Orientador: Rodrigo Braga Moruzzi Moruzzi / Banca: Andre Luiz de Oliveira / Banca: Marcos Von Sperling / Resumo: Esta dissertação teve como objetivos a investigação da resistência e do recrescimento de flocos, produzidos durante a floculação de água destinada ao abastecimento, e foi dividida em duas etapas. Em primeiro lugar a resistência de agregados à quebra induzida por distúrbio hidrodinâmico foi investigada por meio de três técnicas macroscópicas de medição, a saber: fator de resistência (FR), a tensão local (σ) e o coeficiente de resistência do floco (γ). Num segundo momento a capacidade de recuperação do tamanho dos agregados foi investigada. O diâmetro estável (d) e o parâmetro característico da função de distribuição de tamanho de agregados (β) foram utilizados para analisar o processo refloculação após a quebra induzida dos agregados. Para obtenção das variáveis de interesse, foi utilizado método não intrusivo de análise de imagem e equipamento baseado em dispersão de luz. As águas de estudo foram preparadas em laboratório a partir de solução de ácido húmico (água tipo 1) e suspensão de caulinita (tipo 2), e coaguladas por dosagem de sal de alumínio em região do mecanismo de varredura. A floculação ocorreu em gradientes de velocidade médios (G) entre 20 e 120 s-1, e a ruptura ocorreu sob condições controladas com Gquebra de 800 s-1 por 10 segundos. Após a ruptura, a condição inicial foi reestabelecida para análise da recuperação de tamanho do agregado. Os resultados mostraram, para as duas água de estudo, uma tendência crescente para FR em resposta ao aumento de G. A mesma ten... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This dissertation has aimed to investigate the strength and re-growth during the flocculation of drinking water, and was divided into two steps. The first one was investigate the rupture of floc caused by shear induced forces through three macroscopic techniques, namely: strength factor (FR), the average strength per unit area at the plane of rupture (σ) and the floc strength coefficient (γ). The second one was investigate the re-growth ability of flocs. The stable diameter (d) and the characteristic parameter of the aggregate size distribution function (β) were used to analyze the re-growth process after the induced breakage of the aggregates. The method was based on a non-intrusive image analysis monitoring technique and a light scattering equipment. The study waters were prepared in laboratory from humic acid solution (water type 1) and kaolinite suspension (type 2) and coagulated by dosing aluminum salt in the region of the "sweep flocculation" mechanism. The flocculation occurred for average velocity gradients (G) from 20 to 120 s-1 and the breakage occurred under controlled conditions for Gquebra of 800 s-1 for 10 seconds. After breakage, the initial condition was re-established for aggregate size recovery analysis. For the two study waters the results showed an increasing trend for FR in response to the increase of G. The same trend was observed for γ which may indicate that high agitation conditions produce more resistant flocs. The reflocculation analysis results sho... (Complete abstract click electronic access below) / Mestre

