Les matières premières biosourcées s'avèrent être une possibilité de substitution du pétrole de plus en plus prisée dans le domaine des matériaux. De plus, l'utilisation de procédé propre limitant l'impact environnemental du développement de matériau est aujourd'hui incontournable. Dans ce contexte, l'acide aminé L-lysine, un nouveau synthon issu des biotechnologies blanches peu étudié dans le domaine de la chimie des matériaux, a été retenu. Ce synthon sera modifié pour la conception de macromonomères polymérisables sous irradiation UV. En effet, la technique de photopolymérisation est un procédé propre en plein essor, et qui permet le développement de revêtement.La L-lysine étant peu soluble dans les milieux organiques classiques, une étape de transformation est nécessaire pour améliorer sa processabilité. Ainsi, la polycondensation en masse de la L-lysine a conduit à des oligomères de poly-L-lysine de faibles masses molaires. La détermination de la structure obtenue a été réalisée par différentes techniques d'analyses. Ces oligomères sont alors greffés par des fonctions photopolymérisables dans des conditions douces. Le choix s'est porté sur des fonctions accepteur et donneur d'électron. Enfin, l'étude de la photopolymérisation des oligomères de L-lysine greffés accepteurs donneurs a été effectuée par la technique UV aqueuse, une technique innovante et respectueuse de l'environnement, dans différentes conditions pour en optimiser le système. / Biobased raw materials are an interesting and promising option for the substitution of fossil resources in material design. Moreover, using green processes which limit environmental impact of the material conception can't be avoided nowadays. In this context, the L-lysine amino acid, a building block made by white biotechnologies and poorly described in material field has been evaluated. As photopolymerization is a green process in great expansion and allowing coating design, this building block has been modified into a photocurable macromonomer.L-lysine is hardly soluble in usual organic solvents, a transformation step is necessary in order to improve its processability. Thus, L-lysine polycondensation has been tackled and led to oligomers of poly-L-lysine with low molar mass and improved solubility. In addition, the structure determination has been undertaken by different analytic technics. These oligomers can thus be grafted with photocurable functional groups in mild conditions. The chosen photocurable functional groups are donor acceptor of electron. At last, the photopolymerization of L-lysine based oligomers grafted with donor acceptor functional groups has been done by UV waterborne technic which is innovative and environmentally friendly. The photopolymerization has been carried out in different conditions in order to optimize the process.

Les épidémies de gastro-entérite aigüe liées à l’eau du robinet demeurent un enjeu de santé publique au 21ème siècle dans les pays développés. La majorité des dispositifs de surveillance mis en place dans les pays se caractérisent par une sous-déclaration. En France, l’amélioration de la surveillance de ces évènements repose sur l’exploitation des données de l’Assurance Maladie. L’objectif de notre travail est de proposer une méthode pour améliorer la sensibilité et la spécificité de la détection des épidémies de gastro-entérite aigüe d’origine hydrique. Trois études ont été menées pour i) évaluer la capacité des données de l’Assurance Maladie à décrire des épidémies de gastro-entérite aigüe d’origine hydrique, ii) adapter une méthode de détection spatio-temporelle en intégrant l’exposition à l’eau du robinet, iii) évaluer les performances de cette méthode. Notre travail a permis de développer une méthode de détection spatio-temporelle des épidémies hydriques en tenant compte des unités géographiques de distribution d’eau avec une bonne sensibilité et une bonne valeur prédictive positive. Les performances de détection sont principalement liées à la taille de l’épidémie. La capacité des données de l’Assurance Maladie à détecter des épidémies d’origine hydrique peut être influencée par les habitudes de recours aux soins, la sensibilisation de la population au risque infectieux d’origine hydrique et le niveau d’agrégation temporel des cas de gastro-entérite aigüe. La finalité de nos travaux de recherche est l’application opérationnelle pour la détection automatisée des épidémies hydriques dans une finalité de prévention et de réduction de leur impact sanitaire. / Waterborne disease outbreaks (WBDO) of acute gastrointestinal illness remain a public health concern in the 21st century in developed countries. Almost all surveillance systems implemented in countries are characterized by underreporting. In France, the improvement of monitoring these events is based on the use of data from the French Health Insurance. The aim of our work was to propose a method to improve the sensitivity and specificity of the detection of WBDO. Three studies were conducted to i) evaluate the ability of French Health Insurance data to describe WBDO ii) apply a method of space-time detection by integrating the exposure to tap water, iii) evaluate the performance of this method. Our work allowed developing a method of space-time detection of WBDO by taking into account geographical units for drinking water networks units with a good sensitivity and positive predictive value. The performances for detection are mainly related to the size of the epidemic. The ability of the data from the French Health Insurance to detect WBDO can be influenced by the health-seeking behavior of people, awareness of the population to the risk of WBDO and the temporal aggregation level of cases of acute gastrointestinal illness. The purpose of our research is to carry out an operational design for the automated detection of WBDO in a purpose of prevention and reduction of health impact.

