pressão transmembrana no sistema MBR. Maiores concentrações de sólidos em suspensão totais no liquor misto dos sistemas de MBR e MB-MBR, resultaram em maiores fluxos críticos e, consequentemente, maior produção de permeado. / Treatment systems that combine activated sludge processes, with suspended or adhered growth, with membrane technology, Membrane Bioreactor (MBR) and Moving Bed Membrane Bioreactor (MB-MBR) are considered compact and efficient options for domestic wastewater treatment. Although this promising technology still presents the reduction of membrane performance as a relevant issue. This reduction on the membrane performance is caused by a complex phenomenon called fouling. An approach to improve the membrane performance and extend its life span is the addition of nanoclay during the synthesis process. Considering what was exposed, this study aimed the production and evaluation of composite polyethersulfone and clay nanoparticles membranes for domestic wastewater treatment. For this purpose, two pilot plants were constructed using the produced membranes for the treatment of the wastewater from the student housing at the University of São Paulo. The best composition of the modified membranes was 4% of nanoclay and 4% of pore former, both based on the polymer mass. This composition resulted in membranes with an average permeability of 293 L.m-2.h-1.bar-1 for demineralized water while membranes without modification had a permeability of less than 50 L.m-2.h-1.bar-1. For performance comparison, commercial membranes were used in the same pilot reactor. During the operation, the average Biological Oxygen Demand (BOD5) from raw effluent was 440 mg.L-1 and the removal efficiency was higher than 94%, for both treatment systems. When the MBR system started to operate with a Total Suspended Solids (TSS) concentration above 8,000 mg.L-1, it reached a stable condition in which the average permeability of the modified membranes, normalized to 20 ° C, was 1,166.1 L.m-2.h-1.bar-1, while for the commercial membranes the permeability was 326.7 L.m-2.h-1.bar-1. The average permeates flux for the MBR system was 6 L.m-2.h-1 for both the membranes types operating at stable conditions. With MBR and MB-MBR systems operating in parallel, with modified membranes, it was found that the quality of the produced permeates were similar, but the MB-MBR system presented lower operating pressures and, consequently, lower propensity to fouling. The filterability assays demonstrated that the modified membranes presented less resistance to filtration of MBR and MB-MBR mixed liquor than the commercial membranes. However, the MB-MBR mixed liquor presented less resistance to filtration. Overall, the comparison tests allowed to conclude that the nanoclay addition in the modification of the membranes resulted in longer pores, which increased the modified membranes permeability. Regarding the operation of the MBR and MB-MBR systems, the transmembrane pressure for the MB-MBR system was about 10 times lower than the transmembrane pressure in the MBR system. Higher concentrations of total suspended solids in the mixed liquor of the MBR and MB-MBR systems resulted in higher critical fluxes and, consequently, higher permeate production.

No / The water permeability constant, (K-w), is one of the many important parameters that affect optimal design and operation of RO processes. In model based studies, e.g. within the RO process model, estimation of W-w is therefore important There are only two available literature correlations for calculating the dynamic K-w values. However, each of them is only applicable for a given membrane type, given feed salinity over a certain operating pressure range. In this work, we develop a time dependent neural network (NN) based correlation to predict K-w in RO desalination processes under fouling conditions. It is found that the NN based correlation can predict the K-w values very closely to those obtained by the existing correlations for the same membrane type, operating pressure range and feed salinity. However, the novel feature of this correlation is that it is able to predict K-w values for any of the two membrane types and for any operating pressure and any feed salinity within a wide range. In addition, for the first time the effect of feed salinity on Kw values at low pressure operation is reported. Whilst developing the correlation, the effect of numbers of hidden layers and neurons in each layer and the transfer functions is also investigated. (C) 2014 Elsevier B.V. All rights reserved.

