With the continual concern over the presence of naturally occurring and anthropogenic inorganic and trace organic contaminants in the aquatic environment there is a growing need for the implementation of innovative treatment processes for the elimination of these contaminants from natural waters and wastewater effluents. While conventional treatment methods are ineffective in the removal of emerging contaminants such as steroidal hormones and pesticides, membrane technology, including electrodialysis (ED), has been highlighted as a potential treatment option. However, the clear lack of fundamental understanding of the behaviour of contaminants in ED is a current limitation for its extensive utilisation and is a critical issue that needs to be addressed. ED processing potentialities have not been fully exploited and more research is needed to account for all the key parameters such as contaminant physicochemical properties, solution chemistry and the presence of organic matter. The purpose of this study was to elucidate the mechanisms of inorganic and trace organic contaminant removal by ED. The inorganic contaminants fluoride, nitrate and boron were selected due to their ubiquitous nature in the environment and public health concerns resulting from longterm exposure. The hydrated radius and strength of hydration shells played a significant role in ionic transport, whereby nitrate with a smaller hydrated radius was removed more effectively (94.1 %) than fluoride (68.3 %) with a larger hydrated radius. While fluoride and nitrate removal was pH independent, the pH dependent speciation of boron enhanced its removal with increasing pH. Territorial binding and/or complexation of the inorganics with organic matter enhanced removal. The removal of a range of trace inorganics (e.g. arsenic, calcium, magnesium, uranium) from a brackish groundwater from a remote Australian community was investigated. Undissociated inorganics were not transported through the membranes, whereas dissociated inorganics were due to electrostatic attraction. At acidic-neutral conditions ionic transport was the dominant removal mechanism. At neutral to alkaline conditions insoluble carbonate species precipitated and deposited as a membrane scaling layer (60 μm). This has serious implications for the long-term practical applicability of ED to treat real waters as scaling increased ED stack resistance (pH 3: 27.5 4, pH 11: 50 4) and decreased total dissolved solids removal (pH 3: 99 %, pH 11: 89.5 %). While the treatment of trace organics by other membrane processes has been widely studied, their fate in ED and interaction with ED membranes is relatively unknown. Trace contaminant-membrane interaction studies were undertaken to quantify the partitioning of trace organics; namely steroidal hormones and the pesticide endosulfan, to ED membranes by measuring membrane-water partition coefficients (log KM). The extremely high sorption capacity of the membranes was attributed to hydrogen bonding between the trace organic and membrane functional groups. Hormone sorption during ED was influenced by solution pH and organic matter. In the case of estrone, membrane sorption decreased at pH 11 (487 μg/cm3) compared to pH 7 (591 μg/cm3) due to dissociation and membrane electrostatic repulsion .At pH 11, repulsion between dissociated estrone and HA coupled with membrane electrostatic attraction resulted in increased sorption. The findings from this study highlight that the transport of trace contaminants will depend largely on the characteristics of the membranes used in the ED process as well as the physicochemical characteristics of the contaminants, their interaction with the ED membranes and the presence of other inorganic and/or organic compounds. The knowledge gained has direct applications to current problems and uncertainties in water and wastewater treatment with regards to the fate and transport of contaminants.

Around 770 million people lack access to improved drinking water sources (WHO 2013), urgently necessitating implementation of contaminant removal by e.g. desalination systems on a large scale. To improve water quality and enable use of brackish water sources for human consumption in remote arid areas, a directly coupled wind – electrodialysis system (Wind-ED) was developed. Modularity, sustainability and above all suitability for the practical use in off-grid locations were the main motivations and design objectives. The direct coupling of wind energy with membranes reduces the system costs as well as technical drawbacks associated with using intermediate energy storage systems. During this research, systematic experiments were performed using the Wind-ED system in order to determine desalination performance and clean water production, specific energy consumption (SEC) and current efficiency (ηc) under relevant conditions, such as varying: i) wind speed, ii) wind turbulence intensity, iii) oscillation periods, iv) varying NaCl concentrations and v) flow rates. Moreover, the competitive removal of four commonly available inorganic contaminants in brackish groundwater sources, nitrate (NO3-), fluoride (F-), sulphate (SO42-) and chloride (Cl-), were investigated. Firstly, to establish a systematic understanding of how and to what extent energy fluctuations influence the transport of the salt (i.e. NaCl) ions across the membranes, experiments were conducted using pulsed electric field assisted electrodialysis (pulsed-ED) over a wide range of frequencies (0.001 – 10 Hz) and duty cycles (20 – 80). The results showed that pulsation applied in the sub-limiting regime resulted in reduced water production, explained by the delays caused by the off-periods during the pulsed desalination process. At higher current densities, pulsation led to considerable improvements in current (e.g. up to 95%, for a