In recent years, surface water used for domestic, industrial, and irrigation purposes in South Africa has deteriorated due to inadequate wastewater treatment, urban and agricultural runoff, and rural settlements with deficient sanitation. Access to safe drinking water and sanitation is a basic human right, and if waterborne pathogens are present in the water environment, they compose a human health risk. With some hydrological models, e.g., Hydrological Predictions of the Environment (HYPE), it is possible to model microbial water quality and predict how land use and climate changes affect recipient water sources. In this thesis, waterborne pathogen transport in South Africa is investigated using World-Wide HYPE (WWH), to increase the understanding of the largest sources affecting pathogen concentration in surface water and processes affecting pathogen transport. Initially, a literature study was performed with emphasis on finding the most suitable pathogen to simulate. Because of the amount of available data, the indicator microorganism, E. coli, was chosen. Observed E. coli concentrations in surface water were used to evaluate the conformity of the simulated concentration, and contributions from separate sources were analysed. A sensitivity analysis was performed to increase the understanding of process parameters affecting the transport of E. coli in WWH. The findings of this project show that the largest contributions of E. coli originate from humans with unsatisfactory waste management, where wastewater is partially released directly to surface water. The largest deviation in average E. coli load per year was obtained when altering t1expdec, which denotes the half-life time of the simulated microorganism. The half-life time was also the process parameter with the most significant effect on the simulated concentration. In addition, when the parameter that specifies the fraction of E. coli that is released directly to surface water was altered, which affects one of the largest E. coli sources, a large deviation in average E. coli load per year was observed. This finding shows the importance of estimating the load from contamination sources accurately. The conformity of simulated and observed E.coli load was acceptable, but the simulated discharge needs to be improved to achieve better conformity of the E. coli concentration in surface water. WWH has great potential to simulate waterborne pathogens, but further developments to improve the simulated discharge are encouraged to obtain more reliable results. / Under de senaste åren har kvaliteten av ytvattnet i Sydafrika försämrats på grund av bristfälliga vattenreningsverk, avrinning från urbana miljöer och åkermark och områden med undermålig sanitet. Att ha tillgång till rent vatten och fungerande sanitet är en grundläggande mänsklig rättighet och om patogener är närvarande utgör detta en hälsorisk för människor som kommer i kontakt med dessa smittoämnen. Det är möjligt att modellera vattens kvalitet med avseende på mikroorganismer och att förutse hur markanvändning påverkar kvaliteten i recipienten. I detta arbete har transporten av vattenburna patogener i Sydafrika undersökts genom World-Wide HYPE (WWH) med syftet att öka förståelsen av de största källorna som bidrar till ökande koncentrationer av patogener i ytvatten, samt att öka förståelsen av processerna som påverkar transporten. En litteraturstudie utfördes för att hitta en passande patogen att simulera, och på grund av mängd tillgängliga data valdes indikatororganismen E. coli. Uppmätt koncentration av E. coli i ytvatten i Sydafrika användes för att utvärdera överrensstämmelsen med simulerad koncentration, och bidrag från olika källor av E. coli analyserades. En kompletterande känslighetsanalys utfördes för att öka förståelsen om transportprocesserna i WWH. Resultatet visade att de största bidragskällorna av E. coli till ytvatten i modellen är människor med otillräcklig hantering av mänskligt avfall där genererat avloppsvatten delvis släpps ut direkt till ytvattnet. Från känslighetsanalysen visade det sig att den mest känsliga modellparametern var t1expdec som beskriver mikroorganismenshalveringstid. Det var också den processparameter som också hade störst påverkan på den simulerade E. coli koncentrationen. När parametern som bestämmer andelen av E.coli som släpps ut direkt till ytvatten varierades, som påverkar en av de största källorna, resulterade det också i stor förändring i genomsnittlig belastning av E. coli per år. Detta indikerar att det är viktigt att estimera bidragskällorna korrekt. Överrensstämmelsen mellan simulerad och uppmätt belastning av E. coli per dag var acceptabel men det simulerade vattenflödet bör förbättras för att uppnå en bättre överrensstämmelse mellan simulerade och uppmätta koncentrationer av E. coli. WWH har stor potential att modellera vattenburna patogener, men vidareutveckling av simulerade vattenflöden behöver utföras att få mer tillförlitliga resultat.

