Over 30% of the world's population does not have access to safe drinking water, and the need for clean water spans further than just for human consumption. Currently, we use freshwater for growing agriculture, raising livestock, generating power, sanitizing waste, mining resources, and fabricating consumer goods. With that being said, the world is beginning to feel pressure from the excessive freshwater withdrawal compared to the current freshwater supply. This water stress is causing a water crisis. Places including Australia, South Africa, and California in the United States, just to name a few, are beginning to run out of fresh water to support daily societal demands. This is a phenomenon that is indiscriminately observed in all ranges of economically and politically developed countries and environments. However, it is important to note that less politically and economically developed countries especially those in arid climates, experience higher water stress than countries without such qualities. With only 2.5% of the world's water being freshwater and 30% of it being accessible as either ground or surface water, freshwater is a scarce resource, especially with the growing population and society's demand for water. Since the remaining 97.5% of water is composed of either brackish or seawater (saline water sources), one way to overcome the water stress would be to convert saline water into freshwater. As a result, various desalination techniques have been developed in the last 80 years that employ either membrane technology or temperature alterations to desalinate either brackish or seawater. One of the fastest growing methods for producing freshwater is reverse osmosis. Reverse osmosis uses an externally applied pressure, in the form of a cross flow back pressure, to overcome the osmotic pressure produced by the saline gradient across a semi-permeable membrane. The semi permeable membrane commercially consists of an interfacially polymerized aromatic polyamide thin film composite with a polysulfone porous backing that allows water to pass through while barring the transport of salt ions. This research focuses on the development of sulfonated poly(arylene ether sulfone) derivatives with differing amounts of sulfonation and with the ions placed at different structural positions. Previously, such materials were tested as potential high performance fuel cell membranes, but they are also of interest as potential high performance water desalination membranes, specifically for reverse osmosis. Two different methods were used to synthesize the sulfonated polysulfone derivatives: direct polymerization and post-modification of a non-sulfonated active polysulfone. The polysulfones from direct polymerization incorporated specialty sulfonated monomers, which were stoichiometrically controlled during the polymerization. Sulfonated polysulfones that were synthesized from post sulfonation incorporated biphenol and hydroquinone monomer units randomly throughout the polysufone backbones. These units could be sulfonated selectively because of their activation towards electrophilic aromatic substitution with sulfuric acid. Each of the polymers were cast into films ranging between 20-100 microns in thickness and tested for water uptake, hydrated uniaxial tensile properties, crossflow water and salt transport properties, and for crosslinked samples, gel fractions. The water uptakes from all the polysulfones were tuned by the degree of sulfonation or disulfonation present in the polymer. This was either controlled via the presence of a sulfonated monomer or a monomer that was active toward electrophilic aromatic substitution after polycondensation of the polysulfone. All polymers exhibited increases in their water uptake as the degree of sulfonation increased. We also observed a decreasing trend in the hydrated mechanical properties of the films for all the high molecular weight linear polymers as the water uptake was increased. The directly polymerized sulfonated polysulfones were found to have high hydrated elastic moduli ranging between 400 and 1000 MPa, while the post sulfonated counterparts (with either hydroquinone or biphenol incorporated in their structures) exhibited elastic moduli ranging between 1000 and 1500 MPa. It is important to note that the structures of the polymers were slightly different from one another because of the technique used to synthesize them. Thus, the increases in hydrated moduli among polymers synthesized via different routes may have influences from differences in chemical structures. Some of the polymers with higher degrees of sulfonation were synthesized as amine terminated oligomers with varying controlled molecular weights. The two targeted molecular weights were 5 and 10 kDa. Those oligomers were then crosslinked with a tetra-functional epoxide agent. The increases in sulfonation allowed for increases in water uptake and in theory, the water throughput through the sulfonated polysulfone membrane. Decreases in hydrated mechanical performance of the crosslinked networks with increasing degrees of sulfonation were also observed, similar to their high molecular weight linear counterparts. The directly polymerized crosslinked networks had salt permeabilities that plateaued at 70% disulfonation for both the 5 and 10 kDa polymers. Thus, we expect disulfonation content greater than 70% would lead to higher water