Flocculation has been widely adopted as one of the most effective methods to remove colloidal particles in water or wastewater treatment. Synthetic flocculants are conventionally used because of their high flocculating efficiency and cost-effectiveness. However, they have been reported to have hazardous properties and implicated in some serious health problems including senile dementia and neuro-toxicity, as well as being recalcitrant in the environment. Consequently, efforts are being geared away from the use of synthetic flocculants in water and wastewater treatment. Hence, the need for safe and eco-friendly flocculants has become imperative. Compared with synthetic flocculants, bioflocculants have special advantages such as safety, biodegradability and harmlessness to the environment and humans; attributes which make them potential alternatives in water treatment, downstream as well as fermentation processes. In the current study, the potentials of bacterial isolates recovered from Algoa Bay in the Eastern Cape Province of South Africa for bioflocculant production were investigated. The bacterial isolates were identified by polymerase chain reaction (PCR) as belonging to the Bacillus genus. The analysis of 16S ribosomal deoxyribonucleic acid (rDNA) nucleotide sequence of isolate M72 showed 99 percent similarity to Bacillus toyonensis strain BCT-7112 and was deposited in the GenBank as Bacillus toyonensis strain AEMREG6 with accession number KP406731. Likewise, the 16S rDNA nucleotide sequences of isolates M69 and M67 showed 98 percent sequence similarity to Bacillus licheniformis strain W7 and Bacillus algicola strain QD43 respectively; and M67 isolate was subsequently deposited in the GenBank as Bacillus sp. AEMREG7 with accession number KF933697.1. The results of the nutritional requirements and fermentation conditions revealed that optimum inoculum size for REG-6 production was 4 percent (v/v), while 5 percent (v/v) and 3 percent (v/v) were most favourable for MBF-W7 and MBF-UFH production respectively. Glucose was the best carbon source for the production of bioflocculants (REG-6 and MBF-UFH) by Bacillus toyonensis AEMREG6 and Bacillus sp. AEMREG7 respectively, while maltose supported optimum bioflocculant (MBF-W7) production by Bacillus specie. Inorganic nitrogen (NH4NO3) was the favoured nitrogen source for both REG-6 and MBF-W7 production, while mixed nitrogen sources [yeast extract + urea + (NH4)2SO4] supported the maximum production of MBF-UFH. The initial medium pH for REG-6 was 5, while MBF-W7 and MBF-UFH were both maximally produced at the initial pH of 6. After a 96 h cultivation period under optimal culture conditions, 3.2 g of purified REG-6 with a maximum flocculating activity of 77 percent was recovered from 1 L fermented broth of Bacillus toyonensis AEMREG6. Yields of 3.8 g and 1.6 g pure bioflocculants with the respective highest flocculating activities of 94.9 percent and 83.2 percent were also obtained from 1 L, 72 h-fermented broths of Bacillus licheniformis and Bacillus sp. AEMREG7 respectively. Furthermore, all the three bioflocculants (REG-6, MBF-W7 and MBF-UFH), displayed thermal stability within the temperature range of 50 to 100 oC, with strong flocculating activities of over 80 percent against kaolin suspension over a wide range of pH range (3–11) and relatively low dosage requirements of 0.1-03 mg/ml in the presence of divalent cations in the treatment of kaolin clay suspension and Thyme River waters. Chemical composition analyses of the bioflocculants showed them to be glycoproteins with a predominantly polysaccharide backbones as shown by the following carbohydrate/protein (w/w) ratios: 77.8 percent:11.5 percent (REG-6); 73.7 percent:6.2 percent (MBF-W7) and 76 percent:14 percent (MBF-UFH).

Advanced oxidation processes are capable of removing organic compounds that cannot be removed by conventional water treatment methods. Among the oxidation processes, photo-catalysis using titanium dioxide (TiO2) is a promising method but suffers from rapid electron-hole recombination rates and only absorbs UV light which is a small percentage (5 percent) of the total solar radiation. Therefore there is a need to reduce the recombination rates and also extend the absorption of the photo-catalyst into the visible region which constitutes 55 percent of the total solar radiation. The major aims of this study were to prepare plasmon metal decorated and doped TiO2 photo-catalysts immobilized on quartz substrates and test their photo-catalytic and antimicrobial activities. The effect of film thickness (loading) and use of different shapes of plasmon metal nanostructures was investigated. TiO2 thin films were prepared by a sputter coating technique while plasmon metal (Au & Ag)/carbon co-doped TiO2 by a simple sol gel process and plasmon metal films were prepared by the thermal evaporation technique. Different plasmon metal nanostructures (nanorods, dendrites, nanowires and spherical nanoparticles) were prepared using a wet chemical technique using sodium borohydride as the reducing agent. Nanocomposites of co-doped TiO2 photo-catalyst and plasmon elements of different proportions were also prepared. The prepared photo-catalysts were coated onto etched and MPTMS (3-Mercaptopropyl trimethoxysliane) treated quartz glass substrate which is a stable support favouring easy recovery. The prepared materials were characterized by XRD, HRTEM, TEM, HRSEM, FT-IR, SEM, PIXE and TGA while the doped TiO2 was characterized by XPS, BET, CHNS and Raman Spectroscopy. The effect of pH of solution, presence of other contaminants and salts in solution, initial concentration of the model pollutant and type of the plasmonic elements on the photocatalytic activity of TiO2 towards 4-(4-sulfophenylazo)-N,N-dimethyl aniline (methyl orange) were also investigated. The selected TiO2 photo-catalyst films were tested for antimicrobial properties. The effect of different types of plasmon elements on the antimicrobial activity of TiO2 against E. coli ATCC 3695 was evaluated under both sunlight and weak UV light. Under UV light, Ag showed the highest enhancement in photo-catalytic activity of TiO2 than Au and Cu. The photo-catalytic activity of TiO2 increased with an increase in Ag content to an optimum loading and then started to decrease with a further increase in loading. For Cu and Au, photo-activity activity increased with an increase in plasmon metal content. Under sunlight, Cu showed the highest enhancement of TiO2 photocatalytic compared to Ag and Au. The change in order of deposition showed that Au films enhanced the photo-activity better when they were deposited underneath rather than on top of TiO2 on quartz supports but Ag films performed better in enhancing photo-activity when they were deposited on top of TiO2. The use of bimetallic layers and three layer systems of different plasmon elements enhanced photo-catalytic activity better than the use of a monometallic layer. The presence of other organic contaminants and salts in solutions was found to reduce the photo-degradation of methyl orange due to preferential adsorption of other contaminants. When the pH was increased, the photocatalytic activity of TiO2 towards methyl orange was reduced. In antimicrobial studies, it was found that the plasmon elements greatly improved the antibacterial action of TiO2 against Escherichia coli ATCC 3695 in water and the best antibacterial action was observed with silver/carbon co-doped TiO2 photo-catalyst under sunlight The doped samples consisted of polydisperse nanoparticles which were found to be beneficial for photo-catalytic activity enhancement under sunlight.