Waterborne diseases are illnesses caused by microscopic organisms, like viruses, bacteria and  parasites, that transmitted via the fecal-oral route through ingestion of contaminated water or food or by direct person to person contact. The transmission cycle can be broken through safe water supplies, maintaining standards of sanitation and proper handwashing practices. Two waterborne diseases are considered in this study: hepatitis A and amebic dysentery. The study aimed to understand the important factors for preventing waterborne diseases in order to improve public health. A descriptive cross-sectional study was conducted to assess the effect of different drinking water sources, sewage systems and different active practices of soap use for hand washing on incidence of waterborne diseases in different regions in Saudi Arabia. Data was obtained from Ministry of Health and Household Environment Survey provided by General Authority for Statistics. Statistical analysis performed by using general linear model and type II Analysis of Variance. In comparison of different drinking water sources, this study showed borderline rise in incidence of waterborne diseases with the use of private well water. Whereas different sewage systems had no clear effect on the incidence of waterborne diseases. The study also revealed that not using soap for hand washing would increase the risk for hepatitis A infection. Moreover, the study showed significant decline in waterborne diseases incidence when access to filtered water combined with regular soap use in the same linear model.

Department of Ecology and Resource Management / PhDENV / Groundwater has traditionally been perceived to be low in chemical species toxicity and microbiologically 'pure'. However, depending on the geological chemistry, formations and anthropogenic activities creating the frequent occurrence of microbiological contamination and excess toxic chemical constituents, the high quality of groundwater as a drinking water source can easily be compromised rendering it unsafe, thus, leading to severe waterborne epidemics. The rapid increase in fluoride and microbial contamination of groundwater have become a global problem to human health. Fluoride in its acceptable concentration in drinking water (< 1.5 mg/L); is known to be beneficial for human growth and development but becomes detrimental at higher concentrations (> 1.5 mg/L) leading to the prevalence of dental and crippling skeletal fluorosis. On the other hand, consumption of microbiologically contaminated water has led to many types of diseases including diarrhea, cholera, typhoid, dysentery and other serious illnesses often leading to millions of deaths annually worldwide. South Africa had experienced water-borne diseases epidemic in the recent past due to failing water treatment facilities in many parts of the country including rural areas. Fluorosis, diarrhea, and cholera are among the chronic health hazards affecting a large population in South Africa. Continuous outbreaks of water-related diseases have been at an unimaginable high level with a reported increase in death rate. The inefficiency of conventional water treatment plants to remove fluoride and disinfect these pathogens from the contaminated domestic and rural community has led to the development of many techniques. These include membrane filtration, ion-exchange, coagulation-precipitation, adsorption among others of which adsorption process proves to be a more significant technology for fluoride removal. Equally, the emergence of nanomaterials has also proved to be the natural answer to solve problems associated with microbes in water since these are absolute barriers to pathogens whose size exceeds most sorbent pore sizes. Also, materials from natural biopolymers or biomass can be utilized at an affordable cost as effective sorbent material for toxic chemical ions and pathogens removal from contaminated water. Consequently, extensive research works have been channeled into the development of more advanced low cost sustainable functionalized sorbent materials and technologies with multifunctional properties for effective water purification. The present study focused on the development of a functionalized chitosan-cellulose hybrid nanocomposite decorated with metal-metal oxides nanoparticles for simultaneous fluoride and microbial removal from groundwater. This was to increase the selectivity and disruption of such pollutants for effective groundwater purification technology. The thesis is presented in nine chapters: (1) General introduction, problem statement, and motivation, research objectives, hypothesis and delimitations of the research are briefly discussed, (2) This chapter gives the literature review of occurrence and sources of fluoride, various fluoride removal techniques; sources, control measures and prevention of microbial pollution in groundwater; the importance of biosynthesis of nanomaterials as emerging novel water treatment adsorbents, the strength of Point-Of-Use as a means of water treatment, water treatment adsorbents synthesis and types of adsorbents with emphasis on hydroxyapatites and biopolymeric based sorbent materials, (3) Optimization of microwave-assisted synthesis of silver nanoparticle by Citrus paradisi peel extracts and its application against pathogenic water strain, (4) Biosynthesis of ultrasonically modified Ag-MgO nanocomposite and Its potential for antimicrobial activity, (5) Green synthesis of Ag/MgO nanoparticle modified nanohydroxyapatite and its potential for defluoridation and pathogen removal in groundwater (6) Green Synthesis of AgMgOnHaP nanoparticles supported on Chitosan matrix: defluoridation and antibacterial effects in groundwater, (7) Biosynthesis