Le fer est un métal abondant dans l'environnement. La présence d'espèces de fer dans l'environnement peut affecter un grand nombre de processus. Les contaminants peuvent être largement trouvés dans les systèmes environnementaux. Différentes espèces peuvent exister, y compris pour les polluants inorganiques et les polluants organiques. L'étude de la transformation et la mobilité de ces contaminants en présence d'espèces de fer aura sans doute des implications importantes sur l'environnement. Le mémoire de thèse est divisé en quatre chapitres. Dans le premier chapitre, nous présenterons une synthèse bibliographique sur la contamination actuelle de l'arsenic et plusieurs contaminants émergents, la présence d'espèces de fer (fer dissous et oxydes de fer) dans l'environnement, et les interactions entre les contaminants et les espèces de fer. Le deuxième chapitre est une étude de l’adsorption de l’As(III) sur l'hydroxyde ferrique colloïdal et sa transformation sous lumière visible dans un système de fer(III)/ sulfite. Dans ce travail, l'oxydation de l’As(III) en As(V) dans un système de fer(III)/sulfite en utilisant la lumière du soleil ou d'une lampe à diode électroluminescente (λ = 404 nm) a été étudiée. Plusieurs types d’agents de piégeage des radicaux hydroxyles, d'azote et agents de complexation ont été utilisés pour l'étude du mécanisme d’oxydation. En comparant le a) le fer(III) avec l'irradiation et b) le fer(III)/sulfite sans irradiation, nos résultats montrent une amélioration significative de l’oxydation de l’As(III) à pH 6 dans un système de fer(III)/sulfite-visible correspondant à une constante de vitesse initiale de 0,196 min-1. L’étude du mécanisme a révélé que les voies de l'oxydation d’As(III) à pH neutre est assez complexe. En effet, les radicaux libres (principalement les HO•, SO4-• et SO5-•) et mécanismes de transfert ligand-métal charge entre As (III) et ferrique colloïdal hydroxyde (CFH) des particules sont impliqués. Le troisième chapitre est une étude de l'adsorption coopérative d'acide nalidixique (NA) et de l'acide niflumique (NFA) sur goethite. Dans ce travail, la cinétique d’adsorption de NA et NFA a été réalisée en single et binaire. Les résultats montrent que le qe de NA est 8 fois de NFA dans un système à seul composant. Dans le système binaire, qe de NA était légèrement plus grand que pour le système single, alors que l’adsorption de NFA était environ 4 fois plus grande que pour le système single, ce qui suggère que l'adsorption est coopérative ou une co-liaison a eu lieu entre NA et NFA. La désorption a confirmé qu'aucune transformation de NA ou NFA a eu lieu en présence de la goethite. Des expériences en infra-rouge (ATR-FTIR) et la modélisation de complexation multi-site (MUSIC) ont été également effectuées. L'adsorption de NA et NFA dans les deux systèmes de composants simples et binaires peut être décrit par MUSIC. Ensuite, le quatrième chapitre est une étude de l'adsorption de NA et NFA sur du sable recouvert de goethite (GCS) sous conditions hydrodynamiques contrôlées. L'étude cinétique et les isothermes d’adsorption ont confirmé l'effet de co-liaison de NA et NFA sur la surface de GCS. Le comportement de NA et de NFA dans la colonne a montré de différence significative en raison de la différence de capacité et des mécanismes d'adsorption. Dans le système binaire, le comportement d'une substance peut être affectée par la présence de l'autre substance, tandis que l'effet sur la NFA est beaucoup plus prononcée que celle de NA. La modélisation de la complexation de surface a été utilisée pour prédire les courbes de percée, mais un désaccord a été observée entre la modélisation et les données expérimentales. Le point de percée et la quantité d'adsorption sont surestimés par le modèle, ce qui pourrait du à des limitations cinétique d’origine chimique. / Iron is an abundant metal in the environment. The occurrence of iron species in the environment can affect a wide range of processes. Contaminants can be widely found in the aqueous and solid phase environment. Their species are complex and diverse, including inorganic pollutants and organic pollutants. The studying on the mobility and redox transformation of these contaminants in the presence of iron spices and thereby the treatment methods have important environmental implications. This thesis includes 4 chapters. In the first chapter, we presented the bibliography on the current contamination situation of arsenic and several emerging contaminants, occurrence of iron species (dissolved iron and iron oxides) in the environment, and the interactions between contaminations and iron species. The second chapter is a study of the sorption of As(III) on colloidal ferric hydroxide and the transformation of As(III) under the visible light induced iron(III)/sulfite system. In this work, the oxidation of As(III) to As(V) in an iron(III)/sulfite system under visible light using sunlight or a light-emitting diode lamp (λ = 404 nm) were investigated. Several kinds of free radical quenchers, nitrogen and complexation competing agent were used for mechanism study. Comparing to a) iron(III) system with irradiation of light and b) iron(III)/sulfite system without irradiation light, our results show a significant enhancement of As(III) oxidation efficiency at pH 6 in iron(III)/sulfite-visible light (LED) system, corresponding to an initial rate constant of 0.196 min−1. Mechanism investigation revealed that the pathways of As(III) oxidation at circumneutral pH is complicated that involved free radicals (mainly