Nitrogen is the major component of biosphere. Paradoxically, nitrogen pollution is the concern globally. Ammonia pollution is due to its unceasing rejection into nature such as groundwater, current water and the atmosphere. This phenomenon constitutes a threat for the humanity, land and aquatic flora, and consequently disturbs the balance of natural ecosystem. Recently, that situation has lead to develop various techniques and/or technologies for ammonia removal from municipal and industrial wastewaters. Particularly in the environmental biotechnology area, two main objectives were recently aimed in many research activities: the development of new configurations of competitive bioreactors and the monitoring of partial nitrification process, which are the fundamental basis of this thesis project. In this study, the partial ammonium oxidation process, also called nitrite route, was studied in a 60 litre jet-loop submerged membrane bioreactor pilot plant. The research was organized around six chapters. An exhaustive literature review of the state-of- art of the biological nitrification process and the membrane technologies was performed. The materials and measurement methods were presented. The colorimetric method, the chromatography analysis, the biomass estimation by the suspended solids (SS), the aggregates size measurement, the gas holdup, the gas-liquid mass transfer, the bubbles gas diameter determination, the medium rheology aspects, etc., and the complete equipment of the bioreactor were studied in detail. The plant automation functioning was also studied. Membrane module (Mitsubishi Sterapore-L) characterization was carried out and three characteristic parameters were estimated: the membrane intrinsic resistance Rm, the membrane permeability Lp and the membrane porosity εm. Estimations revealed good agreement between experimental results and theoretical methods based on the Darcys law and the Carman-Kozeny law applicable in microfiltration system. Hydrodynamics and aeration aspects were studied. The mixing in the jet-loop system was characterized by the mixing time (tmix) and the circulation time (tc), respectively. The results showed that the characteristic times (tmix and tc) decrease with an increase in input gas flowrate and the circulated liquid flowrate. A model correlation involving the air and the combined liquid effects was proposed to describe the circulation time evolution. The classical non-steady state clean water test was used to determine the gas-liquid mass transfer coefficient (kLa). It was found to be influenced by the combined action of air and recirculated-liquid flowrates and a correlation has been proposed to describe their influence. The interpretation of kLa results and the system mixing data showed that the developed reactor corresponds to a near perfect mixing tank. This criterion was satisfactorily verified by literature data. The gas holdup (εg) was directly measured by the volume expansion method. In the absence of liquid circulation, εg ranged between 1 and 4% for the investigated range of gas liquid superficial velocities. It was found to increase linearly with the air superficial velocity, which corresponds to the bubbly flow regime. However, in the presence of liquid flowrate, εg slightly increased (from 1 to 6%) with increase in the superficial liquid velocity. A model has been proposed to correlate εg and the air and the recirculated-liquid velocities. The average diameter of the bubbles gas (dB) in the system was also estimated by the Leibson theoretical model based on the Reynolds number at the orifice of the gas distributor. Finally, biological aspects were studied. Respirometry measurements were conducted to characterize the process medium. The mass transfer, the gas holdup and the medium viscosity were determined. The obtained data allowed estimating the α factor and the β factor, respectively. The interaction of the growth of microorganisms into the process and the membrane performance was also investigated and a correlation model was proposed to describe membrane fouling with time. The optimal conditions for ammonium partial oxidation were determined using process monitoring and simulation. Dissolved oxygen (DO), temperature (T) and hydraulic retention time (HRT) were selected to achieve a high nitrite accumulation in the system. The results obtained showed that the selected parameters should be fixed at DO ≈ 2 mgO2.l-1, HRT ≈ 6 7 h and T = 30°C, respectively. The partial nitrification was simulated by the use of the TwoPopNitrification model included into the BioWin 2.2 software. For these simulations, a sequencing ammonia oxidation assumption was adopted: the nitrozation followed by the nitration step, respectively. The corresponding kinetics and stoichiometric constants were estimated by combining literature data and experimental nitrification results. For these estimates, the ammonium oxidation was monitored on several process samples taken at different times. The estimates were also delivered by monitoring the ammonium oxidation on the process operated in the batch mode. The plotting of simulations and experimental results revealed good agreement. In order to investigate the process performance in terms of biological stability, a long time period (≈ 600 days) was simulated. The results showed that a high stable nitrite accumulation (> 95%) could be achieved when the above optimal conditions are imposed to the system. However, after a long time, the accumulated nitrite is converted into nitrate and then the system is disrupted. For the simulated experimental conditions, the process disruption period was located between 180 and 350 days. At this period, a corresponding theoretical purge flowrate was found to range between 0.15 10-3 m3.d-1 and 3.0 10-3 m3.d-1. Simulations also showed that increasing the purge flowrate decreases the sludge retention time and then favours nitrite accumulation into the process. That is an interesting strategy to increase the performance of the biological partial nitrification process.