of nanofibrous cellulose decorated Ag-MgO-nanohydoxyapatite composite for fluoride and bacterial removal in groundwater, (8) Defluoridation and removal of pathogens from groundwater by hybrid vi cross-linked biopolymeric matrix impregnated Ag-MgOnHaP nanocomposite (9) Conclusions and Recommendations. It is important to point out that Chapters 3 to 8 contains a collection of the research deliverables produced in forms of paper publications and manuscripts and are summarized in a systemic order of experimental protocol. This first output (Chapter 3) of this study evaluated the optimization of a time-dependent microwave-assisted biosynthesis of silver nanoparticles using aqueous peel extracts of Citrus paradisi (Grapefruit red) as a reducing, stabilizing and capping agent with emphasis on its antibacterial property. Optical, structural and morphological properties of the synthesized Citrus paradisi peel extract silver nanoparticle (CPAgNp) were characterized using UV-visible spectrophotometer, transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), Brunauer–Emmett–Teller (BET) and X-ray diffractometer (XRD). The antimicrobial activity was evaluated using the well- and disc-diffusion as well as microdilution methods. Characteristic surface plasmon resonance (SPR) wavelength in the range of 420-440 nm at an optimized intensity growth rate typical of silver nanoparticles was obtained. Microwave irradiation accelerates the reaction medium within seconds of nucleation compared to conventional heating methods of synthesis. The influence of the reaction mixtures affected the SPR patterns on the different nucleation, stability and nanoparticle growth. The mixing ratio of 2:3 (C. paradisi peel extracts: 1 mM AgNO3) was chosen as the optimum reaction mixing ratio relative to the bio-reduction intensity of SPR process contributing to the particle size growth of CPAgNps. The presence, interaction and shifting of the functional groups in the FT-IR spectra of biosynthesized CPAgNps indicated that bioactive compounds present in C. paradisi peel extract were responsible for the bio-reduction of the silver ion to silver nanoparticles. The electron micrographs of the synthesized CPAgNps showed a face-centered cubic (FCC) unit phase structure, spherically-shaped nanoparticles size of 14.84 ± 5 nm with a BET pore diameter of 14.31 nm. The use of biological material allowed the control of the size and stability of the nanoparticle but was obtained in low quantity. The Citrus paradisi peel extract mediated AgNp were found to possess a broad-spectrum antimicrobial activity against water-borne pathogenic microbes in the order: Escherichia coli > Staphylococcus aureus > Klebsiella pneumonia. In Chapter 4, a synergistic bi-layered Ag-MgO nanocomposite from Ag and MgO precursor salts using a natural source from the waste product (citrus fruits outer cover) as a reducing and capping agent was successfully synthesized by a simple rapid, integrated bio-mediated microwave and ultrasonic methods. This was carried out to investigate the interfacial interaction and the encapsulated growth rate behind their combination in obtaining an enhanced antibacterial activity against common water fecal pathogen (Escherichia coli). The growth sequence, structural and morphology interface as well as the composition of the nanocomposite were examined and evaluated by the different characterization techniques. The respective potential application as an antimicrobial agent was evaluated and compared against Escherichia coli. The bio-mediated core-shell Ag-MgO nanocomposite showed characteristic synergetic UV-visible absorption bands at 290 nm for MgO nanoparticle and at around 440 nm for Ag nanoparticle, which moved to a lower wavelength of 380 nm in the composite. The shifting to a lower wavelength confirmed the reduction in the particle size as influenced by the growth rate optical property of biomolecular capped Ag-MgO nanocomposite from the phytochemical constituents in the peel extract of the Citrus paradisi. FTIR analysis further elaborated the role of the organic moieties in the Citrus paradisi extracts acting as the capping and stabilizing agent in the formation of the core-shell Ag-MgO nanocomposite. SEM analysis revealed an agglomeration of layered clustered particles, which was poly-dispersed while XRD showed the cubical crystal lattice network phase structure of the Ag-MgO nanocomposite. The TEM micrograph vii showed a structurally uniform and spherical biosynthesized Ag-MgO nanocomposite with a diameter of about 20–100 nm with an average particle size of 11.92 nm. The bi-layered Ag-MgO nanocomposite exhibited a higher level broad-spectrum of antibacterial potential on E. coli with 22 mm zone of inhibition and MIC of 20 (μg/mL) in comparison with the Ag (9 mm; 40 μg/mL) and MgO (9 mm; 80 μg/mL) nanoparticles. The leaching and toxicity level of the time-dependent releases of metal ions indicates that the effluents contain a lower concentration of Ag and Mg ions as compared to World Health Organization permissible limit of < 100 ppb (Ag). The biosynthesized Ag-MgO nanocomposite exhibited an enhanced antibacterial activity synergistic effect against E. coli than Ag and MgO nanoparticles, thus, proving to be a potential disinfect material against common pathogens in water treatment. Chapter 5 presented the biosynthesis, characterization, and assessment of simultaneous fluoride and pathogen removal potential in aqueous solutions of a multi-layered Ag-MgO/nanohydroxyapatite (Ag-MgOnHaP) composite. The successful incorporation of Ag-MgO into nanohydroxyapatite (Ag-MgOnHaP) sorbent via an in-situ solution-gelation (sol-gel) method was ascertained from UV-visible absorption spectrum bands at 