HO•, SO4−• and SO5−•) and ligand-to-metal charge transfer between As(III) and colloidal ferric hydroxide (CFH) particles. The third chapter is a study of cooperative adsorption of nalidixic acid (NA) and niflumic acid (NFA) on nano-size goethite. In this work, the adsorption of NA and NFA in single and binary component systems was conducted by kinetic adsorption experiments and batch experiments for macroscopic study. Results show that qe of NA is 8 times of NFA in the single component system. In the binary component system, qe of NA was slightly larger than for the single system, whereas NFA adsorption was about 4 times larger than for the single system, suggesting that cooperative adsorption or co-binding occurred between NA and NFA. Desorption experiment confirmed no transformation of NA and NFA occurred in the presence of goethite. Attenuated Total Reflectance-Fourier Transform InfraRed (ATR-FTIR) spectroscopy and multi-site complexation (MUSIC) modeling was used for the microscopy study. The adsorption of NA and NFA in both single and binary component systems can be described by MUSIC modeling well. Afterwards, the fourth chapter is a study of the cooperative adsorption of NA and NFA onto goethite coated sand (GCS) under batch and flow through conditions. Batch experiments, including kinetic study, pH edges and isotherms, confirmed the co-binding effect of NA and NFA on GCS surface. The breakthrough behavior of NA and NFA in the column study showed significant difference in single component system due to the difference in adsorption ability and mechanisms. In binary component system, the breakthrough behavior of one substance can be affected by the presence of the other substance, while the effect on NFA is much pronounced than NA. Surface complexation modeling was used to predict the breakthrough behavior, however a disagreement was observed between modeling and experimental data in breakthrough point and adsorption amount, which might due to the chemical sorption kinetic limitation.

O presente trabalho estuda a degradação fotocatalítica da nicotina em solução aquosa, um alcaloide altamente tóxico que tem sido detectado em efluentes, águas subterrâneas e água mineral. Os experimentos foram realizados em um reator batelada sob irradiação ultravioleta, tendo sido avaliadas três principais variáveis: concentração inicial do contaminante, concentração de catalisador e pH inicial da solução. Foram realizados dois planejamentos de experimentos para os catalisadores comerciais ZnO e TiO2, com o objetivo de encontrar a melhor condição para promover a degradação da nicotina em água. Outros catalisadores, preparados a partir de resíduos industriais e laboratoriais, foram testados nas condições otimizadas. O método analítico empregado para quantificar a nicotina nas amostras foi a cromatografia líquida de alta eficiência, o que permitiu registrar a formação de intermediários e subprodutos de reação. Os resultados experimentais demostraram que a degradação da nicotina por fotocatálise heterogênea é um processo bastante eficiente. Em ambos os planejamentos, o pH foi a variável que exerceu o maior efeito sobre a degradação, sendo este fortemente positivo. Já a concentração inicial de nicotina exerceu efeito negativo sobre a resposta e a concentração de catalisador em suspensão exibiu um ponto ótimo, que correspondeu a 0,91 g.L-1 para o ZnO, e 1,20 g.L-1 para o TiO2. Ensaios foram realizados nas condições otimizadas encontradas, onde cerca de 98% da molécula foi degradada utilizando ZnO em suspensão e 88% empregando TiO2, em uma hora de reação. A degradação fotocatalítica da nicotina demonstrou seguir uma cinética de pseudoprimeira ordem dentro do tempo de reação de 60 minutos, para os dois catalisadores comerciais. Entre os catalisadores não convencionais que foram testados, aquele que demonstrou o maior percentual de degradação foi obtido a partir de resíduo de uma indústria petroquímica, cerca de 43%. / The present work studies the photocatalytic degradation of nicotine in aqueous solution. This alkaloid is highly toxic and it has been detected in wastewater, groundwater and mineral water. The experiments were performed in a batch reactor under ultraviolet radiation. Three main variables of process were evaluated: initial concentration of pollutant, catalyst concentration and initial pH of the solution. Two experimental designs were performed for commercial catalysts ZnO and TiO2. The purpose was to find the best condition to promote the nicotine degradation in water. Other catalysts prepared from industrial and laboratory waste were tested under the optimized conditions. Analytical method used to quantify nicotine and its degradation products in all samples was high performance liquid chromatography. Experimental results showed that nicotine degradation by heterogeneous photocatalysis is a very efficient process. In both designs, initial pH was the most significant variable which has a strong positive effect. Initial nicotine concentration showed a negative effect, and catalyst concentration exhibited an optimal value for both commercial catalysts: 0,91 g.L-1 using ZnO, and 1,20 g.L-1 with TiO2. At the best conditions, about 98% of the molecule was degraded using ZnO and 88% with TiO2. Photocatalytic nicotine degradation followed a pseudo first order kinetic until 60 minutes of reaction for both commercial catalysts. Among the non-conventional catalysts tested, the one prepared from a petrochemical industry residue exhibited the highest photocatalytic degradation, about 43%.