throughput without significant increases in salt transport. / Doctor of Philosophy / A worldwide shortage of freshwater is becoming more problematic by each passing day. The World Health Organization and the United Nation's World Water Assessment Program predict that by 2025, 50-66% of the world's population will be living in a water-stressed area. This includes any area that experiences higher clean water withdrawals than are available. This includes but is not limited to areas that are politically unstable, technologically disadvantaged, resource deficient, located in arid climates, and highly populated. To put this further into perspective, only 2.5% of the available water on earth is freshwater. Freshwater typically has low concentrations of dissolved salts that are safe for human consumption and use. Of the available freshwater, only 30% of it is actually accessible for use through either surface or groundwater reservoirs, making the amount of clean water available for usage already a scarce resource. On the other hand, 97.5% of the world's water is composed of saline water reservoirs in the form of brackish and seawater. Through harnessing, seawater and removing the excess dissolved salt ions, the salt water can be converted to freshwater. Two major methods have been developed to remove the dissolved ions from water through either membrane filtration or thermal phase changes. One of the fastest growing membrane filtration techniques used worldwide is reverse osmosis. Reverse osmosis refers to the use of applied pressure across a semipermeable membrane to desalinate saline water. The semipermeable membrane prevents the migration of salt ions through the membrane while allowing transport of water. This work has focused on developing new polymers that can increase the overall efficiency of water desalination. Different types of high performance sulfonated polysulfone derivative polymers were synthesized and used to make membranes that were subsequently tested for performance. Relationships between the polymer structure, process, and properties were quantified through different analytical techniques. This study showed how the properties of sulfonated polysulfone membranes may be manipulated depending on structural modifications and processing to increase both the material's water throughput and salt rejection.

Sulfonated poly(arylene ether sulfone)s can exhibit several ideal features as potential desalination membranes for reverse osmosis applications, including chlorine resistance, low surface fouling, and high water flux. However, this class of polymer membranes has suffered from two major drawbacks that jeopardize effective levels of salt rejection in order to achieve high water flux. In mixed salt feed sources, monovalent salt rejection decreases when divalent cations such as Ca2+ bind with the anionic sulfonate groups to cause charge screening, and this can lead to too much salt passage for the membranes to be competitive with interfacially produced polyamides. Sulfonate fixed charge concentration must be high enough for sufficient membrane water uptake to obtain high membrane water flux, but if the water uptake is too high, this permits increased salt passage. The research described in this dissertation attempts to address both of these challenges through the design of a sulfonated monomer that strategically spaces the ionic groups along the polymer backbone chains to inhibit divalent ion binding. Free radical crosslinking further tunes the hydrated free volume in the RO membranes. A mono-sulfonated comonomer, sodium 3-sulfonate-4,4'-dichlorodiphenylsulfone (ms-DCDPS), was synthesized by stoichiometrically controlled electrophilic aromatic sulfonation of 4,4'-dichlorodiphenylsulfone (DCDPS). HPLC-UV revealed complete isolation of ms-DCDPS free of by-products after the 1st recrystallization and 1H NMR analysis confirmed the structure. A standard calibration curve was developed to accurately determine the leftover quantity of excess NaCl that was used for precipitation during the work-up procedures. A series of linear sulfonated poly(arylene ether sulfone)s with varying ms-DCDPS incorporation was synthesized. 1H NMR confirmed the structure of the polymers and size-exclusion chromatography confirmed that the intended molecular weights were achieved. The copolymers were cast into dense films and the mechanical and transport properties were measured in their fully hydrated states. Tensile tests revealed mechanically robust, tough membranes with glassy elastic moduli and high strains at break. The dense membrane prepared from sulfonated poly(arylene ether sulfone) with 51% of the repeat units sulfonated had NaCl rejection = 99.3% measured at 400 psi and 2000 ppm NaCl with a water permeability coefficient of 0.57 x 10-6 cm2/s. The salt rejection remained greater than 99% when a mixed salt feed source containing Ca2+ in the 0-200 ppm range together with the 2000 ppm NaCl was introduced. Crosslinked mono-sulfonated oligomers were synthesized with targeted molecular weights by utilizing stoichiometric quantities of monomers with the desired degrees of sulfonation, and the endgroups were functionalized with tetrafluorostryene. These end-functionalized sulfonated oligomers were crosslinked by both thermal and UV free radical methods in the presence of initiators without any additional crosslinking agents. Reaction conditions were thoroughly