Made available in DSpace on 2014-06-11T19:29:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-02-18Bitstream added on 2014-06-13T18:38:59Z : No. of bitstreams: 1 silva_jp_me_ilha.pdf: 828352 bytes, checksum: a6de240d9a22a15199a0537f9e0c41e2 (MD5) / O recente interesse da comunidade científica em relação à presença de produtos farmacêuticos na água potável tem levantado questões importantes, como o problema para a saúde pública e o impacto ambiental ainda pouco conhecido sobre a cadeia trófica, principalmente nos sistemas aquáticos. Em vista disso, o desenvolvimento de tecnologias avançadas que promovam a remoção efetiva dos fármacos residuais tornou-se necessária, uma vez que os sistemas convencionais de tratamento de água e esgoto são incapazes de eliminá-los completamente. O processo de adsorção por carvão ativado granular (CAG) é uma tecnologia que tem demonstrado eficiência na remoção de fármacos. Por outro lado, o poli(tereftalato de etileno) (PET) também vem comprovando sua capacidade de adsorção em diversos trabalhos, somando ainda vantagens econômicas e ambientais na sua utilização. Diante destas informações, a pesquisa avaliou a eficiência de remoção de cinco fármacos (diclofenaco, naproxeno, ibuprofeno, piroxicam e paracetamol) através de um sistema de filtros lentos de areia seguidos por dois pós-tratamentos distintos: (i) filtro de carvão ativado (filtro CAG) e (ii) filtro de PET ativado (filtro PET). Ao final de 10 semanas de ensaio, o filtro PET demonstrou eficiência de remoção superior para os fármacos diclofenaco e piroxicam e equivalente para o ibuprofeno, paracetamol e naproxeno em comparação ao filtro CAG / The recent interest of the scientific community regarding the presence of pharmaceutical products in drinking water has raised important issues such as the problem for public health and environmental impact still little known about the food chain, especially in aquatic systems. In view of this, the development of advanced technologies that promote effective removal of residual drugs became necessary, since conventional water treatment and sewage are unable to eliminate them completely. The process of adsorption for granular activated carbon (GAC) is a technology that has been successful in removal of drugs. On the other hand, poly (ethylene terephthalate) (PET) has also been proving its adsorption capacity in several studies, adding further economic and environmental advantages in using them. Given these informations, the survey evaluated the efficiency of removal of five drugs (diclofenac, naproxen, ibuprofen, piroxicam and acetaminophen) through a system of slow sand filters followed by two post-treatments: (i) activated carbon filter (GAC filter) and (ii) activated PET filter (PET filter). At the end of 10 weeks of test, PET filter showed higher removal efficiency for drugs diclofenac and piroxicam and equivalent for ibuprofen, paracetamol, and naproxen in comparison to the filter CAG

High F- groundwaters occur in various parts of South Africa, namely, the larger part of the Karoo, Limpopo, North West and Northern Cape Provinces. The use of these waters for drinking purposes on continual basis can lead to fluorosis. Fluorosis is a debilitating disease caused by drinking water with F- concentrations higher than ca. 1 mg.L-1. The disease is characterized by mottled teeth in dental fluorosis and brittle bones in severe skeletal fluorosis. Solution to this problem involves the implementation of a method for F- removal from water. Defluoridation has become a widely practiced process worldwide due to the problem of fluorosis caused by the presence of F- in drinking waters. Methods such as adsorption, precipitation, ion exchange and membrane processes have been employed for F- removal. Adsorption techniques, in particular using activated alumina have proven successful in removing F- from water. However, this method can not always be used in rural areas because of high costs and technical requirements. In this study, locally available clays were studied as potential substrates for F- removal from water. The first part of the study focused on the explanation of mechanisms and the development of an adsorption model. The exchange of OH- by F- in the clay structure is the principal mechanism that takes place during adsorption. The change in pH during this exchange process was studied to support and verify the fluoride-hydroxide exchange mechanism. In the second part of the study, locally available South African clays were studied as possible adsorbents for F- removal from water. Clays containing aluminium and iron oxide surfaces proved to be useful substrates for F- adsorption. The adsorption of F- onto clay samples was found to be pH dependent. Maximum adsorption was achieved at pH 5 for aluminium oxide type sorbents and pH 4 for iron oxides types such as goethite. The effect of physical and chemical pretreatment improved the adsorption capacity of some clays. Coating clay samples with aluminium and iron oxides enhanced the adsorption capacity of clays. The last part of the study involves the development of a cost-effective and quick way to assess the performance of clays as adsorbents for F- removal using laboratory scale defluoridation columns. / Prof. P.P. Coetzee