Conventional wastewater treatment plants are able to reduce contaminant loads within regulations but do not take into account emerging contaminants. Antibiotic resistance genes and antibiotic resistant bacteria have been shown to survive wastewater treatment and remain detectable in effluents. The safety of treated wastewaters is crucial, otherwise unregulated and unmitigated emerging contaminants pose risks to public health and impede wastewater reuse. This dissertation aimed to further understanding of emerging microbial threats, and tested two natural and low-cost tools for their mitigation: sunlight, and bacteriophages. A wastewater bacterial isolate, named E. coli PI-7, which is highly antibiotic resistant, carries the novel antibiotic resistance gene New Delhi metallo-beta-lactamase NDM-1 gene, and displays pathogenic traits, was chosen to model responses to the treatments. Results found that solar irradiation was able to achieve a 5-log reduction in E. coli PI-7 numbers within 12 hours of exposure. However, the results also emphasized the risks from emerging microbial contaminants since E. coli PI-7, when compared with a non-pathogenic strain E. coli DSM1103 that has less antibiotic resistance, showed longer survival under solar irradiation. In certain instances, E. coli PI-7 persisted for over 6 hours before starting to inactivate, exhibited complex stress resistance gene responses, and activated many of its concerning pathogenicity and antibiotic resistance traits. However, upon solar irradiation, gene expression results obtained from both E. coli strains also showed increased susceptibility to bacteriophages. Hence, bacteriophages were coupled with solar irradiation as an additional mitigation strategy. Results using the coupled treatment found reduced cell-wall and extracellular matrix production in E. coli PI-7. DNA repair and other cellular defense functions like oxidative stress responses were also impeded, rendering E. coli PI-7 more susceptible to both stressors and successfully hastening the onset of its inactivation. Overall, the dissertation is built upon the need to develop strategies to further mitigate risks associated with emerging microbial contaminants. Solar irradiation and bacteriophages demonstrate potential as natural and low-cost mitigation strategies. Sunlight was able to achieve significant log-reductions in tested E. coli numbers within a day’s exposure. Bacteriophages were able to overwhelm E. coli PI-7’s capacity to resist solar inactivation while not affecting the indigenous microbiota.

With a growing population and continuous accumulation of pollutants, water resources worldwide are quickly being depleted. Drastic improvements need to be made in both water conservation and treatment. Advanced oxidation processes (AOPs) have been developed to go above and beyond the capabilities of traditional wastewater treatment facilities to eliminate emerging contaminants from our water systems. AOPs increase the generation of hydroxyl radicals (•OH) in oxidation reactions, which are less selective and more reactive than other oxidants, such as ozone, so they are more effective at degrading persistent compounds. This study explored an AOP that utilizes ozonated multi-walled carbon nanotubes (MWCNTs) to generate •OH; past research has proven the success of this method of water treatment, showing a significant decrease in the effluent concentration of the tested compounds. However, these previous studies used a batch system with an initial aliquot of ozone, which would not be a feasible option in a commercial application. This research compares results from a semi-batch system with a continuous injection of ozone to these previous batch system studies to determine if continuous ozonation improves •OH generation capability, contaminant degradation, and the associated reaction kinetics. Results from batch studies had shown limitations to both •OH generation and contaminant degradation which were suspected to be due to ozone degradation; however, these results suggest that ozone availability is in fact not a limiting factor to •OH or contaminant degradation, and another mechanism must be at play. Further, to advance the AOP toward a commercially feasible design, a continuous flow-through system with a MWCNT embedded membrane was explored. The continuous system achieved 80% contaminant degradation in some cases, however, with varying retention times and efficiencies over time, the results were inconclusive and additional experimentation is required.