feed solution of 500 mg/L and a pulse regime of 1 Hz at 50 V peak voltage) and significant reduction in water dissociation, explained by a reduction of concentration polarisation. Importantly, the pulsation had no significant effect on energy consumption or current efficiency suggesting that ED could be suitable for direct coupling to fluctuating energy sources such as wind energy. ED was consequently coupled to a wind turbine system and a series of desalination tests were performed over a wide range of wind speeds (2-10 m/s), turbulence intensities (TI of 0-0.6) and oscillation periods (0-180 s). Results showed that water production and SEC increased with wind speed. However, both the water production and SEC stopped increasing as the power output from the turbine levelled off at wind speeds above the rated value (vrated: 7.9 – 8.4 m/s). The impact of wind speed fluctuations on the system performance were insignificant up to a TI of 0.4. The desalination performance declined under high turbulence intensity fluctuations (TIs ≥ 0.5) and long periods of oscillation (> 40 s), as the wind-ED system periodically cycled off in response to operation below the cut-in wind speed of the wind turbine (vcut-in: ~ 2 m/s). The off-cycling of the system caused significant delays in the desalination process, and thus resulted in reduced water production. Further reduction in the water production resulted as the wind-ED system operated under intermittent wind speed conditions with off-wind periods longer than 10 s. It was concluded that the main challenge in direct coupling of ED to a wind resource was not the magnitude of the fluctuations but the impact of the power cycling off during long periods of oscillation and lengthy periods of no wind. Interestingly, the SEC of the process remained relatively unaffected by the fluctuations and intermittencies in the wind resource. The effect of energy fluctuations on the competitive transport of F-, Cl-, NO3- and SO42- from artificial brackish water (TDS ~4350 mg/L) was investigated using different sets of real wind data. The ion removal, independent of the wind regime tested, followed the order: NO3- ≥ Cl- > F- > SO42-. The competitive removal of the ions was linked to differences in physicochemical properties (i.e. hydration energy, ionic mobility and valence). The specific selectivity (e.g. preferential transport of NO3- over SO42- ions) was found to increase with concentration polarisation being either minimised (by lowering the mean wind speed) or disrupted (by fluctuations in the wind resource). The results from flow rate and feed concentration experiments, showed that power production of the wind turbine depended on not only the available wind energy but also the resistance of the load (i.e. the ED stack). Thus, increasing the feed concentration and the flow rate resulted in reduced resistance in the ED stack (Rstack), which inversely influenced the current induction counter torque force applied on the shaft of the wind turbine and caused the rotor to spin at a lower angular velocity. This led to increased sensitivity of the wind-ED system to wind speed fluctuations (e.g. system cycled off due to extreme fluctuations and intermittencies with low TDS feed concentration of 2400 mg/L) and hence a reduction of desalination performance. Impact of flow rate on the SEC was found to be negligible; this was attributed to the automatic voltage to current adjustments done by the wind turbine, in order to minimise the impacts of Rstack on the power production by the turbine at a given wind speed. Increased flow rate and resulting shrinkage of the boundary layer’s thickness, caused the concentration profiles at the solution-membrane interface to become steeper. This favoured the transport of ions with the highest diffusion coefficients in the mixture (i.e. Cl- and NO3-). Decreased flow rate favoured the transport of ions with larger valence numbers and higher electric mobility inside the electrolyte (i.e. SO42-); as the former property governed the faster migration of SO42- ions through the thick boundary layer and the latter property assisted with the improved affinity of the ion-exchange membrane to SO42- ions compared to the monovalent anions in the mixture. Increasing the feed concentration of Cl- from 500 to 2,550 mg/L led to reduced transport numbers for the other anions in the mixture and significantly reducing their removal rate. The results obtained from both the pulsed-ED and wind-ED experiments showed that, despite direct coupling to the fluctuating energy source the SEC of the process remained relatively unaffected by the energy fluctuations. Although the desalination process might require more time to be completed when operating under extreme wind speed fluctuations and intermittencies, the quality of the drinking water produced was always within the WHO standards. In conclusion, the findings from this research prove the wind-ED system to be an energetically robust and a reliable off-grid desalination technique suitable for the treatment of brackish groundwater in water stressed remote regions.