investigated and optimized to produce highly crosslinked membranes that yielded gel fractions greater than 87%, as measured by solvent extraction in dimethylacetamide. The hydrated crosslinked membranes were tested for both mechanical and transport properties, and the results were compared to their linear membrane counterparts. Crosslinking decreased the hydrated free volume and reduced water uptakes when compared to linear sulfonated membranes. Tensile tests of the fully hydrated crosslinked membranes showed good mechanical properties. The transport properties of a dense UV crosslinked membrane prepared with a 10,000 g/mol oligomer having 50% of the repeat units sulfonated was tested under RO cross-flow conditions at 400 psi and 2000 ppm NaCl in the feed. The membrane demonstrated a salt rejection = 98.4% with a water permeability coefficient of 0.49 x 10-6 cm2/s. / Doctor of Philosophy / Billions of individuals across the world lack clean, affordable drinking water, and the unavailability of fresh drinking water can be attributed to both physical and economic reasons. Several techniques have been utilized to produce potable water for human consumption that include both water desalination and recycling procedures. Water desalination is a process that allows for purifying salt contaminated water into drinking water. The two major desalination processes involve either distillation or passage through polymer membranes. Distillation separates water from salt by heating liquid water to form a gas, and collecting the vapor as condensate while impurities remain in the heated bulk material. Polymer membranes separate impurities through filtration where membranes allow water to pass through a physical barrier while rejecting the unwanted contaminants, including salt. Reverse osmosis desalination is the most common membrane separation process. Reverse osmosis membranes are comprised of either short-chain crosslinked oligomers or long-chain linear polymers. Commercial reverse osmosis membranes are largely poly(amide)s where a thin film is formed in an interfacial reaction. The membranes allow for almost quantitative salt rejection with high water fluxes. But, these membranes degrade over time from periodic cleaning with chlorine disinfectants. This dissertation primarily focuses on the implementation of an alternative polymer membrane material known as a mono-sulfonated polysulfone that strategically distributes the fixed sulfonate charged groups along the polymer backbone. Theses reverse osmosis mono-sulfonated polysulfones display comparable salt rejection with better chemical resistance than commercial poly(amide)-based membranes, and could potentially offer a replacement in the market.

Yes / The implementation of Reverse Osmosis (RO) technology is noticeably increased to produce freshwater from brackish and seawater resources. In this work, performance analysis of a multistage multi pass medium-sized spiral wound brackish water RO (BWRO) desalination plant (1200 m³/day) of Arab Potash Company (APC) located in Jordan is evaluated using modelling and simulation. For this purpose, a mathematical model for the spiral wound RO process based on the principles of solution diffusion model is developed. The model is then used to simulate the operating conditions of low-salinity brackish water RO (BWRO) desalination plant. The results obtained are then compared against the real industrial data of BWRO desalination plant of APC which shows a high-level of consistency. Finally, the model is used to analysis the impact of the operating parameters such as salinity, pressure, temperature, and flow rate on the plant performance. The sensitivity analysis confirms that both feed flow rate and operating pressure as the critical parameters that positively affect the product salinity.

Yes / The Reverse Osmosis (RO) input parameters have key roles in mass transport and performance indicators. Several studies can be found in open literature. However, an experimental research on evaluating the brackish water RO input parameters influence on the performance metrics with justifying the interference between them via a robust model has not been addressed yet. This paper aims to design, construct, and experimentally evaluate the performance of a 50 m3/d RO pilot-plant to desalinate brackish water in Shahid Chamran University of Ahvaz, Iran. Water samples with various salinity ranging from 1000 to 5000 ppm were fed to a semi-permeable membrane under variable operating pressures from 5 to 13 bar. By evaluating permeate flux and brine flowrate, permeate and brine salinities, membrane water recovery, and salt rejection, some logical relations were derived. The results indicated that the performance of an RO unit is largely dependent on feed pressure and feed salinity. At a fixed feed concentration, an almost linear relationship was found to relate feed pressure and both permeate and brine flowrates. Statistically, it was found that 13 bar feed pressure results in a maximum salt rejection of 98.8% at a minimum permeate concentration of 12 ppm. Moreover, 73.3% reduction in permeate salinity and 30.8% increase in brine salinity are reported when feed pressure increases from 5 to 13 bar. Finally, it is concluded that the water transport coefficient is a function of feed pressure, salinity, and temperature, which is experimentally estimated to be 2.8552 L/(m2 h bar).