M.Sc. / Dissolved salts, mainly carbonates and sulphates such as those of calcium and magnesium, form hard water, which when heated produces an insoluble precipitate of scale forming crystals. Scale formation affects performance in industry and ouseholds. Besides the problem of energy costs, there are all the additional problems and maintenance costs of scale removal. Traditional methods of combatting scale build-up based on chemical water treatment do exist. These include: the addition of strong acid to remove the bicarbonate ion from the water, the use of chemicals to prevent or retard the formation of hard scale and, other techniques such as ion exchange process. A cost-effective alternative to these methods is Physical Water Treatment (PWT). Many different types of equipment claiming to treat water physically, for scale reduction are commercially available. These include magnetic, electric (high frequency or radio frequency) or electrostatic, catalytic and ultrasonic devices. In this work attempts have been made to unravel the mechanisms involved in PWT. For this it was necessary to develop experimental methods to determine the effect of electromagnetic fields and selected magnetic and radio frequency (rf) water treatment devices on precipitation reactions. The most significant finding of this study involves the effect of Zn on scale formation. When supersaturated Ca(HCO3 )2 solutions were tested in a glass heat exchanger, a 77% reduction in the formation of scale was found when the solutions were spiked with Zn.

M.Sc. / Calcium carbonate scale formation is a major problem in industrial water and cooling systems as well as in household systems. The resulting reduction in heat transfer and the removal of the scale are very costly processes. One of the methods used in the past 50 years and investigated for nearly a century, is the use of physical fields to reduce, remove and / or inhibit scale formation. These physical fields are usually magnetic fields, but RF electric and electrostatic fields are also used. These fields are claimed to reduce the cost involved in the removal of scale to a minimum. To investigate these claimed effects on scale formation, a pure calcium bicarbonate solution was exposed to some of the commercial available units: The exposed solution was then forced to precipitate by elevating the temperature. The pH was monitored against time, to investigate the nucleation process of CaCO 3 and the resulting precipitate analysed for changes in crystal morphology. The principle conclusions made from the results were, firstly that the nucleation of CaCO 3 was significantly delayed in one of the units tested and that the preferred morphology was changed from the thermodynamically more stable calcite to the more unstable aragonite in that unit. Secondly, that a direct correlation existed between the release of trace amounts of metals from the unit and the observed effects.

M.Ing. / Fouling of suspended solids on piping and equipment causes severe operating and maintenance problems in process, water treatment and miningrelated plants. In the SASOL environment fouling related problems are mainly experienced on equipment operating in process cooling water services. Suspended solids appear in the form of activated sludge in the cooling water system and the solid particle sizes are usually submicron in size. Conventional solid liquid separation techniques like centrifuging, sedimentation, filtration, etc. could up to this stage not be applied successfully to remove the finest solids from the process cooling water system. The possibility to separate solid liquid suspensions by means of acoustic energy was investigated. The theoretical principles of acoustic waves, especially standing waves, were studied and explained. A theoretical model indicates that separation of solid/liquid suspensions can be obtained virtually immediately after acoustic energy is applied. Theoretically the size and frequency of a tipical acoustic transducer can be calculated for a specific application. Based on theoretical calculations and findings, an experimental setup was prepared to carryout experiments on different suspensions. A control suspension made-up of water and powder, of Yttlich the particle sizes were approximately 10 pm, was prepared and exposed to a standing acoustic wave. Separation was achieved successfully. Follow-up experiments were carried out to establish the optimum conditions to which separation could be achieved. Different flow velocities were tested as well as different power inputs. The best separation was achieved with the lowest flow rate of 2.5 mils and the highest available voltage of 12 Volt. These conditions were not only used to separate a control suspension but also in a real situation where it was attempted to separate suspended solids from the cooling water system. The attempts were unsuccessful. Additional experiments were also done on ash water and cooling water blowdown which also failed. The failure of effective separation of the process cooling water suspensions is due to the extremely small sizes of the solid partides in suspension. Greater energy input than was available for this project, is required as the particle sizes decreases. Provision needs to be made for all particle sizes to achieve effective results. The separation of solid liquid suspensions is achievable with the aid of acoustic energy. The physical properties of the suspension however determines the size and magnitude of the separating equipment. A proposal for the implementation of a full scale acoustic separation system is given. The proposal comprises of a parallel system to ensure continuity of the cooling process.