290 and 440-378 nm typical of MgO and Ag nanoparticles combination in Ag-MgOnHaP composite. FTIR analysis showed the main surface functional groups involved to be –OH, C=N, carbonate and phosphate species on the backbone of Mg-O-Mg vibrational mode. The hydroxyl and amine groups indicated the interaction of a variety of metabolites components present in citrus peel extract as bio-reductive compounds associated with the Ag-MgO and also in fluoride ion exchange. SEM, TEM images and XRD analysis showed a well-dispersed discretely embedded layered-spherical Ag-MgOnHaP nanocomposite without any form of agglomeration after ultrasound exposure ranging in size from 20 to 100 nm with an average mean particle size diameter of 16.44 nm. The high purity of the synthesized Ag-MgOnHaP nanocomposite was confirmed by the presence Ag, Mg and O impregnated on the nanohydroxyapatite template from EDS spectrum analysis. Batch sorption studies using the nanocomposite under different experimental parameters were conducted and optimized. Equilibrium fluoride adsorption capacity of 2.146 mg/g at 298 K was recorded with more than 90% fluoride removal at optimized conditions of 60 min, 10 mg/L initial F- concentration, 0.3 g/L dosage, and pH 6 at 250 rpm. pHpzc of Ag-MgOnHaP nanocomposite was established to be 8. The equilibrium data were best fitted to the Freundlich isotherm model and followed the pseudo-second-order kinetics model at room temperature. The presence of competing anions such as Cl−, NO3−, does not have an impact on percentage fluoride uptake efficiency, but SO42− and CO32− reduce the F- removal efficiency. Moreover, as the concentration of the co-anions increased, fluoride adsorption uptake decreases. The biosynthesized nanohydroxyapatite incorporated Ag/MgO nanoparticle adsorbent (Ag-MgOnHaP) showed strong antibacterial activity against Escherichia coli and Klebsiella pneumonia when compared to hydroxyapatite alone. The presence and interaction between the Ag, MgO nanoparticles with the respective bacterial genomes was suggested to have accounted for this bioactivity. The synthesized Ag-MgOnHaP sorbent was found to portray a better sorption capacity compared to other adsorbents of similar composition in the literature and could be successfully regenerated with 0.01 M NaOH with fluoride removal of 74.24% at the 4th cycle of re-use. The impregnation of metal-metal oxide nanoparticles on sustainable natural biopolymers from waste products was presented in Chapters 6, 7 and 8. The use of these sustainable natural biopolymers (chitosan and cellulose) was targeted with more emphasis on surface functionalization, improved structural diversity and improved specific surface area with the sole aim of increasing the adsorptive capacity of fluoride ions as well as antimicrobial properties. The selected polymers were chosen because of their biodegradability, viii non-toxicity, renewability, selectivity and abundance in nature, which makes them promising starting materials for the purpose of sustainable water treatment. Chapter 6 presents the successful sol-gel biosynthesis, characterization, potential application for fluoride and pathogens removal from aqueous solution using Ag-MgOnHaP embedded on a chitosan polymer backbone (AgMgOnHaP@CSn) sorbent material. The overall formation of the AgMgOnHaP@CSn nanocomposite from different surface functionalization precursors and phases were supported by the various characterization methods such as UV–vis spectroscopy, SEM-EDS, FTIR, TEM, and Brunauer–Emmett–Teller (BET) techniques. Batch fluoride sorption experiments were conducted to assess fluoride uptake efficiency through optimization of several operational parameters such as contact time, adsorbent dosage, initial pH and co-competing anions. The antimicrobial activity of the synthesized AgMgOnHaP@CSn nanocomposites was also determined. The presence and bio-reduction processes of both Ag and MgO chemical species due to the interaction and coordination of bonds within the bioactive functional species of the polymer matrix was confirmed by the emergence of a sharp peak appearing at around 290 nm to a broad plateau plasmon absorbance above 440 nm on the AgMgOnHaP@CSn nanocomposite. FTIR analysis further supported the presence of the main bioactive functional species to be –OH, –NH2 CO32−, PO43-, Mg–O-Mg amongst other groups on the material surface. SEM and TEM displayed homogeneously dispersed particles within the aggregated biopolymeric composite with a diameter ranging between 5-30 μm. Pore sizes were observed to be in the micro-mesoporous range with an average size of about 35.36 nm and a pore diameter of 33.67 nm. The optimized conditions were as follows: 30 mins contact time, a dose of 0.25 g/50 mL, adsorbate concentration of 10 mg/L F-, initial pH 7 while adsorption capacity decreases with increase in temperature. AgMgOnHaP@CSn composite has a pHpzc value of ≈ 10.6 and the maximum sorption capacity was established to be 6.86 mg/g for 100 mg/L F- concentration at 303 K. The effect of co-existing anions was observed to be of the following order: Cl- < NO3- < SO42- << CO32-. The fluoride sorption experimental data was well described by Langmuir adsorption isotherm while the sorption reaction mechanisms were diffusion-controlled and followed the pseudo-second-order sorption model. F- sorption process could best be described as a combination of ligand exchange, electrostatic attraction, and improved structural surface modification. The antimicrobial susceptibility analysis through the zone of inhibition (mean and standard deviation) showed the potency to pathogens of the following order: Staphylococcus aureus > Escherichia coli. Chapter 7 gives an insight into the development of cellulose