Yes / Brackish water can be considered an important source of fresh water, via desalination, especially for arid districts. Reverse Osmosis (RO) process has been successfully used to produce fresh water from brackish water sources. However, there is still the challenge of improving the performance of multistage RO desalination plants. From the selection of the RO configurations to the selection of the appropriate type of membranes and the operating conditions at the end determines the performance of RO process in terms of recovery, salt rejection, energy consumptions and ultimately the cost of production of freshwater. Using model-based simulation, this work attempts to investigate the most suitable types of membranes for an industrial scale RO plant from a set of different membrane brands that would attain the highest-performance at lowest specific energy consumption (SEC). As a case study, we considered a multistage multi-pass medium-scale RO plant (1200 m3/day) of Arab Potash Company (APC, Jordan) which produces high quality water for the boilers after pre-treatment stage. The simulation results confirmed that employment of the Filmtec BW30LE-440 would increase water recovery by about 22% besides reducing the product salinity and SEC by about 15% and 10%, respectively compared to the existing membrane.

Yes / The reverse osmosis (RO) process is one of the best desalination methods, using membranes to reject several impurities from seawater and brackish water. To systematically perceive the transport phenomena of solvent and solutes via the membrane texture, several mathematical models have been developed. To date, a large number of simulation and optimisation studies have been achieved to gauge the influence of control variables on the performance indexes, to adjust the key variables at optimum values, and to realise the optimum production indexes. This paper delivers an intensive review of the successful models of theROprocess and both simulation and optimisation studies carried out on the basis of the models developed. In general, this paper investigates the scope and limitations of the RO process, as well as proving the maturity of the associated perspective methodologies.

Una de las aplicaciones más importante de los procesos de filtración por membrana es en el área de tratamiento de agua por ultrafiltración, nanofiltración u ósmosis inversa. Entre los problemas más serios encontrados en estos procesos destaca la aparición de los fenómenos de ensuciamiento y envejecimiento de las membranas que limitan la eficacia de la operación tanto en la separación de los solutos, como en el flujo de permeado, afectando también el ciclo de vida de las membranas.Para reducir el coste de la producción y mejorar la robustez y eficacia de estos procesos es imprescindible disponer de modelos capaces de representar y predecir la eficiencia y el comportamiento de las membranas durante la operación. Una alternativa viable a los modelos teóricos, que presentan varias particularidades que dificultan su postulado, la constituyen los modelos basados en el análisis de los datos experimentales, entre cuales destaca el uso de las redes neuronales. Dos metodologías han sido evaluadas e investigadas, una constando en la caracterización de las interacciones entre las membranas y los compuestos orgánicos presentes en el agua de alimentación, y la segunda basada en el modelado de la dinámica de operación de las plantas de desalinización por ósmosis inversa.Relaciones cuantitativas estructura‐propiedad se han derivado usando redes neuronales de tipo back‐propagation, para establecer correlaciones entre los descriptores moleculares de 50 compuestos orgánicos de preocupación para la salud pública y su comportamiento frente a 5 membranas comerciales de ósmosis inversa, en términos de permeación, absorción y rechazo. Para reducir la dimensión del espacio de entrada, y para evitar el uso de la información redundante en el entrenamiento de los modelos, se han usado tres métodos para seleccionar el menor número de los descriptores moleculares relevantes entre un total de 45 que caracterizan cada molécula. Los modelos obtenidos se han validado utilizando un método basado en el balance de materia, aplicado no solo a los 50 compuestos utilizados para el desarrollo de los modelos, sino que también a un conjunto de 143 compuestos orgánicos nuevos. La calidad de los modelos obtenidos es prometedora para la extensión de la presente metodología para disponer de una herramienta comprensiva para entender, determinar y evaluar el comportamiento de los solutos orgánicos en el proceso de ósmosis inversa. Esto serviría también para el diseño de nuevas y más eficaces membranas que se usan en este tipo de procesos.En la segunda parte, se ha desarrollado una metodología para modelar la dinámica de los procesos de ósmosis inversa, usando redes neuronales de tipo backpropagation y Fuzzy ARTMAP y datos experimentales que proceden de una planta de desalinización de agua salobre Los modelos desarrollados son capaces de evaluar los efectos de los parámetros de proceso, la calidad del agua de alimentación y la aparición de los fenómenos de ensuciamiento sobre la dinámica de operación de las plantas de desalinización por osmosis inversa. Se ha demostrado que estos modelos se pueden usar para predecir el funcionamiento del proceso a corto tiempo, permitiendo de esta manera la identificación de posibles problemas de operación debidas a los fenómenos de ensuciamiento y envejecimiento de las membranas. Los resultados obtenidos son prometedores