Integrated algae pond systems (IAPS) combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. Although, IAPS as a technology process offers many advantages including efficient and simultaneous N and P removal, no requirement for additional chemicals, O2 generation, CO2 mitigation, and a biomass with potential for valorization, a lack of technological advancement and the need for large land area, has limited the reach of this technology at industrial scale. In mitigation, peroxonation was introduced as a tertiary treatment unit and its effect on COD and TSS of IAPS treated water investigated. An effort was made to characterize the soluble but persistent COD in IAPS treated water and, productivity of the HRAOP mixed liquor was investigated to gain insight into the potential use of this biomass. Results show that peroxone treatment effectively reduced COD, TSS, and nutrient load of IAPS water without any significant impact on land area requirement. Indeed, summary data describing the effect of peroxone on quality of IAPS-treated water confirmed that it complies with the general limit values for either irrigation or discharge into a water resource that is not a listed water resource for volumes up to 2 ML of treated wastewater on any given day. Extraction followed by FT-IR spectroscopy was used to confirm albeit tentatively, the identity of the soluble but persistent COD in IAPS treated water as MaB-floc EPS. Results show that MaB-flocs from HRAOPs are assemblages of microorganisms produced as discrete aggregates as a result of microbial EPS production. A relationship between photosynthesis and EPS production was established by quantification of the EPS following exposure of MaB-flocs to either continuous light or darkness. Several novel strains of bacteria were isolated from HRAOP mixed liquor and 16S ribosomal genomic sequence analysis resulted in the molecular characterization of Planococcus maitriensis strain ECCN 45b. This is the first report of Planococcus maitriensis from a wastewater treatment process. Productivity and change in MaB-flocs concentration, measured as mixed liquor suspended solids (MLSS) between morning and evening were monitored and revealed that MLSS is composed of microalgae and bacteria but not fungi. Concentration varied from 77 mg L-1 in September (winter) to 285 mg L-1 in November (spring); pond productivity increased from 5.8 g m-2 d-1 (winter) to 21.5 g m-2 d-1 (spring); and, irrespective of MLSS concentration in late afternoon, approximately 39% was lost overnight, which presumably occurred due to passive removal by the algae settling pond. The outcomes of this research are discussed in terms of the quality of treated water, and the further development of IAPS as a platform technology for establishing a biorefinery within the wastewater treatment sector.

D.Phil. (Chemistry) / Polycaprolactone (PCL), a linear, biodegradable polymer, and ethylene vinyl acetate (EVA), a branched copolymer, were used to prepare PCNs via the melt-blending method. Organoclay of the type Cloisite® 20A (C20A) and bentonite clay were used as fillers. The results show that the structure of a polymer matrix plays a significant role towards compatibilisation with the silicate layers of the clay. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed an exfoliated-intercalated mixed morphology for the PCL matrix. However, for the EVA matrix, silicate layers agglomerated to form tactoids and resulted primarily in an intercalated morphology. Fourier transform infrared (FT-IR) spectroscopy was used to determine the nature of the interactions between the polymer and the filler. The thermal properties were investigated using thermogravimetric analysis (TGA) and indicated that, with an increase in clay loading, the thermal stability was reduced for both matrices, notwithstanding the type of polymer or clay used. Using EVA and C20A, this study revealed that more exfoliated nanocomposite structures can be obtained by using a modified solution-blending technique. This technique is a hybrid of the melt-blending and solution-blending methods. When compared to the melt-blending method, the modified solution method was found to be an efficient method for producing nanocomposite strips with uniform dispersion of the clay at organoclay loading of 8% and crystallinity by extrusion. However, the melt-blending method produced nanocomposites with high porosity, intercalation and thermal stability whereas the modified solution-blending technique resulted in more intercalated-exfoliated morphology, but less porosity and thermal stability. Despite the positives drawn from the modified solution method, the melt-blending method was used throughout for nanocomposites intended for application in water treatment. This was done because the solution used in the modified solution method could not be completely removed from the nanocomposite. Organic solvents can have a negative effect on the environment and human life.