Biological invasions are an important issue of global change and an increased understanding of invasion processes is of crucial importance for both conservation managers and international trade. In this thesis, I have studied the invasion of the brown seaweed Fucus evanescens, to investigate the fate and effect of a perennial, habitat-forming seaweed introduced to a coastal ecosystem. A long-term study of the spread of F. evanescens in Öresund (southern Sweden) showed that the species was able to expand its range quickly during the first 20 years after the introduction, but that the expansion has been slow during the subsequent 30 years. Both in Öresund and in Skagerrak, the species is largely restricted to sites where native fucoids are scarce. Laboratory experiments showed that the restricted spread of F. evanescens cannot be explained by the investigated abiotic factors (wave exposure and salinity), although salinity restricts the species from spreading into the Baltic Sea. Neither did I find evidence for that herbivores or epibiota provide biotic resistance to the invader. On the contrary, F. evanescens was less consumed by native herbivores, both compared to the native fucoids and to F. evanescens populations in its native range, and little overgrown by epiphytes. Instead, the restricted spread may be due to competition from native seaweeds, probably by pre-occupation of space, and the establishment has probably been facilitated by disturbance. The studies provided little support for a general enemy release in introduced seaweeds. The low herbivore consumption of F. evanescens in Sweden could not be explained by release from specialist herbivores. Instead, high levels of chemical anti-herbivore defence metabolites (phlorotannins) could explain the pattern of herbivore preference for different fucoids. Likewise, the low epibiotic colonisation of F. evanescens plants could be explained by high resistance to epibiotic survival. This shows that colonisation of invading seaweeds by native herbivores and epibionts depends on properties of the invading species. The large differences between fucoid species in their quality as food and habitat for epibionts and herbivores imply that invasions of such habitat-forming species may have a considerable effect on a number of other species in shallow coastal areas. However, since F. evanescens did not exclude other fucoids in its new range, its effect on the recipient biota is probably small.

No description available.

Fresh water resources in many of the world's oil producing regions, such as western Texas, are scarce, while produced water from oil wells is plentiful, though unfit for most applications due to high salinity and other contamination. Disposing of this water is a great expense to oil producers. This research seeks to advance a technology developed to treat produced water by reverse osmosis and other means to render it suitable for agricultural or industrial use, while simultaneously reducing disposal costs. Pilot testing of the process thus far has demonstrated the technology's capability to produce good-quality water, but process optimization and control were yet to be fully addressed and are focuses of this work. Also, the use of renewable resources (wind and solar) are analyzed as potential power sources for the process, and an overview of reverse osmosis membrane fouling is presented. A computer model of the process was created using a dynamic simulator, Aspen Dynamics, to determine energy consumption of various process design alternatives, and to test control strategies. By preserving the mechanical energy of the concentrate stream of the reverse osmosis membrane, process energy requirements can be reduced several fold from that of the current configuration. Process control schemes utilizing basic feedback control methods with proportional-integral (PI) controllers are proposed, with the feasibility of the strategy for the most complex process design verified by successful dynamic simulation. A macro-driven spreadsheet was created to allow for quick and easy cost comparisons of renewable energy sources in a variety of locations. Using this tool, wind and solar costs were compared for cities in regions throughout Texas. The renewable energy resource showing the greatest potential was wind power, with the analysis showing that in windy regions such as the Texas Panhandle, wind-generated power costs are approximately equal to those generated with diesel fuel.

<p>Car exhaust catalysts were introduced in the early 1980’s, to limit the release of pollutants such as hydrocarbons, carbon monoxides and nitrogen oxides. These catalysts contain noble metals such as palladium (Pd), platinum (Pt) and rhodium (Rh) and are able to simultaneously abate all three of the above-mentioned pollutants, hence the name three-way catalyst (TWC). The exposure to high temperatures (800-1000 °C) during operation and the presence of additives in petrol such as lead, calcium, silicon, magnesium, manganese, chromium, sulphur and phosphorus will after a certain time start to lower the overall effectiveness of the catalyst. These effects are either of a mechanical or a chemical nature. High temperatures reduce the active area by causing the noble metals to agglomerate and sinter whereas the additives alter the activity by either fouling the pores of the support material (phosphorus) or by interacting with the metals (sulphur and lead).</p><p>The main objective of this work was to develop a method to redisperse the catalytically active sites, comprising Pd, Pt and Rh on the washcoat surface, in an effort to regain lost catalyst activity. For this purpose, a wide spectrum of different commercial car exhaust catalysts containing varying noble metal loadings, aged under various driving conditions and with mileages ranging from 30 to 100 000 km were evaluated.</p><p>The influence of a thermal treatment in a controlled gas atmosphere, such as oxygen or hydrogen and a redispersing agent, e.g. chlorine, on the activity of TWC was investigated by means of laboratory-scale activity measurements. Several complementary characterisation methods such as SEM/TEM, XRD, BET and TPR were used to verify the effects of the regeneration treatments on the catalyst morphology (Paper I). Partial regeneration of catalyst activity and noble metal dispersion was achieved after thermal treatment in an oxygen-chlorine rich atmosphere at temperatures below 500 °C.</p><p>Finally, an investigation of the effects of an oxy-chlorine thermal treatment for regeneration of a ‘full-scale’ commercial automotive three-way catalyst was performed. Catalyst activity and performance prior to and after the oxy-chlorine thermal treatment was measured on a test vehicle in accordance with the European driving cycle (EC2000). The catalyst surface was further characterised using XRD and EDX (Paper II). Improved catalyst activity for a high mileage catalyst could be observed, with emissions lowered by approximately 30 to 40 vol% over the EC2000 driving cycle</p>