nanofibrous matrix (isolated from saw-dust) decorated with Ag-MgO-nanohydroxyapatite (CNF-AgMgOnHaP) and its application in fluoride and pathogen removal from contaminated water. The synthesized CNF-AgMgOnHaP, unlike the cellulose nanofiber, showed characteristic absorption bands in UV–vis spectroscopy between 270-290 nm typical of MgO together with a broad band around 420 nm associated with the characteristic of silver nanoparticles. FTIR spectrometry suggested the presence of nanohydroxyapatite (nHaP) and MgO species impregnation within the CNF matrix. SEM, TEM, XRD, and EDS analysis showed a well-established structural and morphological modifications between cellulose nanofiber alone, biosynthesized CNF-AgMgOnHaP and fluoride sorbed CNF-AgMgOnHaP nanocomposite. A granulated aggregation of micro-mesoporous particles with an improved BET surface area of 160.17 m²/g was developed. Optimum fluoride sorption capacity was 8.71 mg/g for 100 mg/L F- solution at 303 K. F- sorption capacities decreased as the operating temperatures increases. Optimum F- removal of 93 % was achieved at optimum conditions established: pH 5, solid/liquid ratio of 0.25 g/ 50 mL, 10 mg/L F-, contact time 10 min, temperature 25 ± 3 °C and shaking speed of 250 rpm. Percent F- removal decreased with increasing initial adsorbate concentration. The pHpzc value of the CNF-AgMgOnHaP occurred at ≈ 4.7. Co-existing ions were observed to have an effect on the adsorption of F- in the following order: NO3- < Cl- < SO42- <<CO32-. Equilibrium fluoride sorption onto the CNF-AgMgOnHaP was best described by non-linear Freundlich isotherm model across all the operating temperatures. The linear Dubinin-Radushkevvich (D-R) model for F- sorption energies were in the 3.54 – 4.08 kJ/mol across all operating temperature. This suggested the physical adsorption mechanism processes were involved in the F- uptake by the CNF-AgMgOnHaP sorbent. The overall kinetic results indicated that the mechanisms not only depend on the pseudo-second-order process but were also governed by mass transfer of the adsorbate molecules across the CNF-AgMgOnHaP surface. The thermodynamic parameters revealed that the sorption process of F- onto CNF-AgMgOnHaP was endothermic and spontaneous at the sorbent/solution interface. The regeneration-reuse study showed that the synthesized adsorbent can be reused for a maximum of 5 adsorption-desorption cycles using Na2CO3 and NaOH as regenerants. Overall surface chemistry by XPS, FTIR, EDS as well as sorption isotherm and kinetic models analysis suggested that both physical and chemical adsorption processes were involved in the fluoride uptake by CNF-AgMgOnHaP nanocomposite. The observed zone of inhibition demonstrated that CNF-AgMgOnHaP adsorbent possesses antibacterial activity against all the bacterial strains in the following order: E. Coli > S. aureus > K. pneumonia. The antibacterial potency increased with increasing sorbent concentration. In chapter 8, Defluoridation and antimicrobial activity of synthesized cross-linked cellulose-chitosan impregnated with the developed nanomaterial (AgMgOnHap) are presented. The before and after fluoride sorption by the synthesized CECS@nHapAgMgO nanocomposites were characterized using several physical and chemical techniques which include, BET, SEM-EDS, TEM, XPS, XRD, and FTIR. The overall batch fluoride sorption processes and adsorption capacity through optimization of different experimental sorption parameters, sorption isotherms, and kinetic mechanisms as well as antibacterial potency were studied and reported. SEM and TEM analysis showed densely irregular multiple-layered structures, homogeneous deposition of the AgMgOnHaP on the polymeric matrices. Equilibrium fluoride sorption capacity on CECS@nHapAgMgO sorbents showed an increased affinity of 26.11 mg/g for 150 mg/L F- solution at 313 K.at optimized conditions of 40 min contact time, dosage of 0.3 g and pH of 5. The pH point of zero charge was found to be 7.27. The reaction pathway model sequence of fitness follows the order Pseudo first order < Elovich < Pseudo-second order kinetic model while intra-particle diffusion model and mass transfer of fluoride molecules from the external surface onto the improved pores of the adsorbent were found to be involved in the rate-controlling step. Although both non-linear Langmuir and Freundlich isotherms showed appropriate trends in the F- sorption process, the adsorption isotherm data were better fitted to the non-linear Freundlich isotherms models, suggesting stronger heterogeneous adsorption onto the active binding sites of the CECS@nHapAgMgO surface. The fluoride sorption was observed to be a favorable process across the operating temperatures. Temkin heat of sorption (BT) and the mean free adsorption energy (E) of the D-R isotherm model was within the range of 0.68-3.39 J/mol and 1.58 -7.45 kJ/mol respectively. The fluoride sorption process was observed to be temperature-dependent; while adsorption capacities (Qm) and Temkin heat of sorption (BT) increased with increasing temperature, D-R Mean free sorption energy (E) decreased at higher temperatures. The thermodynamic analysis demonstrated that fluoride sorption on the CECS@nHapAgMgO surface was exothermic, feasible and spontaneously inclined with a decrease in the degree of randomness at the sorbate-sorbent interface. The influence of co-existing anions on fluoride removal exhibited the following trend Cl−< NO3− <SO42- << CO32- <<HCO3−. The practical and economic viability, potential for regeneration showed its reusability up to 3 cycles with water and Na2CO3 as regenerants. The potential ability of CECS@nHapAgMgO to disinfect both gram- positive and gram-negative water bacterial was confirmed by