<p>One of the main problems our actual society faces is the shortage of water. Despite the great effort made by authorities and researchers, multiple countries with poor economic resources are experiencing serious difficulties derivative of water scarcity. Desalination provides a feasible solution for inland and coastal areas. Through literature and reviewed articles analysis the reader will meet the actual issues regarding designing a desalination plant, and more over with reverse osmosis (RO) processes, which are the main arguments of this work. One of the big deals is the environmental concern when handling the concentrate disposal. Another important point about desalination processes is the increasingly interest in coupling the units with renewable energy sources (RES). The results point out that regardless of the efforts made until today, additional achievement is required in fields such as membrane’s structure materials for RO method, concentrate disposal systems, governmental water policies review and update, and greater distinction researches between brackish water and seawater RO desalination processes. Taking into consideration the previous outcomes it is finally concluded that some particular steps must be accomplished when beginning a desalination plant design.</p>

One of the main problems our actual society faces is the shortage of water. Despite the great effort made by authorities and researchers, multiple countries with poor economic resources are experiencing serious difficulties derivative of water scarcity. Desalination provides a feasible solution for inland and coastal areas. Through literature and reviewed articles analysis the reader will meet the actual issues regarding designing a desalination plant, and more over with reverse osmosis (RO) processes, which are the main arguments of this work. One of the big deals is the environmental concern when handling the concentrate disposal. Another important point about desalination processes is the increasingly interest in coupling the units with renewable energy sources (RES). The results point out that regardless of the efforts made until today, additional achievement is required in fields such as membrane’s structure materials for RO method, concentrate disposal systems, governmental water policies review and update, and greater distinction researches between brackish water and seawater RO desalination processes. Taking into consideration the previous outcomes it is finally concluded that some particular steps must be accomplished when beginning a desalination plant design.

A survey performed over existing two pilot-scale and two full-scale RO desalination facilities to study the current status of boron rejection showed a highest rejection 85% leading to permeate boron concentration of 0.52 mg/L, and recent studies predicted a cost increase due to incorporation of boron reduction systems. Mathematical models were developed to study the process performance and related cost implications. The deterministic process model was verified with pilot-scale experiment performed using a single spiral wound module and was later modified to represent the full-scale design options available to meet the required water quality criteria. Then the selected full-scale design options were simulated to predict their performance in terms of recovery and boron rejection. For cost analysis, to account for uncertainty probability models were developed for stochastic inputs to the cost estimation model and were used with operating parameters from the full-scale simulations to determine the expected total cost of water produced. Later, a sensitivity analysis was performed to observe the effect of change in uncertainty of inputs. Further, the applications of the deterministic process model are suggested.

Thesis (Ph. D.)--University of New South Wales, 2000. / Also available online.