para el desarrollo de estrategias de optimización, monitorización y control de plantas de desalinización de agua salobre. Asimismo, pueden constituir la base del diseño de sistemas de supervisón capaces de predecir y advertir etapas de operación incorrecta del proceso por fallos en el mismo, y actuar en consecuencia para evitar estos inconvenientes. / One of the more serious problems encountered in reverse osmosis (RO) water treatment processes is the occurrence of membrane fouling, which limits both operation efficiency (separation performances, water permeate flux, salt rejection) and membrane life‐time. The development of general deterministic models for studying and predicting the development of fouling in full‐scale reverse osmosis plants is burden due to the complexity and temporal variability of feed composition, diurnal variations, inability to realistically quantify the real‐time variability of feed fouling propensity, lack of understanding of both membrane‐foulants interactions and of the interplay of various fouling mechanisms. A viable alternative to the theoretical approaches is constituted by models developed based on direct analysis of experimental data for predicting process operation performance. In this regard, the use of artificial neural networks (ANN) seems to be a reliable option. Two approaches were considered; one based on characterizing the organic compounds passage through RO membranes, and a second one based on modeling the dynamics of permeate flow and separation performances for a full‐scale RO desalination plant.Organic solute sorption, permeation and rejection by RO membranes from aqueous solutions were studied via artificial neural network based quantitative structure‐property relationships (QSPR) for a set of 50 organic compounds for polyamide and cellulose acetate membranes. The separation performance for the organic molecules was modeled based on available experimental data achieved by radioactivity measurements to determine the solute quantity in feed, permeate and sorbed by the membrane. Solute rejection was determined from a mass balance on the permeated solution volume. ANN based QSPR models were developed for the measured organic sorbed (M) and permeated (P) fractions with the most appropriate set of molecular descriptors and membrane properties selected using three different feature selection methods. Principal component analysis and self‐organizing maps pre‐screening of all 50 organic compounds defined by 45 considered chemical descriptors were used to identify the models applicability domain and chemical similarities between the organic molecules. The ANN‐based QSPRs were validated by means of a mass balance test applied not only to the 50 organic compounds used to develop the models, but also to a set of 143 new compounds. The quality of the QSPR/NN models developed suggests that there is merit in extending the present compound database and extending the present approach to develop a comprehensive tool for assessing organic solute behavior in RO water treatment processes. This would allow also the design and manufacture of new and more performing membranes used in such processes.The dynamics of permeate flow rate and salt passage for a RO brackish water desalination pilot plant were captured by ANN based models. The effects of operating parameters, feed water quality and fouling occurrence over the time evolution of the process performance were successfully modeled by a back‐propagation neural network. In an alternative approach, the prediction of process performance parameters based on previous values was achieved using a Fuzzy ARTMAP analysis. The neural network models built are able to capture changes in RO process performance and can successfully be used for interpolation, as well as for extrapolation prediction, fact that can allow reasonable short time forecasting of the process time evolution. It was shown that using real‐time measurements for various process and feed water quality variables, it is possible to build neural network models that allow better understanding of the onset of fouling. This is very encouraging for further development of optimization and control strategies. The present methodology can be the basis of development of soft sensors able to anticipate process upsets.

Capacitive deionization technologies have gained significant attention in recent years. The development and availability of a variety of materials have enabled the growth of research on electrosorption, which makes capacitive deionization increasingly attractive. This technology has a wide range of applications, such as softening, desalination and selective removal, each of which has been the focus of the experimental part of this work. The theoretical part is devoted to the issue of functioning of capacitive deionization, electrode material and especially the specific application. Water desalination is a major issue, given the global shortage of drinking water and the possibility of using capacitive deionization as a competitive method to conventional desalination methods. Conversely, softening and selective removal of ions can pose everyday problems both in the treatment of drinking water or pre-treatment of industrial water and in the treatment of wastewater. In this diploma thesis, it was proved that the method of capacitive deionization can be used to solve all the above problems. Although capacitive deionization is not a commercially available technology in the Czech Republic yet, it can be expected to be used more and more in the future.