the zone of inhibition and Minimum Inhibitory Concentration (MIC) measurements. The observed values showed the inhibitory efficiency in the following order: S. aureus > E. Coli > K. pneumonia where the MIC values of 20 μg/mL were recorded for S. aureus and E. Coli respectively and 10 μg/mL for K. pneumonia. Lastly, the applicability of the sorbents was tested with a field water sample collected from a high fluoride borehole water from a local village (Lephalale Municipality of Limpopo province, South Africa). The before and after analysis showed the excellent potential of CECS@nHapAgMgO sorbent in removing fluoride. In conclusion, the successful surface functionalization synthesis of these improved surface area hybrid nano-sorbents supported by the different morphological techniques was found to be effective in creating more surface-active binding sites for fluoride adsorption and disinfection of waterborne pathogens from aqueous solution. The originality of this developed sorbent lies firstly, in the ability to simultaneously remove both chemical and biological water pollutants; secondly, the use of biodegradable, eco-friendly and non-toxic abundance wastes raw materials to develop a water purification material and in solving waste management issues was a key factor towards environmental sustainability. Above all the developed materials were established to possess superior fluoride adsorption capacity when compared to other reported sorbent materials. Lastly, the project findings /innovation will contribute to Sustainable Development Goals (SDG) 3 and 6, aimed at improving clean water supply and health of the communities and the world at large. However, the following recommendations were made following the findings from this study: 1) In order to increase the surface area to volume ratio, greater selectivity, porosity, and mechanical stability of the polymers as well as size-exclusion mechanism without a large energy penalty of the microbes and fluoride ion for effective water treatment, a more effective and an enhanced multifunctional, multi-layer nanofibrous hybrid sorbent through electrospinning techniques should be considered for future work, 2) More studies on the mode of actions and morphological changes in the pathogens leading to the cell death through the influence of the nanocomposites should be further explored, 3) Application of this advanced technology vis-à-vis other biomaterials to generate filter membrane towards efficient microbial removal and deflouridation is a great challenge worth looking at, 4) Lastly, materials developed in the present study should be modeled, tested and fabricated at the point of use for fluoride and pathogen removal at household level. / NRF

A Comparison of Solvent and Water-Borne Alkyd Coatings Abstract Conventional solvent based alkyd coatings have gone out of favor due to concerns over volatile organic compound (VOC) content. However, due to recent focus on renewable raw materials, alkyds are making a comeback in waterborne form. Water based alkyd coatings are known to have poor shelf stability and corrosion resistance, as well as other problems during the formulation process. This project focused on comparing solvent borne to two types of water-borne alkyds, water reducible alkyds and alkyds emulsions. The purpose was to understand the differences between the three types of alkyds in terms of their production and final properties. It was ultimately hoped that the formulations used for this project would prove to solve the problems normally experienced by waterborne alkyds. After testing several chemical and physical properties, it was determined that the solvent borne alkyd coatings performed better than both water based systems in corrosion resistance, accelerated weathering, and shelf stability but the water reducible and emulsion alkyd coatings performed similarly to the solvent borne alkyd in gloss, contrast ratio, and durability. The VOC emissions for all three alkyd types were as expected; the solvent borne had the highest emission at 253 g/L, followed by water reducible with 166 g/L, and emulsion with 34 g/L. The History of VOC Regulations in the United States Abstract In another solvent based alkyd coating focused project within my research group, the question of the how volatile organic compound (VOC) regulation in the United States (U.S.) evolved came up. It quickly became apparent that no comprehensive answer to this question existed. Part two of this project is an attempt to answer this question in a comprehensive manner. VOC regulations started in California in the late 1970s, and paints and coatings became a nationally regulated emission source by the 1990s. The U.S. government limited harmful emissions, such as smog and compounds contributing to ozone depletion, through Clean Air Acts. The first Clean Air Act was enacted in 1965, but it wasn’t until the Clean Air Act of 1990 that VOC emissions became a focus. VOCs are not inherently hazardous but are a source of concern because they serve as a precursor to the formation of damaging ground level ozone. The Environmental Protection Agency (EPA) has established the minimum VOC emission limits in the Architectural and Industrial Maintenance (AIM) federal rule, but each state or state subdivision can enforce stricter limits within their borders. The strictest limits are set by the South Coast Air Quality Management District (SCAQMD) in Southern California, but other entities exist. This report thoroughly documents the history of VOC regulation in the United States by collecting, combining, organizing, and summarizing information gathered from various industries and government publications, agency members, and industrial and academic professionals.