Clean water is critical to the safety, security and survivability of humankind. Nearly 41% of the Earth's population lives in water-stressed areas, and water scarcity will be exacerbated by an increasing population. Over 96% of the total water is saline and only 0.8% is accessible fresh water. Thus, saltwater desalination has emerged as the key to tackle the problem of water scarcity. Our current work deals with the membrane process of reverse osmosis. Sulfonated polysulfones are a potential alternative to state-of-the-art thin film polyamides. Synthesized by step growth polymerization, polysulfone membranes have smooth surfaces and they are more chemically resistant relative to polyamides. Previously studied sulfonated polysulfone membranes were synthesized by direct copolymerization of pre-disulfonated comonomer and the sulfonate ions were placed on adjacent rings of bisphenol moiety. This study focuses on placing the sulfonate ions differently along the polysulfone backbone on isolated rings of hydroquinone moiety, and on adjacent rings of biphenol moiety- and its effect on the transport and hydrated mechanical properties of the membranes. Selective post sulfonation of poly(arylene ether sulfone) in mild conditions was also found to be an effective way to strategically place the sulfonate ions along the backbone of the polymer chain without the need to synthesize a new monomer. Hydroquinone based, amine terminated oligomers were synthesized with block molecular weights of 5000 and 10,000 g/mol. They were post-sulfonated and crosslinked at their termini with epoxy reagents. Such crosslinked and linear membranes had sulfonate ions on isolated rings of hydroquinone moiety. Synthesis and kinetics of controlled post-sulfonation of poly(arylene ether sulfones) that contained biphenol units were also reported. The sulfonation reaction proceeded only on the biphenol rings. The linear membranes had sulfonate ions on adjacent rings of biphenol moieties. The tensile measurements were performed on the membranes under fully hydrated conditions. All membranes remained glassy at values of water uptake. It was found that elastic moduli and yield strengths in the hydroquinone- based linear and crosslinked membranes increased with decrease in water uptakes in the membranes. The effect of plasticization of water superseded the effect of block length and degree of sulfonation in the membranes. The highest elastic modulus of 1420 MPa at lowest water uptake of 18% was observed in cross linked membrane with 50% repeat units being sulfonated (50% repeat units contain hydroquinone)and target molecular weight of 5000 g/mol. However, the hydroquinone membranes broke at low strains of < 20%. The hydrated mechanical properties could be improved by replacing the hydroquinone with biphenol moieties. The biphenol based post-sulfonated membrane showed high elastic modulus that was comparable to the hydroquinone-based counterparts at similar values of water uptake. The biphenol based membrane broke at higher strains of >80%. The post-sulfonated membranes- hydroquinone-based linear and crosslinked membranes and biphenol-based linear membranes had better transport properties than the previously studied sulfonated polysulfones that were synthesized by disulfonated comonomers.The post sulfonated hydroquinone-based membranes did not show a compromise in the rejection of monovalent ions in the presence of divalent ions in mixed feed water. The superior properties of the post-sulfonated membranes can potentially be attributed to the kinked backbone that potentially increased the free volume in the membranes and the sulfonate ions were spaced apart to potentially reduce their chelation with calcium (divalent) ions in mixed feed water. Interestingly, the biphenol based post-sulfonated membranes also did not have any compromise in the rejection of monovalent ions in the presence of divalent ions. This was potentially because the sulfonate ions were spaced far apart on the non-planar biphenol rings. / PHD / According to the World Economic Forum, the water crisis has remained one of the top five global risks that has had a huge impact on the society. The world population has tripled in the twentieth century. Close to 2 billion people live in water scarce regions, 1.2 billion people lack access to safe drinking water, 2.6 billion have little or no access to sanitation and countless die due to diseases transmitted through unsafe water. Industrialization and climate change have worsened the water crisis. Furthermore, in today’s economies food, energy and water are inherently linked. Thus, a water crisis can have a cascading effect on availability of food and energy. To obtain an adequate and sustainable supply of water, it is important to improve already existing methods and develop new and inexpensive technologies for water purification. According to the U.S. geological survey over 96% of the earth’s water is saline. Thus, salt water desalination has emerged as the key to tackle the problem of scarcity of potable water. Reverse osmosis is a membrane-based process for water desalination wherein the membrane allows water to pass through while rejecting salts. The membranes are composed of long chain molecules called polymers. The current state of the art polymeric membrane made of polyamides show high rejection of salts with fast permeation of water. However, these membranes can be degraded by the chlorinated disinfectants added to the feed water. An alternative polymeric material, sulfonated polysulfone, can potentially be applied for reverse osmosis as these polymers are resistant to the chlorinated species. These membranes are composed of a polysulfone with sulfonate ions present randomly on the chain. This study investigates the effect of the position of the ions on the polymer chain. It is found that the membranes ability to reject salt from water can be improved by strategically placing the charged species on the polymer chain.

CIVINS / Systems on modern naval vessels are becoming exclusively dependent on electrical power. One example of this is the replacement of distilling and evaporator plants with reverse osmosis units. As the system is in continuous operation, it is critical to have remote real-time monitoring and diagnostic capabilities. The pressure to reduce shipboard manning only adds to the difficulties associated with monitoring such systems. One diagnostic platform that is particularly well suited for use in such an environment is the non-intrusive load monitor (NILM). The primary benefit of the NILM is that it can assess the operational status of multiple electrical loads from a single set of measurements collected at a central point in a ship's power-distribution network. This reduction in sensor count makes the NILM a low cost and highly reliable system. System modeling, laboratory experiments, and field studies have all shown that the NILM can effectively detect and diagnose several critical faults in shipboard fluid systems. For instance, data collected from the reverse osmosis units for two U.S. Coast Guard Medium Endurance Cutters indicate that the NILM can detect micron filter clogging, membrane failures, and several motor-related problems. Field-tested diagnostic indicators have been developed using a combination of physical modeling and laboratory experiments. / CIVINS