Water from the Llobregat is used to supply a significant part of the city of Barcelona. At the same time, 60 wastewater treatment plants discharge into this basin. Two field campaigns conducted in the Llobregat Catchment detected more than 80 pharmaceu-ticals in the water. Therefore, it is clear that water quality in Llobregat is a potential concern. A GIS hydrology water quality model has been applied in order to predict the concentrations of one of the pharmaceuticals, diclofenac, in the catchment. Con-sumption, excretion, and degradation data has been studied to calibrate the model. This exercise proves that it is relatively straightforward to predict the concentrations of new and emerging contaminants at basin scale. Nonetheless, the limited and inac-curate available data was a relevant obstacle in this modelling process.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016. / The release of wastewater to the aquatic environment is most likely to introduce some trace levels of organic contaminants, some of which may be toxic, carcinogenic, or endocrine disruptors, as well as, persistent in the environment. Additionally, increasing contamination of surface waters by wastewater effluents has made water treatment processes more challenging and expensive. The presence of these pollutants in the receiving water body may have negative effects on aquatic species and often pose potential human health risks through the reuse of treated wastewater for drinking purposes and other household use. In countries like South Africa, Namibia, USA, Singapore and Australia, water agencies are intensifying wastewater reclamation/wastewater reuse as part of their water resource agenda: in order to meet the demands of the growing populations. Nowadays, water reuse is generally considered as a viable method of water supply management. This study focused on the identification of the occurrence, quantification of emerging contaminants and evaluation of removal efficiency in wastewater treatment processes of three classes of emerging contaminants (ECs) in wastewater: 1) six types of perfluorinated compounds (PFCs), namely; perfluorooctanoic acid (PFOA), Perfluorooctane sulphonate (PFOS), perfluoroheptanoic acid (PFHpA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUDA); 2) bisphenol A (BPA); and 3) Acetaminophen (ACP). These contaminants were identified and quantified in four wastewater treatment plants in the Western Cape. These treatment plants include three WWTPs in Cape Town, namely: Bellville WWTP, Scottsdene WWTP and Zandvliet WWTP and one WWTP in the central Karoo (Beaufort West wastewater reclamation plant).

Biological nutrient removal (BNR) systems employ engineered biological processes—including nitrification, denitrification, and biological phosphorus removal—to remove nutrients from wastewater. Since their original implementation, BNR systems have adapted to challenges, such as the presence of inhibitory compounds and demands for more energy- and resource-efficient wastewater treatment. Advancements in alternative BNR technologies made in response to these demands have highlighted the metabolic versatility of microbial communities present in BNR systems. This versatility is also observed in the expanded capacity of BNR systems to remove not only human-derived carbon, but also complex trace organic emerging contaminants (ECs). Based on conventional monitoring alone, the roles of specific bacteria and metabolic mechanisms in the removal of nutrients and ECs remain unclear. A detailed understanding of the actors and mechanisms in BNR systems can be attained through application of molecular biology tools, including those targeting community (a) structure and potential function through DNA analysis and (b) extant function through RNA analysis. This dissertation encompasses three objectives, which seek to link detailed molecular-level information to the performance and metabolic versatility of several nutrient-removing communities. The first objective was to assess the utility of gene expression assays to indicate and predict nitrification inhibition by toxic heavy metals based on functional responses of nitrifying bacteria. Through this assessment, it was found that genes related to both catabolic and anabolic pathways could be used as indicators of nitrification inhibition. The second objective was to investigate the effects of reactor operating conditions on simultaneous nitrogen and phosphorus removal by examining the microbial community structure and metabolism of a survey of full-scale BNR systems. A variety of BNR configurations and operating conditions, all capable of sustained nutrient removal, selected for different nitrogen- and phosphorus-removing communities. The activity of these communities was also dependent on configuration and operating conditions, as indicated by analysis of gene expression. Finally, the third objective was to examine the expanded capacity of BNR systems to attenuate ECs by investigating the removal of the EC bisphenol A (BPA) by microbial communities involved in nutrient removal. Communities derived from both full-scale and lab-scale systems were capable of biodegrading BPA, though each community was uniquely influenced by reactor processes and BPA exposure conditions. Results from this work also offered insights into the utility of assessed genes as biomarkers for metabolic activity and the importance of accurately characterizing in-situ responses of BNR systems. In both lab-scale and full-scale studies, certain genes demonstrated increased sensitivity to nutrient-removing activity. At lab-scale, observed differences between inhibition of ammonia oxidation through discrete and continuous Cu(II) exposure indicated that conventional short-term, ex-situ batch assays may underestimate inhibition in a parent reactor of interest. The benefit of gene expression assays to accurately reflect in-situ responses was also examined in full-scale BNR systems removing both nitrogen and phosphorus. Findings from full-scale BNR systems revealed the long-term effects of changes to process configurations on microbial community structure and activity. Despite differences in operating conditions and the resulting nitrogen- and phosphorus-removing communities, a variety of configurations sustained nutrient removal. Long-term effects were also characterized in the context of EC removal. Differences in BPA degradation rates and microbial community profiles in lab-scale mixed culture communities after extended BPA exposure showed the lasting influence of both reactor processes and BPA exposure conditions. Assessment of microbial community structure was also used to identify BPA-degrading bacteria. Results from each of the three objectives could be used in the development of biomarkers to assess and predict (1) process upsets or inhibition, (2) nutrient removal process performance, or (3) capacity for EC removal. Integrating analysis of microbial community structure and function with reactor performance monitoring and mechanistic modeling that includes such advanced knowledge holds the potential to not only guide effective operation of BNR systems, but also identify opportunities for more efficient and even concomitant nitrogen, phosphorus, and EC removal.