I flerbostadshus är radiatorer det vanligaste uppvärmningssystemet. Inte alls många har golvvärme i deras lägenheter. I dagens nyproduktion av flerbostadshus bygger man för det mesta husen med radiatorer och har elburen golvvärme som komfortvärme i badrummen. I villor är det däremot mycket vanligare att man använder sig av vattenburen golvvärme över större delen av huset. Detta examensarbete undersöker varför det inte används golvvärme lika mycket i flerbostadshus, det undersöker även intresset för privatpersoner att ha golvvärme i lägenheter samt om dessa personer isåfall hade kunnat tänka sig betala mer pengar om de fick vattenburen golvvärme installerat vid nyproduktion.Resultaten har fåtts fram genom en enkätundersökning samt intervjuer där vi intervjuat kunniga inom området. Våra resultat visar att nästan 40% av de enkät intervjuade hade velat ha endast golvvärme som uppvärmningssystem medan ungefär 55% hade velat ha både radiatorer och golvvärme som ett gemensamt uppvärmningssystem. De flesta hade då velat ha golvvärme i bland annat toalett, badrum, hall, kök, vardagsrum och sovrum. Resultaten visar även att nästan hälften av de enkät besvarande hade kunnat tänka sig betala mer för en bostad med golvvärme medan den större delen av den andra hälften var osäkra och förmodligen behövde mer tid för att tänka. Resultaten gällande varför man inte använder vattenburen golvvärme i lägenheten lika ofta som man använder radiatorer visade sig variera lite mellan de intervjuade vilket vi tror har med erfarenheter att göra men att ett golvvärmesystem var installationsmässigt dyrare än ett radiatorsystem verkade vara huvudsaken. / In prefabricated apartment blocks the most common thing people have in their homes is radiators as their waterborne heating system but very few have underfloor heating in their apartments. Nowadays the most usual thing to do is to install radiators and have underfloor electric heating in the bathrooms. Most residentials however usually have waterborne underfloor heating across the bigger part of the house. This report digs into why underfloor heating isn’t being used as often in apartment buildings, it also investigates people’s interest to have underfloor heating in apartment buildings plus if they then would be interested in paying more for a new apartment with waterborne underfloor heating.The outcome from our results has been achieved through a survey and interviews where we have questioned competent persons within the sector. Our results show that 40% of the people in the survey would like to have only underfloor heating as their waterborne system while 55% of the people would like to have a combined system with both radiators and underfloor heating. Most of them preferred to have underfloor heating in their toilets, bathrooms, entrance hall, kitchen, living room and bedroom. The results also show that almost half the persons in the survey could pay more money for a place with underfloor heating while the bigger part of the other half weren’t sure and probably needed more time to think. Our outcome on why waterborne underfloor heating in apartment buildings isn’t being used as often as radiators showed to differ between the interviewed persons which we assume have to do with their different backgrounds and experience but the main reason seemed to do with the part that a waterborne underfloor heating system in an installation point of view is more expensive than a radiator system.

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Water is a primary shared resource that connects all species across the landscape and can facilitate shared exposure to a community of waterborne pathogens. Despite remarkable global progress in sanitation and hygiene development in the past two decades, infectious diarrhea remains a prominent public health threat in sub-Saharan Africa. This thesis identifies and discusses persistent challenges limiting the success of current waterborne disease management strategies and several existing research hurdles that continue to impede characterization of microbial transmission and transport. In this work, the Chobe River watershed in Northern Botswana serves as a target study site for the application of hydrological modeling tools to quantify emergent water quality and health challenges in Southern Africa. A watershed model with extensive data requirements, the Hydrological Simulation Program – Fortran (HSPF), is used to identify primary data gaps and model assumptions that limit the progress of model development, and guide opportunities for data collection, tool development, and research direction. Environmental pathogen exposure risk and epidemiological outbreak dynamics are best described by interactions between the coupled human and environmental processes within a system. The challenge of reducing diarrheal disease incidence strengthens a call for research studies and management plans that join multiple disciplines and consider a range of spatiotemporal scales. / Master of Science