Reverse Osmosis membranes have been successfully proven to remove almost 99% of chemicals dissolved in seawater. However, removal of certain trace elements, such as boron is challenging and relatively low for seawater reverse osmosis desalination plants compared to thermal desalination plants. Boron is naturally occurring and is present in seawater at an average concentration of 4.5-5 mg/L. While boron is a vital element, its toxicity has been proven on crops, animals and possibly humans. Additionally, boron should be removed to comply with the current guideline value of 0.5 mg/L, for drinking water, issued by the World Health Organization (WHO), which is barely attained by a single-pass process seawater reverse osmosis plant. Currently, multipass reverse osmosis membrane operations with pH modifications are the only valid method for boron removal. However, this is not economically efficient as it requires higher energy and chemicals consumptions. The objective of this study was to investigate boron removal by commercial TFC RO membranes in addition to custom-made KAUST-synthesized TFC membrane. Five membrane samples were examined: Toray, Sepro, Koch, and KAUST in-house synthesized membrane. Three different feed pH conditions were used: pH6, pH8, and pH10. Filtration experiments were conducted in two parts. In experiment 1, all five membranes were examined for boron rejection in a dead-end permeation system, whereas in experiment 2 the two membranes with the highest boron rejection from experiment 1 were tested in a cross-flow system. Permeate and feed samples were taken continuously and analyzed for boron concentration, rejection calculation. Membrane surfaces were characterized according to hydrophilicity, roughness and surface charge. The results showed for all the tested membranes that boron rejection increased as the feed pH increased. KAUST, defect-free TFC, showed the highest performance for boron rejection for all pH conditions, although, it shows the roughest surface. Toray membranes 80LB and 80B exhibited the second highest boron rejection and had the most negatively charged membrane surfaces. It was observed in this study that the rejection of boron by a membrane is due to size exclusion and charge repulsion mechanisms. It was concluded that, the KAUST, defect free TFC has the potential to be applicable for boron rejection in industrial application as it has better boron rejection than commercially available RO membranes.

No description available.

In spite of abundant water resources, world is suffering from the scarcity of usable water. Seawater Reverse Osmosis (SWRO) desalination technology using polymeric membranes has been recognized as a key solution to water scarcity problem. However, economic sustainability of this advanced technology is adversely impacted by the membrane fouling problem. Fouling of RO membranes is a highly studied phenomenon. However, literature is found to be lacking a detailed study on kinetic and dynamic aspects of SWRO membrane fouling. The factors that impact the fouling dynamics, i.e., pretreatment and water quality were also not adequately studied at full–scale of operation. Our experimental protocol was designed to systematically explore these fouling aspects with the objective to improve the understanding of SWRO membrane fouling mechanisms. An approach with multiple analytical techniques was developed for fouling characterization. In addition to the fouling layer characterization, feed water quality was also analysed to assess its fouling potential. Study of SWRO membrane fouling dynamics and kinetics revealed variations in relative abundance of chemical and microbial constituents of the fouling layer, over operating time. Aromatic substances, most likely humic–like substances, were observed at relatively high abundance in the initial fouling layer, followed by progressive increase in relative abundances of proteins and polysaccharides. Microbial population grown on all membranes was dominated by specific groups/species belonging to different classes of Proteobacteria phylum; however, similar to abiotic foulant, their relative abundance also changed with the biofilm age and with the position of membrane element in RO vessel. Our results demonstrated that source water quality can significantly impact the RO membrane fouling scenarios. Moreover, the major role of chlorination in the SWRO membrane fouling was highlighted. It was found that intermittent mode of chlorination is better than continuous mode of chlorination of seawater, as anti–biofouling strategy. It was also confirmed that significant biofilm development was inevitable even with the use of chlorine to disinfect SWRO membranes. Our findings on the dynamic patterns of SWRO membrane fouling should help in further elaborating research projects focusing on the development of better strategies to minimize this troublesome phenomenon.

Central Arizona Project water was treated using slow sand filtration (SSF) and reverse osmosis (RO) in series. Additional desalination water was recovered from RO brine using the vibratory shear-enhanced processing (VSEP®; New Logic, Inc.). SSF removed 90% of the turbidity in raw CAP water. SSF decreased total organic carbon by almost 20%. After a little more than a year of continuous operation, performance of the RO system declined noticeably, as indicated by a rapid decrease in membrane permeation coefficient and an increase in salt flux. Foulant scrapings contained both clay material and large amounts of unidentified organics. Alternative hypotheses regarding major sources of membrane foulants are discussed in this study.Water lost as brine was reduced from 20% to 2-4% via post-RO VSEP treatment. Estimated costs were compared to those of a no-VSEP option in which disposal of the entire RO brine flow was required. The total annualized cost of brine treatment was fairly insensitive to recovery during VSEP treatment in the range 80-90%, and the period of VSEP operation between cleanings in the range 25-40 hrs. These values define a fairly broad window for near optimal VSEP operation under the conditions of the study. The cost of VSEP treatment to minimize brine loss was estimated at $394- $430 per acre foot ($1.21 - $1.32 per 1000 gal) of 15 MGD CAP water treated. For a hypothetical 3 MGD RO brine flow, the use of VSEP to recover water and reduce the volume of brine for disposal results in a savings of more than $5M/year relative to the no-VSEP brine disposal alternative.