No description available.

Continuous increases in the interest and implementation of wastewater reuse due to intensified water stress has escalated the concerns of emerging contaminants. Among emerging contaminants there are microbial (antibiotic resistance) and chemical (pharmaceuticals) elements which have been shown to survive wastewater treatment. This dissertation aims to mitigate emerging contaminants by means of understanding and/or developing the appropriate disinfection strategies, with the intention to provide knowledge that would facilitate towards safe and sustainable water reuse. The first part of this thesis explored microbial risk component of antibiotic resistance. Antibiotic resistance genes are abundant in treated wastewater, and only pose a risk if taken up by potential pathogens through natural transformation. Our results showed that solar irradiation can double natural transformation rates, mediated by reactive oxygen species generation, which led to upregulation in DNA repair and competence genes in Acinetobacter baylyi ADP1. Treatment with UV-C254 nm irradiation also resulted in upregulation in DNA repair genes, nevertheless we observed a decrease in natural transformation rates. These results imply that direct damage of antibiotic resistance genes (ARG) could inhibit their spread and therefore risk, despite other factors contributing to the contrary. The next chapter in this dissertation postulated that the UV/H2O2 combination would be ideal to treat microbial and chemical emerging contaminants in effluent generated from an anaerobic membrane bioreactor. We demonstrated that at an optimal UV intensity and H2O2 concentration, we were able to achieve a 2 and 6-log reduction of the two antibiotic resistance genes and bacteria and used in this study, respectively, and more than 90% removal of the three pharmaceutical compounds. These observations suggest that UV/H2O2 has great potential in treating effluent with high nitrogen concentrations, preserving the fertilization benefit of AnMBR effluent. Overall, this dissertation revealed the potential of UV-based treatments for treated wastewater intended for reuse. Post-membrane processes effluent allows one to deploy UV-C254 nm to selectively target DNA and therefore ARB and ARG that may be still present in the treated wastewater. At the same time, coupling chemical oxidants with UV-C (i.e., UV AOP) would further enhance the means to simultaneously oxidize and degrade potentially harmful chemical contaminants.

This study explores the efficacy of two advanced oxidation processes for generation of hydroxyl radicals to promote degradation of emerging contaminants. Drought and water shortage have become pressing issues caused by our world’s changing climate. Water reclamation and reuse are increasingly important options for relieving this water stress. Water reuse runs the risk of reintroducing recalcitrant compounds that can accumulate in our bodies and environment. Advanced treatment methods that degrade these compounds are vital to protect our health and the health of the environment while providing necessary water resources. Advanced oxidation processes (AOPs) have shown great promise for removing recalcitrant compounds through the production of highly reactive hydroxyl radicals (·OH). This study investigated two AOPs for their production of ·OH as indicated by the probe compound pCBA. One of the AOPs examined was a proprietary device that utilizes ambient air and UV to generate singlet oxygen, which subsequently produces ·OH in water. The other is a more common method that combines UV and ozone (O3) to produce ·OH. The proprietary method was not found to produce notable hydroxyl radicals compared to the UV/O3 AOP. The UV dose of the UV/O3 AOP was also altered to analyze the impact on hydroxyl radical production and removal of a representative emerging contaminant, diclofenac (DCF). The sleeves made to alter the UV dose were not found to change the UV dose enough to show a consequential difference in degradation for the fluence indicator atrazine (ATZ) or the emerging contaminant DCF. Further testing with thicker sleeves would be important to determine the necessary amounts of UV and reasonably scale this technology for a water treatment facility.