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-03-16T19:29:28Z No. of bitstreams: 1 AKLEINO SILVESTRE DA SILVA - DISSERTAÇÃO PPGEQ 2016..pdf: 6288381 bytes, checksum: f65c5bdc20bfda0cdb5930837d5d1894 (MD5) / Made available in DSpace on 2018-03-16T19:29:28Z (GMT). No. of bitstreams: 1 AKLEINO SILVESTRE DA SILVA - DISSERTAÇÃO PPGEQ 2016..pdf: 6288381 bytes, checksum: f65c5bdc20bfda0cdb5930837d5d1894 (MD5) Previous issue date: 2016-09-29 / O consumo de água doce vem crescendo muito no mundo inteiro e sua possível escassez tornou-se um dos temas mais discutidos na atualidade. Com isso há necessidade de desenvolver novas estratégias para suprir a falta de água potável. Dentre elas, destacam-se a dessalinização. Neste sentido, o presente trabalho tem por objetivo avaliar um ciclone convencional utilizado para dessalinização da água salgada com adição de cinco bicos injetores, localizados na parte superior do mesmo. O modelo matemático adotado considera escoamento tridimensional, turbulento, estacionário e não isotérmico para a fase gasosa, e a aplicação do modelo Lagrangeano para as partículas. As equações de conservação da massa, de momento linear, de energia e as do modelo de turbulência SST , bem como as equações constitutivas e as condições de contorno foram resolvidas com auxílio do software comercial Ansys CFX. São apresentados os resultados dos campos de pressão, temperatura, velocidade e fração mássica, linhas de fluxo, trajetórias das partículas, perfis de velocidade, de pressão total e de temperatura total no interior do separador ciclônico térmico. Constatouse o caráter tridimensional do escoamento gás-partícula no interior do ciclone com presenças de regiões de zonas de recirculação e de inversão de fluxo. Os resultados mostraram que a variação das temperaturas na alimentação, tanto do ar como da água, influência na geração de vapor no interior do separador ciclônico. Porém é preciso um estudo cauteloso, como por exemplo, avaliar a influência do comprimento da parte cônica, tanto na fluidodinâmica quanto na cinética, para tentar aumentar o tempo de residência das partículas e com isso contribuir para o aquecimento da partícula. / The consumption of fresh water has been increasing worldwide and its possible shortage has become one of the most discussed topics today. With this, there is a need to develop new strategies to address the lack of potable water. Among them, desalination. In this sense, the present work aims to evaluate a conventional cyclone used for the desalination of salt water with the addition of five injector nozzles, located in the upper part of the same. The mathematical model adopted considers three-dimensional, turbulent, stationary and nonisothermal flow for the gas phase, and the application of the Lagrangian model to the particles. The equations of conservation of mass, linear momentum, energy and those of the SST w turbulence model, as well as the constitutive equations and the boundary conditions were solved with the commercial software Ansys CFX. The results of the fields of pressure, temperature, velocity and mass fraction, flow lines, particle trajectories, velocity profiles, total pressure and total temperature inside the thermal cyclone separator are presented. It was noted three-dimensional character of the gas-particle flow within the cyclone presence regions with recirculation zones and reverse flow. The results showed that the temperature variation in both air and water influences the generation of steam inside the cyclonic separator. However, a cautious study is required, for example, to evaluate the influence of the length of the conic part, both in fluid dynamics and kinetics, to try to increase the residence time of the particles and thereby contribute to the heating of the particle.

Der Gegenstand dieser Arbeit ist eine neue Optimierungsmethode zur Minimierung der Produktkosten von Kraftwerksprozessen ohne und mit nachgeschalteten Anwendungen. Diese Methode, die Planern und Projektanten als Werkzeug zur Auslegung von Kraftwerken dienen soll, wird erläutert und exemplarisch zur Optimierung eines ausgewählten Gas- und Dampfturbinenkraftwerkes verwendet. Im Rahmen der Untersuchungen werden dabei zwei Varianten betrachtet: Der Kraftwerksentwurf/-betrieb ohne und mit Auskopplung von Energie- und Stoffströmen. Beim Kraftwerksentwurf/-betrieb mit Auskopplung von Energie- und Stoffströmen wird das Gas- und Dampfturbinenkraftwerk mit einer nachgeschalteten hybriden Meerwasserentsalzungsanlage verknüpft. Zur Identifizierung der jeweils zu optimierenden Komponenten/Parameter werden bei der neuen Methode Elemente der thermo- bzw. exergoökonomischen Analyse und der Sensitivitäts- und Trendlinienanalysen verwendet. Die Optimierung selbst folgt dem Koordinatenverfahren nach Gauß und Seidel. Anhand der Optimierungsergebnisse und der Kriterien ’Auswahl/Beitrag der Komponenten/Parameter’ sowie ’Rechenumfang’ wird die neue Optimierungsmethode mit bekannten thermo- bzw. exergoökonomischen Optimierungsmethoden (Quadranten-/Matrix-Methode, thermo-/exergoökonomische Kennzahlen-Methode) verglichen und bewertet. Zur Ergebnisdiskussion werden Parameterstudien erstellt. Abschließend werden Empfehlungen zur Gestaltung des untersuchten Gas- und Dampfturbinenkraftwerkes gegeben und Ansätze für weiterführende Forschungsarbeiten in der Kraftwerkstechnik abgeleitet.

Until a few decades ago few people could imagine that the photovoltaic, solar thermal and other power based on renewable resources, will become a reality. Today people from all over the world on the contrary try at full blast derive benefit from of all possible available source. Using sunlight as a source of energy is first enforced only for small devices such as calculators for charging the battery, but now we are able to produced energy from the sun to supply people around the world. Of course it is not possible supply consumer sector plus firm only from performances renewable power supply. Therefore endeavour is derive benefit from classical energy production at the same time with others power supply. The basic components of photovoltaic and solar thermal power are panels. The panels are made of different materials in different shapes and sizes. During production, the resulting effect looks in addition to costs associated with production. For photovoltaic and solar thermal power plant requires sufficient sunlight. The sunshine has biggest intensity on south of ours planets. Therefore endeavour is build lump these power station just in stand with bigger intensity sunshine. One of them is just Cyprus, too.