The Reverse Osmosis (RO) process has been considered to be one of the most widely utilised techniques for brackish water desalination for its capabilities to produce high-quality water. The RO process characterised by its low energy consumption compared to thermal distillation processes, leading to reduced overall water production cost. To systematically understand the transport phenomena of solvent and solutes via the membrane texture, several mathematical models were developed. This interestingly aids to conduct a huge amount of simulation and optimisation studies to judge the influence of control variables on the performance indexes and to adjust the key variables at optimum values to realise optimum production indexes. In this research, a specific accurate model for a single spiral wound RO process has been successfully developed and used to build accurate models for the multistage brackish water RO desalination process of two different designs. The robustness of the model developed was confirmed via validation against the experimental data collected from simple design of RO system and complicated design of RO system of Arab Potash Company (APC). This is followed by a thorough simulation of the RO process to explore the influence of operating conditions on the process performance indicators. Recently, several contributions were made in this thesis that specifically comprises the improvement of the original design of brackish water RO desalination process. The influence of a retentate recycle design is investigated on the process performance. Moreover, evaluation and minimisation of specific energy consumption (expressed in kWh/m3 of freshwater production) is carried out on the simple and complicated designs of RO process by implementing an energy recovery device. Also, the most suitable brand of membranes was explored for the RO system from a set of different brands of membrane to attain the highest-performance rejection at lowest energy consumption compared to the original membrane. Furthermore, a single optimisation framework was developed to mitigate the specific energy consumption of simple and complicated designs of brackish water RO desalination process. Finally, a thermodynamic limitations and exergy analysis of the complicated design of RO system are outlined via a thoroughly study to investigate the locations of high exergy destruction. These contributions were verified as they promoted the separation performance at a significant energy saving. / Mutah University, Jordan

The global water crisis has often been presented as a crisis of governance and attributed to various factors, including the slowness of institutional adjustments to rapid structural challenges such as demographic growth, resource degradation and economic difficulties (UNU-INWEH, 2012). Despite the rapid growth of cities around the world and a fast increase in the use of desalination for freshwater supply (WHO, 2011), the dynamics of institutional change in desalinated urban water governance have never been researched. This thesis investigates the drivers, barriers and counter-forces to a major institutional change - privatisation - in the desalinated water governance of the coastal cities of the Gulf Cooperation Council (GCC) region. Through the cases of public private partnerships (PPPs) in Abu Dhabi and Doha and the failed attempt to implement similar PPPs in Kuwait City, this research investigates the diverse forces that have led to the implementation of this new institutional arrangement in order to question - both empirically and theoretically - the literature’s general assumption that privatisation reforms in urban water services in the South arise from structural issues, e.g. a water crisis, an economic crisis and/or a governance crisis. The three main schools of comparative studies are used systematically to test hypotheses about causal relationships between selected variables. The structural approach is applied to examine the influences of the redistributive rentier state, oil price fluctuations and regional energy integration over the privatisation process. Adopting a Post-colonial perspective, the political culture approach is used to examine critically the contemporary influences of traditional cultural features, key local institutions and foreign cultural influences over the fluctuating roles of both the State and the markets in the local urban water supply since the late 19^th century. Finally, the rational agency theory is used to examine the role in the recent privatisation process of key political figures from the ruling families. This research demonstrates that the privatisation process of desalination units in Abu Dhabi and Doha was not driven by structural factors during the 2000s, a period of high oil prices, but was initiated in the 1990s and driven the following decade by the agency of a reforming elite wanting to privatize the water sector as part of a broader dynamic of construction of a neoliberal post-rentier economy – i.e. an intermediary political economic paradigm that aims to mediate the transition from rentierism to a fully liberalized economy. The political culture approach shows that these privatisations were facilitated by a gradual shift from pure rentierism towards a post-rentier form of neoliberalism in the political philosophy of liberal water technocrats on the one hand, and towards a regional trend of ‘pious neoliberalism’ (Atia, 2011) among practicing Sunni Muslims. Nevertheless, the enduring rentier mentality has constituted a strong counter-force to privatisation dynamics. The PPPs were implemented in Abu Dhabi and Doha because the local ruling elites situated the political bargaining within the tribal institutional milieus that they mastered completely through the control of the rent and related benefits. In Kuwait however, negotiations between the ruling elites and the leading political forces, the tribes and the opposition, were situated in a parliamentary institutional milieu that the ruling elite could not control and where the opposition and tribal MPs have opposed all reforms of the rentier ruling bargain. These findings illustrate that institutional changes in desalinated water governance are not neutrally driven by uncontrollable structural forces, but are the product of political bargaining between and among various rational political actors and their coalitions. This thesis also shows that in non-democratic or semi-democratic settings, the choice of a specific institutional milieu by the authorities is critical to the successful bargaining of institutional reforms, since it determines whether some key actors - along with structural factors (e.g. rent) and cultural factors (e.g. tribal influence) - will support the process or will be able to act against it.